John, As I understand your post about a 2 x 4 car, I would want to remove the gear and rotate it 180 degrees and re-install to make a vacuum advance single-point distributor work. Correct? I have a 59 2 x 4 car that has the 891 dual-point distributor. I wanted to install a single-point vacuum advance distributor to make it run cooler and be more enjoyable for the street. Did you orient the the distributor differently when you re-installed? Thanks in advance.
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Re: Distributor Indexing for John McGraw w/2x4
Mark,
The distributor will only rotate a few degrees without hitting the manifold. We tried moving one tooth on the distributor gear, but it took it too much the opposite direction. we also tried indexing the wires differently on the cap, but that didn't do the trick either.We had to index the gear backwards, and that allowed it to move 1/2 a tooth away from it's original position. Plan on pulling the distributor at least a couple of times to get it right.
Regards, John McGraw -
Your results may vary.
The dimple alignment works in all Corvette engine applications about 95% of the time. I think the exceptions are the result of poor manufacturing tolerances in the indexing of the 1) advance cam on the top of the distributor mainshaft, 2) distributor bottom gear retaining pin hole, 3) distributor drive gear teeth on cam, or 4) cam timing gear dowel pin hole. And then there's timing chain stretch in an old engine.....
My advice is to try the distributor as-is. If the vacuum canister doesn't fit, then turn the bottom gear around.Comment
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Re: Your results may vary.
I would agree with Jerry, try moving the distributor one a tooth at a time and see if you can hit it right before changing the gear index. Let us know how it works out.
Regards, John McGrawComment
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Re: Distributor Indexing for John McGraw w/2x4
Mark, your car should run cool enough with the 891 distributor. Have you checked it with a dail back timming light to make sure you have enough advance? Have you replaced the radiator core?
My 56 2X4 would warm up in traffic too.I found a 56 dist with a vacuum advance and thought i'd try it. Instead I recored the radiator with a Dewitts core and it did the trick. I also set the timming at 38 - 39 degrees total advance at about 2500 rpms.Try the timming first. It's much better to watch the road and the behinds in short shorts instead of the gauges .Comment
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Re: Distributor Indexing for John McGraw w/2x4
I have wondered about using a vac advance distributor instead of my dual point set up to improve the fuel economy. I would be curious if you or anyone elso saw much improvement when such a swap was made.Comment
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Re: Distributor Indexing for John McGraw w/2x4
Doug reference your question about fuel economy. My experience is not with a dual point and no vacuum advance, but with a single point distributor and vacuum advance. My 70 came from the factory with a emissions component that would not allow vacuum advance unit function 100% of the time. Gas mileage in city driving improved 2-3 miles per gallon when I disconnected the vacuum going to and from the emissions component and connected a vacuum line directly from the carb to the distributor. This improved city mileage. When the turbo 400 shifted into 3rd the emissions component would permit full vacuum to the distributor vacuum advance and highway mileage was not restricted, so straight highway mileage was not affected by the change, but in your case it would. The emissions component would also allow full unresticted vacuum if the engine temp escalated in city driving which would help the engine run cooler. So with a vacuum advance distributor there are two benefits, cooler runing engine and increase in fuel economy.Comment
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