Fuel PSI for the Indy 440-25

[AtomicWedgie]

I am trying to get my 440-25 set up. I had a backfire mishap while loading the car onto the trailer. It blew the top off and destroyed my hood.
I inspected the intake and no real damage. I didn't realize when I bought the intake that the bolts Indy provided where way to short. They only attacked the top to the bottom with a few threads. When it blew off it striped the top few threads in each hole. I installed longer studs and they threaded right in so no real damage.
I think I found out why it backfired. I think I had a vacumm leak. I didn't seal the spacers to the intake. So I am going to do that but also the carbs were dumping a lot of fuel into the intake on the right side(pass). When I took the top off the carbs the right bank had fuel in it and the left had none. Is this normal?
Today I sealed the spacers and set the float levels per Edelbrocks reccommendation. Tuesday I will seal the top to bottom and get the carbs back on.

What fuel pressure should I be using with this intake? I am using 7.5psi now but is that to much? Should I be using 6-6.5psi?
I also locked my distibutor at 34* timing; is this ok for low RPM use. What I mean is would this affect the off idle performance. The car ran great in the garage before I moved it out into the street to load it up on the trailer. I left the car running and got out to lower the rear door, got back in the car and gave it some gas and that is when I had an earth shattering Ka-boom. I don't think the timing is the issue but I am trying to cover all the bases.

If I can't get this figured out I am going to switch to a cross ram set up but I would rather run this one.

[texoutsider]

You are not the first to do this...........a very common problem.......get in touch with Damon Kuhn at Diamondback........he can get you sorted out.........

Mark

[whompinwedge]

yea Id call Damon he will hook you up.

Didnt we warn you to put a blow off valve on? lol we did the same thing not sealing the spacers too.

Casey

[Dave Schultz]

Yup there are two type of people with those intakes -- those who have had a backfire, and those who will. I never allow for starting the cars in the trailer,

Get a NOS pop-off valve

Have your machinist fix, and tap for a little longer bolts -- but a back backfire with longer bolts will only tear more of the intake up.

The backfires occur more because of gas puddling in the intake than because of fuel pressure. On a cold engine -- I give three quick pumps, then roll the starter to suck the fumes out of the intake before hitting the ignition. On warmer engines -- one pump then roll over to suck the fumes out then give it fire.

Fuel pressure is a matter of dispute, and I'm guessing it has a lot to do with the power of your engine and carbs. Some run 5-7 pounds because more will spring leaks in the carbs -- and others free the carbs can take it and run 7-9 pounds.

[nssracer]

My dad blew up the the prototype of this intake. I have raced one since they have been out. I have never blown one up. First on a cold motor pump the the throttle 3 times and open the throttle almost half way. Spin the the stater over and the hit the ignition. Another factor is a weak battery. A strong 16V battery is best but if you have a 12V system keep your battery fully charged. Most of these explosions occur in the trailer after the car has sat for a period of time. Thanks, Doug

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[Dave Schultz]

The only one we blew up was on the red Coronet after Dallas had changed the gas pedal in the car. In the process of pushing pedal and holding down to get the cable on and adjust -- too much gas puddled in bottom of the intake. If he'd thought more about that -- he would have rolled the starter for a lot longer before giving it fire -- but he didn't and it blew the shit out of the intake and a nice little fire that he was able to suck out.

We immediately ordered pop-off valves and installed them on all four Indy NSS intakes. We've not yet had another backfire to see how effective the pop of valves are.

Another thing (I'm sure you know -- but in case you don't) -- if you backfire and see flames, roll the starter without gas or fire to try to suck out the flames. These things can flame up pretty good on a backfire -- and this is why we never start the car in the trailer.

[fugly]

If they are stock Eddy carbs, keep them at 7 or under. If there is alot of puddling, either you floats are too high and it's percolating or you have a weak needle and seat. Just for the record, I am not personally a big believer in the need for the pop off valves- can't hurt, but I can't tell you how many thousand times I have started an engine with that intake and I have never blown one. Two of the best keys are what Doug mentioned- strong battery and throttle open- not too far.....if you don't already have it, you should have an ignition switch and a start button- get the engine spinning first and then hit the button- if it spins slow, you are a prime candidate for a backfire especially with a long duration cam. Another thing I do is turn the fuel pump on for a few seconds to prime the carb, pump it and start-only after it lights off hit the fuel switch again- this way if something does go wrong you are not pumping fuel to the fire

[nssguy]

I don't run an indy intake, but always turn the fuel pump off and let the car run a minute or two to empty out the carbs before shutting off the motor.
this will keep any gas from seeping into the intake when sitting for any time.
This may be why those intakes always blowup in the trailers

just my 2 cents

[texoutsider]

the term is "Mag Start"...........spin er over and then throw the fire to it.........

M.

[AtomicWedgie]

I know these are prone to backfire during start up. I have taken all of your advice on start up and I am sure that I have the start up down. BUT this didn't happen during start up. This happened while the car was running and gave it some gas to get it moving.

I DO HAVE A POP OFF VALVE ON IT!!!!!

Anyone want to buy a slightly used Indy 440-25 intake set up(with pop off valve)

[fugly]

if it was running and backfired, it likely had a major vacuum leak and went lean, not rich and or the timing was not right- from your description ( I re read) I believe you are correct on the spacer seal- it does sound like the carbs may be set rich and overfeeding- there is some mismatch in flow depending on the size/rpm range of the engine, but there should be no more than staining/ wet spots if it was running- any more than that and you have a carb feeding too much at idle- more often than not this is due to the metering rods "fluttering".....proper spring setup will eliminate that

[Dave Schultz]

The intake can be repaired. Mine was in pretty bad shape and needed some material welded onto it and retapped.

Bummer that a pop-off didn't help to keep the lid on. It must have been a Hell of a backfire

[AtomicWedgie]

Believe it or not there was no real damage to the intake. It stripped of the first couple of threads per hole but I installed longer studs and they threaded right in with no issues.

FUGLY: Are you talking accelerator pump spring?

[fugly]

metering rod springs

[poppaj]

I think that the duration on some cams cause this to happen on certain motors, in your case there is other isssues it sounds like fuel is seeping in at random. I was thinking you bought the whole setup new from Indy. I always check needle and seats and float height along with installing lighter springs. Don't give up on the setup yet. poppaj