Hi all,

I've searched the forum and haven't found any good answers. I've got an '87 305 (from a truck) that I'd like to put the L31 roller cam package into. Everything has gone great until I got to the timing chain. A new, stock replacement one is way too loose. So I'm looking for a .010 shorter one. But after calling the big boys (Summit, Jegs, etc.), I haven't had any luck in finding a factory roller cam timing chain that's .010 shorter and will fit under my stock timing cover. Does anyone know of an option (P/N) that might work for me?

The best Summit could offer was this one: https://www.summitracing.com/parts/clo-9-3145-10 But it says "Will not fit behind stock plastic timing covers." Which I think they mean the 93-ish and newer Vortec-headed roller blocks, right? So I'm wondering if this set WILL fit under my stamped steel cover on my earlier roller block?

 

Can you Post a video of how loose it is?

Some Timing Chains are sold "Pre-Stretched"... and fit loosely.

Too Loose is better than too tight, as long as the Chain can not skip Teeth.

 

It's definitely too loose. There's at least 1/8"+ of slack on either (both) side. To be fair, it is an OEM, "multi-link" chain and not a double or even single roller type.

 

What matters is how many degress back and forth rotation the crank moves before the cam gear moves.

 

I think all OEM style chains are loose but they'll last a lot longer than an aftermarket double roller chain.

 

I can say for certain that running on the loose side Vs. the tight side...
Shows beneficial on the Dyno.

Depending on the rest of the Valve-Train configuration... a good 15 HP.

 

True. and I never buy the roller type chains.
Have always used the factory style link belt chain and gears. They seem to last longer.

 

Factory chains are also a lot quieter.

I gave up on chains in my race engine. Milodon fixed idler gear system. Very expensive, however cam and ignition timing will never move due to stretch or flex like with chains.

 

1/8" is looser than I'd expect, but IDK that it's TOO loose to run properly. To me, 1/8" doesn't seem like a meaningful issue.

 

A .010" longer chain isn't gonna make a DENT in the 1/8" (.125") situation you're describing. You're playing with "measure with micrometer, mark with chalk, cut with axe".

305, roller, etc. are all totally irrelevant, since the chain for a SBC is the same length for 262.5, 265, 267, 283, 302, 305, 327, 350, & 400; as well as for factory roller-tappet vs "legacy" flat-tappet systems. Only thing different between roller and "legacy" is the cam sprocket, specifically the parts around the center.

Most "roller" chains will develop WWWWWWAAAAAAAAAAAAYYYYYYYYYY more than .125" of slack in the first couple k miles of use. A QUALITY roller chain - NOT a $30 special - maybe not so much. Butt hay, a LinkBelt style chain will last HUNDREDS of thousands of miles before developing that much.

IMO you're misdirecting your n00b angst. Just buy a good quality chain, either factory style or a "TRUE" roller style (NOT "truck roller" aka "bushing roller") and you'll be fine. To give you some idea of how serious the World At Large considers this to be a problem, there is NOT ONE SINGLE PRODUCT available at Summit to deal with it. And if there's ONE THING I've learned about hot-rod marketing from being in this hobby for a length of time readily compared to a CENTURY, it is that if people are ready and willing to BUY something (i.e. if they "perceive" a "need"), someone will MAKE it and happily SELL it to them, whether it does any factual "good" or not. Just to separate the fools from their money. So that'll give you some clue as to how "critical" and "necessary" dealing with that tiny bit of slack is.

 

Most of the Cheap Double Roller Chain Sets will seem to fit with a small amount of slack...
As already said, they quickly become looser/ stretched.

Loose is fine if it is not skipping tech/ coming off of the Gears/ allowing Valve Timing issues and...
causing corresponding Distributor/ Ignition Timing issues.

The higher quality Chain Sets will come "Pre-Stretched" and will present to the Builder as stretched as the Chain should ever be (Less oil starvation or damages).
The higher quality Chain Sets can be very lose by comparison.

The only real benefit from the "True" Double Roller Chain Sets would be freeing up some HP from lack of friction/ tension.

Gear-Drive Sets are relatively more accurate and do not have a way to stretch like a cheap Roller Chain Set.
But the Gear-Drive Sets do eat up some 10 - 20 HP by comparison in some applications.

The Stock Link Chain Sets don't even consume that much HP.

The Dry/ Rubber-Belt Type Systems free up almost as much HP as a True Roller Chain Set, and do not really stretch...
But they do not last as long, and when they are done... they just rip/ fly apart (not something that you want to worry about when daily driving).

Every type of Valve Timing Set has its Pros and Cons.