Dual vacuum distributor with Pertronixs

cvicky

cvicky

Senior Member
I do not have the history of the car, it's a 272 V8 and I am running it with the vacuum disconnected (busted). It starts ok, and idles ok, but misses when I try to accelerate when driving car. The car also has a 4 barrel holy Tpot. The accelerator pump seems to be OK. The Napa coil is putting out 2.2 ohms.

Is it a carb issue or distributor issue??
Thanks
Cvicky
 
Distributor issue. It's not advancing, causing your misfire. You need to fix that before attempting further diagnosis.
 
1956 dual diaphragm distributors only had vacuum advanced based on a lower vacuum signal from the Holley teapot carb. Max of 4" of vacuum. No centrifugal advance. Without the vacuum lines hooked up, you are only getting the base timing ignition advance. The spark will never change from that, and the engine will have very poor performance and outrageous exhaust temperatures.


Sal
 
Rockauto lists the distributor but only on a return and reman basis. Prices range from about $80 t0 $120 plus the ride.
 
cvicky said:
Dual vacuum distributor with Pertronixs

I do not have the history of the car, it's a 272 V8 and I am running it with the vacuum disconnected (busted). It starts ok, and idles ok, but misses when I try to accelerate when driving car. The car also has a 4 barrel holy Tpot. The accelerator pump seems to be OK. The Napa coil is putting out 2.2 ohms.

Is it a carb issue or distributor issue??
Click to expand...

By DUAL VACUUM, are you referring to the LOADOMATIC SYSTEM or a/the 1956 DUAL DIAPHRAM?

PERTRONIX only regulates the intensity of the spark and has nothing to do with timing advance. Do you have the proper SHOP MANUAL to follow a diagnostic sequence?

What year and model is the car?
 
1) You need to verify vacuum signal from carb


2) Verify advance diaphram holds vacuum


3) Verify dist plate moves freely


4) Verify correct initial timing and curb idle
 
cvicky said:
what year distributor is the best for yBlock with Tpot

some say 57 with single vacuum
Click to expand...

It all depends if you want the car original or performance.

The easiest way out of it is with a 57/59 - 60/ Y-BLOCK dist. This will also require a later style carb (H4000 does not have correct vacuum signal) or a CARTER WCFB of the period (so that you can retain your present intake) to deliver a ported vacuum signal for the advance.

The LOAD-O-MATIC can be repaired/modified. It all depends on how you want to go.

Referring URL- http://m571.com/yblock/loadomatic.htm
 
cvicky said:
what year distributor is the best for yBlock with Tpot
some say 57 with single vacuum
Click to expand...
Teapot carbs from '55 and '56 are vacuum pressure matched to a distributor from only that year.
Does your dist look like the one in the photo below?
What year is the carb you have? '55 & '56 aren't always the same.

A '57+ distributor is the better dist but needs a vac signal from a '57+ carb to advance the timing correctly. I've been told the teapot carbs can be modified to work with a '57+ dist.

Attach a photo or two of the distributor you have. The carb too if you aren't sure which one it is.

Driving the car without timing advance can burn the exhaust valves and fracture exh manifolds.
https://www.ctci.org/gilsgarage/CrackedExhaustManifold.php

A Pertronix kit in the distributor only replaces the points.
It does not control or alter any other functions of the distributor... or repair other worn, faulty or damaged parts. A '55/'56 kit will not fit in a '57+ distributor.
.
 

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I have modified a few of the teapots as Teds article explains with success.


Using a 57 distributor and the mod Ted came up with works well.


EXCEPT - the teapot carb bowls still leak down after a week or so of sitting. The addition of an electric pump used on startup fixed that situation also.


Oldmics
 
I think Mac's still offers a replacement dual vacuum can assembly, but some of the resto suppliers have discontinued the standard single vacuum unit for the 2-bbl carbs. If you need to replace you vacuum unit, now might be a good time to order one (unless you decide to swap out the dizzy altogether with a '57 or later Y-block dizzy AND more modern carb for use with the mechanical advance distributor).
 
The 55 can take either of two PN's for the advance diaphram depending on the DIST I.D.No. -

FAB 12370-A or B5S 12370-A.

Both seem to be available NOS.

The thing is, if the carb and/or distributor is updated and the car is totally original or a dedicated restoration, it may hurt re-sale value. A buyer paying big bucks is going to want the real thing.

I wouldn't drive it much unless to keep the car lubricated as the absence of the advance feature isn't good for the engine.

HOLLEY also offered dualing point mechanical distributors during this time frame so there is another out.
 
Here is a basic synopsis (?) of the LOADOMATIC DISTRIBUTOR from a knowledgeable poster familiar with them-

From The Y-Block Forum- http://forums.y-blocksforever.com/P...eIndex=3&Task=PostQuotedReply&ParentID=138631

56Roger (8/3/2018)

I am not posting on this thread to agree or disagree with anything anyone else has posted, although most of it seems more or less valid given the context.

What I can say is I have two Sun Distributor machines, a 404 (1970) and a 504 (1974, real close to the end of the line). Spent an inordinate amount of researching, learning and working on these machines. I love them. Anyone in the old car (restoration, repair, hobby, general information exchange) probably should love them too. Even the full blast youngsters with no other experience than late model computerized stuff should love them too. These machines will tell you everything there is to know about what is happening with your ignition whatever type of distributor you have. If you have a distributor you can benefit from using on of these machines. The computerized stuff does the same thing with only a more refined way of doing it. And I don't have a problem with that, just not my bag. But if you learn the old way you understand the modern way and you have a leg up on those that don't. Nothing new under the sun.

That said, there is an accessory, for the (so called) late model machines that I have, which is specifically designed to test/set up Load-O-Matic distributors on said machines. They call it a manometer type unit, as Miker mentions. Those distributors were out of date (waay out) in 1970. So much so that even the top distributor machine company of the time did not offer it as standard equipment when there was a chance there were some still in everyday use. The machines I have are equipped with vacuum pumps that simulate everything necessary to know for "ordinary " distributors right up until distributors disappeared. But the Load-O-Matic is a different thing all together.

I have never seen one of these test units (pictures, manuals, anything) in any of the research I've done, nor heard from anyone that used one, or any other evidence of one. My only advice is if you have one of these distributors, yank it. Box it up and save it for someone else that absolutely has to have it. Don't waste anymore time /money with it. Nothing to be gained except more trouble every time you have to deal with it.
Click to expand...
The thing is, this system does work, but requires extensive knowledge and tools to maintain it. Everything is adjustable and at one time the knowledge was pretty common I would think.

But the quickest and easiest way out is to update the system.
 
I have and have used the Manometer on my Sun distributor machine on the Load "O" Matic distributors. ( Ford sure named those distributors correctly as they are LOADS ! )


I currently have it removed from the machine to clean and rebuild the unit.


Thought I would post a few pics of what the tool looks like. Its a somewhat rare item as most of them get destroyed.


Oldmics
 

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