Headhunter 395 MC on alcohol?

October 30, 2023, 04:45 PM

I did talk to James, he said he hasn't heard of anyone needing extended tipped plugs before??? I did have the Chambers 'Softened' when built. It definitely seems like the alky is putting out the spark. I'm swapping to my aluminum block in the off season, I'll check on those FR5 plugs. Sunset told me Alky would not work well.. Car runs too hot on gas to round robin. Currently running -8 heat, would a -7 help the issue?

October 30, 2023, 05:11 PM

SP 124X

quote:
Originally posted by Richie:
I did talk to James, he said he hasn't heard of anyone needing extended tipped plugs before??? I did have the Chambers 'Softened' when built. It definitely seems like the alky is putting out the spark. I'm swapping to my aluminum block in the off season, I'll check on those FR5 plugs. Sunset told me Alky would not work well.. Car runs too hot on gas to round robin. Currently running -8 heat, would a -7 help the issue?

On carbureted alcohol I like -7 they seem to get on the chip cleaner. The FR5 is a hotter plug it's a 5.

November 03, 2023, 10:57 AM

Dave Koehler

quote:
Originally posted by Doug:
anyone run alcohol successfully with Headhunter 395 MC's on a 632? I recently put this motor together with a new APD 1250 and cannot get it to run clean on alcohol, it breaks up and misfires under load, tried different heat range plugs, 8,9,10's with different gaps from .018-.030, tried timing from 32-36 degrees with no change, switched to a gas carb and it runs fine, after some research was told to put a projected tip spark plug such as a R5672A-9 with alcohol? I also run nitrous and from what I am being told, I should not run a projected tip plug with nitrous? I'd like to run alcohol with this because we have a second car on alcohol and its easier to stay with 1 fuel type, but not a big deal. It has 15.6:1 compression so I have been running C16 the last 2 weeks and it seems good but if I can't get it to run good on alcohol is it worth the extra money for C16 vs. 112? Any input is appreciated.

Late to the party and wondering.
Is your complaint when running the bottle?
Have you done your best tuning without the bottle?
Do you have enough ignition firepower for the alky?

General FWIW. I find anything over 14:1 on alky yields limited gains if any.

November 08, 2023, 08:10 AM

Doug

quote:
Originally posted by Dave Koehler:
quote:
Originally posted by Doug:
anyone run alcohol successfully with Headhunter 395 MC's on a 632? I recently put this motor together with a new APD 1250 and cannot get it to run clean on alcohol, it breaks up and misfires under load, tried different heat range plugs, 8,9,10's with different gaps from .018-.030, tried timing from 32-36 degrees with no change, switched to a gas carb and it runs fine, after some research was told to put a projected tip spark plug such as a R5672A-9 with alcohol? I also run nitrous and from what I am being told, I should not run a projected tip plug with nitrous? I'd like to run alcohol with this because we have a second car on alcohol and its easier to stay with 1 fuel type, but not a big deal. It has 15.6:1 compression so I have been running C16 the last 2 weeks and it seems good but if I can't get it to run good on alcohol is it worth the extra money for C16 vs. 112? Any input is appreciated.

Late to the party and wondering.
Is your complaint when running the bottle?
Have you done your best tuning without the bottle?
Do you have enough ignition firepower for the alky?

General FWIW. I find anything over 14:1 on alky yields limited gains if any.

_____________________________________________________________________________________________________________________________________________________________________________________________________________-

Dave,
We have determined the cam does not have enough exhaust duration to run alcohol with this combination, If I decide to switch back, I will have to make a cam swap, but I ran gas this year with no issues and I most likely will leave it that way

November 19, 2023, 08:05 PM

Richie

I called NGK to get some info on different plugs I could try...FR5 was a NO!. Besides the R5672A-8 plugs I could go w/ BKR7EIX > -7 heat range -or- if I have room a plug NGK makes for Blown & Turbo applications: FR7BHX-S (stock 92400) <- <- these plugs look really cool... I was looking to go 1 step beyond the R5672A-8 ext. tip plug and be able to gap .020, heat range stops @ 8 for those.