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.

Just run gas. It's better all around. My 632 wasn't happy on alcohol either.

Did you call APD I doubt they would have built you an alcohol carb knowing it wouldnt work. Belt drive or electric pump?

As for gas I have a friend with a new 615 with the APD 16 degree heads. The builder dynod it on c14 he's run it on c14 and x16 with no noticable change in performance or in the o2s.

Yes, APD built the carb as per the specs I supplied from the engine builder, they have been great to work with as they have been researching a solution and will convert the carb to gas for me if needed. It has a Magnafuel 500 pump. We dyno'd it on 112 but never tried alcohol because the carb was not ready at the time

quote:

Originally posted by SP 124X:
Did you call APD I doubt they would have built you an alcohol carb knowing it wouldnt work.

They’ve built many carbs that didn’t work, gas and alcohol, mine included, also many with blades hanging up, the threads are here.

APD is great to work with. They helped me find the problem with my Duke engine that wouldnt run on Alky. Talk with John and he will get you squared away.

Not the experience of all, just do a search here

quote:

Originally posted by 1320racer:

quote:

Originally posted by SP 124X:
Did you call APD I doubt they would have built you an alcohol carb knowing it wouldnt work.

They’ve built many carbs that didn’t work, gas and alcohol, mine included, also many with blades hanging up, the threads are here.

Big difference between missing a build and building a carb for a head they know doesn't like alcohol.

You assume they know and it’s not missing the build when you let countless carbs go out the door with blades hanging up

Big difference between missing a build and building a carb for a head they know doesn't like alcohol.[/QUOTE]
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agreed, but it can also be put on myself and the engine builder as I specifically stated that I wanted to stay with a 24 degree head to be able to run alcohol, I would have built an SR20 motor if I knew I had to run gas with the 395 MC's. Wasted time and money because I didn't research enough I guess

Doug

Moons ago I ran a 565 with 383 HH heads with both an alky carb and Ron's injection. Both worked very good. You are running a 632, the larger motor does complicate things a bit as it requires more fuel! I ran 30 degrees of timing also. You can get this to work on alky but it will run faster on gas. Do you have a data logger with O'2? This would be helpful.

As for projected plugs vs non with NOS. If you are running a smaller shot don't worry about the tip length and we either plug type, keep the timing conservative and you won't have an issue! I also ran NOS with the injection setup, but I did use gas for the enrichment fuel. NX has a good alky NOS kits! Use them!

Not the same combo but I had a similar issue on a 582 several years ago. Projected tip plugs did help and I have ran them ever since. I am a little suprised they didnt reccomend a 1450 carb for this engine.

My 632 with conventional Pro-Filers needed a projected plug to run clean on the dyno with my Ron's injection. It was fine on gas with the R5671A plug.

I've been running the FR5. There aren't any available specs on projection length, but the pics on NGK's website appear to show a slightly longer tip on the FR5 when compared to the R5672A. It is also a resistor plug, and pretty hot. I've been running it since 2017 with no issues.

quote:

Originally posted by cartman:
Not the same combo but I had a similar issue on a 582 several years ago. Projected tip plugs did help and I have ran them ever since. I am a little suprised they didnt reccomend a 1450 carb for this engine.

I'm surprised as well, although I did try a friends 1450 gas carb last week and it made no difference over the 1250 I had on it

Of course it didn’t, typically they have the same throttle bore. Forget claimed CFM, it’s all about throttle bore size. The big power 632’s of friends and competitors have 2.375 throttle bore carbs and they all run gas.

quote:

Originally posted by Lenny5160:
My 632 with conventional Pro-Filers needed a projected plug to run clean on the dyno with my Ron's injection. It was fine on gas with the R5671A plug.

I've been running the FR5. There aren't any available specs on projection length, but the pics on NGK's website appear to show a slightly longer tip on the FR5 when compared to the R5672A. It is also a resistor plug, and pretty hot. I've been running it since 2017 with no issues.

Is that fr5 plug part number 7373?

quote:

Originally posted by 1320racer:
Of course it didn’t, typically they have the same throttle bore. Forget claimed CFM, it’s all about throttle bore size. The big power 632’s of friends and competitors have 2.375 throttle bore carbs and they all run gas.

Thank you, I think that is the best route, I can see it being a waste of time trying to make it run good on alcohol

quote:

Originally posted by SP 124X:

quote:

Originally posted by Lenny5160:
My 632 with conventional Pro-Filers needed a projected plug to run clean on the dyno with my Ron's injection. It was fine on gas with the R5671A plug.

I've been running the FR5. There aren't any available specs on projection length, but the pics on NGK's website appear to show a slightly longer tip on the FR5 when compared to the R5672A. It is also a resistor plug, and pretty hot. I've been running it since 2017 with no issues.

Is that fr5 plug part number 7373?

Yes, that's the one.

If you dont have atleast a 308 exhaust lobe, and a 115 centerline, nothing will prolly fix it. I have an alky injected 632 with profiler 174x, with ti valves, and it takes autolight 3934 or ngk -8 to keep it lit. -9 plug will miss when up stairs.

quote:

Originally posted by 329L:
If you dont have atleast a 308 exhaust lobe, and a 115 centerline, nothing will prolly fix it. I have an alky injected 632 with profiler 174x, with ti valves, and it takes autolight 3934 or ngk -8 to keep it lit. -9 plug will miss when up stairs.

296 @ .050, 114 centerline