10-05-2012, 08:34 PM | #1 |
RAT1968 '68 Cab/'71 Parts
Join Date: Feb 2002
Location: Coarsegold, CA
Posts: 2,375
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Timing Tip
I've been messing with the timing now for a couple of weeks. Last week I bit the bullet and bought an Innova 3568 series timing light. It was pricey ($100),
but I'm a guy working almost always alone, and I really wanted to have a digital that read out RPM and advance rate. So, I treated myself. So, I was also doing too many things at once. New carb, dialing in the electric fans, going to the "shop" for 134a in the Vintage Air system, new coil on the HEI.... ...Too many variables. And....to top it all off, I couldn't find the dots on the harmonic balancer that I had made while we were wrenching on the motor when it was out. And while we were "stabbing" the Accel HEI. I thought I had the timing good enough using the "running good" method of advance and retard. Then, the putz wouldn't start after sitting for 6 hours. I blamed everything I listed above. Then, I found the mark(s) on tyhe balancer....Yay!!!! Went to 14/29 (idle/total timing) degrees using that mark....Wanted 12/33 or 34 but that wasn't in the "run good in the garage" cards. So, I went with the former. Road test. "Ouch!" Ran like a pig. Seemed really, really retarded. But what do I know. I slewpt on it. I read the Forum on it...Seemed like I better check the balancer mark for TDC. No lie, it took two of us an hour with a 1/2 18" ratchet to hand-turn the motor on the lower pulley, one thumb over the empty #1 spark plug hole "feeling" for the air on the compression stroke, cutting an 8" chunk of plastic hanger to use as a feeler in the same hole. Then, we were certain about where TDC was on the compression stroke on #1. I painted a dot. It was at least 45 degrees away from the mark I had made before. Now, I'm, at 12/32. No test drive yet today. No "start when cool" test, either. But, I bet it's a done deal. All the indicators are that she's right on the money. Like, the fact that the back two header pipes on the exhaust ports don't glow red under higher RPMs. The tip? Unless you really, really trust who put the TDC "dot" on your balancer, verify that it's correct. This little fubar cost me a cruise in the truck to a gathering tomorrow. I need to work the bugs out and not leave myself and my woman stranded on the side of the road. So, we take the car......Had I checked the TDC earlier, I'd bet tomorrow would be a smooth truck ride with fresh, cold air conditioning. Oh, well!
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10-05-2012, 09:59 PM | #2 |
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Join Date: Jun 2010
Location: Upland Ca
Posts: 4,147
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Re: Timing Tip
Yup, as stated on this forum many times by many people, verifying TDC with the balancer and tab is timing 101. It's the first thing that should be checked. Glad you got it figured out. Hope the test drive is great!
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1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
10-05-2012, 10:31 PM | #3 |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: Timing Tip
What!! So your not bringing the truck tomorrow?!?! Man that's a bummer
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" |
10-05-2012, 10:50 PM | #4 |
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Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,229
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Re: Timing Tip
Some models of those engines had the timing mark straight up on the damper. You timed it through the gap between the water pump & the ting cover. Your damper probably came from one of those engines. The tab will be correct within about 2 degrees + or - with the correct damper.
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10-05-2012, 11:00 PM | #5 |
RAT1968 '68 Cab/'71 Parts
Join Date: Feb 2002
Location: Coarsegold, CA
Posts: 2,375
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Re: Timing Tip
Yeah, Wrench.
But that's what (I think) got me screwed up. The balancer had a machined groove cut across it's circumference that I may have taken to be the TDC mark...That's where I made the original corresponding "dots" on the face of the balancer to read on the "pointer". Speaking of points...The point for me was that I really didn't know *what* I had. So now I know that in the future, if I don't ABSOLUTELY KNOW where TDC is, I had better find out before I make any ASSumptions.
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M17 Coarsegold, CA RAT's shiny now. But always a rat. |
10-05-2012, 11:02 PM | #6 |
RAT1968 '68 Cab/'71 Parts
Join Date: Feb 2002
Location: Coarsegold, CA
Posts: 2,375
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Re: Timing Tip
Thanks. Agreed.
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