Vacuume advance

Engine, ignition, fuel, cooling, exhaust

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slamons
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Vacuume advance

Post by slamons »

Replaced points with petronix...Awsome...Problem is under load, first strating out, acts like missing, Fine at idle and hi speed. Could this be a problem with the advance, and if it is how do I check and fix problem?????
Jake11
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Re: Vacuume advance

Post by Jake11 »

Take the hose off and see if it works better!
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theskytoucher
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Re: Vacuume advance

Post by theskytoucher »

Also make sure you have a full 12v to the pertronix system!
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two-bit
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Re: Vacuume advance

Post by two-bit »

I second to check on the 12vlt thing. I have run across a few guys who put these in various makes and models of cars and have had problems thru the "spark range".
The original wiring in your bump for the coil is not 12vlt, its usually between 6 to 8vlt. The wire that goes from the back of your ignition switch to the "hot side" of the coil is a resistor wire. It has an in-line resistor some where along the way that drops the voltage from 12 to 6-8. This was done as common practice by lots of manufacturers to keep the points from burning up prematurely. Points don't like 12vlt. Never have, never will.
If you had no hesitation/running problems before you put in the electronic unit, then i would check your voltage feed.

However, i could be wrong.
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cdherman
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Re: Vacuume advance

Post by cdherman »

You do have a timing light, right? First off, just hook up the timing light and rev the engine up. Should advance pretty quickly up to 16 or 18 deg ahead of where it was at idle. It will advance much quicker at no load, but on the road, since its lugging, the advance curve will be later (as the vacumn being produced is lower with a load).

If you get advance that way, then your vacumn advance canister is likely OK. But the Pertroix unit may not be opening the points (it has a solid state equivalent of points) at the same time as your original points were. Would have been useful to hook up a timing light and just see where you were at before you took the points out, but its too late for that......

Even if you didn't turn the dizzy at all, the mechanics of the Pertronix setup may have changed with regards to the location of the "points".

You need a timing light. Takeing off the vac hose and seeing if it helps is OK, but I doubt highly that the problem is too MUCH vac advance. Too much advance causes pinging (detonation) not dogging as you describe. At least in my experience....
65 f-100 SWB, 240 I6, T-18, now swapped to C4 with difficulty. Yeah, I know. Its a 67-72 site. But my frame and entire drive train are just like yours!!!!
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