Big LS1 Camshaft questions?

[RB30X]

Hi, I'm looking at upgrading the cam in my standard 2001' LS1 (in my 240Z). I dont mind going something big as this is just my weekend car and not a daily driver. Maybe 232/234 or 238/240 etc.

Apart from the cam this engine will have ported and polished 241 heads with about 20th shaved, 25% UD balancer, ARP head, cam, balancer and bolts, LS6 injectors, ported factory throttle body, LS6 manifold.

 

My questions to the LS gurus are a follows:

 

What size cam or rpm limit can still have the standard lifters?

 

At what size cam do you require solid lifters?

 

At what point does the LS1/6 run into piston to valve clearance issues?

 

I know I will need new pushrods but I will measure the gap once the heads are installed, I already have PAC1218 springs.

 

I'm sure I will have more Q's but that its for now.

 

Thanks in advance.

[SUNNY Z]

First off, LS6 injectors might not be enough. I'd hold off on buying them until you get it tuned with the new cam, and see what kind of lb/hr you'll need. Also, by a 20th do you mean like .020" Decked? What CC combustion chamber would that yield?

 

Standard lifters are good fairly high. I have LS7 lifters in my camaro, and it Pulls HARD to the 6750 limiter.

 

Cam size generally does not denote the need for solid lifters. That is more of an RPM - based decision. ALSO when spinning to high rpm, or with a big, high lift cam, you really should go to a dual spring.

 

PTV clearance can vary greatly from cam to cam. It also has a LOT to do with the LSA of the cam, and the lift, not just the duration.

 

For what it's worth, I run a 62cc AFR 205 head on my Camaro (stock 2002 bottom end), with a Vengeance VRX4 cam (228/230 .588 /.591 on a 112 LSA) , and i had PTV issues. I had only .007" on the intake and ~.085" on the exhaust. I ended up flycutting my piston for the intake valve .093" to yield the recommended .100".

 

Here is a GREAT Sticky pulled from the GURUS over on LS1tech.com

 

http://www.ls1tech.com/forums/generation-iii-internal-engine/327734-cam-guide.html

 

Read up, and good luck!

[Zzeal]

A 25% underdrive balancer is intended for racing and will slow down your water pump too much for street use. You could add an electric water pump ($$$) or go with a 10% underdrive.

 

Steve

[RB30X]

The UD balancer will slow the water pump down but it won't be slow enough to effect the coolant system. Also stops cavitation at high rpm. I don't think millions of LS owners would run them if they were crap.

 

I'm interested about the PTV clearance issue you had with that cam. Was the cam advanced? Or was the cylinder head shaved for a higher compression? I'm thinking more of a 228-230 cam now, with less than 0.600 lift, something that retains standard lifters and pulls from 2500-6500ish.

[Zzeal]

I'm not theorizing, I'm speaking from experience.

Just trying to help out.

 

Steve

[SUNNY Z]

The UD balancer will slow the water pump down but it won't be slow enough to effect the coolant system. Also stops cavitation at high rpm. I don't think millions of LS owners would run them if they were crap.

 

I'm interested about the PTV clearance issue you had with that cam. Was the cam advanced? Or was the cylinder head shaved for a higher compression? I'm thinking more of a 228-230 cam now, with less than 0.600 lift, something that retains standard lifters and pulls from 2500-6500ish.

 

Yes, the heads were milled to 62cc (66cc stock IIRC) to bump compression. Cam was installed straight up, with no advance ground into it.

[saxfiend1967]

two cents cams with 238 @.050 are not big cams especially on 112 lobe center. always check vtp clearance as some cams have better quality control than others. bullet racing cams dead on sometimes herbert cams off a little you should select cam based on usage but if its a weekend driver I would look at cams with at least 244 @ .050 taking into account cutting heads for more compression. I would also go to a 108 centerline. I built a 23 degree engine street car 427 11:1 compression cam 644 lift 253 -259 duration @ .050 on 108 should run til around 6500 maybe 7 with afr 220 heads. The heads on a ls engine are good out of the box, take advantage of them.but do not even think about installing a cam with out checking piston to valve clearance. It will likely end badly. there are way too many variables. A local machinist hear built a 604 for an aquaintance of mine,assumed the ptv was good and destroyed a 22000 engine , of course it (wasnt his fault it was parts failure)yes a valve through a piston without even running was parts failure I will never use this guy. anyway call bullet cams or even summit racing tech line they are very very knowledgable. By the way you didnt say if this car is auto or stick. Im going to throw this out there too what about zo6 cam they run 0 -60 in high 3s or low 4s stock in a 3500 # vette. I have a 2000 vette convertible stock its bruuuuutal

[SUNNY Z]

two cents cams with 238 @.050 are not big cams especially on 112 lobe center. always check vtp clearance as some cams have better quality control than others. bullet racing cams dead on sometimes herbert cams off a little you should select cam based on usage but if its a weekend driver I would look at cams with at least 244 @ .050 taking into account cutting heads for more compression. I would also go to a 108 centerline. I built a 23 degree engine street car 427 11:1 compression cam 644 lift 253 -259 duration @ .050 on 108 should run til around 6500 maybe 7 with afr 220 heads. The heads on a ls engine are good out of the box, take advantage of them.but do not even think about installing a cam with out checking piston to valve clearance. It will likely end badly. there are way too many variables. A local machinist hear built a 604 for an aquaintance of mine,assumed the ptv was good and destroyed a 22000 engine , of course it (wasnt his fault it was parts failure)yes a valve through a piston without even running was parts failure I will never use this guy. anyway call bullet cams or even summit racing tech line they are very very knowledgable. By the way you didnt say if this car is auto or stick. Im going to throw this out there too what about zo6 cam they run 0 -60 in high 3s or low 4s stock in a 3500 # vette. I have a 2000 vette convertible stock its bruuuuutal

 

WHY would you want a 108* centerline, unless you are trying to spin the engine to 10,000 rpms? These motors make great power on 112-114*, with a nice torque curve.

 

It appears to me you are speaking in carbuerated, SBC terms, which have little to no bearing on the LSX world. .....Not trying to offend you here......

 

And also, you must not be familiar with the LSX motors because there is no way in high heaven you could fit a 25x /25x duration cam in an LSX with milled heads, without pistons with cast-in valve reliefs.

 

and just because your "bruuuuutal" vette runs whatever, those cams are EXTREMELY mild (Duration@.050: 205* intake, 219* exhaust , Lift: 0.551 intake, 0.549 exhaust , LSA: 117.4*) So that being said, please don't confuse this guy more without researching your claims.

Edited November 10, 2011 by SUNNY Z