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Guys, this was quite a task for me. I heard the timing chain skipping against the cover. When I pulled the cover I was amazed the chain had never skipped teeth because THERE WEREN'T ANY! It was a plastic covered gear and it had only 4 mostly formed teeth left, the rest was just a shadow of a sprocket (see pictures). I installed a Cloyes double roller chain and sprocket set (only $29!). But a club friend who had a career in Chevrolet maintenance warned me that I have to pull the oil pan and find the plastic pieces before they clog the oil pump pickup screen. He suspected that the oil pump pickup screen would be clogged. So I did and so it was--- sort of. The visible part of the screen was clear or pieces (pieces could float back down into the pan when engine off) and very little of the pieces were found in the pan. (The pan, with 220,000 miles on it, looked like the place where sludge goes to DIE. See picture of pan cleaned with mineral spirits and scrotchbright.) So I used a small hook tool to pull the pieces out from the covered part of the screen (see picture of saved pieces). I used the new one piece rubber oil pan gasket. Very convenient kit. That thing could seal a submarine. Topped off the fix with a new water pump. No leaks, no chain scraping noise. In fact, I can't be sure whether I can hear the new chain or not. I don't see the noise advantage of the plastic, but that's moot now.
NOW I have to figure out the timing. It was so far off that (following the shop manual procedure) the #1 wire is now pointed at the passenger side of the engine. Set with the ESC wire (marked "TACH" on the distributor) disconnected for 8 degrees BDC. When the ESC is connected the timing mark disappears beneath the water pump even at idle. But I think the stronger chain has revealed other internal issues. On warm up it has a miss that causes exhaust popping. Once in a while it appears again on acceleration. Suspect 1 or more lifters not getting enough oil. I replaced the lifters 18 months ago. The miss was there before the new chain but it didn't pop as loudly as it does now. After I do a bit more troubleshooting I might be back with some questions. I just need to get this thing to last a little longer till I can afford a crate motor. Thinking ZZ6 SBC.
From: Las Vegas - Just stop perpetuating myths please.
First when installing the new timing set you should put the gear marks both at 12 O'clock position by turning the cam and crankshaft then installing the chain. You need to use a piston stop to verify #1 piston is at TDC. Now with the marks set and the #1 at TDC the distributor rotor needs to be aimed at the #1 spark plug wire. That's what will make it work.
Hope this helps.
Last edited by cardo0; Jul 8, 2020 at 12:34 PM.
Reason: stupid auto correct
Chain sprocket marks were aligned to each other, Cam sprocket at 6:00 and the Crank sprocket at 12:00 with the #1 cylinder at TDC with a piston stop. That's the instructions with the part and all over the web.
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Looks like you are at TDC on #1 but on the exhaust stroke.
Turn the crank one more revolution and you will be on #1 compression stroke then drop in the distributor in with the rotor pointing at the #1 piston.
Chain sprocket marks were aligned to each other, Cam sprocket at 6:00 and the Crank sprocket at 12:00 with the #1 cylinder at TDC with a piston stop. That's the instructions with the part and all over the web.
Yep...instructions all over the web, but in this position, it is at TDC #6. Rotate the crank one more turn so the cam gear dot is at 12 o'clock and that is TDC #1. The cam spins 1/2 the speed of the crank.....2 to 1.....so the piston on #1 will be all the way up......but it is not TDC#1 compression.
Next thing you have to check is if your balancer is spun...the outer shell can spin out of clocking and the timing mark will be way off. Find TDC #1 with a piston stop and verify or just bolt a new $60 balancer on.
It started on the first pull. I think it is set properly. TDC #1 is TDC. Compression is determined by the valves via the cam. I used the instructions from Cloyes and several Youtube videos.
I don't give a **** what the video says or who says what. Dot to Dot is TDC #6. 12 and 12 is TDC #1. In both positions, the pistons on 1 and 6 are at the top.....but that is not considered TDC. I have built over 200 Chevrolet V8's from junk to 40k Big Chief engines and this applies to all. You can put it all together dot to dot and the mark will be in the correct spot but if you drop the distributor in pointing toward #1, you WILL be 180 degrees out. Always.
I never pulled the distributor out on this. it kept its relation to the cam throughout the replacement. If I'm out how come it runs?
Because the distributor never lost its relation to the cam. You installed the chain at #6....and when you did, the rotor was pointing to #6 terminal on the cap.....so no issue.
But if you pull the distributor.....and do dot to dot, then point the rotor toward #1 it will be 180 out. It has to be.
OK so I guess I artfully screwed up. Saved by a slip up I guess?
You didn't screw up at all......I just did a 94' TBI 350 pickup without pulling the distributor.....fired right up. I highly recommend a new balancer anytime this job is done though. The 26 year old balancer on the pickup was actually wobbling on the outer shell......now add 12+ more years.....
It is a replacement balancer. Mine separated years ago, would spin for a minute after shutoff. While it was off I painted it gloss black and paint
ed the timing mark white.
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you say its back firing. is it all the time or when you rev it up? when you put the balancer on, how well did the timing marks line up? You put it together correctly, Different manufactureres align the dots differently. When i put my rotor on 180 out it wouldnt run at all. You are probably not advanced enough or too much. ...just check the timing
Regarding the miss.
seems the pan was filled with nylon timing teeth which may've restricted oil screen. Didn't happen overnight evidenced by driver not noticing noise difference between old and new. Driver indicates lifters were replaced.
Suggest cam and lifters may've been starved for oil. If so, they may have enough wear to produce a miss / backfire / pop. Just sayin'
also, seems damper was replaced. Note early dampers have timing mark-groove in slightly different location in relation to crank key than do later dampers. They both fit same but if mismatched will result in erroneous TDC ignition timing
Camshaft is likely very worn also, and that is the next place I'd look.
The last high mileage engine I had to "save" got rebuilt heads, New ; oil pump, timing set, cam and lifters. Ran for many yrs more and it ran great. Not suggesting this is what the OP needs to do, but the ZZ6 may be needed much sooner than hoped !
(typed while the above post was sent saying the same)
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Well if that’s true the lifters were replaced then it very well could have flat lobes....kind of silly to replace one and not the other with today’s oil issues
Timing Chain
