Hey guys I have a 12A full bridgeport with a 48IDA carb. My jetting is this- 220main, 110air, 65idler, 40mm chokes with F11 emulsion tubes. My timing is close to 22 leading and 12 trailing BTDC. I am running Racing beat road/race header with 3" exhaust all the way back to RB 3" muffler.

First off, what do you think of my jetting? Second, when I turn the car off hot and try to restart it is real hard to restart. I have to floor the gas pedal to get it to start which leads to me thinking that it is floodeding maybe? Do you think this is what's happening and if so why? Or do I have another problem?

Thanks,

Jarrett

 

Pull the plugs and let me know.

 

jetting sounds good.. check the compression of the motor when its hot please

 

junk it

 

Pulled the plugs and they are black and fouled.

Robert, my tools are at work so I'll get the compression test done tomorrow.

 

Thanks for the help, *****.

 

fuel pressure? floats too high?

 

Fuel pressure is at 5psi and I'll have to check the float.

 

crack the throttle open slightly before you crank, hold it slightly open as you crank.
works for me on my weber'ed scoob.

isaac

 

I agree.I have had lots of hard starting problems with my float that was to high.

Make sure its not too high.

Allways helps to open the throttle a bit when hot starting with a IDA Like flight-of-pain said

 

Actually none of the ones I have done including the IDA's in my RX-3 and FB require any of the above steps. Just turn on the key for a few minutes (to allow the fuel bowl to fill-up) and start away. As Robert noted, hard starting on a hot motor is a sign of low compression.

 

I don't know a damned thing about these carbs, but whenever I hear "hard to start when hot" I automatically think of timing.... Probably way off base, but thought I'd throw it out there anyway. Good luck man.

 

Wacky,Doesnt it also depend on the jetting? I`am waayy hell and gone 5800 feet above sea level here.

 

Provided that the engine has a good compression (hot), a hard starting will occur when the idle circuit is clogged (this occurs also when cold) and flooding due to improperly set float.

 

Is fuel pressure at 5 psi too high for a weber? I know it is for a Dellorto and they are very similiar.

 

I tuned my carbs on different fuel pressure and used the best one. Im above 5psi.

 

Well, bad news for me. I did a compression test with the engine hot and got- front rotor-75psi and rear=65psi. I bought this engine second hand and have no real info on it other than it looked recently rebuild due to visable signs of hylomar. The engine doesn't smoke and even with those compression readings runs pretty strong. This is my first bridgey so I have no other comparison. My only hope is that maybe the motor is still beaking in and may gain some compression in a couple of weeks of driving. If not, time to break it down and rebuild it myself. I had a chance of checking the compression before buying and forgot my guage so i just listened to it run and checked for smoke. It started right up and I got a killer deal, so I bought it. So let this be a lesson to others to check the compression of a used engine before buying, especially if the engine is in a car running that way you can check for oil buring, coolant burning, overheating and compression.

 

A full ported race motor has lower compression than a stock port motor. Don't worry about those numbers being low - I would worry some about their being a 10 psi (15%) difference between the two. Still, the low compression is not the main reason it is hard to hot start.

My Peripheral port road racer has about 60 psi cranking compression - normal for race porting. Hot starts sometimes take a little while - you must have a good, very strong battery and cables and starter motor. My PP motor likes me to pump the gas pedal once or twice before hot starting. Warm starts take a half a gas pedal pump. Cold starts take 8 to 12 gas pedal pumps before cranking.

 

Thanks, that makes me feel a little better. On cold starts, my engine fires right up with just a couple gas pedal pumps on hot it takes about 5-8 pumps and sometimes i have to hold wide open. I'm going to check my float level and double check that too. How much timing can I run on this bridgeport? It seems to run alot better with alot of timing. Right now I am at about 35leading and 16t btdc at 5000rpm's. If I run any lower the engine will hesitate and bog between 4000rpm- 8000rpm's. Am I just way rich?

 

You might want to try running some Seafoam through a partial tank of gas to free up any sticking seals. This can raise the compression back up if you have anything stuck in there.

Not sure about the timing you've got, but I think that's a bit too far advanced. Wait for an expert to confirm this...

 

Boy, 35* total advance is a lot. Anything over 30 is getting dangerous and you really don't get much more HP above 30 and it's in detonation territory. One tank of bad gas is all it takes at >30.

Why not go down to 28.5, that's what I run on my J-bridgeport and it has ceramic apex seals which like and want more advance than carbon or stock. U got carbons?

Is the hot motor heatsoaking up the manifold and heating the carb? Causing fuel boiling or vaporlock? Do you have a phenolic or rubber spacer between carb and manifold? And a aluminum heat shield over headers?

I think the air jets are too small. RB specs 170 air jets with your motor yet you have 110 air jets = much richer on topend and since the smaller air jet = less signal bleed off, the mains will come online earlier = richer. The 220 main fuels should be close with 40mm chokes.

RB:
12A Bridge Port Engine
(Equipped with open headers)
12A Engine
Venturi - 42mm • Fuel Jet - No. 240
Air Jet - No. 170 • Emulsion tube - F-11
Needle Valve - No. 300

If it's too rich the motor would like more timing to start the fuel buring process earlier........

Where in CA are you? And the AEM UEGO wideband really helped me tune my REPU's carb. It's worth it. What color are the plugs still?