408 cam choices
Thread Starter
Staging Lane
Joined: Apr 2010
Posts: 56
Likes: 0
From: Joliet, Il
408 cam choices Building an LQ4 408 for my t56 camaro and I need some input as for the cam selections.
Build sheet:
LQ4 bored 4.030
Scat forged crankshaft
Scat Ultra Q-lite rods (H-Beams)
AutoTec 4032 Forged Pistons -5.1cc
ARP Main studs
ARP Rod Bolts
ARP Head Bolts
243 heads w/ 7 angle valve job and p&p
Fast 102mm intake
Nick Williams Throttle body
LS7 Lifters
Trunion upgrade
Melling 10296 oil pump
TSP 1 7/8 headers w/ true dual setup
injectors have not been purchased, but a 42 lb. injector is likely.
I'm looking for a torque cam as peak HP isn't the goal for this build. I'd like to stay away from the cams that surge in the low end as I want a comfortable daily driver setup. Thanks for the help. -Rich
P.S. I'd like to go the Pat G. route, but I can barely fill out 1/3 of all the info he needs.
Build sheet:
LQ4 bored 4.030
Scat forged crankshaft
Scat Ultra Q-lite rods (H-Beams)
AutoTec 4032 Forged Pistons -5.1cc
ARP Main studs
ARP Rod Bolts
ARP Head Bolts
243 heads w/ 7 angle valve job and p&p
Fast 102mm intake
Nick Williams Throttle body
LS7 Lifters
Trunion upgrade
Melling 10296 oil pump
TSP 1 7/8 headers w/ true dual setup
injectors have not been purchased, but a 42 lb. injector is likely.
I'm looking for a torque cam as peak HP isn't the goal for this build. I'd like to stay away from the cams that surge in the low end as I want a comfortable daily driver setup. Thanks for the help. -Rich
P.S. I'd like to go the Pat G. route, but I can barely fill out 1/3 of all the info he needs.
TECH Senior Member
Joined: Jul 2009
Posts: 8,032
Likes: 661
Contact Patrick G (use the SEARCH function) or Martin @ www.tickperformance.com to have a custom spec'd cam. Why leave such a important selection to anyone but a pro?
There are a lot of factors to be considered for cam selection and I tend to agree with Jimbo.
That said....If you want some people to take a real crack at it.....
Going with some assumptions like a .051 gasket and 64CC chamber heads...
I vote something like a Texas-Speed MS3. 237/242 prob with about a 113+0 LSA. That will keep overlap relatively low for street manners and still make good torque numbers.
Smallish for a stroker motor, but should have good street manners with bigger cubes.
That said....If you want some people to take a real crack at it.....
Going with some assumptions like a .051 gasket and 64CC chamber heads...
I vote something like a Texas-Speed MS3. 237/242 prob with about a 113+0 LSA. That will keep overlap relatively low for street manners and still make good torque numbers.
Smallish for a stroker motor, but should have good street manners with bigger cubes.
If you want to minimize the light throttle/low rpm surge with a manual trans, you want no more than 4* valve overlap. I would go with a 230/238/117+2 .600/.600 cam. This cam will idle very smooth at 900-950 rpm with it's 0* overlap. And will have very little to no light throttle/low rpm surge.
And the 36 lb/hr Bosch/Fast injectors are more than enough
Russ Kemp
And the 36 lb/hr Bosch/Fast injectors are more than enough
Russ Kemp
I'd do something like a 239/247 114+2 or 243/251 114+2 (depending on compression). More compression makes a bigger cam "act" better.
In a 346, you can tune a cam to have stock-like streetable up to about 8 degrees. Once you up the cubes to 408, you can realistically add about 8-10 degrees of overlap to it and it will drive the same. The 239/247 cam has about 15 degrees of overlap. The 243/251 114+2 has 19 degrees (which would be my choice if you're at 11.5:1 or more on the compression).
In a 346, you can tune a cam to have stock-like streetable up to about 8 degrees. Once you up the cubes to 408, you can realistically add about 8-10 degrees of overlap to it and it will drive the same. The 239/247 cam has about 15 degrees of overlap. The 243/251 114+2 has 19 degrees (which would be my choice if you're at 11.5:1 or more on the compression).
Thread Starter
Staging Lane
Joined: Apr 2010
Posts: 56
Likes: 0
From: Joliet, Il
Thanks for the replies everyone! And yes the chambers are 64cc and the head gasket is the LS9 gasket at .051 thickness. my math tell me the CR should be around 11.25 depending on deck height.
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I'd do something like a 239/247 114+2 or 243/251 114+2 (depending on compression). More compression makes a bigger cam "act" better.
In a 346, you can tune a cam to have stock-like streetable up to about 8 degrees. Once you up the cubes to 408, you can realistically add about 8-10 degrees of overlap to it and it will drive the same. The 239/247 cam has about 15 degrees of overlap. The 243/251 114+2 has 19 degrees (which would be my choice if you're at 11.5:1 or more on the compression).
In a 346, you can tune a cam to have stock-like streetable up to about 8 degrees. Once you up the cubes to 408, you can realistically add about 8-10 degrees of overlap to it and it will drive the same. The 239/247 cam has about 15 degrees of overlap. The 243/251 114+2 has 19 degrees (which would be my choice if you're at 11.5:1 or more on the compression).
A 234/242/114 cam had a lot of light throttle/low rpm surge with in my 346 engine. With the 418, the drive-ability only improved slightly. So I installed a 234/242/117+2 cam, the car now drives 10x better, has next to no light throttle/low rpm surge and still has stupid bottom end power yet has more mid range to top end power due to the earlier exhaust valve opening. I like driving my car again. And I know others that installed 10+* overlap cams in 416-418 engines with manual trans. They all buck/surge and the owners are thinking about changing cams
Sure, you can get away with a lot of valve overlap in an auto with a loose convertor, but try and drive your car with the convertor locked at 1500 rpm in 3rd at 30-35 mph
Russ Kemp
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Verdad Gallardo Jake, the op said he's not looking for peak hp, and wants no cam surge. All those cams are max effort and will surge/buck big time with a manual trans.
A 234/242/114 cam had a lot of light throttle/low rpm surge with in my 346 engine. With the 418, the drive-ability only improved slightly. So I installed a 234/242/117+2 cam, the car now drives 10x better, has next to no light throttle/low rpm surge and still has stupid bottom end power yet has more mid range to top end power due to the earlier exhaust valve opening. I like driving my car again. And I know others that installed 10+* overlap cams in 416-418 engines with manual trans. They all buck/surge and the owners are thinking about changing cams
Sure, you can get away with a lot of valve overlap in an auto with a loose convertor, but try and drive your car with the convertor locked at 1500 rpm in 3rd at 30-35 mph
Russ Kemp
A 234/242/114 cam had a lot of light throttle/low rpm surge with in my 346 engine. With the 418, the drive-ability only improved slightly. So I installed a 234/242/117+2 cam, the car now drives 10x better, has next to no light throttle/low rpm surge and still has stupid bottom end power yet has more mid range to top end power due to the earlier exhaust valve opening. I like driving my car again. And I know others that installed 10+* overlap cams in 416-418 engines with manual trans. They all buck/surge and the owners are thinking about changing cams
Sure, you can get away with a lot of valve overlap in an auto with a loose convertor, but try and drive your car with the convertor locked at 1500 rpm in 3rd at 30-35 mph
Russ Kemp
I actually can drive my car locked up in OD at 1100 RPM with no bucking or surging going down the highway. I had to increase the airflow mutliplier big time in the Idle follower tables. I'm at like 7g/sec in the low RPMs.
The idle follower table does not affect how the car drives at with you foot on the throttle. I just slows the return to idle when you close the throttle.
Russ Kemp
The follower table isn't just at idle. It's an airflow adder with the IAC in an F-Body I thought? The cracker is for off-idle transitions and closing the IAC as you return to idle, or so I thought? Either way, I don't command lock-up in anything but 4th as there is no good reason to with a big stall.
I also thought low-load (like 5th and 6th with a manual or 4th with an auto) produced a lot more bucking than the taller gears? Maybe that's just because you're lower in the RPM range with them. But I know a lot of people complain about cruising at low RPM in 6th with big cams, and it takes a lot of tuning to get that out of the car. Maybe it's worse in 3rd gear for them but they don't cruise in 3rd so it's a moot point. But I could see that being aggravating around a parking lot below 15mph.
I also thought low-load (like 5th and 6th with a manual or 4th with an auto) produced a lot more bucking than the taller gears? Maybe that's just because you're lower in the RPM range with them. But I know a lot of people complain about cruising at low RPM in 6th with big cams, and it takes a lot of tuning to get that out of the car. Maybe it's worse in 3rd gear for them but they don't cruise in 3rd so it's a moot point. But I could see that being aggravating around a parking lot below 15mph.
The follower table isn't just at idle. It's an airflow adder with the IAC in an F-Body I thought? The cracker is for off-idle transitions and closing the IAC as you return to idle, or so I thought? Either way, I don't command lock-up in anything but 4th as there is no good reason to with a big stall.
I also thought low-load (like 5th and 6th with a manual or 4th with an auto) produced a lot more bucking than the taller gears? Maybe that's just because you're lower in the RPM range with them. But I know a lot of people complain about cruising at low RPM in 6th with big cams, and it takes a lot of tuning to get that out of the car. Maybe it's worse in 3rd gear for them but they don't cruise in 3rd so it's a moot point. But I could see that being aggravating around a parking lot below 15mph.
I also thought low-load (like 5th and 6th with a manual or 4th with an auto) produced a lot more bucking than the taller gears? Maybe that's just because you're lower in the RPM range with them. But I know a lot of people complain about cruising at low RPM in 6th with big cams, and it takes a lot of tuning to get that out of the car. Maybe it's worse in 3rd gear for them but they don't cruise in 3rd so it's a moot point. But I could see that being aggravating around a parking lot below 15mph.
Like I said before, it's the light throttle/low rpm conditions were the surge/buck occurs. Think about when the manifold vacuum is high, as that is when the exhaust is pulled back into the cylinder when the intake valve is starting to open and the exhaust valve is still open during the intake stroke. So now the intake charge is diluted with exhaust. And that is what causes the light throttle/low rpm surge. Now the surge/buck at low rpm goes away when you open the throttle, as the manifold vacuum drops, thus less exhaust is pulled back into the cylinder during the valve overlap. And you can't tune around that.
Russ Kemp
Mine is a 239/247 112 +0 in a 408. Based on how it does for me, I would suggest something with a bit less overlap for "good" street manners. Not that I'm complaining. I love mine.
I have -8cc pistons, so his -5's will have a bit more compression and with the 114+2 Jake suggested, it may be a good option for the OP.
I'm also an auto which makes a difference because of stall speed and TC lockup among other factors, but mine doesn't like the TC locked under around 2000 RPM...or roughly 55-60 in 4th. It wants to buck a bit.....maybe less bucking and more just that you can feel it through the drivetrain some.
I have -8cc pistons, so his -5's will have a bit more compression and with the 114+2 Jake suggested, it may be a good option for the OP.
I'm also an auto which makes a difference because of stall speed and TC lockup among other factors, but mine doesn't like the TC locked under around 2000 RPM...or roughly 55-60 in 4th. It wants to buck a bit.....maybe less bucking and more just that you can feel it through the drivetrain some.
The throttle follower is active even with the car not moving, it just slows the return to idle like a dash pot on an old carb'd engine. The throttle cracker only slows the return to idle when the car is above the enable mph. Just use my idle .cfg file and you will see how the follower & cracker works. Has nothing do due with the drive-ability.
Like I said before, it's the light throttle/low rpm conditions were the surge/buck occurs. Think about when the manifold vacuum is high, as that is when the exhaust is pulled back into the cylinder when the intake valve is starting to open and the exhaust valve is still open during the intake stroke. So now the intake charge is diluted with exhaust. And that is what causes the light throttle/low rpm surge. Now the surge/buck at low rpm goes away when you open the throttle, as the manifold vacuum drops, thus less exhaust is pulled back into the cylinder during the valve overlap. And you can't tune around that.
Russ Kemp
Like I said before, it's the light throttle/low rpm conditions were the surge/buck occurs. Think about when the manifold vacuum is high, as that is when the exhaust is pulled back into the cylinder when the intake valve is starting to open and the exhaust valve is still open during the intake stroke. So now the intake charge is diluted with exhaust. And that is what causes the light throttle/low rpm surge. Now the surge/buck at low rpm goes away when you open the throttle, as the manifold vacuum drops, thus less exhaust is pulled back into the cylinder during the valve overlap. And you can't tune around that.
Russ Kemp
a speed density tune will eliminate the bucking. i thought my cam was small at 244/248 on a 110 for my 408. i can't remember the overlap but it bucked some. not anymore after the sd tune.
I have HP tuners and run OLMAF most of the time, but I put a full Speed Density tune on it before plugging the MAF in.
In my experience, large timing transitions add considerably to the low RPM bucking and smoothing them goes a long way, but there is some ....lets call it "shudder" that I just plain can't get rid of completely.
I eliminated 90% of mine by only locking the TC in 4th gear over 62 MPH.
In my experience, large timing transitions add considerably to the low RPM bucking and smoothing them goes a long way, but there is some ....lets call it "shudder" that I just plain can't get rid of completely.
I eliminated 90% of mine by only locking the TC in 4th gear over 62 MPH.
I have HP tuners and run OLMAF most of the time, but I put a full Speed Density tune on it before plugging the MAF in.
In my experience, large timing transitions add considerably to the low RPM bucking and smoothing them goes a long way, but there is some ....lets call it "shudder" that I just plain can't get rid of completely.
I eliminated 90% of mine by only locking the TC in 4th gear over 62 MPH.
In my experience, large timing transitions add considerably to the low RPM bucking and smoothing them goes a long way, but there is some ....lets call it "shudder" that I just plain can't get rid of completely.
I eliminated 90% of mine by only locking the TC in 4th gear over 62 MPH.
Russ Kemp
Thread Starter
Staging Lane
Joined: Apr 2010
Posts: 56
Likes: 0
From: Joliet, Il
http://www.csgnetwork.com/compcalc.html
I'm looking for a torque cam as peak HP isn't the goal for this build. I'd like to stay away from the cams that surge in the low end as I want a comfortable daily driver setup.
I'd go smaller then most are suggesting, like a Cam Motion 234/238 112lsa+2.
I also came up with about 11.27 SCR with a .008" DH and the other info you provided.
I'd go smaller then most are suggesting, like a Cam Motion 234/238 112lsa+2.
I also came up with about 11.27 SCR with a .008" DH and the other info you provided.
Last edited by 99Bluz28; Oct 24, 2014 at 07:24 PM.