Distributor Timing Problem

[Duke W.]

Re: Distributor Timing Problem

A couple of thoughts - as you're probably aware, the OE centrifugal curve is start @ 700, 24 @ 4600, so unless you have light springs installed (that I highly recommend) that brings full centrifugal in at less than 3000, setting total WOT advance at 3000 will result in too much advance.

It's very difficult to set initial advance on mechanical lifter engines because you have to get the engine below 700, and it will barely run at that speed and maybe stall before you get the timing set. Also the timing tab is not accurate with the 8" balancer, so if you set it at 12, it's really about 10.

That's why it's best to set total WOT advance (VAC disconnected) at above the engine speed that you must verify where the centrifugal is all in. My 340 HP has '64-'65 SHP/FI weights and springs, so advance is all in by 2350, and I can set total WOT advance at 2500-3000.

Best power is 38 not 36 based on dyno tests.

The fact that the VAC is against the manifold at 12 indicates that the gear was installed correctly to begin with, so maybe you just had it installed a tooth off, but I know you said you reindexed it a tooth earlier and later and still had the problem. I'm still suspicious of the electronic points conversion.

Maybe you should go back and install the distributor as if it was on a freshly rebuilt engine.

1. Rotate the gear so the dimple is in line with the rotor tip.

2. Set the crank at 12-14 BTC on the #1 compression stroke.

3. Orient the distributor as if you were going to drop it in with the rotor tip pointing along engine centerline.

4. Observe the position of the oil pump drive pin and slot and line them up as best you can.

5. With the rotor pointed along engine centerline drop in the distributor. As the gear engages the rotor should move about 20 degrees CW.

6. With an ohmmeter or by eye, rotate the seated distributor housing until the points just barely open, and at this point the VAC will be about midway between the interference points - coil bracket and manifold. (Oh never mind, you don't have points.)

7. The above static timing procedure should be close enough to start the engine to do a final timing check and snug down the clamp.


If this procedure doesnt work, then I think the problem is the electronic conversion that does not send a pulse at the same position as points.

Duke

[Steve G.]

Re: Distributor Timing Problem

If you're up against the manifold you are half a tooth out, pretty much exactly what turning the gear on the shaft gives you.

Steve

[Steve G.]

Re: Distributor Timing Problem

To simplify this correction and all future dealings involving removal of your dist I would take this opportunity to identify the firing point in your pertonix so that you can do a proper static timing set.

Before you touch anything check your initial timing with vac disconnected using your timing light. Mark down where you're at. Stop the engine and rotate it to whatever timing setting you read (#1 firing of course). The relationship of the reluctor wheel to the pickup as you see it now is the point at which it is firing. Take a pencil or a sharpie and draw a line on the reluctor wheel then onto the pickup body somewhere. Doesn't matter where as long as the two line up with one another. If the pickup can be removed from the breaker plate, don't make your mark on the plate.

This now represents the "point opening" I referred to in the static timing setup I described where points are used.

Now re-install your dist and with your timing marks set to whatever initial timing and align the two marks for an accurate static timing. Recheck with your light.

I don't bother fooling around with the pump drive trying to line things up for a drop in. I set it in on the tooth I want then spin it on the starter. The dist will drop down when it finds alignment. I reset the marks to my initial timing setting and fine tune my static setting.

Steve

[Stuart F.]

Re: Distributor Timing Problem

Duke;

1) My actual initial timing was set probably closer to 700 than 750 rpm because I had to use the car tach as my electric meter failed, and the engine did kill a couple times.

2) I use a 1.3 degree per timing mark as a correction factor for the 63 SHP balancer to timing tab situation. Therefore, typically; 9 marks would be 11.7 degrees. I set it for just above the ninth mark.

3) Due again to my meter failure, I checked the total advance doing a run up by ear. It peaked at somewhere between 36 and 38 degrees, or so I saw with my timing light and my bad vision. I went back to standard springs with my advance weights as I didn't want to push the timing too much until I could dial in my initial timing. With the drive gear positioned as it was before, I was seeing over 20 degrees initial with the VAC against the plug wire bracket.

4) No doubt the static timing is the way to go, either using points or figuring a way with my Pertronics, but I'm going to take a break to take stock with where I'm at and wait for another cool weather stretch. Here in Florida, that might not be until late next fall. It ran like a banshee this morning on a test drive. Cleared out all the loose combustion carbon and the plugs recovered just fine.

Steve;

Thanks for your valuable advice as well. I appreciate it. I did get my original objective accomplished with my plug wire brackets. I can now get my top shield off and on much easier, even though I had to bend my driver's side bracket back toward the firewall in order to get my air cleaner on. I should have dealt with that alone and not pulled the distributor, which is how I found the cross gear problem though before it failed.

Thanks to all again.

Stu Fox

[John H.]

Re: Distributor Timing Problem

Stu
Is #1 plug wire on the cap terminal that is on the window door opening? Is rotor when dropped in pointing towards #1 cylinder in the block?

Gene -

The #1 wire tower is the first one clockwise from the adjusting window (to the left of the window when viewing the distributor from the front). The engine isn't going to start or run if the rotor tip is pointing at the actual #1 cylinder location in the block; the rotor tip must point directly at the #1 wire tower in the cap, not at the #1 cylinder in the block.

[John M.]

Re: Distributor Timing Problem

Stu, Duke,
I have a 65 Fi car that does not like to idle below 900 rpm which will cause centrifugal advance so I remove the springs and tape the weights together, green tape. Then I'm sure there's no advance for setting the initial. Also tells you how much centrifugal at idle with springs back on.

[Duke W.]

Re: Distributor Timing Problem

It's easy to set total WOT advance on 365/375 HP engines because the centrifugal is all in at 2350. Of course this should be verified with a timing light. Then with the VAC disconnected and plugged, rev the engine to 2500-3000 with a dial back light set at 38-39, and rotate the distributor to bring the notch opposite zero on the timing tab.

Then connect the vacuum advance and at 900 total idle advance should be in the range of 30-34 because a few degrees of centrifugal are added at 900 (It starts at about 700), which is what the very high overlap 30-30 cam likes for best idle quality and stability.

Duke

[Stuart F.]

Re: Distributor Timing Problem

John M.;

Thanks for the tip to ensure no mechanical advance at idle.

It's been a long time since I installed the weights and springs I was using, and I have not located my notes on my time on the distributor machine which was before we moved south in 2004. Does anyone know a source for F.I. Weights and springs at this time?? I have an aftermarket HP kit that I never used and the cad plated weights match the profile of the ones I still am using.

Stu Fox

[John M.]

Re: Distributor Timing Problem

Stu
Mine came from Don Baker. He rebuilds distributors. Good guy. He must be a member; if not ask John deGregory.
John

[Frank D.]

Re: Distributor Timing Problem

John M.;

Thanks for the tip to ensure no mechanical advance at idle.

It's been a long time since I installed the weights and springs I was using, and I have not located my notes on my time on the distributor machine which was before we moved south in 2004. Does anyone know a source for F.I. Weights and springs at this time?? I have an aftermarket HP kit that I never used and the cad plated weights match the profile of the ones I still am using.

Stu Fox

Be careful with those aftermarket spring kits; as Lars will tell you - the lighter weights in the Chinesium kits are not hardened and won't keep their factory characteristics for long...

[Stuart F.]

Re: Distributor Timing Problem

Frank;

My kit is from before Noxon went to China.

Thanks .

Stu Fox

[Gene M.]

Re: Distributor Timing Problem

Gene -

The #1 wire tower is the first one clockwise from the adjusting window (to the left of the window when viewing the distributor from the front). The engine isn't going to start or run if the rotor tip is pointing at the actual #1 cylinder location in the block; the rotor tip must point directly at the #1 wire tower in the cap, not at the #1 cylinder in the block.

I set the rotor tip pointing directly at the #1 wire tower in the cap, and at the #1 cylinder in the block. Just like I said because this takes all the strain off the tach drive cable so it stays straight. This is one distributor cap tower position off, placing #1 wire on the window tower. A full range of the distributor vacuum can is clear of manifold and braces. This is NOT correct position according to GM details but works out well.