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289 HEI install problems

5152 Views 5 Replies 2 Participants Last post by  Grimbrand
Hi all,

66 coupe 289 auto, trying to install this GM-style HEI distributor a friend bought for me but can't get it to run.

I got the engine to 0 degrees on the crank pulley and the #1 piston all the way up and got the distributor to seat all the way. Is it possible to have the crank at 0* and #1 piston all the way up and still be on the exhaust stroke? I lined up the rotor with where I wanted the #1 plug wire to go and worked my way around in the correct firing order. But whenever I try to start it, it either doesn't start at all or barely starts, sputters for a few seconds and then dies. Also I ran a new switched 12v wire from the ignition switch to the new distributor with 10 gauge wire so that shouldn't be a problem.

Prior to the install the engine ran fine. Any help would be appreciated!
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There are two "TDC" spots for your crankshaft. Your cam is what determines if it's the "real" top dead center. Easy way to tell is if you pull the #1 plug, and turn the crank, it'll be blowing air out as you head towards TDC with both valves closed. On the other end, it'll have the exhaust AND intake valves open as it's coming to the top, so no air will be trying to come out the plug hole.

Remember, it's a 4-cycle engine - suck, squeeze, bang, blow - so the piston has to reach TCD twice during the combustion cycle. You want the *compression* stroke TDC.

If you can make your engine run at ALL with the firing order verified, then you definitely have it starting from TDC.

My suggestion would be to 1) check your plug order, 2) check your wiring, and 3) I hate HEI distributors SO MUCH. Even when they work right, which they often do. ;) Ugly Chevy monstrosities.

In all honesty, my only real gripe with them is that they interfere with Monte Carlo bars and air cleaners. If they're the type that has an integral coil built into the cap they're not too great, because they tend to overheat and fail - especially when you're not running a resistor wire to dial your voltage back a bit when the engine's running.

I don't know much about your engine's other hardware, but with your typical cam, you would want between 6-12 degrees of mechanical advance at idle (with vacuum disconnected and plugged so you don't have a vac leak). If you have an original firing-order cam for a 289/302, your timing order is 15426378. If you put in a roller cam, it may well need the HO firing order - which is 13726548.

You should be all in no later than 3000 rpms (2800, usually), with total advance around 32 degrees. A couple degrees higher, if you have good heads with faster burn characteristics.

Hopefully, you have a vacuum can on your HEI, so you can be more conservative on the mechanical idle advance, and still enjoy easy starting and smooth running.
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Thanks for the detailed reply Grimbrand!

So I am working with the HEI distributor with the coil integrated into the cap, specifically the one you hate haha. It does have a vacuum advance can/port on the front. I have a mild Edelbrock cam, still using flat tappet lifters with roller rockers. Nothing too crazy. I do have Edelbrock E-street heads and their 500 cfm 4bbl carb.

Anyway, I'm going to make sure the engine is at true TDC on the compression stroke and try reinstalling the distributor. Correct me if I'm wrong, but as long as I'm at TDC, and the distributor fully seats, then it doesn't matter where the rotor is facing as long as I use that as my #1 and then follow the firing order? I know alot of write-ups say to have it pointing at the #1 cylinder but I figured that was just for easier reference.

Also do I want the rotor and the #1 cylinder on the cap aligned exactly, or should the rotor be a little before it so it's somewhat close to the 6-10 degrees BTDC?
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As you say, so long as you know which wire you used for #1, and you've got the bug pointed at it, it will work fine. Only "tradition" says you want the bug pointed at the actual #1 cylinder at TDC, and you're right -- it's not a big deal.

When you first assemble the dizzy and put plugs on the cap, you should mostly be concerned with where the vac advance can is at, so you have some room to turn the housing either direction. Generally, you just try to get as close as you can to pointing the bug right at the #1 plug on the cap. You're not going to be 'dead on' probably, but if you do well, you'll be in the ballpark at least enough to get the engine to fire and see where things are at with your timing gun. Your ultimate goal is to get it to 6 BTDC or thereabouts, but you'll be checking it anyway. Just get it close as you can. That's a little tricky anyway, since it 'twists' a few degrees as it meshes with the cam gear.

Don't forget to check with Edelbrock about the timing order! It will *probably* be 15426378, but if you get it wrong, you'll only be running on 4 cylinders.

Best wishes!
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Thanks for the guidance Grimbrand, got it running! When I installed the distributor the first time I must have not been on the compression stroke. It ran enough to let me set base timing and idle.

Now I have a problem with starting it when hot, but I'm thinking that's more of a carb/fuel issue than related to the distributor.

Thanks again!
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Just a couple tips for "hot start" problems:

1) If you are running too much timing (too far advanced) your engine will have trouble turning over, because the explosions are happening early enough that the starter doesn't have enough "oomph" to squish them and spin the engine properly. Reducing the timing just a bit may help. Having it too far retarded will hurt your economy, and make your headers really hot because of all the still-burning fuel you'll blow out the tailpipes.

Vacuum advance means you can have your mechanical ignition timing set nice and low, but still idle smoothly, get crisp throttle response, and good gas mileage.

2) If your carb is getting so hot that the gasoline boils in the bowls from heat soak, that will pour gas out the vent tubes and flood your engine on hot starts. If this is what's happening, the "easy" cure is usually to just add a phenolic spacer so you're not transferring so much heat from your intake to the carb. The added benefit is that the spacer will increase your plenum size just a bit, and help your engine's high RPM performance. Just make sure that you've got enough hood clearance before you go hog wild and grab a 2" spacer. Given the mild nature of your engine, I would think that even a 1/2" spacer would be a good choice. You may also need longer studs for your intake, but they are often included with the spacer you purchase.

Happy motoring, Mr. McGinley!
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