Timing chain?
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
1/2" play is too much. It may or may not help the idle....depends on a LOT of things.....but put a timing set on it, then get it back together and set timing properly. Go from there.
I have a really nice 1994 K1500 350 5 speed 4x4 sitting in my driveway with one inch of play in the timing chain.......the complaint was that it runs rich and then rough sometimes......well the injectors are fired by the distributor on these, so there it is......at one inch of play, you can have about 5-6 degrees of float at the distributor......on and off the accelerator causes a lot of back and forth as the chain loads and unloads......you do not have EFI, but it is still moving around.....it throws cam timing off too....just fix it.
Jebby
I have a really nice 1994 K1500 350 5 speed 4x4 sitting in my driveway with one inch of play in the timing chain.......the complaint was that it runs rich and then rough sometimes......well the injectors are fired by the distributor on these, so there it is......at one inch of play, you can have about 5-6 degrees of float at the distributor......on and off the accelerator causes a lot of back and forth as the chain loads and unloads......you do not have EFI, but it is still moving around.....it throws cam timing off too....just fix it.
Jebby
Last edited by Jebbysan; May 26, 2020 at 05:08 PM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
That's too bad you can't get some info off of the cam. Some manufactures have their info on the butt end. So its up to you if want to go further with this, pulling lifters, resetting lash to get your part number.
Its been rumored by several that a timing chain is broken-in or mated to the new sprockets just like the sprockets get mated to the chain. A break-in period, so to speak.
I have swapped a "chain only" before, and leaving brand new sprockets in place. But I knew exactly how many miles were on the gear-set. (less than 600)
It makes absolutely no sense to put a brand new chain on sprockets that could have 10s of thousands of miles on them.
If you have the gear puller / installer tool, by all means put all new in.
Its been rumored by several that a timing chain is broken-in or mated to the new sprockets just like the sprockets get mated to the chain. A break-in period, so to speak.
I have swapped a "chain only" before, and leaving brand new sprockets in place. But I knew exactly how many miles were on the gear-set. (less than 600)
It makes absolutely no sense to put a brand new chain on sprockets that could have 10s of thousands of miles on them.
If you have the gear puller / installer tool, by all means put all new in.
Last edited by HeadsU.P.; May 26, 2020 at 05:19 PM.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
service manual specs: deflection for THAT chain ≤ 0.43" (11 mm)
ditto..................cam gear bolt torque = 18 lb ft
No, that cam gear was Not OE (re: p7) ... it was installed later ...
... original 71 sbc pass car cam gear had nylon-clad teeth ... current gear an HD upgrade.
A fresh chain alone will tighten it right back up.
But that 1/2" of chain slack ain't causing it to mimic a hot rod.
ditto..................cam gear bolt torque = 18 lb ft
No, that cam gear was Not OE (re: p7) ... it was installed later ...
... original 71 sbc pass car cam gear had nylon-clad teeth ... current gear an HD upgrade.
A fresh chain alone will tighten it right back up.
But that 1/2" of chain slack ain't causing it to mimic a hot rod.
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,501
From: Little Rock AR
You are in the middle of a frame off..... If this were mine, I would be identifying the cam now. You have it apart and NOTHING in the way. You need to know what cam is in there so you can rule it out once and for all.
Carefully removing the lifters and identifying them so they all can go back to the original holes is not that big of a job. If you already have the tranny or clutch off, you could pull the plug off the back but remove and replace the cam would be my first choice. Need to remove fuel pump too.
After that, I would want to know about the distributor setup. Curve and vacuum advance can give you idle stability problems. The carb and vacuum leaks are always suspect too.
Just looking over your shoulder holding my beer here.
Carefully removing the lifters and identifying them so they all can go back to the original holes is not that big of a job. If you already have the tranny or clutch off, you could pull the plug off the back but remove and replace the cam would be my first choice. Need to remove fuel pump too.
After that, I would want to know about the distributor setup. Curve and vacuum advance can give you idle stability problems. The carb and vacuum leaks are always suspect too.
Just looking over your shoulder holding my beer here.
Heel & Toe
Joined: Jan 2022
Posts: 16
Likes: 1
From: WESTCHESTER ILLINOIS
Double row timing chain clearance
Stick a 9-1100 Cloyes Street True roller in there.......one of the best bargains in the performance world. My street builds get this......the hotter stuff gets a Hex-a-Just.
https://www.summitracing.com/parts/clo-9-1100
https://www.summitracing.com/parts/clo-9-1100
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Any mods needed to install a Cloyes 9-1100 double row chain. I'm building my 81 c3 into a 365 hp car. I know my present timing cover(stock) is right up against the water pump now. any mod at all would change all the belt alignments if I had to space the water pump. Wouldn't a good single row roller timing chain be adequate enough to spin a Comp Cam L-79 spec 470 by 480 lift flat tappet cam? I doubt this motor will ever spin past 6200rpm. Thanks for your help...
Jebby
