cutlass_455

iTrader: (2)

Guys, I was just doing some ptv checking and I got about .080-.085 on both intake and exhaust on LS3 heads going on a LQ4. Is this too tight to run?? The intake seems 'ok'ish from what Ive read, but the exhaust might be a bit tight.

I might have to do that cheap-o fly cutting trick and sacrifice a couple couple valves.

cutlass_455

iTrader: (2)

So I just went and did the playdoh method. Check out the pics, I got. The tightest I measured was about .125, which is pretty good actually. Please look at my pics and see whats going on here. Its weird cuz I got such different values by mocking up and measuring with a dial indicator on the valve retainer and pushing on the rocker. I have checking springs installed.

What do you guys think of the way this looks??

cutlass_455

iTrader: (2)

No one has any thoughts on this??

MattSapp95_T/A

iTrader: (35)

well we were told by Advanced Induction on a friend of mines LT1 build that they go as tight as .050 on intake and exhaust... I thought that sounded tight but they know their stuff...

I think you would be ok with those clearances... However if you do Flycut..you would only need to on the exhaust side...

MattSapp95_T/A

iTrader: (35)

out of curiosity what are the cam specs if you don't mind sharing?

Thanks
Matt

cutlass_455

iTrader: (2)

Matt, its an out of the box comp cams part number 54-470-11.
Intake Duration at 050 inch Lift 235
Exhaust Duration at 050 inch Lift 251
Duration at 050 inch Lift 235 int./251 exh.
0.621 int./0.624 exh.
LSA 113

I dont know what to think about this ptv clearance I got. One way I do it, I get really tight, another way I get lots of clearance. Just weird.

SuperSport01

With a dial indicator you got .080"-.085" at TDC pushing the valves down by hand? With playdoh you got .125"... was that pushing the valves by hand or turning the motor letting the cam move the rockers and valves?

cutlass_455

iTrader: (2)

I put some playdoh down on the piston, then rotated the engine so that it was down in the hole a bit. Bolted a head down completed torqued it and the whole bit. This head has checking springs in #1. I then extended my adjustable pushrod to the correct length and installed it in the intake side and bolted down the intake rocker. I then rotated the engine around a couple of times very slowly and made sure it wasnt binding or anything like that. After a couple of good rotations on the intake, I took the adjustable pushrod out of the intake side and put it the exhaust side and repeated. Removed the head and the pics are what I found.

I might actually go and do this again and put the playdoh down and put the dial indicator on the spring retainer to make sure its going down the entire amount and not squishing the lifter. Im sure it didnt, but measuring is the only way to find out for sure.

EDIT: Also, that .080-.085 was actually not at TDC, it was a few degrees before I believe. I didnt have degree wheel on when I did that. But it wasnt at max lift Im pretty sure.

S10xGN

iTrader: (11)

Headgasket?

Petraszewsky

iTrader: (28)

With that size cam and lsa I'm pretty sure you will have PTV issues using the LS3 heads on a LQ4....

cutlass_455

iTrader: (2)

Yes, a head gasket was in there too.

I did some more playing, found out my lifters (especially the intake one) were squishing about .100 or so and therefore throwing off my readings.

So I converted an old lifter to be solid and re-did the playdoh method with a dial indicator on to make sure all the lift was coming in. It was. The playdoh still looked good actually, the smallest I got was on the exhaust around .120, which is good, I think.

So with "solid" lifters, a head gasket totally torqued down the thinnest playdoh I got was around .120. The thinnest is where the top of the piston dips down into the dish of the piston, along that edge there.

briancb1

Are your heads milled?

briancb1

Only reason I ask is I'm about to install a 231/243 113+4 with LSL lobes on my LS2, but my heads are milled .030"
It's a DD so downtime has to be done within a weekend... Sigh

cutlass_455

iTrader: (2)

My heads arent milled.

How much lift is your cam?? And what you doing to pushrods?? Shaving .030 off the heads will effect the preload.

rojs234

iTrader: (5)

I'm back. Mike, it sounds like you've figured it out. You definately need to use a solid lifter or a converted one. You need a head gasket torqued down. Like we talked before, you need the "wiggle" adjusted out on the base circle. I like to set my converted lifters up to pretty well match the pre load distance of the ones I'm going to use. (pushrod socket down .050) This way, when you turn it over the geometry is close to the finished engine. One other thing....I always check it every 5* from about 15* BTDC to 15* ATDC. If a cam is advanced or retarded you will sometimes be surprised where the close point of valve to piston interference is. I sent you a PM. Ron

cutlass_455

iTrader: (2)

Thanks Ron, I appreciate the help. I did the check it every few degrees thing too. With the pics of the playdoh, you can see there is lots of clearance there. I think the playdoh doesnt lie, it will show the minimum clearance no matter where in the rotation it happens.

I actually sent you a PM back before I seen you came back in here, I appreciate the help.

briancb1

My CURRENT cam is a 227@.050" w/ .614" lift and 235@.050" w/ .621" lift 113+4 on LSL lobes, I didn't check the PVT but it obviously works fine.

The cam I WANT is a custom spec 231@.050" w/ .617" lift and 243@.050" w/ .624" lift 113+4 on LSL lobes

I know my heads cut .030" make it closer to the piston, but your increase in duration also puts you closer to the piston. I just wonder by how much though...

My pushrods are 7.425", that was given to me from the guy who sold me the cam. When I swap cams I want to measure it to verify.

What lifters are you running?

Also, your head gaskets crush to .051", correct? Would you be able to do a quick mock up with a .020" shims and the playdoh? If you cant its cool just wondering while your engine is on a stand.

MattSapp95_T/A

iTrader: (35)

Sounds like you are good to go...cam should sound nasty too...

I am running a EPS 230/242 with all stock LQ9 block and LS3 heads....

Came up with .096 intake and .109 exhaust... Using a solid lifter...

cutlass_455

iTrader: (2)

I am running Comp 850 lifters. Im not sure, they could be the same as something else, like an LS7 lifter....I dont know. Those gaskets supposedly crush to .051". I took a previously crushed one and mic'd it while pressing it together, and the smallest number I could get was .051".

Ya, Im going to put the heads on today and close this chapter of the engine assembly I hope.

Thanks for the help guys.

cutlass_455

iTrader: (2)

Im going to obsolutely lose my mind.

Today I decided to check ptv with the dial indicator and solid lifters in and torque the head down with a gasket and checking springs in. Intake I got like .035 intake, .070 exhaust before the valve stopped going down. Im going to stab myself in the eye with my dial indicator soon. I even pushed on the valve and rotated the engine a bit to make sure it was hitting the piston and it was the piston.

How is this possible?? Im so pissed right now, I dont know what to do anymore.