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Discussion Starter · #1 ·
EDIT-I could not get the fuel pressure low enough(below 15) to run the carb, so i used a gravity feed system for testing.

I need to know if I can run a carburetor with an 190lph EFI fuel pump. Basically i have it set up with the BOSS EFI system right now like this.
Pump->Filter->Pressure Regulator->Dual Feed Line
With a line at the bottom of the regulator that drains back to the tank.
If i can run it like this then what sort of pressure would i want the regulator set at??
Thanks!

Also, what size carb do you think would work best with a 331 with an air gap dual plane intake.
It needs to be a 4150 style carb

[ October 17, 2007, 05:38 PM: Message edited by: cobrastang ]
 

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FFCobra Craftsman
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I have a 347 with Air Gap and run mechanical pump at 7 lbs. I recomend the AED 650HO which is a "prepared" Holley (choke horn milled off, holes in the throttle plates etc. Mechanical secondaries and runs great right out of the box. Above all FIRST CLASS tech support (they respond to e-mails Sunday night!!!)
Steve
 

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BLUBLUR
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5 - 7 psi will be good. I have mine at set at 6psi...Speed Demon Carb. I would say 650DP for yours.
Be sure your return line is bigger than the supply line.
 

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Discussion Starter · #4 ·
I have 6AN line run already for both sides. I just need to make sure i can get the pressure low enough with the 190lph pump that it will work.

Basically, we are trying to figure out what is wrong with the BOSS EFI system. They sent me a new computer which arrived today, but it didnt help. i have replaced the distributor and the coil and that didnt help. I have checked top dead center 900 times along with the plug order. I have also readjusted the valves. The only way i can get the car to run is at 50 degrees advanced and its not pretty. I've turned the distributor around about 8 times and it alwasy shoots fire out. So, everytime i check for TDC i take the spark plug out and put my finger in the hole until air starts to come out and then i located TDC from that point.
I have no idea what is wrong since the system ran with the Mass flo unit installed. It wasnt perfect, but it was running well enough to drive without bellowing black smoke etc.

So, if it runs with the carb then i will be able to say its the system and not something like the camshaft.
 

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FFCobra Fanatic
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650 holley or holley clone will be fine for that engine.
Hate to see you spend that sort of money if it's not the answer to the problem. do you have a carb local to try instead?
How did the engine run with the mass flow installed? Good the way it should have or just ok and barely got the job done?
Has engine run well since built? Can't recall if all problems were ever corrected.
When you check for TDC. Did you remove the passenger side valve cover and visually verify both valves closed and truley on tdc and not 180 off?
Should be able to tell cam's timing if in doupt without removeing timing cover.
Use dail indicator on #1 valve,positive piston stop in #1 cylinder,marks on balancer or better yet inexpensive degree wheel on crank.
You can also verify what fireing order cam has checking this way and watching the valve movement.
What kind of vacum does motor pull once it's running? Should be alot at 50* timing. Needle steady? Cost labor instead of dollars to check cam timeing opposed to replaceing induction set up.
 

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Land Shark!
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Do you know what cam is in the motor? I had a similar issue and it turned
out that even though I have a 302, the cam is a 351 firing order.
 

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Discussion Starter · #7 ·
The cam has a 351 firing order. I watched the valves when i was adjusting them the other night to confirm just incase Compcams screwed up.

I dont know what could be wrong besides something in the wiring. The car ran before.


I have not removed the valve covers to verify TDC. I was only sticking my finger in the Number 1 plug hole and feeling for the air to come out of the cylinder. ONce that happened i watched the dampner so that i could set the timing mark. When i flip it 180 from where it is now it just shoots fire out the throttle body.

I've been at this for three weeks now so its embarrasing and frustrating. I'm trying not to spend money, but when you get desperate and can only elimanate one thing at a time thats what happens. I've been on the phone with retrotek for hours and hours and they have viewed the system from their computer as well. They are convinced that something is wrong with the timing since we took the TFI distributor out of the equation and it ran the same. I'm going to check the vacuum for you in a little while as soon as i can get a chance.
Thanks so much once again for your help and insight.
 

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Can you plug in a manual vacum gauge. This will verify the electric reading your seeing.
6" is too low and -6" is'nt really possible on a n/a engine at idle.
What are the cam's specs,mostly duration @ 50?
Radical cam will be a good 11" or so.
A severe vacum leak would cause it to be lower.
As would retarded ignition or valve timeing = low vacum.
Needle would still appear steady with either timings too retarded.
A moveing/flickering needle shows more of a cylinder dependant problem,such as valve seal or ignition fireing to that cylinder.
Can you give macahnical vacum gauge reading?
Can you pull pass. valve cover and verify(again) tdc but knowing for sure both valves are closed,but also with dial indicator along with spec's on cam;s card. Tell exsactlly when the #1 intake opens and close's useing the marks on balancer. Balancer marks will show if cam's timeing is suspect since if even off by a tooth the coarse balancer marks will show it. Degree wheel if possible makes it easyer and more accurate. You do know for fact,marks on balancer are correct?
Another check if you can. While engine is running although rough. If you slowlly lower your hand over the intake of the throttle body. Does engine seem to respond by gaining rpm's?
Trying to get idea of afr at idle and if adding to problem.
Since on screen vacum reading is off from accurate. It may be possible the system is useing vacum as well as other parameters to adjust mixture. If true the actual afr at idle would be extremelly rich since computer believes engine is under a heavy load by the lesser amount of intake vacum.
Let us know what you find.
 

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Discussion Starter · #10 ·
Cam specs at .50 are
lift .565/.574
Duration: 232/240

I just bought a new guage(backed over the old one somehow) so now i can test for vacuum. Where should i take the reading-off of the manifold or off of a t-coming from the line that runs to the MAP??

Balancer marks were dead on when i assembled the engine. I marked the timing chain with paint and checked it with a ruler.

A/F said 14 when running at around 1,000rpm

Yes, it seems like it is running really rich. I've unplugged the fuel injectors when the system gets flooded and then started it and it seems to run real nice at idle with just that remaining fuel in the engine.

I've got a carb hooked up now and i will test it in about an hour. The battery was dead so i am letting it charge for a while.
I'm guessing that i must have some massive vacuum leak somewhere and i hope it isnt where the heads meet the intake(lower portion) from where i ported them to match the super victor manifold. If that's the case then its not going to be good.
 

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Those cam specs look for around 13" or so vacum.
Be interested to hear the results once you fire it up.
Vacum leak still could be possible cause.
being electronically controled afr. It may be over fueling due to a vacum leak. Also show itself with low vacum reading once running.By over advanceing the ignition timeing you could have been providing just enough manifold vacum to allow engine to barely run.
Check vacum at intake manifold below throttle plates.
 

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Discussion Starter · #12 ·
Well, i got the boss EFI hooked back up and started it with the gauge attached to an intake runner. It reads 5" of vacuum.
I guess i have aleak going on somewhere, which disturbs me since i sprayed carb cleaner all around the intake to see if the rpms would go up and nothing happened. I am praying that its not leaking into the valley, but if it is, then i guess my only recourse is to buy a victor jr intake to seal it..
 

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You need to swap out the fuel pressure regulator for one designed for a carb. I just did this exact thing when installing a carb. I am still running my high pressure EFI pump, but with a carb regulator that is adjustable between 3 and 15 pounds.
 

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Discussion Starter · #14 ·
Its ok with the boss EFI because it requires 45pds. I was just testing the car to see if it would run with a carb so that i could eliminate all other problems before i pulled the manifold.

So, here i go to pull the manifold-yea fun

[ October 17, 2007, 05:35 PM: Message edited by: cobrastang ]
 

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Discussion Starter · #15 ·
Well, i think the problem was been located. When i started to pull up on the manifold it realeased right away. I didnt have to put any strength into it to get the rear and front seals to come loose.
I measured the thickness of the silicon at the front of the intake and it was .001"(about as thick as 3 pieces of stacked paper) Pretty much the intake was touching the block. The gasket stuck to the block, but not to the intake at all.
Now i just need to figure out what gaskets to buy that are thicker. I was using the 1262 ford gaskets.
 

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Read your other post on manifold fitment.
Replace or machine the intake to get a better seal.
The efi was probally covering up the leaness caused by the leaking intake seal. Reason rpm's did'nt increase when sprayed with carb cleaner.
 
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