I just purchased a 72 Duster with a 408 Stroker. Specs are Indy X series heads, 286 Hydraulic roller cam .544int/.541exh, aluminum roller rockers, forged internals, eagle crank. 750 holley double pumper mechanical. Previous owner said compression ratio was 10:3:1. He said he used 90 pump gas and 110 race fuel mix at 3 to 1. So a 16 gallon tank would be 12 gallons of 90 and 4 gallons 110. A 5 gallon container to order of 110 is $100 and not conducive for my picket book. Is 93 pump gas fine? And if so, is the 93 pump gas that has the small amount of ethanol ok? Or will the ethanol chew up my carburetor? There is 93 ethanol free on the otherside of town which means im gonna have to fill it up in containers to fill car cause driving over to fill will kill my gas coming back lol. Trying to figure out my best options. I was also told if i add stp carburetor and fuel treatment to a tank of 93 pump gas as a preventative it will help prevent deposit build up from the ethanol. Looking forward to help here thank you.
408 stroker fuel requirement?
- Thread starter J.B.
- Start date
-
Newbomb Turk
Well-Known Member
There is no way that engine at that compression ratio and it need anything but pump gas.
No way. Unless something is very very wrong.
My first guess would be the timing curve is locked out or close to it.
My second guess is the engine is too hot. At that compression ratio 180 is hot enough.
My third guess is the plugs are probably too hot.
There is no way that engine needs ANY race gas added to it.
No way. Unless something is very very wrong.
My first guess would be the timing curve is locked out or close to it.
My second guess is the engine is too hot. At that compression ratio 180 is hot enough.
My third guess is the plugs are probably too hot.
There is no way that engine needs ANY race gas added to it.
Last edited:
Ok what about the 93 that has ethanol in it is it ok to use with the fuel treatment so it doesnt ruin carb seals?
Scody21
Just send it
You don’t get extra power from race gas…
Scody21
Just send it
You can use pump gas, the only issue is if the car sits too long. If there is a boat dock close by, they sell non-ethanol…. Out on the west coast 110-112 race gas is about 12-15 per gallon at the tracks. They rip you off if you buy from a parts store. Look up VP or Sonoco and see who is the distributor in your area.
autoxcuda
Well-Known Member
- Joined
- Apr 6, 2007
- Messages
- 9,061
- Reaction score
- 4,172
There are owners out there have that notion conjured up in their heads.
Check total ignition timing. Get it to something safe. Then put 93 in it. And then drive it and listen really close. If it got loud exhaust might be tough.
OldmanRick
Well-Known Member
Do a compression test...
Race fuel burns slower and doesn't pre detonate like lower octane fuels do. That's the reason higher octanes are used in race engines.
At 10.3 to 1 that engine should run fine on straight 93 octane pump gas.
Tom
At 10.3 to 1 that engine should run fine on straight 93 octane pump gas.
Tom
Last edited:
I have a similar build. Pump gas should work . Just make sure your timing and jetting is correct . If you are new to engines find a qualified member that is close and have them tune it . Or a reputable speed shop . Shouldn’t be hard to find in Florida.
B3422w5
Well-Known Member
Why would race gas make extra power?
Often times, if run on something lower compression than required for race fuel, it will hurt power.
Race fuel burns slower, that isn’t always an advantage.
Nice ! Now make sure you have no lean spots in the fuel curve . Idle , cruise ,power ….
Do some research on how to identify and fix them .
I have actually run cheap 10% alcohol regular gas in my 418 stroker. My compression is about where yours is. I richened it up some, it ran fine on it, but started a little hard. Went back to straight BP premium. You do not need race gas.
My 408 is an actual 10.5 CR with Eddy heads. I run nothing but pump 93 octane in it. And I don't worry about ethanol-free. Street or strip, it gets the same fuel. Your build is similar enough that you should have no issue using the same fuel.
At a freaking $1 PER GALLON difference between 87 and 93 these days it would kill me to have to be forced to run premium. WTF ever happened to 10¢ a gallon difference between grades of gas?
Then if I tune it for E85 type octane I'm also screwed as E85 is less efficient than plain pump gas ......
What's the most CR that could be reasonably expected to be happy with pump 87?
Then if I tune it for E85 type octane I'm also screwed as E85 is less efficient than plain pump gas ......
What's the most CR that could be reasonably expected to be happy with pump 87?
furrystump
Well-Known Member
- Joined
- Nov 13, 2004
- Messages
- 2,310
- Reaction score
- 1,935
It’s an utter PITA, but if you’re really nervous about the ethanol. Buy a 5 gallon pail of the cheapest non ethanol race fuel you can get. Pull the inlet line off the pump and stick it in the pail. Run it a couple of mins and shut it off. Do this every time it is going to sit for a bit. I never cared. Never had an issue. Same needle seats 10 years old. 1/2 was pump gas use.
Ironmike
Well-Known Member
Run 93 and forget about it. Make sure your tune in good, though.
When I dyno'd my current engine, it made better power with Kwik Fill 93 than with Sunoco 110. 11.25 to 1, with aluminum heads.
When I dyno'd my current engine, it made better power with Kwik Fill 93 than with Sunoco 110. 11.25 to 1, with aluminum heads.
That 408 will put a grin on your face every time you "urge" the loud pedal!!
Jay E.
Member
I was going to ask the same question here. 418 stroker, Auto 3.91 gears. Thermoquad and stock manifolds. 10.5:1. 34 degrees total advance about 8 degrees initial. Starts and runs well EXCEPT when it shifts between gears and pulling hard. Has a bad detonation there that is very worrysome. I have to back it to 30 degrees total to get it to stop, but then it runs really crappy. Using 93 super from Chevron. The former owner said to use the 3:1 mix of race gas, but I drive it a lot and that get tiresome and expensive. So I have to baby it. It was much worse on 92 non ethenol. Hard to understand 1 point octane could make a difference, but I was told that the non gas sits a long time in the station tank and often has much less than shown on the pump.
Newbomb Turk
Well-Known Member
34 total at what rpm? Are you using vacuum advance? What spark plug heat range? What is the coolant temperature?
At your compression ratio you should never ever need race gas at any ratio.
Guys saying **** like that are stuck in the 1980’s. And you didn’t need it back then either.
The only way you might have an issue is if the builder picked a cam that’s better suited for 8.5:1 compression.
Then I’d say get the correct cam.
Aluminum heads would help. What do your plugs look like, is it lean? My initial is 20, total 34, and I have run 10% ethanol gas, but it started differently and I did richen it up. I went back to BP premium. My compression is somewhere between 10 and 10 1/2. I will admit, I am not an ignition guy, timing coming in to fast?
-
