Chevy engine timing.

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Lakota

Rides a rusted horse
Joined
May 12, 2007
Messages
305
Location
Elmendorf (San Antonio), Tx
I seem to be having trouble timing my engine. It's a 1968 327 CID/300 HP. It has a chrome aftermarket timing chain cover with a bolt on timing marker. The book calls for 4-8 DEG BTDC, depending on the HP. I'm at 12 BTDC, and if I get closer to 8 it begins to sputter and miss. I've got the idle set at 650 RPM's, but when I shift to drive it drops so low it stalls. I've adjusted the idle set screws on the carb, but doesn't help. Before I timed it, it was around 18-20 BTDC and it didn't stall when you dropped it in gear. I'm not sure if the damper is from a 283, 327, or a 350. I'm beginning to wonder about the damper, if there's a difference in diameter or the timing mark is in a different place.
Any ideas on this???
 
Ive also heard that the outer dampener ring can sometimes move. I would be suspicious of the mark and/or tab and get a cheap TDC finder that screws in the plug hole and make a new reference. I have three smallblocks each with a different size dampener and the newest is a 79 "001" 4-bolt from a z-28 and it has the timing tab welded to the original timing cover at the very top at "12 o'clock". Soon Im going to replace that one as the original balancer is seemingly hollowed out and its the smallest one in diameter compared to the other two.........

Oh yea, I have my stuff set at 10-12 degrees BTDC........
 
Thanks for the quick reply Jimmy. You have a timing tab at the 12 o'clock position. Mine bolts on at the 2 o'clock position...I wonder if that's the problem. If it is, then I'm running at about 20 deg ATDC. I remember when I was timing it, as I got closer to 8 BTDC the engine RPM's were dropping.
 
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That particular motor is a '79 and it is peculiar in that it has the tab welded to the cover and its balancer is odd as well. The other two motors have the conventional bolt on tabs on the driverside of the cover and Im sure that yours is correct to have that. I dont think it would run at any degrees ATDC. I believe my 74 truck block has the 8" balancer and the other is a 70 truck block with a bit smaller balancer at 7" Im guessing. Now I will say this too, I have different tabs for each of those as it appears that the tab would match the balancer diameter. I remember trying to put an aftermarket tab on the larger balancer and it was different than the original so I kept the original one on there. If your tab seems to be in a nice parallel relation to you balancer then I would say yours is correctly matched, mine was obvious when it didnt look like the gap was parallel. Sorry for all this hallabalu but I just want to say that there are more than a few variables out there with balancers and tabs. My guess is that if your engine doesnt turn over hard when starting at the 12 degrees, then it is OK but the only way to know for sure is to get an accurate TDC reference. :) I like smallblocks,hehehe.......

Oh yea, you will for sure notice a drop in RPMs as you retard the timing........
 
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Oh yea, one more thing,hehehe.... are you checking your timing with the distributor advance disabled/un-plugged? It should be unplugged for setting your initial timing (again, I like 10-12 degrees btdc). One way I know my initial timing is too much is when the motor turns over hard when starting. I actually havent checked the timing lately on any of my stuff as I usually am turning the distributer back a bit when it turns over hard,hehehe.........
 
Yeah, I remembered to block off the dizzy line. I talked with a friend earlier and he said that Chevy made three different dampeners. With the keyway at the 12 o'clock position, one has a timing mark on the left at the 10 o'clock position, one directly above the keyway, and one at the 2 o'clock position. Tomorrow I'll pull the bolt and washer to see how the timing scribe line is set to the keyway
 
Also, the type of cam will dictate initial timing. I had an extreme energy 262 cam in my 32'. It like lots of initial. I ran at 18 degrees. In the old days, for optimum timing, you would accelerate fairly hard. If the car didn't ping, you would keep advancing until pinging could be detected, then back off a couple of degrees.
 
My cam is stock. I remember setting up my dizzy months ago when I adjusted the valves. I set the #1 cylinder at TDC and turned the dizzy to the #1 plug. It fired right up. When I put the timing light to it, it showed the dampener mark at the 12 o'clock position. I had to turn the dizzy almost to the next tower to get the mark to come close to the tab on the timing gear cover at the 2 o'clock position. I think this may be my problem. I think the dampener was designed for a timing tab at the 12 o'clock position, and I've advanced it too far...Back to the drawing board.
 
Lakota,For that year engine the timing pointer should be at the 2 oclock position.The newer ones went to 12 oclock.Do you have the origianal dampner?The dampner that belongs on that motor should be a 6 3/4" dampner.
 
I just noticed this last month with the 64. Do you have the connector thingy on the timing light for the spark plug wire going the right way? I didn't think this mattered, but when I had the connector on backwards my timing mark was at the 12 o clock position, when I flipped the connector, it went back to where it was supposed to be.

Does that make any sense?
 
This was a crate engine, I had to add the damper, intake, and water pump. The intake and water pump are new, but the damper is one a friend gave me. I ended up working on the kids car today. tomorrow I think I'll use the old method of turning the engine by hand to TDC and putting a chalk mark on the damper.
 
This was a crate engine, I had to add the damper, intake, and water pump. The intake and water pump are new, but the damper is one a friend gave me. I ended up working on the kids car today. tomorrow I think I'll use the old method of turning the engine by hand to TDC and putting a chalk mark on the damper.

i found out the hard way that all the sbc replacement balancers are keyed for the 12 oclock position ...when i used the bolt on timing tabs supplied with the crate engines i started cutting new marks when i had to use a replacement balancer.
 
Yup, that's what I discovered. This damper must be a replacement part, the mark is at the 12 o'clock position. I made a new paint mark, fired it up and reset the timing to about 4 DEG BTDC. WOW, what a difference.
Thanks guys for all the help.
 

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