hope to

Timing can only be set with distributor gear installed with dimple pointed away from rotor tip! There is not room between intake runner and coil bracket to set timing with distributor gear properly indexed to rotor. It lacks about 10 degrees of advance when all is correct. 66 327, 350 HP. I have tried everything to rectify this situation to no avail, hope someone has run into this and if not a cure perhaps a reason. Just about crazy trying to figure this out!

silver837

Do you have the correct coil bracket ?

DansYellow66

It’s not too uncommon and doesn’t hurt to run it 180 degrees off. I guess you’ve checked the position of the #1 cylinder terminal on the cap against the service manual for your year.

Boyan

If everything aligns up and allows adjustment…..what’s the problem?

hope to

Yes, the plug wires are properly situated in the distributor cap. And, the car runs ok with the distributor gear 180* out of phase. And the problem I guess is in my hard head. If the GM engineers wanted the tip of the rotor and the dimple on the gear aligned then that is how I want them too. There must be a reason for this situation - something is wrong and yes I can compensate and cover it up but in my eighty years on this earth I have learned that two wrong things are seldom the way to make one right thing. Is this a common occurrence? Are there other engines that have the distributor gear 180* out of phase? I would like to correct this, or if not correctable would like to know what causes this issue and if others have had the same problems and what did they do.

Boyan

Maybe your dimple got punched on the wrong side….and as far as you mention, EVERYTHING lines up…so I don’t know what you mean by 2 wrongs…..

63 340HP

It is a known result from how some aftermarket cam's distributor drive gear is indexed and cut. It has no effect on performance, other than the (hidden) dimple to rotor alignment.

Replace the cam, or live with knowing why it's indexed that way.

R66

Let's step back and start at the basics.
1. Is this a new to you C2 or did you do anything that may have contributed to the problem (e.g. rebuild the distributor, cam change, intake change, etc.).
2. You have the GM snowflake intake for a 66 327 or an aftermarket?
3. If the vehicle ran well before pulling the distributor, what prompted the removal?
4. You double checked to verify the rotor is clocked properly with the square peg in the square hole and round peg in the round hole? I have seen them forced on 180 degrees out.
5. You verified the advance weights are free and springs are good.
6. You used a piston stop and determined #1 TDC and the mark on the harmonic dampener is correct?
7. You verified the firing order per the GM Chassis Service Manual

Here is a picture of R66 distributor set at 10 degrees mechanical advance and the relationship to the intake runner. The driven gear on the distributor is clocked to match the rotor.


Note there is still a bit of clearance between the vacuum can and the intake runner.

I have found most of the time when it won't fit, it is something I did wrong and have to start at the beginning again, although that may not be your case.

Ron

Sky65

Look at the gear tooth closest to the roll pin on the dot side of the gear. Then look at the gear tooth closest to the roll pin on the opposite side from the dot. What you will see is there is about 1/2 a tooth difference. That allows the 1/2 a tooth adjustment if you need it for distributor clearance. All that said why yours needs the 1/2 tooth adjustment I don't know. R66 has some good ideas.

Tom

C2Dude

Just to back up what was said earlier, I have the same situation. The explanation I was given here is that somewhere in the 50 something year history of my 66 an aftermarket cam was installed, presumably after an engine rebuild. Cam gear has to be 180 out of phase to time her. She runs great.

hope to

To answer some of your questions: The rotor is on correctly, square peg in square hole. Car runs ok with gear 180 out, cannot set timing when gear is installed correctly with rotor tip and dimple on gear lining up.
Damper was rebuilt by damper dudes. The reason for posting this is because stuff such as this just simply drives me crazy. Guess that just running it with the gear 180 out of phase will have to do but had hope someone would have an explanation. And that explanation seems to be that the camshaft gear was made with improper indexing of the gear. Thanks for all of the replies, I appreciate the help that is always offered on this forum.

tbarb

Don't let it drive you crazy, your engine is fine. The answer as stated above is that the replacement aftermarket (non GM) camshaft in your engine has the gear that drives the distributor gear not indexed on the camshaft like the GM made camshafts. This results in the situation you describe and the solution is to simply rotate the distributor gear 180* which allows the initial timing to be set and the vacuum advance control to fall in the middle of it's very limited travel on the Corvette engine.

data174

It’s also possible that the distributor was installed 180 degree off. Some times this is a common mistake.
When you line up the TDC it must be on the compression stroke.