ringram

Flycut and relax

briancb1

Those readings sound about right actually.

If you read the famous GM High Tech Performance LS3 Cam Comparison article, it states:

"We checked the biggest cam with the tightest LSA (that subsequently was not chosen for the test because of too much cam overlap) to verify piston to valve clearance. With a 232/246-duration, 0.614/0.619-inch lift on a 112 LSA, this cam still had 0.100-inch clearance on the intake valve and 0.120-inch on the exhaust valve. We generally like to see at least 0.080-0.100-inch clearance on the intake and 0.100-0.120-inch on the exhaust, depending on how brave you are and how confident you are the valvetrain is in control."

I know your pistons are dished in the center and these are flat, but the outer ring of the piston (it being flat) I assume should be similar in relation to the deck of the block.

cutlass_455

iTrader: (2)

Im going to do the poor mans fly cut and get an intake and exhaust valve and mount some sand paper to them and sand them down. Seen that trick on here somewhere. The great guys at Scoggin Dickey are sending me some valves.

Brian, Ive never read that article but ya my cam is bigger then that one so, and the numbers are close, so that makes sense. The fly cutting will solve my problems.

Larry

iTrader: (4)

Are you sure the solid lifter was the same height as the installed and adjusted height of Comp 850 hydraulic lifter? Back in my Mustang days I would compress my lifter .060 and take all my clearance readings from that height. I installed the checking springs on #1 intake and exhaust with dial indicator vertical on the valve tip for checking. You can push each valve down by hand and take your readings. The two lifters must be at the correct adjusted height or you will get erroneous readings.

rojs234

iTrader: (5)

Hey, Mike. Frustrating is'nt it? Take a big deep breath and sit down and think. It's hard to believe there could be that much difference between the two methods, so obviously YOU are doing something in the process that is affecting the outcome. You said that you checked to make sure you were getting FULL lift at the VALVE when you turned the engine over with the playdo...right? If so, I would probably trust the playdo. That being said...I would want to know WHY you did'nt come up with a similar measurement doing it the other way. I know this sounds stupid and simple, but are you sure your reading the dial indicator right and that your not running out of travel with the way its set up? The lite checking springs will give a slightly less measure than checking it with the actual springs, because the heavy ones take up the slack,(maybe .010-.015) but it is hard to set up any leverage to do it that way. (I have). I would go back through it with the dial indicator set up on the retainer inline with valvestem, making sure it has enough travel for full valve drop and then check my numbers. It's easy to read .030 instead of .130. Don't give up! It's going to be something simple you missed. I'll bet on it. Ron

cutlass_455

iTrader: (2)

Yes, I checked with my adjustable pushrod how it compared to readings of what my pushrod length would be versus the comp 850s and it was almost the same reading, virtually identical.

I set the lifters up to be as close to the retainer as possible, so they got almost no play in it at all, should I have set them up a little different simulated some preload?? Thats one thing Im not sure of, is with a normal hyd lifter in a running engine, where does the lifter run?? Like is it always at the preset preload that you setup during assembly while running??

Should I take my lifters apart and set the cup down a bit to represent my preload?? This still may not be enough to get me into the safe zone.


Yes, Im getting full lift at the valve, I made sure with my dial indicator. I think wasnt finding the tightest spot with the playdoh, I didt it again and by cutting the playdoh I found a spot with like .030 or something in the intake, and thats pretty close to what I was seeing on the dial indicator. And yes, Im sure I was reading it properly, the valve was barely moving.

Im watching the two year old today, so I wont be able to get too much done, but Ill try.

Thanks for the help you guys.

Larry

iTrader: (4)

Yes, you must have the lifter compressed at the recommended deflection before taking measurements. On the 88 Mustang lifter compression was .060. Not sure of the GM. Also you want the push rod adjusted assuming you have roller rockers so the roller is centered equally across the valve tip. You can use a marker to mark an intake and exhaust valve tip to see exactly where the rocker roller is rolling as you manually turn the engine over. I have never adjusted stock rockers but they should move equally in both directions across the valve tip as well.

cutlass_455

iTrader: (2)

Thanks Larry, thats helpful. So just now Im out in the garage. Here's what Ive done.

I adjusted my lifters to be as close as I can to my calculated preload will be. They are both around .050.

Now Ive installed my head with checking springs with a gasket torqued down. My adjustable pushrod was set for a length of 7.35" and my lifters are 'preloaded". This has given me a bit of slack at the tip of the rocker. Intake ptv is .090, exhaust ptv is lots at .125.

When I adjust the pushrod to 7.400 ( the length of rod Im going to run and gives me the preload that Ive set my 'solid' lifters to) the clearance drops off, Intake is .018 and exhaust is .095".

The exhaust clearance is right near the end of the valve closing event as the piston is chasing the valve up.

The intake is shortly after the valve starts opening and the piston is right around TDC. With this cam the intake valve is opening a few degrees before the piston gets to TDC.

Looks to me I need to do about .085 flycutting to get me up to .100 on the intake and exhaust is marginal, I might just leave it.

briancb1

Do us a favor, take detailed pics on the garage fly-cutting and parts/steps you took etc.
It would be an awesome sticky that would be helpful to our community.
Thanks

cutlass_455

iTrader: (2)

Brian, I think this has been covered pretty good in this post, the inventor of this method...
https://ls1tech.com/forums/generatio...ee-almost.html

Its where I got the idea from.

Petraszewsky

iTrader: (28)

I like that^^^ Thanks for posting...

cutlass_455

iTrader: (2)

Ya, no prob. Im about to go do mine. I had to take a couple days and be a daddy and a husband. Now its my turn to play again.

rojs234

iTrader: (5)

Hey, Mike. I finally accessed your #2 page. Never did figure out why I could'nt do it earlier. Anyway, after reading yours and everyone elses posts, it looks like you have decided to flycut the intake. I would like to make a suggestion if I'm not too late. Call Dave at Lindy Tools and rent one of his tools. You'll be glad you did. He's a great guy and will set you up with the right size and they are simple to use and fast. I used one on my LS2 not long ago. I think it cost me $114.00 for the tool and UPS and when I sent it back he refunded I think $48.00? You can see the tool and find his phone # by going to the search box and typing in flycutting tools or I can dig up his # and PM it to you. Good luck on whatever way you decide. I went back and found his # in case you or someone else wanted it. Ron

www.lindytools.com 1-800-823-2887

cutlass_455

iTrader: (2)

Thanks Ron, Ive already done the poor mans flycutting. It worked ok. The hardest part is making sure you go down a consistent amount into each piston. I sent you a PM too.

Ill look into lindy tools tho. I called Isky Cams last week or the week before and they 'rent' the tools too, but they didnt have any till like the middle of July he said.

Ill post some pics later of what my pistons look like now. I took a good bit out for the intake and just a little bit for the exhaust.

briancb1

updates? How'd the garage flycutting work out? How was rechecking the PVT?

cutlass_455

iTrader: (2)

Everything went pretty good with the garage fly cutting. The biggest problem I had was getting consistancy from cylinder to cylinder. I just got the car running for the first time last week and I've been on vacation with the family since. It ran barely but seemed like a healthy camshaft. Gotta tune it now.

rojs234

iTrader: (5)

I just happened to notice your post when I logged on this morning. I'm really glad to hear that you finally got it running. Should be a good (and proud) feeling after all the little nit-picking problems. I probably missed it in one of your posts, but.... out of curiosity....is this going to be a carbureted engine or EFI? Anyway, just wanted to say good job and good luck. Ron