E85 Carb for Pontiac 400 - Chevelle Tech
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post #1 of 29 (permalink) Old Jun 19th, 20, 9:53 AM Thread Starter
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Gene
 
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E85 Carb for Pontiac 400

Has anyone done the E85 Holley conversions? Am considering going that route on my 72 GTO due to ~10.25:1 requiring 100 octane fuel. 100 octane is up to $10/gal right now and I am sick of paying that. Not sure where to start in selecting a carb. Do I need to replace all the fuel lines due to varnish being cleaned out by the ethanol? Is there a reliable way to flush out the varnish?

For reference, there is a long assed thread about when I bought my GTO and finding out it could not run on 93 Octane like the seller told me here: https://www.chevelles.com/forums/18-...ithout-11.html

I have not really driven the car much due to the 100 octane issue, nor have I found the time to do a deep dive into deciding to rebuild the 7K3 heads to get the compression ratio down or go with an E85 setup. E85 is readily available around here and that option seems like the cheaper option unless I'm dealing with a new gas tank and all new fuel lines.

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post #2 of 29 (permalink) Old Jun 19th, 20, 10:51 AM
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Tom
 
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Re: E85 Carb for Pontiac 400

Remember 100 Octane back in the 1960's and into the mid 1970's was rated as Research Octane of 100 required for the cars then, by todays method (R+M)/2 you would be looking for 96 Octane. I run pump premium and a bottle of Lucas Octane Boos in my 1969 Grand Prix - since premium here is 91 plus 3 from the Lucas I achieve 94 octane. I do have to reduce the timing by 5* but the high compression 400 runs fine and hard on that combo.
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post #3 of 29 (permalink) Old Jun 19th, 20, 11:05 AM
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Re: E85 Carb for Pontiac 400

have you looked at 100LL-aviation fuel;
at smaller airports you can drive up to the pump and fill up 5-gal. jugs and fuel tanks;
i did use this fuel for years both straight and mixed 50/50ish with 91-octane premium...
last i used it was still less than $5-perGal..
my compression was 11.6 with iron heads on a 427bbc + L88cam...

68-Malibu 427bbc/t4oo/3.73-12bolt/pro charger f1-r
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post #4 of 29 (permalink) Old Jun 19th, 20, 11:32 AM
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Re: E85 Carb for Pontiac 400

I've been running E85 for the last 2 year. I love the stuff! Cheaper than 87 octane with much more octane than premium. Your mileage will drop some but if your alternative is race gas, its still much cheaper. Since switching I found that my oil doesn't get dirty as fast as it did with race gas. My friends that run E85 with carbs have used Eric at Horsepower Innovations.


https://www.horsepowerinnovations.com/
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'69 Camaro - 429 SBC Dart Iron Eagle 9.325" block, Crower crank, Crower 6" Billet rods, Ross pistons (10:1), Total Seal S/S rings, AFR 245 heads, T&D steel rockers, Cloyes Timing Set, 4-7 swap solid roller 274/286 @ .050", .704" lift, Dart single plane, Dominator EFI, Stef's #1705R pan, F2 Procharger on E85
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post #5 of 29 (permalink) Old Jun 19th, 20, 11:40 AM
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Re: E85 Carb for Pontiac 400

are you using a spreadbore carb? do you need a choke? do you have MSD or other ignition box?
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post #6 of 29 (permalink) Old Jun 19th, 20, 11:57 AM Thread Starter
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Gene
 
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Re: E85 Carb for Pontiac 400

Quote:
Originally Posted by pbcbob View Post
are you using a spreadbore carb? do you need a choke? do you have MSD or other ignition box?
Carb is currently a Q-Jet (so spreadbore) with a divorced choke and vacuum secondaries. Would I need a different intake? No MSD box, just points distributor with coil.

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post #7 of 29 (permalink) Old Jun 19th, 20, 6:24 PM
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Bob
 
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Re: E85 Carb for Pontiac 400

doubt you find an effective spreadbore carb for E85, might need more spark for the larger fuel volume
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post #8 of 29 (permalink) Old Jun 19th, 20, 7:13 PM
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Re: E85 Carb for Pontiac 400

What about switching to a set of open chamber heads?

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post #9 of 29 (permalink) Old Jun 19th, 20, 7:27 PM
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Rame
 
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Re: E85 Carb for Pontiac 400

I can't really help as E 85 is still unavailable in my area but I thought it was really neat on what you can do with it. Try checking with https://cliffshighperformance.com/ and also check their forums about it, I've read about some spread bore conversions there, can't tell you if they will help with you situation or not as I still have no experience with E 85, I just like to read about stuff.

.
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post #10 of 29 (permalink) Old Jun 19th, 20, 10:20 PM
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Re: E85 Carb for Pontiac 400

Try www.customrebuiltcarbs.com Click on the link and call them, Phil is the owner and answers the phone, good luck!!

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post #11 of 29 (permalink) Old Jun 22nd, 20, 12:03 PM
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Re: E85 Carb for Pontiac 400

You can get the parts from Cliff's High Performance to convert your quadrajet to E85 if you want to keep your manifold and the stock look. I like to buy my parts from Cliff's because they are compatible with alcohol so if I have to run the stuff with 10% ethanol it will not mess up the carb.
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post #12 of 29 (permalink) Old Jun 22nd, 20, 12:55 PM
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Mr Bill
 
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Re: E85 Carb for Pontiac 400

Quote:
Originally Posted by ETD66SS View Post
Has anyone done the E85 Holley conversions? Am considering going that route on my 72 GTO due to ~10.25:1 requiring 100 octane fuel.

10.25 to 1 will run fine on 93 Octane unleaded, at least it does around here
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post #13 of 29 (permalink) Old Jun 24th, 20, 10:33 AM Thread Starter
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Gene
 
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Re: E85 Carb for Pontiac 400

Quote:
Originally Posted by BillK View Post
10.25 to 1 will run fine on 93 Octane unleaded, at least it does around here
But it doesn't run "fine" on 93, it pings badly.

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post #14 of 29 (permalink) Old Jun 24th, 20, 11:23 AM
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Re: E85 Carb for Pontiac 400

My 68 L79 uses 11 to 1 forged pistons and 64 cc heads and runs great on Shell and Mobile 93. I am running a .039 Felpro head gasket that lowers it to about 10.6 to 1. However I am still using the original distributor and carburetor with no modifications like headers or other power makers that will lean out my AFR. Also engine temp and timing can have a big influence not to mention carbon or even rough casting edges. 10.25 should run on 93 IMO

Don't go to E85 unless you want to fill your tank every 50 miles. Guys in my Shelby club did that so they could increase supercharger boost for their engines to make over 850HP but at a huge cost in fuel.
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post #15 of 29 (permalink) Old Jun 24th, 20, 4:03 PM
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Re: E85 Carb for Pontiac 400

My fuel cost per mile is about the same with E85. Where I live in California Premium 91 cost about $0.70 more per gallon than E85 but I do use about 30% more E85. Works out to be $0.30 per mile for 91 and $0.33 for E85, so about $0.03 more per mile in a car with 4.11 gears and no overdrive.

'69 Camaro - 429 SBC Dart Iron Eagle 9.325" block, Crower crank, Crower 6" Billet rods, Ross pistons (10:1), Total Seal S/S rings, AFR 245 heads, T&D steel rockers, Cloyes Timing Set, 4-7 swap solid roller 274/286 @ .050", .704" lift, Dart single plane, Dominator EFI, Stef's #1705R pan, F2 Procharger on E85
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