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LT1 Camshaft/Valvetrain Selection Guide by Matt

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Old 03-28-2009, 06:57 PM   #1
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Default LT1 Camshaft/Valvetrain Selection Guide by Matt

Updated as of 6/5/17

Intro

Part 1: Choosing a Camshaft
A. A few important things to get out of the way
B. Get your supporting mods done first
C. Basic high-level overview of camshaft specs
D. A note about larger cams/those of you in the market for a cam purely for that choppy idle
E. List of some well-known/proven/most asked about camshafts options for your LT1/LT4
Part 2: Recommended/Required Valvetrain Components for a Cam Swap
A. Valve Springs
B. Roller Rockers
C. Pushrods
D. Lifters
E. Others
Conclusion

---------------------------------------------------------------------------------------------------------------------------

Intro:

Installing a cam into our LT1/LT4 powered vehicles is a great way to enhance the performance and fun factor. The Gen II LT1 motor debuted over 25 years ago so as you can imagine there are quite a few choices available when it comes to camshaft selection and valvetrain selection and the choices can sometimes be overwhelming. The purpose of this guide is to provide a high-level overview to camming your car and to introduce some of the more well-known, proven, or asked about camshafts and valvetrain components available for these motors with a specific focus on your typical stock bottom end car with stock LT1/LT4 heads. In addition, the guide also introduces the option to consider a custom grind cam and/or the pre-existing array of custom cams developed by and available from a couple of reknowned shops in the LTx world which for many folks may be the best overall option.

As you reach the part of the guide that introduces some off-the-shelf cam options, you will notice that many of these cams are older technology 1990s grinds. These same cams we’re considered old technology even back in 2008 when I originally put this guide together (thanks to the much appreciated thoughts, assistance, and contributions of a few others!); however, I still feel it’s important to include these older cams given their reputation and familiarity in the LT1 world. In addition to a custom cam, I also encourage you to consider some of newer style grinds as technology and experience in the LT1 world has grown and advanced over the years. In many cases, newer grinds tend to produce more power, better vacuum and improved throttle response versus otherwise similar older grinds making them a potentially more attractive option.

In closing out the introduction, I’ve personally been around the LT1 scene for quite awhile, have ran or experienced several cams mentioned in this guide and have made my fair share of mistakes along the way that I hope you can learn from but I am not nor do I pretend to be a camshaft or valvetrain expert. With that said, don’t take the guide as 100% gospel but do utilize it as a learning tool and a tool to enable yourself to make an informed decisions when piecing together the right cam and valvetrain components for yourself.

Part 1: Choosing a Camshaft

A. A few important things to get out of the way:
1. There is no predetermined BEST or ONE SIZE FITS ALL camshaft. The “best” camshaft is a very relative term because what is truly best for one person may be horribly wrong for the next person.
2. Bigger is NOT always better.
3. Sound does NOT equal power.
4. Before camming your car, do yourself a favor and ensure you have the proper supporting modifications taken care of first.
5. Before selecting a cam you should first determine your specific uses/needs/wants/plans/goals, etc. for your car and you should be honest with yourself in doing so. You should also access your current and future planned modifications, any rpm limitations, emissions limitations, etc. These are all important aspects that go into determining what cam is right for you.
B. Get your supporting mods done first:

I’m not going to go into too much detail here but a camshaft is something that truly needs to be complimented with a supporting cast of mods. Yes, some small enough/mild enough cams can be ran perfectly fine on an automatic vehicle with the stock torque converter and sometimes even with the stock exhaust if that’s your thing but realize you will be leaving performance, drivability and fun factor on the table. However, the vast majority of the time, the typical LT1 owner looking to cam their car is selecting a cam that is going to absolutely require a cast of supporting modifications in order to exhibit the proper drivability and deliver the proper performance from the cam. Basically, the cam is not your first mod, it’s a mod you should perform after the proper peripherals have already been met. Ask me how I know, been there done. Do yourself a favor and do things the right way. Begin by allowing the motor to breath via headers, cold air intake, etc. Then if you have a manual decide if you want steeper gears or not and if you have an automatic get yourself a stall converter first (please) and determine if you want to run steeper gears or not. A converter will do a heck of a lot more good for an automatic car than a cam will so remember that. Another thing to remember, a heavier B-Body will often want/require more converter and gear given the same cam vs. say a lighter weight F-Body or Y-Body would. All of the above will play a very important role into determining what cam(s) are appropriate for you and once you have all of that ironed out then you are at the optimal stage to consider camming your car.

**And let’s not forget, when you are effectively changing the brain of the motor aka the cam, YES A TUNE IS REQUIRED. This is not a place to half-*** it. Do not expect optimal/desired performance results, drivability results, etc. on a stock tune or on an inadequate tune. A quality tune is imperative to achieving optimal/desired results after a cam swap or after any series of modifications for that matter**

C. Basic high-level overview of camshaft specs:
Stock 1997 F-Body Camshaft Specs: 200/207 .447/.459 117
Duration: Duration is the time that the valve is open. Increasing the duration keeps the valves open longer which increases top-end power therefore raising the power band of the motor.
Lift: Lift is the maximum amount in inches that the valves are open. Increasing lift equals more horsepower and torque but at the same time can lead to more peaky torque curves.
Lobe Separation Angle (LSA): LSA is something that is ground into every cam and denotes the number of degrees the intake and exhaust lobes are separated. Many people don’t realize this but the LSA does not determine the idle quality, it’s actually determined by overlap. Given the same intake and exhaust duration, the lower the LSA is, the more overlap the cam will haveh. The opposite is also true, given the same intake and exhaust duration, the higher the LSA is, the less overlap the will have. More on overlap...overlap is the angle in crankshaft degrees that both the intake and exhaust valves are open. Increasing overlap leads to increased top-end power while reducing low-speed power and idle quality (more chop). It’s entirely possible for a modest sized cam to exhibit a choppier idle than a larger cam, it’s all dependent on the overlap of the two cams.

Speaking of overlap...here's one of the ways to calculate overlap using the cam specs at .050". Let's use the popular cc503 cam as an example: (cc503 = 224/230 .537/.544 112 LSA at w/1.6RRs)
Overlap = (Intake Duration + Exhaust Duration / 2) – (Lobe Separation Angle x 2)
(224+230/2) – (112x2)
(227) - (224)
= +3 degrees of overlap
(FYI, +3 degrees of overlap will give the idle a nice moderate chop and will still have the potential to exhibit good drivability without cam surge assuming a quality tune and proper supporting mods are performed.)

D. A note about large cams/for those of you in the market for a cam purely for that choppy idle:

If you’re seeking out a cam just to obtain that ground shaking idle you have the wrong mentality, period. Most of us love that choppy idle but if you are not careful, seeking out a cam for that nasty idle may bite you in the ***. Given the relatively wide lobe separation angles (LSA) that all major cam manufacturer shelf cams seem to have, the majority of the shelf cams that will deliver that absolute mean as all hell idle (cc306, GM847, XFI292, etc.) are larger in duration by nature and will therefore sacrifice drivability, low-speed throttle response and power under the curve. In addition, these cams will desire higher shift points (6500rpm+) to extract the full potential from them. Not everyone who wants that ground pounding idle will want or be able to deal with the trade-offs associated with these cams. That’s not to say these cams are bad because they aren’t, it’s just to say that these large camshafts aren’t for everyone, that’s all. Fortunately, I have a potential resolution for you…custom grind/custom shelf cam…more on that in a minute or two.

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Getting back to these larger style cams, it is also very important to keep in mind that many of them really should be revved out to and shifted at or beyond the RPM limits deemed safe for a stock short block in order to obtain the full potential from them. Some of us have pushed the envelope and have been lucky while others have not been. This is something that you and only you will need to make a decision on and be comfortable with. In addition, the larger cams are truly best suited to motors with increased cubic inches and compression (which absorbs duration and overlap) and that have aftermarket or ported stock cylinder heads (which aren’t holding the cams back from an airflow perspective). Again, I am not knocking these aforementioned cams at all, in fact there have been many LTx cars over the years that have produced great dyno numbers and track times even on the stock bottom end/stock heads. I am just trying to introduce the fact that ALL camshafts will exhibit some level of give and take and it’s imperative that you decide what you want and are comfortable with. Typically speaking, larger cams give up low-speed drivability and throttle response and power under the curve to achieve the upper mid-range and top-end rushes that they provide. On the flip side, say you want a smaller torque monster style cam, don’t expect it to make record dyno numbers or for it to be a top-end superstar.

Example:

Hypothetical scenario…Let’s say we have two 6-speed LT1 cars that are driven by the same person and are 100% identical for the exception of the cam they are running. Car #1 has the large 234/242 duration GM847 cam and shifts at 6,000 RPM. Car #2 has the small 210/224 duration Crane cam and also shifts at 6,000 RPM. Again all else being equal, Car #2 is very likely to beat Car #1 in a race and arguably be more fun to drive because it will be making more average horsepower and torque up to that 6,000 RPM shift point vs. the larger cam. Now the opposite is true as well. Same cars, same cams as discussed above this time with 6,500 RPM shift points. In this case, all else being equal Car #1 with the larger cam is very likely beat Car #2 with the smaller cam because the small cam stopped making power a long time ago and is being revved out far too high while the large cam is closer to its sweet spot. The purpose of this illustration is this…determine what kind of RPM range you want from the cam and what RPMs you’re willing to rev your motor to. If you select a cam that is mismatched to your desired rpm range and rpm limitations then you end up with a rather non-optimized setup that may negatively impact your overall satisfaction.

I personally know this all too well. Many years ago I had bolt-on LT1 car with the cc503 cam and I shifted the car at 6,000 RPM which turned out to be less than ideal for that cam. Although I was very pleased with the performance on the street, I was less than happy with my results at the track. When I increased my shift points to a more ideal 6,300 RPM, my car picked up .4 tenths and 4 mph in the mile while also making the car more fun to wind out on the street. Live and learn.


Now, remember I mentioned custom grind cam/custom shelf cams and that I’d get to that in a minute or two? Here we are. I have some good news for those of you who want that nasty idle of the large cams but may not want to rev the car as high in the RPM range or want more power under the curve, etc. For you a custom grind cam or a custom shelf cam might be a solid consideration. Remember from section B. I discussed overlap and its effect on the idle…you can sort of have your cake and eat it to a degree, remember all cams are give and take but you can play with things a bit just remember too much positive overlap has drawbacks too. Fortunately, we have some excellent shops in the country that can create you a custom grind camshaft (more on that later) or if you have your heart set on a specific off-the-shelf cam you could potentially have the manufacturer cut it on a tighter LSA to increase the overlap. It’s also worth noting that aspects of the tune such as idle speed, your exhaust system, and many other factors will ultimately contribute to the idle quality. And lastly, this is not the only or sole reason to opt for a custom cam (because there's more potential pros) I am just utilizing a custom cam for illustrative purposes.

Example:

GM847 = 234/242 duration, 112 LSA. Using the calculation above, we can determine that this cam has a healthy +14 degrees of overlap so she’s gonna thump hard at idle. Let’s say we have an individual who wants the GM847 idle but wants a cam with less duration so we come up with the hypothetical cam below.

Hypothetical Custom Grind = 226/234, 108 LSA. Also using the calculation above, we can determine that this cam has +14 degrees of overlap just like that of the GM847. Given the same car, the “choppiness” of the idle between both cams is going to be indistinguishable despite the custom cam having 8 degrees less intake duration and 8 degrees less exhaust duration and that is because the overlap of both cams is the same.

E. List of some well-known/proven/most asked about camshaft options for your LT1/LT4:

Below are some of the most popular, proven, or asked about off-the-shelf camshafts available for the LT1 and LT4 motors listed from smallest intake duration to largest intake duration simply for organizational purposes. As you’ll note, this is not a 100% exhaustive list. There are some more cams and cam manufacturers (Lunati, Crower) that produce cams for the LT1 that are not listed here. Like I mentioned earlier, I primarily wanted to focus on the more well-known, proven or asked about options available for our motors and provide a snap shot into what you could expect from each. I do want to reiterate again that the descriptions and information provided below is really geared towards stock bottom end/stock headed LT1s. As described in the introduction, some of these cams are older technology aka 90s grinds and some are newer technology which is something to consider when assessing them.

For each cam I have provided its .050 specs and a brief description. In addition, I have included if the cam is capable of passing emissions, amount of overlap, idle quality, if gears are required for a 6-speed car and if a larger converter is required for an automatic car. Keep in mind that a heavy B-Body will potentially and often require more converter and gear than a lighter weight F-Body or Y-Body given the same cam. You may notice that during my last revision I have since removed the optimal shift points for each cam because I feel it’s a bit tricky to quantify. There’s many variables that make it difficult to really say xxxx RPM is perfect or ideal for this cam. The general rule of thumb is that the most ideal shift point from a performance perspective is a few hundred RPM beyond where the motor makes its peak hp. The only true way to determine what shift point is 100% optimal is to dyno the car, see where the motor stops making power, experiment with your shift points anywhere from say 300-500RPM beyond your peak hp RPM and examine your results. I will say this, general speaking the first few cams on the list (~210ish intake duration) will work fairly well in the ~6,000ish RPM range, the cams hovering in the middle (~218-224ish intake duration) are likely to favor shift points in the ~6200-6400 RPM range and the cams towards the bottom of the list (~230+ intake duration) will favor 6,500+ RPM shift points.

*Something I want to throw out there as an FYI…if you take a look at the descriptions provided by the cam manufacturers for some of the below cams please keep in mind that some of them tend to provide rather inaccurate RPM ranges for their LT1 cams for whatever reasons.

Custom Grind Cam:

Pros: Potentially the optimal choice for the most power and best drivability because the camshaft is ground specifically for your setup and what you want out of the car.
Cons: Cost can sometimes be a little more than an off the-shelf camshaft (another $50-100 or so) but it isn’t always. If you change your setup down the road, the custom cam may not work to its potential on your new setup; however, it can be argued that the same could be said for a shelf-cam.
Where can I get a custom grind? Elliotts Port Works (Lloyd Elliott) and Advanced Induction are who immediately come to mind. Both have great reputations and have been committed to the LTx platform for quite a long time. There are plenty of other individuals.shops in the industry who can cut a custom cam for you but these two are arguably the most prominent in the LTx world. In addition, these two particular shops also offer their own vast array of pre-designed and proven custom cams kind of like their own “shelf-cams” so to speak that I strongly encourage you to consider given the expertise put into their design, newer lobe technologies utilized, quality, etc.

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Comp Cams XFI 465: (210/218 .560/.555 113 LSA) w/ 1.6RRs
Utilizes Comp’s newer Xtreme Fuel Injection (XFI) lobes which are the most aggressive of the Xtreme line of lobes and are designed to provide the most power and response. This is essentially a more modern day torque cam or "baby" cam that’s going to deliver stock-like drivability with low-end power and torque that starts low and is consistent throughout the entire mid-range. Due to the aggressive nature of the XFI lobes, the proper selection of valve train components is even more so critically important.
Capable of Passing Emissions?: Yes
Overlap: -12 degrees
Idle Characteristics: Smooth
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Technically no, but highly advisable.

Crane 227: (210/224 .511/.533 112 LSA) w/ 1.6RRs
An older grind that has created a solid reputation for itself over the years. Affectionately known as a “stump puller” or “torque monster” this is going to be your torquey low-end/mid-range style cam. You can expect stock-like drivability and low-end power and torque that starts low and is consistent throughout the entire mid-range. Over the years, this cam has been a popular choice among folks with heavy B-Bodys and daily drivers.
Capable of Passing Emissions?: Yes
Overlap: -7 degrees
Idle Characteristics: Smooth
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Technically no, but highly advisable.

Lingenfelter (LPE) 211/219: (211/219 .530/.560 112 LSA) w/ 1.6RRs
Just like the previously mentioned Crane 227, this is an older "baby" grind that has created a solid reputation for itself over the years. This is your torquey low-end/mid-range style cam. You can expect stock-like drivability and low-end power and torque starts low and is consistent through the entire mid-range making it a popular choice among folks with heavy vehicles and daily drivers.
Capable of Passing Emissions?: Yes
Overlap: -9 degrees
Idle Characteristics: Smooth
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Technically no, but highly advisable.

Comp Cams cc501: (212/218 .521/.528 112 LSA) w/ 1.6RRs
Utilizes Comp's semi-newer Xtreme Energy (XE) lobes which lie in the middle between the softer Magnum lobes and more aggressive XFI lobes. The XE lobes are designed for increased power under the curve and response vs. the Magnum lobes and aren’t as tough on the valvetrain as the XFI lobes. Similar to XFI465 mentioned above, this cam is essentially a more modern offering in the torquey "baby" cam realm. You can expect stock-like drivability with low-end power and torque that starts low and is consistent throughout the entire mid-range.
Capable of Passing Emissions?: Yes
Overlap: -9 degrees
Idle Characteristics: Smooth
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Technically no, but highly advisable.

Comp Cams cc502: (218/224 .528/.537 112 LSA) w/ 1.6RRs
Utilizes Comp's semi-newer Xtreme Energy (XE) lobes which lie in the middle between the softer Magnum lobes and more aggressive XFI lobes. The XE lobes are designed for increased power under the curve and response vs. the Magnum lobes and aren’t as tough on the valvetrain as the XFI lobes. This is your mid-range focused cam with great drivability and a broad power curve. This cam has been a popular choice amongst the B-Body crowd over the years.
Capable of Passing Emissions?: Yes
Overlap: -3 degrees
Idle Characteristics: Mild, slightly detectable chop
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Technically no, but highly advisable.

XFI 466: (218/224 .570/.565 113 LSA) w/ 1.6RRs
Utilizes Comp’s newer Xtreme Fuel Injection (XFI) lobes which are the most aggressive of the Xtreme line of lobes and are designed to provide the most power and response. Similarly to the previously mentioned cc502 and soon to be mentioned LT4 Hot Cam, this is your mid-range style cam with great drivability and a broad power curve. Due to the aggressive nature of the XFI lobes, the proper selection of valve train components is even more so critically important.
Capable of Passing Emissions?: Yes
Overlap: -5 degrees
Idle Characteristics: Mild, slightly detectable chop
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Technically no, but highly advisable.

GM LT4 Hot Cam: (218/228 .525/.525 112 LSA) w/ 1.6RRs
An older grind that has proven itself in reliability and decent power output over the years. Was very popular and commonly used in the past but has since been overshadowed by some of the similarly sized newer tech cams. This is your mid-range style cam with a broad power curve and good drivability. This is the only cam on this list that is available in a complete kit that includes accompanying valvetrain components for a decent value; however, keep in mind that the adequacy of the LT4 valve springs has been questioned.
Capable of Passing Emissions?: Yes
Overlap: -1 degrees
Idle Characteristics: Slightly choppy
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Technically no, but highly advisable.

Comp Cams cc305: (220/230 .544/.544 114 LSA) w/ 1.6RRs
An older grind that previously utilized Comp’s Magnum lobes which are known as being lazy/softer compared to today’s newer lobes but proven not to take a beating on the valvetrain. According to Comp’s website, this cam now appears to be offered on the newer and better performing Xtreme Energy lobes. Also to note, this cam was previously available in a 112 LSA version but it no longer appears to exist. This cam will exhibit a broad power curve and good drivability. Over the years this cam has been quite popular with folks running forced induction.
Capable of Passing Emissions?: Yes
Overlap: -3 degrees
Idle Characteristics: Mild idle with a slightly detectable chop
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Technically no, but highly advisable.

GM 846: (222/230 .543/.563 112 LSA) w/ 1.6RRs
An older grind that has created a solid reputation for itself over the years. It’s up there with the ever so slightly larger and more aggressive cc503 cam as being considered one of the largest cams you can run in a stock bottom end/stock headed car without having to sacrifice usable power and drivability. This cam will exhibit a broad power curve with strong mid-range, good top-end and good drivability.
Capable of Passing Emissions?: Yes
Overlap: +2 degrees
Idle Characteristics: Moderately choppy
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Yes

Comp Cams cc503: (224/230 .537/.544 112 LSA) w/ 1.6RRs
Utilizes Comp's semi-newer Xtreme Energy (XE) lobes which lie in the middle between the softer Magnum lobes and more aggressive XFI lobes. The XE lobes are designed for increased power under the curve and response vs. the Magnum lobes and aren’t as tough on the valvetrain as the XFI lobes. In the F-Body world, this is perhaps the most popular/commonly used LT1 shelf grind in the past 10 years and widely regarded for being the biggest cam you can run on a stock bottom end/stock headed car without having to sacrifice usable power and drivability. You can expect a nice broad power curve with a strong mid-range, good top-end and good drivability. You can also expect more power and a more pronounced idle vs. cams such as the LT4 Hot Cam, cc305 and GM846. Should not exhibit cam surge with a good tune and proper supporting mods.
Capable of Passing Emissions?: Yes
Overlap: +3 degrees
Idle Characteristics: Moderately choppy
Manual; Steeper Gear Required?: No
Automatic; Larger Converter Required?: Yes

Comp Cams XFI 467: (230/236 .576/.570 113 LSA) w/ 1.6RRs
Utilizes Comp’s newer Xtreme Fuel Injection (XFI) lobes which are the most aggressive of the Xtreme line of lobes and are designed to provide the most power and response. This cam essentially bridges the gap between the mid-size cc503/GM846 cams and the larger cc306 and GM847 cams. You can expect some loss in the low-end with this being more of a strong mid-range/top-end cam. You can expect similar power numbers to that of the cc306 but with better drivability since it has almost half the overlap. Not recommend for daily drivers and is the beginning of pushing the limit with the stock bottom end from an RPM standpoint. Works best in cars with built bottom ends and head work which enables it to be used to its full potential. May have cam surge, depends how good the tune is as well as the stall size/gearing. Due to the aggressive nature of the XFI lobes, the proper selection of valve train components is even more so critically important.
Capable of Passing Emissions?: No
Overlap: +7 degrees
Idle Characteristics: Choppy
Manual; Steeper Gear Required?: Yes
Automatic; Larger Converter Required?: Yes. Steeper gears also required.

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Comp Cams cc306: (230/244 .544/.576 112 LSA) w/ 1.6RRs
An older grind that has created a solid reputation for itself over the years for producing strong numbers and track times in optimized setups. It previously utilized Comp’s Magnum lobes which are known as being lazy/softer compared to today’s newer lobes but proven not to take a beating on the valvetrain. According to Comp’s website, this cam now appears to be offered on the newer and better performing Xtreme Energy lobes. Expect a loss in low-end power and response with this being more of a peaky mid-range to top-end style cam. This cam is not recommend for daily drivers and or for most folks with stock bottom end/stock headed cars. This cam is truly best suited to cars with built bottom ends and head work which enables it to be used to its full potential. Expect cam surge in stock cubic inch motor, the degree of which will be determined via the quality of the tune and the gearing/converter sizes.
Capable of Passing Emissions?: No
Overlap: +13 degrees
Idle Characteristics: Very Choppy
Manual; Steeper Gear Required?: Yes
Automatic; Larger Converter Required?: Yes. Steeper gears also required.

GM 847: (234/242 .575/.595 112 LSA) w/ 1.6RRs
An older grind that has created a solid reputation for itself over the years as a cam that puts out strong dyno numbers and track times in optimized setups. You can expect a loss in low-end power and response with this being a more peaky mid-range to top-end style cam. You could expect this cam to make a few more hp than the cc306. Not recommended for daily drivers or for most folks with stock bottom end/stock headed cars. It is truly best suited to cars with built bottom ends and head work which enables it to be used to its full potential. Expect cam surge in stock cubic inch motor, the degree of which will be determined via the quality of the tune and the gearing/converter sizes.
Capable of Passing Emissions?: No
Overlap: +14 degrees
Idle Characteristics: Very Choppy
Manual; Steeper Gear Required?: Yes
Automatic; Larger Converter Required?: Yes. Steeper gears also required.

XFI 292: (242/248 .584/.579 113 LSA) w/ 1.6RRs
The largest cam on this list, this cam is BIG. Utilizes Comp’s newer Xtreme Fuel Injection (XFI) lobes which are the most aggressive of the Xtreme line of lobes and are designed to provide the most power and response. You can expect a noticeable loss in low-end power and response with this cam being more of a peaky upper mid-range to top-end rock star style cam. Not recommended for stock bottom end cars, period. This cam absolutely belongs in vehicles with high compression stroker motors that will absorb the enormous amount of overlap and duration. You can count on noticeable cam surge in stock cubic inch motor, the degree of which will be determined via the quality of the tune and the gearing/converter sizes. Due to the aggressive nature of the XFI lobes, the proper selection of valve train components is even more so critically important.
Capable of Passing Emissions?: No
Overlap: +19 degrees
Idle Characteristics: Very Choppy
Manual; Steeper Gear Required?: Yes
Automatic; Larger Converter Required?: Yes. Steeper gears also required.

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Part 2: Recommended/Required Valvetrain Components for a Cam Swap

The following are valvetrain components + more that are either required or highly recommended when performing a cam swap. The valvetrain is not a good place to cut corners with, period. With some of the more aggressive lobe designs of today’s newer cams, it is exceedingly important to piece together a properly matched, high quality valvetrain to ensure proper valve control, reliability and performance. It is highly recommended to do the valvetrain right the first time, so it can all be done one time and one time only thus saving you money and aggravation in the end.

A. Valve Springs:

Purpose: Keep the valve in control.
Benefit of Upgrading: Upgrading the valve springs is ABSOLUTELY mandatory in doing a cam swap. The stock valve springs CANNOT handle any more lift or RPM than the stock cam puts out as well as a cam with a more aggressive lobe design.
Required: YES.
Popular Choices: Crane Dual Spring Kit 10308-1 (includes locks, retainers, shims) (Fits aluminum heads only), PAC 1218 Beehives, PAC 1518 Beehives, Comp Cams 26918 Beehives, Lunati Dual Spring Kit 73925k5 (includes retainers, seats, locks, valve stem seals) (Fits aluminum heads only).
Note: Make sure the valve springs you purchase are matched to the camshaft you plan to run. This is critical no matter what cam you run and even more so with today’s more modern and aggressive lobe designs. You do not want the valve springs to go into coil bind which is maximum compression of the spring till it’s solid because this will cause a major failure in the motor.
Along with valve springs, you will need locks, retainers, shims, and valve stem seals (16).
It is generally accepted that the LT4 valve springs located in the LT4 "Hot Cam" kit should not be considered to be run with any cam due to the fact they are known to be very weak and only have a max lift rating of .540 which is not high enough for most off-the-shelf camshafts. Now with that said, some folks have ran them with the LT4 Hot Cam for years without any issues so it's something I recommend researching and drawing your own conclusions on.

B. Roller Rockers:

Purpose: Transfers the motion of the cam along the pushrods and assists the valves to open.
Benefit of Upgrading: Upgrading from the stock 1.5 stamped steel rockers to 1.6RR's will increase the lift that the camshaft is putting out.
Ex: .050” lift of cc503 cam w/1.5 RR's = (.503/.510). If you divide the camshaft’s .050” lift figures by 1.5 then multiply that number by 1.6 you will get the .050” lift with 1.6RR's which in this case = (.537/.544).
Required?: Technically no, but highly recommended.
Popular Choices: Comp Cams Ultra Pro Magnums, Crane Golds, Comp Cams Magnums (roller tips, not full roller)
Self Aligning (SA) or Non-Self Aligning?: SA should work fine for some of the smaller camshafts that do not see revs past 6200/6300 RPM. NSA is cheap insurance that can handle high RPM rev's better because the use of guide plates will ensure that the rockers cannot slip off the valve tips. NSA rockers use 7/16" studs which is stronger than the 3/8" studs that most SA rockers have. NSA will require the use of hardened chromoly pushrods, studs, and guideplates.
Note: Be aware that some aftermarket rocker arms may require clearancing of the stock valve covers. It’s very easy to do and there are threads on the subject so it's really no big deal.

C. Pushrods:

Purpose: Transfers the motion of the cam to the roller rockers.
Benefit of Upgrading: A stiffer pushrod helps to reduce pushrod flex and along with the valve springs helps to keep the valves under proper control and away from valve float. Upgrading the pushrods is important for durability of the system and should be done when upgrading the cam.
Required?: Technically no, but highly recommended.
Popular Choices: Chromoly 5/16" outside diameter. Hardened chromoly pushrods are required if using guide plates. Trick Flow and Comp Cams both offer good options.
Note: Pushrod length should be checked during any camshaft or cylinder head change. There are a lot of variables that can change the length of the pushrods needed from camshaft base circle, deck height of the block, milling of the heads, valve job height and valve length, the use of different lifters, etc. If the pushrods are too long or too short they will cause premature wearing of the guides and valvetrain failure could be possible. LT1s with stock heads (assuming none of the mentioned changes have been done) will more than likely still use stock length 7.200" pushrods but that is not a 100% absolute. It is so easy to measure pushrod length that it should be done regardless. A very easy to use tool to measure pushrod length is the Comp Cams pushrod length checker part# (7702-1).

D. Lifters:

Purpose: Rides along the lobes as the cam rotates around and follows cam up the lobe ramp which pushes the pushrods up.
Benefit of Upgrading: Over time with higher mileage motors the lifters tend to wear out.
Required?: No, highly recommended for higher mileage motors.
Popular Choices: GM LS7 lifters, Comp Cams hydraulic roller, Crane Cams hydraulic roller.
Note: Yes the LS7 lifters will work in an LTx motor, they are one of the only interchangeable components between LSx and LTx motors. If you go to your local GM dealer to order lifters for your LT1, they will give you LS7's because they are the newly revised replacements.

E. Others:

Gaskets: The following gaskets will be needed:
Front timing cover gasket, optispark seal, crank seal, water pump drive seal, egr gaskets, throttle body gasket, intake manifold gaskets, valve cover gaskets, water pump gaskets.

Timing Chain: Over time the stock timing chain wears and can develop slack. It is highly recommended to swap out the chain for a new one. A stock LT1 replacement chain from GM will do just fine for most. Depending on your mileage, replacing the sprockets with new ones may not be a bad idea. If you plan on degreeing your cam, you will need to purchase an adjustable timing set. Note: An LT4 timing chain will NOT fit on LT1 sprockets, as me how I know.

Valve Stem Seals: Worn out valve stem seals will allow oil to come up through the valves which leads to accelerated oil consumption and blue smoke coming from the exhaust. The perfect time to replace them is during a cam swap and considering their low cost they should be replaced every time without doubt. Some valve spring kits include these.

Optispark: If the optispark has not yet been changed it is a good idea to R&R it with a new cap and rotor or considering replacing it at this point. Whether you're doing the cam swap yourself or having it done by a shop, the optispark distributor has to come off, therefore, it is the easiest time to R&R it or replace it and will save you time and effort in the long run. For many years now, the genuine OEM ACDelco/Delphi unit has established itself as perhaps the most reliable, longest-lasting, most recommend opti available.

Water Pump: Same goes for the water pump as with the optispark. If the mileage is getting up there or the pump is starting to show signs of leaking this is the time to replace it. It will save you time, effort, and money to do it at this time.

Conclusion:

Your typical cam swap will run roughly ~$1,000 give or take in parts alone. That’s not including if you replace the Optispark or Waterpump, etc. Labor depends on the shop and part of the country you live in but figure $600+ and that’s if you can find a shop that will touch an LT1. Tackling a cam swap yourself can be done with the right tools and patience. I would like to extend a big thanks to the people (Bret, Karl, and others) who assisted me with their thoughts and contributions when I was originally putting this guide together back in 2008. I hope you were able to learn something and found it to be useful, thanks for reading!

-Matt (StealthFormula)

Last edited by StealthFormula; 06-05-2017 at 06:10 PM.
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Old 06-05-2017, 06:06 PM   #6
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Please do not respond to thread. This cam sticky has been opened back up so I could make my edits and updates and is in the process of being re-stickied. Thanks!
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