71 429 timing/starting problems

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Jan 2, 2007 | 02:49 PM

fordguy76

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Laughing Gas

Joined: Apr 2001

Posts: 1,191

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From: West Union, OH USA

71 429 timing/starting problems

I have a 71 429 thunderjet, originally a 2bbl now 4bbl, rebuilt around 11:1 compression. I've put the edelbrock intake, carb, and now cam in it. I first had a rv cam installed by the machine shop that put the bottom end together. The rv cam had too much lift, so I changed to the edelbrock performer. I lined up the timing marks on the timing chain like the chiltons books says. The cam mark at 6 o'clock and crank at 12 o'clock. I brought the #1 cylinder up to top dead center and dropped in the distributor. The engine would barely turn over and wouldn't start. None of the timing marks on the balancer are even close to the timing indicator when I bring up the piston. The engine ran before with the rv cam, but I noticed that the machine shop didn't line up the timing marks like I did. So what's my problem here guys? Thanks

Jan 2, 2007 | 05:24 PM

RTM

Cargo Master

Joined: Dec 2003

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From: Sunny Florida

You have to make sure that when you drop the dizzy in that you are on the compression stroke and not the exhaust stroke. Bring the engine to TDC and make sure the intake valve opens and then closes. This puts you on TDC and then the dizzy can be dropped in pointing to number 1 like it should.

Jan 2, 2007 | 09:52 PM

fordguy76

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Laughing Gas

Joined: Apr 2001

Posts: 1,191

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From: West Union, OH USA

I put my thumb over the spark plug hole and had my brother turn the engine over until the compression blew my thumb off the hole. I thought that was tdc on the compression stroke. It still doesn't make sense how the timing marks don't line up. And shouldn't the tdc mark on the balancer line up when the cylinder is at tdc?

Jan 2, 2007 | 10:12 PM

T.R.Bauer

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Yes, they should line up.

Jan 3, 2007 | 10:58 AM

fordguy76

Thread Starter

Laughing Gas

Joined: Apr 2001

Posts: 1,191

Likes: 4

From: West Union, OH USA

OK, so I have more questions now. 1st, how did the machine shop line up the timing set if it wasn't straight up? 2nd, How do I line it up like they had it? I know edelbrock sells a chain and sprocket set that has 3 keyway slots on the crank sprocket. Would that help me any? Or can I just use the timing set I have now and somehow line it up different. Also, isn't top dead center the highest point that the piston reaches in the cylinder or is it not?

Jan 3, 2007 | 05:04 PM

T.R.Bauer

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Joined: Oct 2005

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TDC is the very top of the piston travel. Your timing mark should be zero degrees on your dampener at that point. Sometimes they are "off" because the timing tab is slightly bent. How close are you to 0 degrees at TDC? If you are fairly close, then you may want to check that timing tab to make sure that it didn't get bent on the install. I really doubt the machine shop even used the marks on the dampener to set the timing set up. The timing set has its own marks and those are the ones that you use when you install the timing gears. Advancing or retarding the timing set only changing your valve timing, and moving that valve timing either way will not effect the ignition timing marks on your dampener or where your piston's TDC is located. So, with all that said, I would say that you have a problem with your timing mark, or perhaps even your dampener.

T.R.

Quote:

Originally Posted by fordguy76

Jan 4, 2007 | 04:42 PM

RTM

Cargo Master

Joined: Dec 2003

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From: Sunny Florida

What did you do after it blew your thumb off? You need to still make sure that you are TDC and I do this by watching the timing marks and using a screw driver to feel when the piston comes up and goes back down. What you can not do is just rotate the motor backwards and set it from that direction. You must go past TDC and the rotate back to the TDC from the clockwise direction. This is to avoid an error in the slack in the timing chain.

Not that it has much bearing on the issues but the piston will have a slight dwell time at TDC meaning the crank is still turning and the piston is sitting still. To truely determine TDC one needs a degreeing wheel and a piston stop to set it.