possible too much play in new timing chain

[80sguitarcarguy]

just recently bought a nice 71 skylark unfinished project i'm preparing to pull the "whoever?remanufactured" 455 to check the bottom end clearances. i felt some play in what looks to be a new timing chain set in this rebuilt block, everything looks fresh unused,motor has not been fired yet. im new to buicks after 24 yrs of running amc amxs and chevelles,pontiacs.and dont remember this much slack,could it be wrong size cam bearings and crank bearing adding up for this slack effect?or is it my imagination.its about 1/4 or more inch flop.

[Bob]

Its more likely that it is a used timing chain. The Buick one should be as tight as the others.

[Bob Gibbs]

an engine that has been line honed or line bored can have a looser than normal timing chain. they have undersize timing sets to compensate for this problem

[80sguitarcarguy]

wow!never had to deal with that issue before i checked ta perf they have several sizes,what is the technique to measure what size?i m guessing the rebuilder had ordered one that is oversized not knowing about this?could be my block is factory standard spec crank/bearings and just needs the original smaller factory orig size.??its very floppy,grrr! im getting my hoist ready.

[BigRivy]

I'm with Bob, I've read your other thread and it sounds like you have a real peach of a rebuild. I'd say you probably have a used timing set on there now. Look at the gear teeth and see if there is any wear from chain contact. New teeth should be perfectly smooth obviously. If you have a nylon coated top gear I'd say that it's a real good chance that you have a used set. Chain looseness really does not tell you much. You have to measure how many degrees of crank rotation you get before the cam moves, when turning the crank back and forth. I would try a new stock timing set first. If you determine that it needs an undersized timing set I would call TA and ask their advice on how to measure it. I can tell you that without an extensive collection of specialized measuring tools that this is something that is beyond the scope of the home mechanic and can be a challenge for an established machine shop. I would beware a timing set that is too tight. Really tight timing chains are real hard on the front cam bearing till the chain loosens up and Buicks are exceedingly hard on the front cam bearing as it is. So don't just buy a .005 under timing set and pry it on just to get a "tight" chain. It will do way more harm to the engine than a chain with a couple of degrees of slop in it. Good Luck.

[80sguitarcarguy]

well they just delivered my optional-sized timing set from ta performance to compensate for the lined block.merry xmas!.and it just "fits"dead-on,and i mean,no prying the top sprocket,it slid right on and bolted to the cam,no struggle,no forcing,but it was close,it seamed like a fraction anymore and it wouldnt have slid on. is this too tight mabee?the chain has 1/8 side to side movement now. i dont want risk of burning up the cam bearing should it be a little looser? my other brand-new stock timing set was 1/2+ too slack at the point of "chain-sawing the cover"and so sloppy it litterlly created a 1/8 +and- cam movement! any advice?they had more set size options.

[BigRivy]

I'd say that if it slid on with no prying like you said then you should be fine.

[80sguitarcarguy]

thanks for the encouragement,now i can hopefully close this can of worms,now iv'e worked out the bugs.i realize you have to handle these buick,oiling issues with kid gloves,now im snakebit, never worried so much about a build,cause this one costs so much.that loose chain and buick timing cover design is giving me flashbacks to my 69 amc amx.it had a stretched chain,and really retarded the cam alot.kicking myself for trading that one,back in 1988,most part 390 with go-package was bulletproof.