A tune up place took my distributor out, and put it back in. Now it starts and runs when the number 1 plug wire is to the right of the adjustment window
(driver's side). If I move it to the left side it won't even start. Plug wires are in correct order. Can the distributor be put back in off a notch or two?

Many Thanks,
COC

 

In a word - YES. The distributor is driven by a gear off the camshaft,

It's very possible that the place that pulled the distributor put it in a tooth (or two) off.

It really doesn't matter where the distributor is (with respect to the intake manifold - in terms of rotation) as long as the timing is right, and the wires are in the right order.

 

Absolute utter NONSENSE!!!

No more than two weeks ago I started a thread explaining in great detail how to properly install a distributor if you want your engine to perform properly, and it starts with proper removal. This thread also has input from Lars, and it was very received.

STOP POSTING MISINFORMATION!

The mechanics who worked on the OP's car are hacks and should not be in business working on old Chevrolets. Anyone who can change a light bulb should be able to correct improper distributor assembly and installation by following the step by step instructions.

Duke

 

From your description the plug wires are not properly indexed. The distributor is also likely not installed properly and who knows how the dimple is oriented. If the plane of the cap window is not near perpendicular to engine centerline with the initial timing in the normal range, then there are one or more problems with the distributor assembly and/or installation.

​​​​​​All right-left references to a car should be from the viewpoint of the driver sitting in the car. Therefore, the PASSENGER SIDE is RIGHT, not the driver's side, so you need to remove the distributor with the crankshaft properly indexed. Verify the orientation of the DIMPLE. Then proceed to install it properly and perform static timing. Then install the #1 wire in the correct cap terminal and the rest IAW the firing order.

Once you have a little experience static timing you don't even need a timing light to be confident that you got the proper value within a degree. Like Lars said, this is the way airplane engines are timed, because you don't want your head in the engine compartment live timing an engine with your body inches away from a spinning propeller.

Duke

 

This is the exceptionally well written thread that Duke recently posted. It's worth saving as a PDF or printing for posterity.

https://www.corvetteforum.com/forums...sb-and-bb.html

 

Thats what Ive always thought, so please explain why #1 on the cap needs to be on the right terminal next to the window ?
I’ve read above article but Im still trying to get my head around why this is critical and what the negative effects may be ?
Im not an engineer obviously, so please don’t flame me, Im just trying to improve my tuning techniques



You can see in the above photo #1 is way off where it’s supposed to be, I’ve corrected that now and timed it again, but there was no noticeable difference in idle quality or WOT performance.
I’ve re read the article again, but it’s late, so I must me missing something ?
Thanks for your patience, hope you can enlighten me.
Cheers

 

I have to agree with Duke.

When I recently pulled mine last weekend I simple read his-and Lars instructions---followed them explicitly---very clear and easy to do by the way----the car started up without even a short spin and ran like a top.

The instructions in PDF form are right here for the taking. This is no secret! If you cant download the PDF simply copy the text and paste it into a text document and print it.

There is absolutely no need to re-invent this particular wheel.

Thanks again Duke and Lars.
Best
Eddie

 

I believe a lot of this stems from the need to time the engine AND have the disributor parts fit inside the shielding. This is one of those things that depend on starting with the crankshaft being in the TDC position on the compression stroke. The camshaft rotates at half of the crank speed. If you aren't careful the cam will be 180 off. It's really not that complex. Once you have done a few it's easy. The ignition shields are a Corvette only thing.

 

I can't find it now, but I believe there was a GM Service Notification that advised mechanics to rotate the distributor one tooth to better align the tachometer cable to reduce breakage for C3s. This required moving the plug wiring one hole counter clockwise to put #1 on the right side of the window when facing the distributor. I don't believe this would have any negative affect on performance, but that is just my uneducated opinion.
Ron

 

Ron,
This may be what you're thinking about...issued in December, 1967. There was a distinct reason for doing this for the '68 model year...it's all in the bulletin.

 

Thanks Leif, that is the one. You just proved my wife wrong, I can be right once in a while.
I can't see how GM would recommend this if it affects the performance. The small block Chevy didn't change between the 50s and 70s.

 

Ron,
It's not that it won't run if done like this, it's just not correct. When it's so easy to do things, like this, the correct way why not do so?? If everyone is singing off the same song sheet, it makes diagnosing problems sooooo much easier.

 

There are 208 combinations of wire indexing, gear tooth engagement and dimple indexing - eight wire combinations times 13 gear tooth engagements times two dimple indexing choices. Not all of them yield satisfactory rotor alignment with the cap terminals at the firing point, and this can result in poor driveability such as was the case in this thread.

https://www.corvetteforum.com/forums...-resolved.html

Due to limited rotational freedom of the distributor and the need to have the tach drive reasonably aligned so as to excessively bend in the tach cable. there are a limited number of these 208 combinations that might work, and I'm not interested in testing all to find which ones might work, so I default to the way Chevrolet assembled and installed the distributor.

I figured it out 60 years ago ("the dimple issue"), and I've been helping guys correct screwed up distributor assembly and installations ever since.

I don't know the details of your installation, so I cannot comment on it. Maybe it works, but maybe it doesn't, and you just don't recognize the problems it might be causing.

I'm a mechanical engineer (BSME, MSME), been working on cars since I was a teenager, and my first job was as a production engineer at Pontiac in the late sixties, so I know my way around cars pretty well.

I've also been involved with some pretty sophisticated math - a fluid mechanics problem I had to solve in grad school that required me to develop and solve a system of partial differential equations.

About 20 years ago I ran across a textbook on Einstein's General Theory of Relativity at a library, and since it has always fascinated me, I checked it out to give it a read. Einstein's theory uses some very sophisticated math known as tensor notation that I had never previously been exposed to, and try as I might, I just couldn't get through it and had to give up.

Sometimes you just have to take things on faith, and in the case of Einstein's General Theory of Relatively I decided to take it on faith that gravity really does bend light waves without understanding all the details.

Duke

 

Hi Duke, I'm not doubting your credentials and no disrespect, but that doesn't really answer the question.
The 1968 service bulletin posted above, revises the plug wire indexing for better clearance on basically the same engine.
If it's just to get enough distributor adjustment between the intake runner and the shielding bracket ? Yes, I can understand that.
But I have to wonder what other possible problems there could be by indexing the plug wires one or two post around ?
Cheers
Dave

 

A bit over the top there, Duke. What the guy said wasn't incorrect. The engine (ie: the individual cylinders) DGAS how the distributor is installed as long as the timing is correct. It's the packaging issues caused by the shielding and the tach cable that complicate things in Corvette applications. A simple "Yes, but ...." detailing the packaging constraints would have worked just as well.

 

The TSB reads "The distributor on the 1968 Corvette 327 cu. in. engine has been rotated clockwise to gain needed clearance between the tachometer drive and firewall."

Understand that this applies to C3 Corvettes that have a completely different body, and the cowl is in a different position relative to the engine. It's my understanding that this was done to provide a more gentle bend for the tach cable, and it appears that this particular setup, one of the 208 possible combinations, did not result in rotor misalignment that could cause loss of spark energy that causes driveability problems like what occurred with the '65 L-78 in the thread I referenced.

Assuming you have a C2, perhaps you could try out this C3 setup and determine if is causes any issues with tach cable routing, VAC placement, and/or driveability issues. Let us know?

Duke

 

At this point I'll leave everyone to their own devices. Good Luck!

Duke