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View Full Version : 86 prostar w/ new billet distributor


milehigh970
05-12-2012, 09:55 PM
Ok so here it goes... I got a 86 prostar that i just installed a new 4160 i purchased from holley and a new billet pertronix distributor on. I am having a issue with my secondaries not opening. I only pull 3400 rpm at wot. I set timing to 10 to begin with and have adjusted a lil both ways with no real change. Starts right up cold or warm. Took the engine cover off and had a buddy drive while i watched the carb and sure enough no secondaries. If i let it get to 3400 and push the secondaries open it bogs more then anything. So here is the question... How much total timing does the 351 like? I can change the springs in the distributor. Would not enough timing cause this? The spring that came in it only adds 10 degrees at 3000 and 14 at 3500. Next set of springs would be 22 and 24..

j.mccreight@hotmail.com
05-12-2012, 11:12 PM
Sounds like a carburetor problem to me, you might have a pinhole in, or deformed secondary diaphragm. Also check float levels, linkages all the basis stuff. My 89 did this before with low rpm at wot, ended up being the diaphragm was deformed. Just because the carburetor is new doesn't necessary mean the seals or diaphragms have dried out sitting on the shelf waiting on a buyer. I would check the carburetor first, before changing the springs in the distributor, but iirc most fords like about 32-36 of total timing, so you might have to go up on the springs anyway.

milehigh970
05-13-2012, 12:43 AM
Thanks for the reply. I too thought the carb was the issue till I opened the secondaries manually and she didnt scream to 4500! I have never been a v8 guy.. But would have to assume it isnt going to pull the rpm it shoild without proper timing. From my searches I think your numbers are more the range it should see. I will say when i had it at 6 degrees base it only went to about 3200 and when i bumped it to 10 I was able to pull 3500.

learjet2230
05-13-2012, 10:11 AM
Compare the secondary diaphram spring (color) on the old carb to the new one. You may need a lighter spring. Summit or Jegs sells a kit with many springs as well as a quick change kit. You could also have a leak at the base gasket that is not causing enough signal strength to open them. How did the old carb work? Why the change? Manually opening the secondaries can send you into circles because its all a Load/timing thing....not distributor timing....but rather timing of demand/load/accel pump...etc So if its bogging when YOU open them really does't mean anything YET . Get them to open under a load by themselves first.

milehigh970
05-13-2012, 01:06 PM
When i purchased the boat the PO had put a automotive carb on it and the secondaries never opened cause the butterflies were bigger then the spacer plates holes. Lol ok something i didnt think of till now.. The base gasket under the spacer was originally the 4 hole style. The only kind my local napa had was the 1 big hole.. Think this could cause a issue?

learjet2230
05-13-2012, 01:46 PM
pics?

milehigh970
05-13-2012, 06:28 PM
I can do that.. What would you like to see pics of?

learjet2230
05-13-2012, 07:24 PM
what was on there...gaskets and spacers....what you put on there!

TRBenj
05-14-2012, 11:19 AM
Thanks for the reply. I too thought the carb was the issue till I opened the secondaries manually and she didnt scream to 4500!
Agreed- if you opened the secondaries manually then those arent the problem... or at least the only problem!

A 351w will want about 35-36 of total advance, as indicated above. That means you need about 24 degrees of advance (10-12 base + 24 advance = 34-36 total).

For a test, I would twist the dizzy around as far as you have to in order to give you ~35 degrees of total... even if this means you have 20+ of initial. Then see if you get closer to 4400rpm out of it.

If so, then recurve the dizzy.

petermegan
05-14-2012, 07:36 PM
I think TR has the right idea. I think maybe because of a lack of advance it hasn't got enough vacuum present to open the secondaries. Timing or distributor advance curve possibly your problem.

mikeg205
05-14-2012, 09:15 PM
pics?

not trying to threadjack...how's your project learjet? did you finish and I missed it?

imracin68j
05-14-2012, 11:43 PM
The best thing I ever did on mine was put an HEI on it. After a coil meltdown I booted that deal to the curb. The HEI's are just about foolproof and you NEVER have to mess with them. You can get them for about 60 new on ebay.

TRBenj
05-15-2012, 09:03 AM
The best thing I ever did on mine was put an HEI on it. After a coil meltdown I booted that deal to the curb. The HEI's are just about foolproof and you NEVER have to mess with them. You can get them for about 60 new on ebay.
A distributor MUST be marine rated. They are sealed and spark arrested for safety. No doubt the one you found for $60 is an auto version.

There are only a few marine HEI distributors available for Fords. They all run north of $300, if Im not mistaken. I use a Davis Unified Ignition (DUI) which is closer to $400.

learjet2230
05-15-2012, 11:18 AM
not trying to threadjack...how's your project learjet? did you finish and I missed it?

slow, nope, and nope! keep checkin!!

learjet2230
05-15-2012, 11:19 AM
A distributor MUST be marine rated. They are sealed and spark arrested for safety. No doubt the one you found for $60 is an auto version.

There are only a few marine HEI distributors available for Fords. They all run north of $300, if Im not mistaken. I use a Davis Unified Ignition (DUI) which is closer to $400.

http://www.summitracing.com/parts/MAA-YLM554CV/

TRBenj
05-15-2012, 12:42 PM
http://www.summitracing.com/parts/MAA-YLM554CV/
The Mallory's are decent distributors. They make a points version, and 2 electronic versions (magnetic and optical). Im not sure what your point is though, as none are a "HEI" style distributor.

Marine DUI by Performance Distributors (http://www.performancedistributors.com/marinedui.htm)

old blue
05-15-2012, 06:18 PM
I just am finished rebuilding by PCM 351w and about to put it in the boat. I should correct that, I am installing a new long block. My first time with all this so am more than a little apprehensive about whether I got it all right. I installed a new Edelbrock intake manifold and also have installed the Mallory electric distributor. New plug wires and plugs. Right now I have the old coil in there and need to probably replace it before I try to start it. Which new coil? I'm little worried about wiring correctly on the Distributor/coil ect. Any hints?

Didn't mean to hijack!!

Kent