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Discussion Starter #1
I have a 3 circuit 1050 that was worked over to 1100 by pro systems. From the time I put it on it would not idle, flooding and hard to crank, car started overheating and it doesn’t want to rev. When I hit the throttle it will get up to 4500 and just seems to go flat.. We went over the floats and mixture screws but nothing seems to work.. It came setup 82/92 jets 36 high speed, 76 int, 60idle, 4.5 front PV and plugged rear.. I swapped to 80 primaries and 2.5 PV and the idle improved slightly.
414 SBF
.688/.688
280/290 @.050
114 L/S
11.5 compression
2828 intake
 

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Seems like there are more issues than the carb itself.
Try a different carb - borrow one from someone.
This will let you know what issues are still occurring.

I would ditch the power valve.

Why such a high duration low lift cam? What is the application? 8500 rpm on pump gas?

Cheers
 

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Switching jet size and power valve have nothing to do with idle circuit at all. Power valve should be based on cruising vacuum, not idle vacuum. I would plug the power valve and square jet to 88 for a start. After you figure it out, you can go back to a power valve and reduce jet size about 6-8 sizes if needed. The 1100 rating of your carb is just a 1050 run on their flow bench that says it is 1100. Salesmanship. They don't open up the main body to flow more, just a cartridge roll finish of a stock body in many cases. No problem with that if that's the size you need. JMO.

Dominators need a lot of timing at idle to burn fuel due to low signal in a big plenum manifold. at least 25 degrees if not locked out. A lot of carburetor problems are timing and ignition related.

Patrick James has his own site with a "Ask the carburetor man" section, prosystems.com I think. Ask away. He may not answer on the weekend. They also rebuild their own carbs for a very reasonable price.

If that carb was not built for you for that engine it may need tuning to get it better.

Transfer slot exposure under throttle plates, transfer slot fuel restrictor orifice and idle fuel restrictor orifice and lower placement that stock position are important to tuning. These are what you pay for when you buy a custom carb, but some still are stock when you look close.
 

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Good info Mark.

The "1100" I received from Pro Systems has a 1.72" venturi instead of the 1.69" from Holley. I suspect that is where the extra 50 cfm comes from?

Primary transfer slot setting before bolting on carb is what I always do. Set idle by changing secondary throttle.

You may also require a T-slot restrictor. 0.058" worked out extremely well on mine.
Eliminated the part throttle richness that I had been chasing.

Idle spark advance (as Mark suggested).

Check fuel pressure. Pro Systems use 0.130" needle and seats. 6 psi is more than enough.

Cheers
 

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Discussion Starter #5 (Edited)
I just received this carb from Pro Systems last week. I sent in a Holley 8896 to be built to work with my application. Fuel psi is set at 6psi and timing is locked at 35*.. This engine previously had a 950 on it that worked perfect. I swapped back to the 950 and all the problems were cured so that leads me to believe the problems are with the carburetor.. This is a nitrous engine that does get driven on the streets 20-30 miles at a time and sees 7000-7200 rpm. When checked it was pulling 5” of vacuum in gear so I had a 2.5PV in the 950, that is why I decided to give it a shot in the Dominator.
 

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I have one that I pulled my hair out with until I switched it from 3 circuit to 2 circuit. In some situations the 3rd circuit is not worth the trouble. Also did transfer slot restrictors like Mark mentioned.

JmarkAudio and several others on here guided us through doing the conversion years ago.
 

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Eljefe pulling 2 out of the PMJ and changing the PV shouldn't have affected the idle. Do you know what idle jet size it has in it? I think the idle jet, with the 60 idle air jets and the idle mixture screws are where you are going to fix the problem.

I would try upping the idle air some since it is easy to do. Might need a smaller idle jet but that is inside on the blocks.
 

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Discussion Starter #8
Eljefe pulling 2 out of the PMJ and changing the PV shouldn't have affected the idle. Do you know what idle jet size it has in it? I think the idle jet, with the 60 idle air jets and the idle mixture screws are where you are going to fix the problem.

I would try upping the idle air some since it is easy to do. Might need a smaller idle jet but that is inside on the blocks.
Would that be the same as “Idle Feed”?? If so the build sheet has it listed at 38
 

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I have a 3 circuit 1050 that was worked over to 1100 by pro systems. From the time I put it on it would not idle, flooding and hard to crank, car started overheating and it doesn’t want to rev. When I hit the throttle it will get up to 4500 and just seems to go flat.. We went over the floats and mixture screws but nothing seems to work.. It came setup 82/92 jets 36 high speed, 76 int, 60idle, 4.5 front PV and plugged rear.. I swapped to 80 primaries and 2.5 PV and the idle improved slightly.
414 SBF
.688/.688
280/290 @.050
114 L/S
11.5 compression
2828 intake

what idle rpm are you trying to get it at?
whats the timing set at,base?
fuel?

did youi check float level?

what fuel press?
 

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Discussion Starter #10
I have a 3 circuit 1050 that was worked over to 1100 by pro systems. From the time I put it on it would not idle, flooding and hard to crank, car started overheating and it doesn’t want to rev. When I hit the throttle it will get up to 4500 and just seems to go flat.. We went over the floats and mixture screws but nothing seems to work.. It came setup 82/92 jets 36 high speed, 76 int, 60idle, 4.5 front PV and plugged rear.. I swapped to 80 primaries and 2.5 PV and the idle improved slightly.
414 SBF
.688/.688
280/290 @.050
114 L/S
11.5 compression
2828 intake

what idle rpm are you trying to get it at?
whats the timing set at,base?
fuel?

did youi check float level?

what fuel press?
1200-1300 is where it idled with my old carb. Timing is locked out at 35. Floats were set to barely trickle out when plugs are removed and fuel pressure is set to 6psi
 

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Give the builder the complete info on the combination again along with your issues and work with him before taking any advise from us. Then if he can't fix it, including taking it back to his shop and redoing it, ask for a refund and start over with another builder. Just my advise.
 

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Give the builder the complete info on the combination again along with your issues and work with him before taking any advise from us. Then if he can't fix it, including taking it back to his shop and redoing it, ask for a refund and start over with another builder. Just my advise.
x2 great advise
 

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Would that be the same as “Idle Feed”?? If so the build sheet has it listed at 38
In my experience, Patrick's carbs do respond well to changes. Also in my experience, 0.038 IFR - Idle Feed Restriction or "Idle Jet" is usually on the big side. 0.060" IAB is also probably on the small side. Both of those items individually make the carb richer at idle. Both together = even more rich idle.

You may have more signal at low/idle speed than Pro Systems was expecting and hence pulling more fuel.

Idle settings were the main thing I had to change on my similar 1050/1100 - 8896 Pro Systems carb. I'll dig it out of the attic this weekend and see what the last settings I ended up with.

Jason G.
 

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the car has issues and you don't know your way around a carb. get it back to the builder and resolve your hard starting problem. You are flooding the engine trying to start it.
 

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Discussion Starter #18
Ok guys, I tried changing IAB and adjusting mixture screws as instructed by Pro Systems and problems still remain. Went both up and down on air bleeds with no real change.

What could be causing the car to heat up so fast after simply swapping a carburetor? Roughly 5 minutes of run time and temp is 195* vs only 165* with my 950 after a 30 mile cruise in 95* weather.

What are some other things I should look at as far as the flooding?? Fuel barely trickles out of bowl when car is rocked. Tried plugging power valve and using 86/86 jetting.

Nothing seems to work with this carb but anytime I swap back to the 950 car goes back to running fine.
 

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Does the carb have a adjustable idle feed brass threaded restrictor orifice? Does the carb have an adjustable transfer slot restrictor? If you have the build sheet it should give those specs. What are they?

How much of the transfer slot is showing below the throttle plates? Are both primary and secondary the same. Usually a .040" square is showing when adjusted correctly.

Are you sure you did not readjust anything else in the combination when you put the new carb on?

Was the carb built for this engine? Any carb builder relies on what info you give him to set the sizing and flow on a custom carb. I have worked on several used Pro Systems carbs for different engines than they were built for. It does take some tinkering then, but nothing magic about it.

If you want post up the specs from the build sheet and the combo it is on and you might get some good help here or talk to Patrick and give him another chance to help you.
 

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Discussion Starter #20
Does the carb have a adjustable idle feed brass threaded restrictor orifice? Does the carb have an adjustable transfer slot restrictor? If you have the build sheet it should give those specs. What are they?

How much of the transfer slot is showing below the throttle plates? Are both primary and secondary the same. Usually a .040" square is showing when adjusted correctly.

Are you sure you did not readjust anything else in the combination when you put the new carb on?

Was the carb built for this engine? Any carb builder relies on what info you give him to set the sizing and flow on a custom carb. I have worked on several used Pro Systems carbs for different engines than they were built for. It does take some tinkering then, but nothing magic about it.

If you want post up the specs from the build sheet and the combo it is on and you might get some good help here or talk to Patrick and give
him another chance to help you.


Neither the idle feed nor transfer slot restrictor is threaded. Build sheet says 38 Idle feed, 86 trans, 86 PV Feed, 40 Int feed, 60 IAB, 76 Int Bleed, 36 HSAB. Both throttle blades are pretty equal with roughly .030” of transfer slot exposed (not sure how to post build sheet).

Nothing about the combination was changed, simply a carb swap to get rid of using this 4150/4500 adapter.


414 SBF
225 Highports
Edelbrock 2828
11.7 compression
688/688. 280/[email protected] 114L/S
 
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