Methanol

[billetbirdcage]

I rarely run a race longer than 25 laps at Eriez Speedway, which is basically 1/3 mile. I run with the back of the pack and have been doing well staying with those guys, especially since I'm a steel block 23 degree guy with a very old chassis that is down about 100hp from most of these guys. Looking to see if I can move up a bit with a bump in power. I'm running a mechanical fuel pump. (I know I should run a belt driven so I can have variable fuel pressure, but there is only so much money) I know I need a different one that is compatible with methanol. Is it true I want about 8.5 psi? I plan to get a Quick Fuel methanol carb. Anything else I need to know? Best top lube?
Thanks!

Everyone has their own opinion and experience so. . .

Now I really haven't messed or built motors in a fairly long time but a while back I did and have my own dyno so I'm not completely stupid.

1. Even with low compression engines alky gained about 20/30# or torque on average even with low HP (down to about 450ish) even on lower compression claimer or street type engines (as low as 10:1). I rarely ever saw any gain in total peak power just torque increase at below torque peak.

2. Most of the older alky carbs where extremely rich, especially the box stock Holley alky carbs. They came with a .125 hole above the metering block and a #80 Jet, Best power was almost always with a #46 to 52 Jet. If it was a newer carb with no hole above the jet, something in the .146 to .162 Jet size was best (least with the carbs I used - doesn't mean it can't vary from that for sure)

3. The old Holley alky mechanical fuel pump that was the smaller one (3 valve vs 6 valve - IIRC) and wasn't the super high pressure one (Thinking 7 to 9 PSI with out regulator) was only good for about 550 HP and it would run out of fuel on the dyno. You couldn't hear it, it just layed down on the top end and was down about 50 HP vs the electric pump system I had on the dyno cell.

4. Fuel pressure, What the carb can handle is directly related to the needle and seats the cabs has. A .150 window N/S can't take as much pressure as a smaller one (say .110 like a gas N/S), it's pressure vs square inches of needle/seat area. Many will over flow as early at 6 to 7 PSI and others can take 9 sometimes. Since generally the N/S is the restriction in getting the fuel in bowls (large lines and ETC), the smaller the N/S the more pressure required to flow a certain volume so with a large N/S it doesn't need anywhere near the pressure to flow the same amount. I see way to many people run way too much pressure and not large enough N/S and this causes the carb to flood over on decel and you hear the carb stutter in the middle of the corner when they pick up the throttle.

5. Small N/S and high pressure: This just Aerates the fuel more and causes more problems, think a 1" garden hose flowing fuel into a bucket. Sure you get some aeration but nothing like that same hose with you finger over it simulating a small needle and seat with higher pressure. I never used over 6.5 PSI, if done correctly you can feed a 500HP with as little as 5 PSI with the right set up and never fight float/flooding issues. I never was a fan of the high pressure stuff (over 7 PSI and especially the regulators that where throttle controlled and bumped pressure up really high at wide open throttle.


Hope this helps

On a side note, for what you spend on a new carb (maybe you need a new one anyways) you could have some simple port work done on the heads and pick up more power then you will get from a new carb by a long shot. There are lots of good small head porters out there that do good work for not a ton of money (not a full port job). I'm sort of guessing on your motor/heads to make this statement

[dfhotlm33c]

Thanks so much for the information. This is a 406, Mahle piston, Dart block, Callies rods, Scat Ultralite crank, 13.5:1 Brodix -10 SP heads ported to all heck, 2.125 valves, matched 2925 intake. Sounds like I have a lot to think about.

[billetbirdcage]

Sorry on the porting as figured you was running a more limited engine and maybe had as cast heads.

I will ask another question: I know nothing about that class or track there, but are you sure your really needing more power? I've seen it time and time again where a crate car can be really competitive against supers on smaller tracks when they aren't hammer down and your talking way less power then you should have right now.

Just an honest question

[fastford]

i agree with billet,s last statement , i was thinking a 350 with iron heads , with your combo and everything right , you should have more than enough power , especially in the slick.....

[Krooser]

Lots of good info here...

My old BG has the holes drilled above the Jets...it has the older style metering blocks with the smaller Jets vs. the newer style.

I prefer to have all the fuel coming thru the Jets to avaid any chance of fuel levels going under those small holes. I will likely use jet extensions on the rear bowl.

I bought a newer 850 a couple days ago. I'll look it over and see how good it is. A good deal @ $200.00. A new kit and some tlc may be all it needs.

As far as methanol use I don't think we've been pouring 15 to 18 gallons of fuel in my friends super..it's a 362 spec motor, Brodix heads, Willy's s 750
He runs it over 8k on Shawano's paperclip 1/2 mile. 35 laps per night plus hot laps.

[Krooser]

Just checked....Adam uses 12-15 gallons of fuel per night.

[Jim11h]

J king, I was guessing on gas but we do run rich that's true. Our biggest reason for fuel useage is caution laps. We took 620hp late model to hilltop last week and made feature so hp isn't everything. We burned about half tank in feature on methanol

[MasterSbilt_Racer]

J king, I was guessing on gas but we do run rich that's true. Our biggest reason for fuel useage is caution laps. We took 620hp late model to hilltop last week and made feature so hp isn't everything. We burned about half tank in feature on methanol

I'd be shocked if T Carp couldn't take the win at Hilltop with 620 ponies.

[dfhotlm33c]

My challenge is that while I agree a lower hp car can work under a certain set of conditions, I am still green as heck as a driver, and make lots of mistakes, and this is an old car (02 wide/combo with RR rail moved in) with a vanilla setup that I finally have working somewhat well, but it certainly isn't going to be capable of carrying the momentum and generating the traction the newer cars can..hence the desire for some "lightning in a bottle" to try to bump me up a bit...

[MasterSbilt_Racer]

My challenge is that while I agree a lower hp car can work under a certain set of conditions, I am still green as heck as a driver, and make lots of mistakes, and this is an old car (02 wide/combo with RR rail moved in) with a vanilla setup that I finally have working somewhat well, but it certainly isn't going to be capable of carrying the momentum and generating the traction the newer cars can..hence the desire for some "lightning in a bottle" to try to bump me up a bit...

You'd be surprised what an underpowered car can do when you use all of it. That chassis needs a front clip in a bad way. I get your struggles.

[50j]

Krooser, carburetor technology peaked decades ago. I don't care how super their bowls are, the new stuff isn't gonna make a difference. Use what you have.

With all due respect, this is completely wrong. The older carbs would corrode, the throttle shafts stick and rust, they are usually excessively rich at idle and part throttle. GOOD modern methanol carburetors don't have these faults. Cheap ones still do.

[MasterSbilt_Racer]

With all due respect, this is completely wrong. The older carbs would corrode, the throttle shafts stick and rust, they are usually excessively rich at idle and part throttle. GOOD modern methanol carburetors don't have these faults. Cheap ones still do.

If that is true (I've not had much issue with my old junk) how much is it going to mean on the stopwatch to his car? He's on a budget, I'm trying to help him get on the track.

[50j]

Something that's dangerous or that shortens engine life is neither really cheap or likely to help lap times. It's your car and your budget though so you have to make that decision. I understand where you're at.

[MasterSbilt_Racer]

Something that's dangerous or that shortens engine life is neither really cheap or likely to help lap times. It's your car and your budget though so you have to make that decision. I understand where you're at.

I guess I was just lucky running 20 year old Holleys in the 90s. Never have I had a carb stick. Krooser also never really said how old his carb is. There is the best available and satisfactory, I get that too.

[50j]

My experience with those back then was that they have cast base plates that corrode, warp, crack and pit. The butterflies and shafts rust. Most of them had 2 or 3 turns on the return spring to try to get the throttle NOT to stick. They had brass floats that would collapse or epoxied floats that would lose epoxy and clog jets. The zinc bowls and metering blocks would corrode and pit if not carefully taken care of. They would use more fuel than needed down low. Good new ones have those problems addressed. Bad new ones do not. My opinion is that if you drive a truck, haul a couple of loads, buy a good modern carb and have money left over in the same amount of time you spend agonizing over trying to rebuild worn out lesser parts. We all have a certain number of hours in a day to use. How do you get your best return for your time spent? Opportunity cost. Best of luck, and I do sincerely hope it works out.