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Discussion Starter · #1 ·
My cam has the specs below (MTI X1), I have been running with it all year. I bought a set of AFR heads, milled to 64cc's thinking I'd have plenty of room. No room at all, pistons hit valves, luckily I checked for clearance first and didn't finish the job.
Can anyone diagnose how the heck it doesn't fit? I was sure it would. I am using a .040 cometic gasket. When I test with the stock gasket I do not hit. Could I have been running with .011 clearance all year? It sure seems like it. If so, I'm shocked that cam is ground that close.

INT EXH
Gross Valve Lift .592 .571
Duration @ .006 Tappit Lift .279 .281

Valve Timing OPEN CLOSE
@ .050 INT 7 BTDC 43 ABDC
EXH 50 BBDC 2- ATDC

108.0 Intake Center Line

INT EXH
Duration @ .050 230 228
Lobe Lift .3480 .3360
LSA 112.0
 

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This a total guess, but the 108 LSA has to be the problem!!
We have guys with LG X-3's on a 114 with 59 cc chambers and no flycuts!!
Timing is everything. AFR's are supposed to have different dome geometry(higher) also??

My .02
Ken
 

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Discussion Starter · #3 ·
LSA is 112
ICL is 108

I'm stumped.
 

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That's weird!!
I've got 66cc (stock) 205's but had .080 intake .160 exhaust and valve drop @.218!! My X-2 is 112 degreed in @109 CL!! Lou doesn't give out the specs but it's bigger than yours, somewhere around 230/232 .597/.608 @.050!!
Maybe popping this to the top will get you a real mechanic to answer!!

Good Luck
Ken
 

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Please go over how you checked your P/V clearance. Did you clay test the clearance or do the valve drop deal? Did you install the cam, place the clay over the piston, set up a light spring, install a rocker, rotate the engine a complete cycle and remove the head and check how much clearance you have by cutting the clay where the valve's hit? Or did you rotate the engine and the engine stuck when the valve hit the head.

D.J.
 

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Kens06 said:
That's weird!!
I've got 66cc (stock) 205's but had .080 intake .160 exhaust and valve drop @.218!! My X-2 is 112 degreed in @109 CL!! Lou doesn't give out the specs but it's bigger than yours, somewhere around 230/232 .597/.608 @.050!!
Maybe popping this to the top will get you a real mechanic to answer!!

Good Luck
Ken
Hi Ken,

If you have the G5X2 LG cam it is published on Lou's site as having 232/240, 595/608 with either a 112 or a 114 LSA. If he grinds 4 degrees advance it will install dot to dot @108 ICL or @111 ICL.

D.J.
 

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Discussion Starter · #7 ·
OneQuickCoupe said:
Please go over how you checked your P/V clearance. Did you clay test the clearance or do the valve drop deal? Did you install the cam, place the clay over the piston, set up a light spring, install a rocker, rotate the engine a complete cycle and remove the head and check how much clearance you have by cutting the clay where the valve's hit? Or did you rotate the engine and the engine stuck when the valve hit the head.

D.J.
I tested first using the clay, I got stuck near TDC, so I figured I had too much clay on the piston, so I took some off and tried it again. I still could not rotate the engine. Just for kicks, I tried with no clay, again, I got hung up, I puched so hard that there is now a clean spot on the piston (slight nick) where it was caught. The actual collision happens before TDC. I even put the stock heads back on with the cometic gasket, no clearance either. Both heads cleared with the stock gasket in place.
 

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Do you think the push rod is to long now with the milled heads or do you have an adjustable push rods to check it? It's hard for be to believe you only had .011 clearance. It sounds like you are doing everything correctly. The stock gasket must be a lot thicker than the aftermarket.

Do you think the lifter is not bleeding down when you do this test? Just another thought.

Is the AFR intake a 2.05" or a 2.08"? That will cut down a lot of clearance.

D.J.
 

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Discussion Starter · #9 ·
OneQuickCoupe said:
Do you think the push rod is to long now with the milled heads or do you have an adjustable push rods to check it? It's hard for be to believe you only had .011 clearance. It sounds like you are doing everything correctly. The stock gasket must be a lot thicker than the aftermarket.

Do you think the lifter is not bleeding down when you do this test? Just another thought.

Is the AFR intake a 2.05" or a 2.08"? That will cut down a lot of clearance.

D.J.
The push rod can't be too long, the heads were barely milled. The stock gasket is .12 thicker, that is where I got the estimated .011. I guess I've just been running that little clearance all along...
 

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Z06-Dave said:
The push rod can't be too long, the heads were barely milled. The stock gasket is .12 thicker, that is where I got the estimated .011. I guess I've just been running that little clearance all along...
Dave,
I'm just trying to go over these things one step at a time. There has to be an answer to the problem. You may be looking at a stack up of clearance issues that you didn't experience with your stock heads. The reason I mentioned the push rods is if they are to long for "this application" it could allow the lifter plunger to bottom out and the valves can't close all the way which will place the valve dynamically closer to the piston even with the valve apparently closed. Are the valve tip's on the AFR heads at the same height as the stock head? Does the AFR head use a longer than stock valve? And you are saying that the stock head gasket is .120" thicker than the aftermarket? Did you need to say .012" thicker? The valve diameter is also a player in this as well. I am just trying to give you some food for thought. I'm sure you have thought of most of this stuff already. It's hard to diagnose a problem over the net.

Ken has also said the chamber is higher than our stock head. That would make the valve seat higher in the head and the valve tips higher. At this point it looks like a push rod issue. Could be wrong. Use your adjustable push rod and see if it checks at the same length that you have installed.

D.J.
 

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Discussion Starter · #11 ·
Yes, I meant .012, sorry.
The reason I don't feel its the push rods is because the stock heads wont even clear with the thinner gasket, but both heads will clear with the stock gasket. The only explanation is that the .012 thickness differenct in the gasket is the issue, but then again it makes no sense that I have had no issues with that little clearance fora year.
 

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Z06-Dave said:
Yes, I meant .012, sorry.
The reason I don't feel its the push rods is because the stock heads wont even clear with the thinner gasket, but both heads will clear with the stock gasket. The only explanation is that the .012 thickness differenct in the gasket is the issue, but then again it makes no sense that I have had no issues with that little clearance fora year.
It may be that you were right at the very limit of clearance with the stock setup and going to the new gasket put you over the top. In other words with the new gasket it is letting the lifter plunger bottom out and now is keeping the valve from closing all the way. With the new gasket in place, the cam on it's base circle, rocker/push rod installed, head tight, can you rotate the push rod with your finger tips? I think I would mock up all of the set up and have the cam on the base circle and then loosen up the rocker arm and watch to see if the valve tip goes up when the pressure is off. Or do the reverse and watch the valve tip when you tighten things up to see if it moves down compressing the spring hanging the valve open.

Are you currently running the stock length push rods or something shorter or longer?

D.J.
 

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Discussion Starter · #14 ·
niphilli said:
Is the cam installed dot to dot?
It is, as far I know. We were pretty thorough. Since I'll have to swap the cam anyway, I'll check it before I remove it. If its off I'll line it up, but the car made so much power, its very doubtful its off.
 

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I have the LG X3 cam 112 lsa with 59 cc heads and .040 head gasket.
I fly cut mine .079
The valves are larger so that being said they will have different clearances than the stock heads even if same head height.
What push tubes are you using?
What lifters are you using?
You can NOT use clay on soft springs as they will not preload the lifters.
I removed the springs on one cylinder, put piston on TDC and with dial indicator measured valve drop. That will tell you what you have and then get the measurement for the valve open specs at the closest piston height from Lou if he will give them to you. It is good to have about .090-.100 (In case you drink beer) I had to take mine to a shop that had a Cam Doctor machine and I got the specs so I could sleep at night. Lou told me I worried to much and put the damn thing together.
 

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22655TD said:
I have the LG X3 cam 112 lsa with 59 cc heads and .040 head gasket.
I fly cut mine .079
The valves are larger so that being said they will have different clearances than the stock heads even if same head height.
What push tubes are you using?
What lifters are you using?
You can NOT use clay on soft springs as they will not preload the lifters.
I removed the springs on one cylinder, put piston on TDC and with dial indicator measured valve drop. That will tell you what you have and then get the measurement for the valve open specs at the closest piston height from Lou if he will give them to you. It is good to have about .090-.100 (In case you drink beer) I had to take mine to a shop that had a Cam Doctor machine and I got the specs so I could sleep at night. Lou told me I worried to much and put the damn thing together.
You have a PM

D.J.
 
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