Dieseling

[Germy]

New demon carb, runs great idles great, but when i turn it off its putters off real bad. Im assuming timing. Is that where i should be looking?

 

[Scooter402]

That's where I would start. I had that issue with a 383 when I had just finished swapping it into my CJ. I chased it around for a while, but after I had gotten rid of the cheap eBay distributor I had in it, and ponied up for a full MSD ignition system, the problem was solved. IMHO, dieseling would be caused by timing and possibly too much compression for the fuel you're running.

Do you happen to know what your compression ratio is? What fuel are you running? Was any head/deck work performed, and what type of pistons are in the engine?

 

[Germy]

I have an hei dizzy, the build was completely factory other than a mild cam. Pistons everything to basic specs. I ran 87 but this is the first run with the carb. The old carbs idle screws did nothing and the choke didnt work, it was timed to that bad setup. Would advancing or retarding be the direction to go?

 

[Old Dog]

You need to retard it a couple degrees. Where do you have it set now?

 

[Germy]

Ill check, mechanic set it when i had intake issues.

 

[Old Dog]

There's also the chance you got some bad gas. Have you filled up lately.

 

[Germy]

About 3* before tdc

 

[Germy]

Just fully filled before carb change

 

[Germy]

3* btdc seems way off, shouldnt i be in the 10 atdc ballpark

 

[Old Dog]

I'm not a 360 guy but I would think it should be more like 8/10 BTDC.
3 would be on the slow side.
Makes me think it might be some (bad) low octane fuel.

 

[Germy]

Advancing is atdc and retardingg is slowing or btdc

 

[Germy]

The mark is to the right of tdc 3 degrees

 

[Scooter402]

Advancing is atdc and retardingg is slowing or btdc

Other way around -- advancing is BTDC, retarding is ATDC. I was going to say the same thing, in that 3 degrees before would be a bit too retarded. I would also agree with Old Dog, with aiming for 8-10 BTDC, as long as your total doesn't go over about 34 degrees BTDC all in.

 

[Germy]

I spead it up and reduced idle screw. Now there is a popping in exhaust. Gonna check plug gaps, they were the culprit after the kast rough run

 

[Germy]

10 degrees

 

[Scooter402]

I spead it up and reduced idle screw. Now there is a popping in exhaust. Gonna check plug gaps, they were the culprit after the kast rough run

idle speed or idle air mixture screw?

 

[Germy]

Idle. Im not touching mixtures

 

[Germy]

.035 gap on a AMC 304 , same on 360?

 

[Old Dog]

Other way around -- advancing is BTDC, retarding is ATDC. I was going to say the same thing, in that 3 degrees before would be a bit too retarded. I would also agree with Old Dog, with aiming for 8-10 BTDC, as long as your total doesn't go over about 34 degrees BTDC all in.

What Scooter said

I think you have a HEI right? if so you should be able to open the plugs up to .040 to .045

 

[Germy]

Gapped to .040 and tweaked dizzy. Too loud for neighborhood, test run in morning.