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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Beastdude32 on October 06, 2014, 01:40:12 am
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Hey guys, i have just Built a semi new engine for my truck its a late 70s 350 and as i was building it everything went smoothly and before i put the heads on i put #1 Piston at TDC compression stroke to check the balancer to make sure it lined up with TDC on the timing tab which it did. now moving on to the next day i went to fire it up. it started without a problem once fuel got to it. it fires right up and runs strong but when i go to put my timing light on it the timing mark is WAY off from the timing tabs, near 12o'clock on the balancer. as i try to adjust the timing to bring the mark all the way down to 10 degrees TDC it will just about die. what has happened here? i followed the book and all the tips Ive gotten from experienced engine builders and the engine runs fine just the timing mark doesn't line up so i cant accurately time it. how can i fix this?
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Is your timing light a basic timing light or one with extra buttons and features. If it's fancy you could have it set on a feature like dwell or its advancing the light flash. If it's a basic timing light then I don't know, maybe the light itself is not working right?? Just a thought.
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Its a brand new basic timing light. I used it on my ranger and it worked great im thinking its something to do with the distributor positioning maybe its off a few teeth
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Are you positive you set the camshaft timing as "straight up" and not advanced or retarded?
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Describe the method you used to find TDC (e.g., piston stop, dial indicator, etc). Recheck the firing order and make sure you are timing off the #1 cylinder (driver side, front).
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My first thought is you have a balancer off of a 305. The timing mark on a 305 is straight up. If you just eyeballed TDC and didn't use a dial indicator then this could happen very easily. You're not going to see much movement in the piston from the twelve oclock position to the two oclock position of the 350.
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x2 on the 305 balancer. Make 100% sure it's a 350 balancer first.
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Some 350's came with timing marks straight up at TDC as well
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Im positive its a 350 balancer. like i said when i was assembling the engine before i put the heads on i installed the balancer and as i turned the engine over to TDC compression stroke the timing mark on the balancer lines up with the timing tab at TDC and the piston is all the way at the top of the cylinder like it should
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Also before i built the new motor all the parts are the same as the old ones harmonic balancer is the same and the old one timed right. the only thing i did different that i can remember is that i changed where #1 spark plug wire is on the cap ill change it back around today and mess with it and see if it changes anything
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Your cylinder 1 wire should be on the cap terminal that points just about at the number 1 cylinder. Allowing a little bit of adjustment for timing of course.
The 305 balancer seems like a possibility also.
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Well i fixed my problem, My distributor was so worn out it had 6 thousands of an inch of end shaft play when maximum play is 2 thousands of an inch. so i got a new ACCEL Distributor and timing mark lines up engine fires no problem and now it sounds like a monster like it should