problem with HEI conversion

[doodah man]

I studied all the threads on here and other websites for HEI conversion, and I'm almost there I think.

I got the new distributor in and the truck starts up, but it's about 4* retarded at idle with the vacuum advance connected and another ~20* retarded with the vacuum advance disconnected. The timing was 16* advanced w/o vac with the points dizzy. It started up ok and idles stable, but it sounds totally different.

Any ideas what's happening before I tear it down and start over?

[doodah man]

some info that might help. It's a 350 V8. The dizzy is a skip white. I wired it up by running a 12G wire with inline 30A fuse from IGN Unfused terminal on fuse box through the speedo grommet to the BAT terminal on the HEI. I checked the voltage at the end of the wire both at start and when running (12 V the whole time).

I'm going to double check the plug wires and make sure they are in the right spot. Which tower should be #1?

Maybe I'm off by a tooth on the the dizzy gear?

[68gmsee]

First thing I would do is to put the #1 piston at top dead center in the compression stroke and make sure the balancer marks aligns with the "0" on the tab. If it doesn't make a new mark and check to make sure balancer is not defective. The vacuum advance seems to be doing it's job if it goes from 20 retarded disconnected to 4 retarded when hooked up.

(to check for TDC if you haven't done it before)

Remove the plug and with your finger in the hole feel for pressure as the piston is coming up then slowly rotate the engine until it comes up to the very top. I usually insert a long screw driver and feel as it reaches the top. Some people say to buy a TDC stop.

[truckster]

You need to make sure your #1 wire is indexed correctly.

Pull the #1 plug and have an assistant turn over the crankshaft by using a wrench on the balancer bolt (just to be safe, disconnect the BAT wire from your distributor). Put your finger in the spark plug hole and watch for the index on the balancer to approach TDC. You'll know it's on the compression stroke when you feel pressure building in the cylinder.

When your close to TDC on the compression stroke of #1, stop at 8 degrees BTDC. Now pull the distributor cap and look where the rotor is pointing. Make a mark on the base of the distributor so you can line #1 plug wire up with that mark.

If it's too far off for your wires to reach, you might have to pull the distributor out slightly and turn the rotor a tooth or two before you stab it back in.

[Longhorn Man]

i may have missed something... loosen the retaining bolt and adjust the timing.

[67c10rustbuket]

the "tower" for number one (when standing at the front bumper looking at the engine) is at the front right of the dist if that makes sense. just google sbc firing order and you find hundreds of sbc diagrams.


http://ww2.justanswer.com/uploads/Ar...ring_order.gif

heres one if i attached the link properly

[BMERDOC]

With that much off retarded I would say the dizzy is retarded a tooth. As the other guys suggested, remove and re stab the distributor. If its one tooth retarded you can take it loose and pull it up just enough to slid it one tooth clockwise.

[BMERDOC]

PS: An inline use generally isn't recommend for that circuit but it makes a great anti theft device if you pull it out when you don't want it to leave its parking spot.

[screaminchevypickup]

Originally Posted by Longhorn Man

i may have missed something... loosen the retaining bolt and adjust the timing.

:agree
Posted via Mobile Device

[LONGHAIR]

The whole "one tooth off" thing only applies if and only if you cannot turn the distributor far enough to get the timing right. The vacuum advance cannister is usually the interference....it hits the firewall or the intake manifold stopping the adjustment.

If it is free to turn in either direction you are not "a tooth off".

BTW, the #1 spark plug wire can be anywhere you choose as long as the rotor is aligned with it.....it doesn't matter at all.

[BMERDOC]

Not arguing but...If he has to crank it so far that it is out of its normal range its not stabbed correctly. If he has to crank it that far to get it into spec timing may be fine but it still needs to be restabbed for it to be "correct" and within its "normal" range. I'm sure he has done his checks and has probably already scrapped off some firewall paint with the advance canister. Not being able to put a feeler gauge between the advance and firewall plus having it pointing at the pass. hood hinge would make me wanna pull it out and reset it. Again, not trying to argue but there is a difference between "correct" and good enough".

[LONGHAIR]

Originally Posted by BMERDOC

Not arguing but...If he has to crank it so far that it is out of its normal range its not stabbed correctly.

Absolutely agreed, but that is exactly what I meant by "not enough clearence".
I would never run one so far out of range either, but a whole lot of guys are intimidated by a distributor install, so when they get it in and running....They would rather move the plug wires by one terminal than pull it back out.

Also, a lot of terms are thrown around w/o the understanding of their real meaning, so written explanations can be difficult.

[bsteenburg]

Referencing this from the front bumper working on the engine. Put the engine up on the #1 cyl. compression and the timing pointer pointing to 0. When you install the dist. in the engine make sure the internal rotor and pick up will line up to each other with the rotor for the cap pointing to number one terminal. I always put number one next to the vacuum can one terminal ccw past the vacuum can. The dist. will gear mesh turning the cap rotor as it engages in. To get the oil pump drive to slot in put some downward pressure on the dist and turn the engine over bumping it with the starter. It will engage. Put the engine back up to TDC #1 and recheck that the internal rotor and pick up are lined up and the rotor for the cap is lined up to #1 terminal on the cap. Usually the vacuum can nipple is pointing to the top inside valve cover bolt. This will get you installed properly. Move the now installed completely dist with the vacuum can ccw about 5-10 degrees. Start the engine and set timing with a timing light to 6* with vacuum line to vacuum can unplugged and the vacuum line plugged. This all presumes that you have the correct dist, good dist with good vacuum can and have run the wires to the plugs in their correct sequence.

[doodah man]

I turned it a tooth clockwise and timed it to 12*. I'm on the road again and it's running better than before.

This is the first big job I've done on it since I got it a couple months ago, and all the advice both direct and through the archives has been a huge help. Thanks again.

[BMERDOC]

Do a burn out for meeee!!!