Under size timming chain & cover ?

R

rw87tt

Member
Joined
Oct 21, 2006
Greetings, brothers and sisters from the dark side. I was wandering if you guys could help me out with a couple of things. I had the mains on my block aligned bored and honed due to new center caps and main studs. I took the center to center measurement on the camshaft and crank (installed) with crank torqued to 90# to see if i needed an undersized timming chain. The measurement came out to 4.320". The factory spec is 4.335. I was expecting a difference of only a few thousands. The chains that are sold, at the most, are .006 under. Am I missing something? Can I get by using a standard T.C. kit?
My other question is. The cam button wore a depression inside the timming cover and I am going with a roller cam. Is there a fix for this so that I can use the roller cam button that requires shims? If I need to get a new one. What do you guys or gals recomend? Thanks for any input. May the BOOST be with you.
 
my cam took a walk and wore out he timing cover front.
had mine bored bal. honed etc.
the over size bearing should get you in specs
i would call weber racing they set me up with eveything
i rate them 5 stars*****
 
rw87tt said:
Greetings, brothers and sisters from the dark side. I was wandering if you guys could help me out with a couple of things. I had the mains on my block aligned bored and honed due to new center caps and main studs. I took the center to center measurement on the camshaft and crank (installed) with crank torqued to 90# to see if i needed an undersized timming chain. The measurement came out to 4.320". The factory spec is 4.335. I was expecting a difference of only a few thousands. The chains that are sold, at the most, are .006 under. Am I missing something? Can I get by using a standard T.C. kit?
My other question is. The cam button wore a depression inside the timming cover and I am going with a roller cam. Is there a fix for this so that I can use the roller cam button that requires shims? If I need to get a new one. What do you guys or gals recomend? Thanks for any input. May the BOOST be with you.
Click to expand...


Just from centre main caps I have never heard of it being that off. I have done 2 & each time either a 2 or 4 thous. under did the job. Sure its measured correctly? When I used the 4 thous chain it was Hard to get it on.
I'm no pro so maybe I'm missing something but just seems like a lot & thats the reason chains are commonly sold in 2-4-6 thous. bet they dont sell a lot of the 6's either. Pretty rare from what I can tell by friends motors.
 
I measured as good as I could with good quality instruments. I had to improvise when I measured from the bottom of the camshaft to the top of the top of the crankshaft. I took a couple of readings on that one and got maybe a .002 differance. I might get a standard timing chain (roller) and see what it looks like. One of the calipers I used could have been off. I did'nt have the instrument to check their zero.
 
rw87tt said:
I measured as good as I could with good quality instruments. I had to improvise when I measured from the bottom of the camshaft to the top of the top of the crankshaft. I took a couple of readings on that one and got maybe a .002 differance. I might get a standard timing chain (roller) and see what it looks like. One of the calipers I used could have been off. I did'nt have the instrument to check their zero.
Click to expand...

For sure you need a 2 under & I will bet at most a 4 under. Start with the 2 & see if you have 1/4" or less chain slop side to side. There was something I read here about it maybe last year some time that helped me out. When you check the slop make it equal on both sides of the chain. You can put tension on the crank in the fore or aft position which loads up one side of chain but I believe it should be even on each side when testing.
PLEASE correct me if I am wrong cuz thats how do mine.
 
TA Performance sells undersized timing chain sets. They have more than a few choices.
 
TA Performance Chains

DonWG said:
TA Performance sells undersized timing chain sets. They have more than a few choices.
Click to expand...

If you are finding that you need an undersized chain shoot me a PM and let me know. I have two chains unused in the plastic wrapping from TA. I wouldn't mind getting rid of them at a good price.
 
What kind of roller cam is it. I have a rollmaster billet timing set for a billet roller cam. It uses the odd fire cam snout. I had to get a .010 oversize when my steel caps were installed on a previous motor. If that is what you need, it is for sale. very good condition with only about 1000 miles on it. Let me know. check out my webshots pics for what I did to my timing cover for the billet cam install. Hope this helps. Jeremy

Here is a pic of the timing chain set. http://www.turbobuick.com/forums/parts-sale/208440-bearings-tchain-tplate.html
 
Thanks for the feed back guys. I wasn't able to get a regular roller timing chain to see what kind of slack was in it. I did get a stock none roller and tried it. It had at the most about 3/8" of play on one side. I called the machine shop and he said it shouldn't be off by much. I did tell him about the amount of slack on the new stock timing chain. He said their is suppose to be no slack at all and told me to try a .002 over. TA. Performance didn't have a .002 over and are on back order. I committed my self to a .004 and a oil pump shim kit and hope for the best. I appreciate the offers on the timing chain kits and would have considered it if I wasn't already committed. The cam is one that Full Throttle Speed and Style sells. It's a 206/210 and .516 lift roller.
 
.004 over T.C. not tight enough.

:confused: Installed a .004 roll master and it is still loose. It has right at 3/8 slop on the chain on one side with the other side tight. Can someone tell me how much over I need to go? I was hoping the .004 would be enough. Should I go with a .006 or .010?
 
rw87tt said:
:confused: Installed a .004 roll master and it is still loose. It has right at 3/8 slop on the chain on one side with the other side tight. Can someone tell me how much over I need to go? I was hoping the .004 would be enough. Should I go with a .006 or .010?
Click to expand...

Measure with Equal Slop on each side. I bet its under 1/4"
 
Good information, so I should just check the centerline distance of the crank and cam, compare this with the Rollmaster Chart link and go from there?

Chuck
 
The general rule is I believe is. Measure center to center and go with half of what ever it is under. Mine was .020 under the stock center to center measurement. I went with a .010 under size timing chain and it was right on. I just cant believe it was that much.
 
rw87tt said:
The general rule is I believe is. Measure center to center and go with half of what ever it is under. Mine was .020 under the stock center to center measurement. I went with a .010 under size timing chain and it was right on. I just cant believe it was that much.
Click to expand...

Thanks, for that information!

Chuck
 
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