CarburetorsCarb discussion and questions. Upgrading a Third Gen carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
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What I'm building is a 421 SBC.. have the short block all assembled and ready to move onto the top end..BUT
should i go ethanol or not?
I have read the articles on here for the most part and it has just added to the mixed feelings about goin to it..I wouldnt mind being flexible to be able to go between the ethanol and premium gas with just a carb swap and gasket change.. so i have some questions and need help/advice
I plan on dropping the money on a good carb from the get go (quick fuel)
What is the range of compression that best suits e85?
It gets cold up here in Mn come fall mornings, whats the cold weather starting like and I see the chokes arent really and option with e85 carbs?
Does anyone know if with QFT's E85 carb all the up jetting "issues" are already taken care of? I know that it takes roughly 30-335 more fuel to use E85
Help and advice are very much appreciated!!!
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I dont know much about the carb aspect of your build but I can say that set up right you can actualy use about the same amount of fuel most of the time compared to gasoline. SAAB/GM was the first to pull this off with both gas and E85 in a SAAB model not available in the states. I assume it uses SAAB's variable C/R technology as aposed to the fixed C/R used in most flexfuel cars.
Thats with EFI though and tuning the car to run lean combined with very high comp ratios. Since Ethanol burns so much cooler both conditions are much less critical than with gasoline.
The temperature difference is so drastic that I have seen one or two ethanol powered cars street driven with no cooling system at all.
In the winter, they drop the percentage down to somewhere in the 70 range for easier cold starting. Not a problem for flex fuel vehicles, as they just monitor the percent of ethanol to gasoline and adjust for the particular ratio you have.
But, a carb can't do that. And, in spring and fall, you'll be getting somewhere between 70 & 85%. Unless you're willing to measure specific gravity at every fill up and jet accordingly, you're going to have problems.
I'm running E85 in the '57, but I only get fuel from the track, where I know it's 85%. Last spring I got desperate and got some from the filing station, took me several races to get rid of the stuff so that I could start depending upon the car again - not good in bracket racing.
You can convert a Holley with QFT's E85 metering blocks - that's where 85% (no pun intended) of the changes reside. The squirters are the other piece. That way you could run a 4150 model carb with choke on E85.
It is a bear to start when it's cold and you don't have a choke. Having a squirt bottle with gasoline handy would make it easier (although I haven't actually tried that).
They make one in a 850 cfm with a choke.. but it seems to be a proform carb..
I know proform main bodies are nice, but what about their other stuff? like the bowls, metering blocks?
This thing is a street car..it will get raced very little.. so looking to get best streetability and willing to give up a little of the needed things for a good racer..
I was checking into heads and saw dart makes a 49cc combustion chamber head with a 230cc port volume, that would get me approx. 14.5:1 on compression.. is that too high to run e85??
I hadn't seen that outfit before. Looks like they use Proform parts and calibrate for E85. I also didn't know Proform made a mainbody with a choke. I have a chokeless Proform mainbody, and had their billet metering blocks for awhile. I was hoping to recalibrate the main emulsion bleeds and PV & idle restrictors, but finding the parts became difficult, and a precision drill bit set cost as much as the QFT E85 metering blocks. So, I got the E85 blocks and sold the Proform billet blocks on eBay.
The Proform parts were high quality. But, I haven't seen their fuel bowls, I assume they're good parts.
I also went with the QFT alcohol throttle plate. The original Holley plate had issues, otherwise I wouldn't have worried about it.
You might be biting off more trouble than it's worth. I'm running E85 for improved consistency at the track and the ability to hot lap. If this is a summer-only driver for you, it might be okay, but the E85 consistency issue might still cause you problems.
14.5:1 is a little high, but manageable. 12.5:1 is the typical number people quote, 13:1 if aluminum heads.
My 396 is a little limited with the 750 CFM and cam I'm running now. An 800 would be better, 850 probably wouldn't hurt. But, I'm not sure the budget would support a new carb right now. Too many other things going on.
I just started switching mine over this week. So far it's running pretty good, my idle vacum is better than I ever had on gas. I was able to run alittle more timing judging from the hard start I had on gas, which went away on
E85. I've gone up from 70's in the front to 82's (biggest i had). Probably end up with 85's or so when I'm done. I'm waiting on my larger jet set to show up tomorrow from jegs. I'm also swapping the squirter for a larger one. I'm sticking with my demon other wise, unless I can't make it run good. I think it's almost there as of now though.
No more black soot on the plugs either which is nice, so I got that going for me.
I'll post more results this weekend when I get the intake back on and it jetted alittle richer.
That's ok with me. If I can get the numbers nailed for rejetting twice a year then I can live with that. I did notice a huge difference in price at 2 different stations here. One is $1.74/gl and another is $2.11/gl. Does summer and winter blends have a different price affect on it? Or is it just stations naming their own price.
It's a station-to-station thing. The Conoco at Broadway and Alameda seemed to have the lowest price, but I haven't followed it lately.
One station set it at their unleaded regular price - of course, they were the station closest to me.
As I mentioned earlier, the main problem will come when the station has half a tank of 70% and fill it with 85%. Unless you check alcohol content every time you fill up (and you could do that), you won't know where your jetting should be.
Sorta another issue I will be running into if i go green..
Mn seems to switch to grade two already in sept/oct and to grade 3 by end of oct. then they dont go back to a grade to till april and finally go grade 1 by may..
being a street driven vehicle that would have me rejetting twice or three times a year just because of fuel switch.. but when to knowthat they switched grades is the fun part.. I really dont feel like testing fuel every fill..
curious.. Five7 you have ran it on the street ever look at MPG?
Bit silly to ask that since these are performance engines and already have low mpg because their nature..but any guesses?
I think that your going to run into the same issues on regular gas at some point through the year. They change to winter and summer blend on it as well. Maybe gas isn't as finicky when changing the mixture. I'll never go to a station on half a tank of anything anyway. Only when it's empty. I'm not to worried about it, but if I have issues I can always go back to my gas jets. (Which I'll probably carry in the car just in case of emergency)
curious.. Five7 you have ran it on the street ever look at MPG?
Bit silly to ask that since these are performance engines and already have low mpg because their nature..but any guesses?
No, never have. I drive it to the track but that's all. 3.73 gears (now 4.11) and 3500 stall (soon to be 4000) with no overdrive or lock-up isn't the stuff MPG is made out of.
I have ran out of fuel several times. All but once I had a 5 gallon can in the trunk ready to go.
