Spark plugs black
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ok good to know. I stopped driving it because I was worried about washing the cylinders
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236 Posts
If it was fuel pressure, needle and seat, or float issue, wouldn’t I see that? My bowls have sight glasses. The level is dead on at all times. No overfilling or dripping into the bores. No dripping boosters. No leaks outside the carb. Almost like a leak under the carb or baseplate.
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1,797 Posts
That will work.
For the carb can you see fuel dripping from the boosters at idle? That shouldnt be happening. Can you kill the engine by turning the idle mix screws in?
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236 Posts
No boosters dripping.
With the primary curb idle set to .020 transition, turning the idle mixture screws will kill the engine except one screw. The front left. It’s not as responsive. I can close it and the engine will still idle fine.
if I open the primary idle to .030 transition. Both fronts go dead.
anymore open than that and all four go dead
With the primary curb idle set to .020 transition, turning the idle mixture screws will kill the engine except one screw. The front left. It’s not as responsive. I can close it and the engine will still idle fine.
if I open the primary idle to .030 transition. Both fronts go dead.
anymore open than that and all four go dead
3924 is a very cold plug for Autolites. I use 3926 for my builds which are a hotter plug in order to keep them clean. I had plugs that looked liked that and it was with a colder plug which would be a similar range like yours. I would get a set of at least 3925 spark plugs and go from there if autolite. I myself use either an NGK if legit plugs as there are counterfeit plugs out there of using FR5 which is a hot plug or a FR4 which is a step hotter.
From what it sounds like to me and this is just my opinion it sounds like your idle circuit could go a step leaner as it seems you don't have much of an adjustment rage on the mixture screws in relation to transfer slot exposure. Now that is just an observation from what you posted and stuff and I would have to be there and see different things in order to be a hundred percent saying it needs to go leaner. I would have to have my hands on the carb and be able to adjust it and other factors to determine if that is a possible issue on your plugs.
The first thing I would is go to a warmer plug as that is a very cold plug your using. I would try hotter plugs first then go from there and give some time and see how they look in different driving conditions and then perhaps lean out your idle circuit on your carb by one step by going down on all four idle feed restrictors by .002 smaller and see how it does and readjust everything and see how it responds and adjusts to things when doing the mixture screws. etc
From what it sounds like to me and this is just my opinion it sounds like your idle circuit could go a step leaner as it seems you don't have much of an adjustment rage on the mixture screws in relation to transfer slot exposure. Now that is just an observation from what you posted and stuff and I would have to be there and see different things in order to be a hundred percent saying it needs to go leaner. I would have to have my hands on the carb and be able to adjust it and other factors to determine if that is a possible issue on your plugs.
The first thing I would is go to a warmer plug as that is a very cold plug your using. I would try hotter plugs first then go from there and give some time and see how they look in different driving conditions and then perhaps lean out your idle circuit on your carb by one step by going down on all four idle feed restrictors by .002 smaller and see how it does and readjust everything and see how it responds and adjusts to things when doing the mixture screws. etc
I know the head makers recommend a plug but for me it is always a cold plug and I am assuming for racing and not for a daily driver that might see stop and go traffic and for me it has never worked out. I always go with a factory plug heat range to start off with and that is what has worked for me most of the time if I am able to run the the proper fuel octane and engine temperature without problems of detonation.
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9,813 Posts
Very possible. Pull it out of the cover and leave it out for now.
Have a leak down tester?
Another easy to do test is lower the floats WAY WAY down and see wha happens. If it's better, it's a indicator of the idle feed circuits. With the levels really low in the bowls, it's much harder for the passing air to pull from any of the main circuits.
Another thing you can do is close off the front or back holes entirely. Shut off the fuel and closed the blades so the carb basically becomes a 2 barral and see what happens. Trying do the same withe other side and note any differences. This process of elimination is free other than time and might lead you to the problems.
Have a leak down tester?
Another easy to do test is lower the floats WAY WAY down and see wha happens. If it's better, it's a indicator of the idle feed circuits. With the levels really low in the bowls, it's much harder for the passing air to pull from any of the main circuits.
Another thing you can do is close off the front or back holes entirely. Shut off the fuel and closed the blades so the carb basically becomes a 2 barral and see what happens. Trying do the same withe other side and note any differences. This process of elimination is free other than time and might lead you to the problems.
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Hey great idea! I’m doing all this this weekend. I really wish I knew wtf I was doing. I been broke all my life and only during the past 5 years was I able to slowly save piece by piece and get this car together. I have researched and read a ton about these matters but have no practical real world experience. Thank you for all your help guys.
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One additional item that came to mind, I recall reading something on aftermarket metering blocks used with an incorrect metering block-to-main body gasket on the primary side.
It left an exposed channel that leaked fuel on the passenger primary side.
Maybe you've got a similar problem since you say the front left mixture screw gets unresponsive....that would be the side that could get the same open channel leak path. Plus it ties in with the general wetness you are finding.
IIRC it leaks to either exterior or the power valve vacuum cavity, or both...?
Something to look for, anyway...
It left an exposed channel that leaked fuel on the passenger primary side.
Maybe you've got a similar problem since you say the front left mixture screw gets unresponsive....that would be the side that could get the same open channel leak path. Plus it ties in with the general wetness you are finding.
IIRC it leaks to either exterior or the power valve vacuum cavity, or both...?
Something to look for, anyway...
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Or warped metering blocks leak same for main body. Sounds like a carb disassembly is in order so these flange surfaces can be inspected for straight and flat and the gaskets them selves can be looked at however unless these are the coated type gasket the standard Holley gasket usually doesn’t survive disassembly.
If the engine is not sensitive to idle mixture screw adjustment it’s getting fuel from somewhere else. That can be the transition circuit, dripping off the main venturies at idle or leaking past internal gaskets or poor fitting major parts. The latter is not uncommon.
Bogie
If the engine is not sensitive to idle mixture screw adjustment it’s getting fuel from somewhere else. That can be the transition circuit, dripping off the main venturies at idle or leaking past internal gaskets or poor fitting major parts. The latter is not uncommon.
Bogie
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236 Posts
Ok guys, here is what I have done….
I used a good machinist straight edge.
1. Front power valve is not blown.
2. Front power valve seal is good.
3. Front metering block not warped.
4. Gaskets seem great. Some kind of non stick red ones.
5. Rear PV plug good.
6. Rear PV plug gasket good.
7. Rear metering block not warped.
8. Gaskets all seem to match up.
9. Needle and seats good.
10. Main body not warped in any way.
11. No cracks that I can see.
12. Main body to base plate seems perfect.
I did notice something. The top of the base plate was not flat. I used a big file to take down the high spots. This base plate has the two plugs that separate the front to rear idle circuit channels.
Lastly, the carb card said this carb comes with 75 jets in the fronts. They are 77. That seems huge. I know the big golden rule that main jets do not affect idle, but should I go down to 75 jets?
I used a good machinist straight edge.
1. Front power valve is not blown.
2. Front power valve seal is good.
3. Front metering block not warped.
4. Gaskets seem great. Some kind of non stick red ones.
5. Rear PV plug good.
6. Rear PV plug gasket good.
7. Rear metering block not warped.
8. Gaskets all seem to match up.
9. Needle and seats good.
10. Main body not warped in any way.
11. No cracks that I can see.
12. Main body to base plate seems perfect.
I did notice something. The top of the base plate was not flat. I used a big file to take down the high spots. This base plate has the two plugs that separate the front to rear idle circuit channels.
Lastly, the carb card said this carb comes with 75 jets in the fronts. They are 77. That seems huge. I know the big golden rule that main jets do not affect idle, but should I go down to 75 jets?
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