I have a 572 engine, indy 440-1 heads (flow 355/280), indy intake, 1150 dominator, compression is 14.6:1, cam is 289/292 @ .050 on 112 degree centerline. I have an lm-1 air/fuel meter with the sensor mounted about 6 inches away from the exhaust port in the #6 header tube (upswept dragster headers).

I am in the process of switching from gas to alcohol and I am having trouble getting the fuel where I think it needs to be. The engine ran good on gas (8.107@165) but I cannot get the alcohol carb to want to run anywhere near right.

The conversion was done to a two circuit 1150 dominator (model 7320 I believe). It is the quick fuel conversion that came with billet metering blocks, screw-in emulsion and idle bleeds on the blocks, screw-in air bleeds (high speed and intermediate) for the main body, black floats, bowl extensions, high flow boosters and .218 booster pins.

The gas carb had .053 intermediate air bleeds and .028 high speed bleeds. The alcohol conversion has .040 intermediate bleeds and .023 high speed bleeds. The gas carb runs at a lambda of .098 to 1.03 at idle and about .086 to .080 at WOT.

When I started the engine up on alcohol, it starts and idles fairly decent. I can adjust the idle screws to a lambda reading on my LM-1 meter of about .98 to 1.0 (varies about that much). I assume that lambda readings for the meter is a correct measurement and it does not need to be set up for a certain fuel. Can someone confirm that the LM-1 when displaying lambda is not fuel dependent?

When I open the throttle and the boosters begin to pull fuel , and they pull a lot of fuel. The reading drops into the .60 range and the engine stumbles badly. I have changed the main jet from .158 to .130 and the operation is still the same. It is good at idle and pulling too much fuel through the booster. The float level was confirmed, a couple of times, at being just at the bottom of the sight hole. I can remove the high speed air bleed completely and the operation is still the same (somewhat better) but still in to .6 to .65 lambda range. The emulsion bleeds have not been measured. There is an emulsion bleed in the bottom hole, then a plug, then a bleed and then a plug (bottom to top). The two emulsion bleeds appear to be about the same size. Do these bleeds control air or fuel?

I need some advice as to what to try to tune next on the carb.

Bob Spelic

The guy that did my 1050 said most of his redos of carbs that were started to be converted to E85 were started with the Quick Fuel conversion. I would send it to a carb shop that does E85 carbs. Why do I know this is because I had to have mine totally redone. Give me a PM and I will give you the guys name that redid mine.My carb came back and it was spot on at idle and just a bit lean at WOT. Alot more has to be done to a carb that is not in the kits you buy.

a little more difference going from gas-E85 than gas-methanal

my conversion works great(E85)

I am switching from race fuel to alcohol (methanol) not E-85.

bob

anyone care to post up thier jets and bleed sizes for thier alcohol (methanol) dominators?

bob Spelic

Lambda is fuel specific and needs to be set for the type of fuel you run. For example:
Gasoline lambda of 1.0 = AFR 14.7:1
Methanol lambda of 1.0 = AFR 6.4:1

The fuel pump is a COMP 250 gph electric pump, -8 lines, dead head style regulator, pressure is set to 5 psi (stainless needle and seat in the carb).

As I read the LM-1 manual, when reading out in lambda, you just make the changes to the carb to get about 1.0 at idle and .85 at WOT. The sensor, at lambda reads a certain voltage and that voltage is independent of fuel. At least that is my interpretation of what I have read. 440Jim’s response confirms that thinking, I think.

I changed the intermediate bleed to .053 from .040 and the boosters dump later in the throttle position. That seems to be going in the right direction. The carb then goes real rich so, I will increase the high speed air bleed next and get back to you guys.

The quick fuel kit is far from being anything standard. It came with .023 HS and .040 Intermediate bleeds and .188 jets. It appears, to get this carb close, I will be looking at .028 or .030 HS and .053 to .058 Intermediate bleeds and jets in the 140 range....maybe.

I am truly struggling here, but I think I am making progress. Without the LM-1, this process would not be possible and I would probably get it to run somewhat and be pig rich and burn everyone’s eyes in the lanes.

If anyone has any additional ideas, please keep them coming.

Bob Spelic

5psi? that won't do it downtrack. I know you are just trying to get it running but you need 8-9psi downtrack for most alky carbs. IMO your pump is marginal. I would prefer to see return sytle regulator your pump will thank you!! Can you borrow an "known" good carburetor to verify if yours is junk or it is your fuel system??
To bad your not closer would let you try my APD or Rupert, both are DEADLY.