BIG Compression

[3gdwrench]

Hey Mark, great site with lots of info !!

I was researching thru the site here and I see where you pretty much draw the line around 16:1. It just so happens my new BBC build has just that ...I'm building a 588 with awesome flowing conv heads and big valves so we're trying to go all out so to speak and maybe you could give us some info on a couple of choices ?? Would love to see 1100 on this beast and have seen close numbers on lesser CI.

1) What would be the optimum CFM rating carb we should use ??....I've checked with alot of the name builders floating around and I hear anywhere from 1250 - 1450+ for my application. Deffinately staying with a single 4 and the car is heavy, RPM should max @ 7500

2) The compression,,,I've been knocking on the doors of a few of these other carb guys as stated , and they are not liking this kind of compression level with this fuel....and I've also researched a few other forums where I have seen the levels as high as 17-18:1 ratio's being used with e85 and they have claimed good results..

Since I am going with 16:1, can you give me a short list of the tune I would need at that ratio and reasons why it is safe at this level ??

TIA

[Mark Sullens]

Dec 10, 2012 22:58:19 GMT -5 3gdwrench said:

Hey Mark, great site with lots of info !!

Thanks

1) What would be the optimum CFM rating carb we should use ??....I've checked with alot of the name builders floating around and I hear anywhere from 1250 - 1450+ for my application. Deffinately staying with a single 4 and the car is heavy, RPM should max @ 7500

Velocity is more important than volume when Ethanol is involved, I would start for yours with a 1250 for the simple reason we want to maintain a higher vacume pull at all times....

2) The compression,,,I've been knocking on the doors of a few of these other carb guys as stated , and they are not liking this kind of compression level with this fuel....and I've also researched a few other forums where I have seen the levels as high as 17-18:1 ratio's being used with e85 and they have claimed good results..

some builders dont build the carbs the way i do and often run a leaner calibration, these leaner calibrations have blown up on higher compression engines, and instead of admitting that maybe they didnt do something right they blame the engine or the way it was built.

Since I am going with 16:1, can you give me a short list of the tune I would need at that ratio and reasons why it is safe at this level ??

I did a 500 inch single carb engine that was 16:1, the fuel is regulated to 87% blend and timing is around 36-38*, the customer ran NGK -8 plugs, but changed to NGK -7 and seen a slight improvement....for safety reasons he went back to the -8s, there is a limit on some things, and most of the time I do suggest the -7 plugs, but for safety reasons....the -8 worked fine at that compression.

hope I answered your questions.
Mark

[3gdwrench]

Thanks Mark, I'll be calling once my ducks are in a row....(right after Holidays)

[1outlaw]

3gdwrench- might want to have your cam specs ready for Mark when you call him so you know your dynamic.

[3gdwrench]

Dec 22, 2012 21:17:19 GMT -5 1outlaw said:

3gdwrench- might want to have your cam specs ready for Mark when you call him so you know your dynamic.

Thanks for the headsup....will do

[3gdwrench]

Man, it's been awhile since I started this thread and did get my carb from Mark....

Believe it or not I just fired this thing up for the first time last weekend too seat the rings and such, still haven't driven it as I still have suspension issue's to finish, but........

I can tell you one thing is for sure.... This Phucker is a BEAST !! I can't wait too get it on the tire's and rolling... Engine fired right up (new), and after a half hour of run in, the throttle is ultra- responsive and runs great. I need to do a bit of fine tuning with the idle on the next fire-up but don't see it being an issue..

I really like how clean this fuel burns also (87%) and how responsive it is....Glad I decided too go this route and hopefully in the next week or two I can get a little seat time in.....


Mark, if I have any issue's I run into I will be sure to give you a call.....

Awesome !!!...... ;D

[Mark Sullens]

thank you buddy, I know you had some questions about E85, glad you made the move, AND don't forget about the Mark Sullens E85 Carburetors tell a friend program...lol