08-25-2012 12:48 AM #1
Dual roller timing sets-Not for SBC hydro rollers??.
Seems to me I read somewhere that you shouldn't use a dual roller timing chain on a SBC hydro roller cam.But for the life of me I don't remember where or why. Alittle help with that I what is am asking.
Also-I seem to remember reading the stock GM timing sets where machined with advance for smog laws. Sure would appreciate comments about that as well.
Last edited by 1gary; 08-25-2012 at 12:52 AM.
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Wouldn't think double roller or single would effect the type of cam in use, clearance of the timing cover and chain should be considered.
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I do think I vaguely remember something about the higher spring pressures with hydro roller cams and a effect of the dual roller chains.
Is this for the 383 SBC that you're planning to build for the Astro Van, which I think you've said will be used primarily for highway with towing capability for your vendor trailer(s); or is this another engine or a general question? I can't help with the dual roller chain question, but I cannot see from a mechanical design standpoint how it could make a difference (other than clearance, as pointed out) so I hope any answer saying it's not to be done includes the "why".
On the stock timing set, wouldn't any "built in" advance be dealt with when you degree the cam to set it where you need it to be for your specific situation? You'll discover any factory "offset" when you run the degree wheel, won't you? Maybe I don't understand the problem?
Last edited by rspears; 08-25-2012 at 08:26 AM.
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The concern with any metal timing gears and chain is harmonics and spark scatter.....If you're keying in on this as a problem, and want the best, then go to a belt drive. Many will buy the double rollers, and probably never run the engine hard enough for it to matter. A quality single chain and gears is just fine for a street machine in about 90% of cases.... In the case of the sbc, then if it's really a concern, go to the belt drive and the front mount distributor, spend the big bucks and have the best!!!!
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The only thing I can think of off hand is cam end play. Roller followers cant tolerate the amount of end play flat tappets can. A thrust bearing version of the double roller might be needed for roller followers.
you do not transfer much harmonics threw a chain nothing like a straight gear set with floating idlers.roller sets/roller cams i do them all the time with single bike chain sprocket step nose cams bbc / sbc long with double true roller sets . there is only about 110to 120 @ seat lbs less then 300tomax 350 open on stock and mild roller cams thats not any thing for a stock set to worry about . as for the stock chain set .i have engine that run 275to 350 on the seat and 800to 1200 open.i use the same roller chain sets i use in my hyd roller engines with no issues.they at one time did played with the key way for smog . but after market you can get 3 key way and 9 use them all the time . i seen cams with the nose pin off more then 8 degrees so all after market cams get checked when i build them end play has to be check but thats not a big deal just did one today use a button on older blocks or new blocks with out step nose cams keep the cam from walking out . with the step nose cams retainer plate. this still need to be check same with fords and other that use this setup i seen the plate and top gear not fit . i cut many top gears to get the chain to track true as well. nice to have a lathe
Last edited by pat mccarthy; 08-26-2012 at 06:15 AM.
I think most of the talk on this particular subject came from some people using early gears on the later cams( button vs thrust plate and different size cam noses) it didn't have anything to do with timing or advance/retard built in-----
YEP jerry the button and thrust plates have nothing to do with how a roller set works or the step nose cam with the bike chain single row chain or the cheaper link belt chain sets. or the dual roller set you can get for the step nose cams . gary.just kind of lumped it all in there ? along with the smog set ? the more i build engines and deal with new parts or parts not made in the usa there is no plug and play nothing leave the shop with out me having some ideal were the cam events are degree wheels are not that much to not know were the cams is at it.s saved my ass more then one time . first time you get it wrong .the cost of pulling it back out and fixing the engine will cost way more then the wheel
must be 10 or 12 different degree wheels around here---I especially liked the one that I think Isky sold---showed what should be happening where--ie--exhaust valve should be closing, etc---and then the big ones-----------------couldn't use one in the car because it wouldn't clear the ground-------
i have a big wheel i like as i get older i can see it for sure. it as finger holds cut in to it and you and grab it the a city bus steering wheel and just turn it with the wheel
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