48 Weber IDA hard to start when hot
#1
48 Weber IDA hard to start when hot
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
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
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Adolf Hitler Verfechter
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#11
RX for fun
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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.
#12
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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.
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Adolf Hitler Verfechter
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Wacky,Doesnt it also depend on the jetting? I`am waayy hell and gone 5800 feet above sea level here.
Last edited by karism; 09-10-07 at 08:22 AM. Reason: stupid ass smiley
#17
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.
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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.
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.
#19
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.
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.
#20
Lives on the Forum
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...
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...
#21
Blood, Sweat and Rotors
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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?
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?
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