Howdy all,

I'm going to start planning my next internal engine mods (pushrods, springs, cam, heads). I want to have a full plan before I buy the first part. However, being the mechanical newbie that I am, I have a lot of unanswered questions that prevent me from making an educated decision.

Rather than ask "What is the best cam?" or something like that, I need answers to a few questions so I can figure that out for myself. I have a fairly solid understanding of cam specs and how they affect a cam. However, I have many questions about what kind of RPMs I'll be able to safely run, how my decision on one part will affect my decision on another, etc. So, without further adieu(sp?):

1) What is a safe RPM on an all-stock LS1? Is the rev limiter (6,250 if I'm not mistaken) about all there is?
2) What are the weak links, and in what order (weakest to strongest)?
3) What would be a safe RPM on an LS1 with a stock bottom end but aftermarket springs and pushrods? (I realize this may totally depend on the springs/pushrods, but answer as best you can)
4) What is a safe RPM with an all-forged bottom end, aftermarket springs/pushrods, etc?
5) What considerations need to be made when choosing springs for a cam with high lift?
6) Is there any advantage to higher lift and smaller ratio rockers vs. lower lift with higher ratio rockers?
7) Are there any good reasons to change the rockers?
8) Should my choice on heads be in any way affected by the specs of the cam, or do you simply want the most CFM you can get your hands on?
9) Should my target compression ratio in any way affect my decision on my cam? If so, in what way?
10) Is there any reason to be concerned with lack of clearance with a high lift cam and stock bottom end, or is the room ample?


I'm sure there will be more questions to come, but I don't want to overwhelm you guys too much. Thanks in advance, everyone!

 

Hey dude, whats up?!? Long time no see...

Anyway, here goes:

Stock rev limit was 6200 on my 2002 m6. I wouldnt go past that till you upgrade the valvetrain.
Rod bolts usually go first (due to rpm), then pistons at ~500 HP, then rods at ~600HP.
Without rodbolts you can safely hit 6800 if youre a clean shifter. Some push it to 7000. With rod bolts you can take it to 7200.
As fast as you can still make power. With proper setups (de-stroked) you can turn 8000.
Id definately go with duals. And change often depending on driving style.
Not really.
Keep the stockers. Some poeple like the crane / vinci accelerated lift rockers because they effectively make the cam lobe more agressive, but it also is harder on springs. Unless you need to upgrade, keep the stockers, as theyre plenty good enough.
If youre gonna go with a baby cam, you might want to keep the intake port volume down to keep velocity up which will keep your low end torque beefy. If you go with a monster cam, lean towards higher flow numbers and some bigger ports as a general guideline.
Bigger cams bleed off compression. You can shoot for under 8.5 dynamic compression, but those calculations are a lot of math, and hard to get all the necessary cam specs. Id just shoot for 11:1 or a max of 11.5:1 static CR
As soon as you mill heads, its time to check them. Mid sized cams ~230 / ~.59x may have room to mill perhaps .030 but thats not set in stone. Youll have to check to be certain youve got enough clearance.

All I can say is DAMN dude, youve come a long way in understanding these motors! Glad to see it!

-Tony

 

Thanks, Tony! Yeah, I was pretty bad at first. I finally got the car into the 12's and now I'm just hungry for more. I've got a Textralia clutch on the way, and after it goes in (which I won't be doing myself, unforunately), I'll be looking into a cam, pushrods, and springs. Eventually, heads will follow. I think I'll have to stick a rear end in between, though.

I wouldn't understand half the stuff I do if it weren't for your newbie lessons! :p

 

11) Since I won't be changing the heads at first, what kind of lift can I safely get without modifying anything? I'd like to not have to worry about that for now. I'll get into that shiznit when I get heads.

 

Lift is not correlated to heads, it has to do with the Piston-to-Valve clearance.

I run a F13 112+0 on 241 heads milled .035 and running .045 cometic gaskets. I also run 7.35 pushrods - and I have room to spare. Thats with 4cc valve reliefs on my Mahle pistons.

I would shoot for 10.6-11.0 : 1 on the compression ratio, and get a good tune. That will help out with the power.

Go with PRC Platinum springs and you won't much have to worry about a good sized cam(230+ duration). PP Gold springs are good too.

 

You can fit anything up to and including the T-rex cam under the stock heads. Keep in mind that max lift does not directly dictate your piston to valve clearance, since max lift occours when the piston has already moved down the bore. Tightest P to V clearance usually occours about 10 BTDC and 10 ATDC. It has more to do with duration and how agressive the lobes are than simply max lift. Get any of the normal ls1 cams. When you finally pull the heads off, you can flycut the pistons if you plan on milling the new heads.

The f-13 cam is really nice. Its really drivable on a good tune. It makes great power up top. You rarely see one that dosnt make it past 400 RWHP cam only. You dont have to spin it up too high either. I shift at 6600 with a 6800 redline. If you dont mind spinning a little higher, and having to work the clutch a little more lightly during daily driving, check out the futral f14, f15, tsp 231/237 or MS3 cams.

I have to replace my f13 and decided to go just a touch bigger with a 232/234 .598/.595 112 cam, otherwise known as the torquer II.

-Tony

 

Most of this stuff is making sense, but I just have no frame of reference. I know what the stock cam specs are, and I see all these other specs, but I just can't gauge to what degree it will become not daily drivable, to what degree I will need more RPMs than I can safely use, etc, etc. I think I need to get a custom cam, or at least speak to someone who makes them.

My goal is to have a car that is just a step or two away from not being daily drivable. My car is a toy now and not a DD. It's not all strip, though. I wouldn't mind having to let it warm up a bit to have it idle/drive comfortably, but I don't want to have the car be a stone before 6k RPMs either. I'm looking for a significant power improvement at a reasonable cost to daily drivability but a minimal cost to the low end. Tall order, huh?

 

not that tall an order. you actually have quite a few off-the-shelf choices that will fit pretty well.

Have you thought about adding gears? Some 4.10s would really open up your options as far as a cam. If its not a daily driver, and you dont mind a little surging and bucking (just clutch out when this happens) Id suggest something on the order of a 232-236/.600 cam. Any lower and you might not feel like youve gone big enough, but any larger and youll really see drivability start to drop off. The gears will help offset any loss of off-idle torque. It would make for a really rippin car. It will chop like a race car but it wont be totally out of hand either. Id go bigger than what Ive got, but I daily drive 70+ miles.

 

my f13 made 397 cam only w/only ~700 miles on the shortblock - yesterday. going to be changing from a FIPK to a lid as well. maybe touch up my tb a little - after its broken in and such, it'll clear 400 i bet.

it could use some 3.73s, but now that it has a full tune it should drive MUCH better. it could probably use a new clutch/flywheel as its starting to slip but overall a very easy cam to drive.

 

Man, you beat me to it. What GuitsBoy said...

 

Gears are definitely in my future. I've been planning on 3.73's, though. I'm not afraid of any gas mileage issues, but I have a friend with an '02 GT that just can't hook with his 4.10's. After getting them his times have gotten worse. I'm afraid of the same problem. Perhaps it's different with the f-bodies, but he certainly suffers from his decision. However, if I'm in danger of bogging the car with 3.73's, I guess that will be a consideration to pull me towards 4.10's. What are your opinions? (I'm not trying to change the subject... it's just a slight tangeant)

 

Well, I'm getting down to it now. The rear end will be ordered with 4.10's in the next few days. After the rear, I'm putting in a cam. I have a few more questions, though, after doing some additional research:

12) Are the lobes always symmetrical? The reason I ask is because if the answer is yes you can calculate the timings of events simply by the duration, LSA, and advance/retard.
13) How do you check your PTV clearance when the time comes?
14) I've read that a lot of people switch to an LS2 timing chain rather than getting an aftermarket double roller setup. Any comments on this? The price of the LS2 chain is certainly enticing.
15) What kind of dynamic compression ratio am I looking for? I've heard that 8.7:1 is a good power-making DCR, but I'm concerned that this may be a bit much in Texas heat on pump gas.
16) If you've got your DCR figured out, is the SCR even worth considering?
17) Should I be looking more at degrees of overlap or LSA? Or, does each have its own consequences meaning both need to be taken into account?
18) In post #10 of jrp's cam guide there is a lot of discussion about degreeing a cam. I really don't understand a bit of this. I don't get what this accomplishes or how. It seems to me like you can only put the cam in advanced or retarded by the degrees allowed by the timing chain. What is all this, and is it something I will have to do?
19) If I were to get the SLP (or Powerbond) pulley and an LS2 timing chain, would the pulley require modification? What about if I got the SLP double-roller chain?

 

 

Yes, i believe theyre symetrical on either side of the centerline. Yes, you can calculate valve events in this manner. Just remember some calculators want events at .006 and others at .050

I like to turn the crank in 2* increments from 10* BTDC to 10* ATDC and check with a dial indicator. Install a light tension checker spring in place of a valve spring. Just make sure you either use an adjustable pushrod and set it for 0 lash / 0 preload, you you can simply undertorque the rockers and use a stock pushrod. hand tighten the rocker until it just barely snugs against the pushrod. If youre questioning wether or not you should get a bigger cam and flycut, do the flycutting and go with the bigger cam! PM me if youre considering notching the pistons.

Yes on ls2 chain.

I shoot for closer to 8.5 or even lower. Ive got 8.25 DCR, 10.9 SCR and I still get some ping up in the northeast, and my timing isnt anything crazy either.

Not really, as long as SCR is sane.

Each has its own consequences. LSA lowers the powerband. Duration raises the powerband but creates more power overall. Overlap defines idle and drivability and is a function of the other two.

I never bothered degreeing a cam, especially since I dont have an adjustable timing set. Its more for piece of mind.

Nope.

 

Good read.

 

Too bad you didnt go into heads Ill have to watch the forums when you bring up heads questions

Im more or less in your boat with about half as much knopwledge hehe. I too went with 4.10's on stock rear/tires. 6spd 99 TA. I went with a 228R from TSP for cam. Jeff @ CAM says it'll be all I need I too ordered the LS2 timing chain, but also got the set top treplace the sprocjets/gears. Don;t forget to get the ls6 oil pump or the ported oil pump.

You may also want to consider everythign for the intake breathing.. if you have the lid, you may wanna look into a ported TB and ls6 intake.

My only next big project will be possible heads. Either patriot ported ls6 heads , or the dart 205s. Though Jeff is pretty sure I wont be able to plant that power to the street

 

Mutang's straight up blow. They suck *****, and I got a 3.8 V6 Camaro and I smoke those GT asses all day long. 5.0, 4.6, anything you Ford turds got. Sorry, but I wish I was joking too. I don't mean to kill the thread, but it's true.

 

the only recent mustang gt you would have a chance against with that v6 is a 96-98 automatic 4.6.

if your stock anyway.

how about we stay on the topic.

 

Sorry about the stray, but I'm FAR from stock. And I apologize for the s*it talk, but I really am not a Ford fan.

 

omfg i really dont much about cars just how to take it apart and put it back together. but after reading this jus broadin my horizons about motors.