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421 is Not Putting Out
I'm not getting the power from my 421 like I think I should. It is a rebuilt '65 421 engine in my 63 Lemans. It has a solid lifter cam that is 282/282 advertised duration and lift .495/.495. Compression is around 10.75. It has rebuilt #62 heads with heavy duty valve springs, push rods, etc. Rocker ratio is 1.52. I am running a dual quad offenhauser intake with two Carter 400 CFM carbs that were totally rebuilt. No progressive linkage. Running a regular Mallory dual point distributer. I am running headers. When I put the throttle to the floor, the car takes off like a rocket but when I hit about 60 MPH it starts to bog down as if not getting enough fuel. or timing may not be right although I have played with the timing advance alot. Put a fuel regulator on the fuel line just before the carburetors (with fuel filter removed) and it shows 4-7 PSI (needle shakes) at idle and hard acceleration. So I don't think the stock fuel pump is the problem. I am running 93 octane and tried adding an octane boost and no difference. Any ideas if this combination of engine components may not be compatible with each other for optimum performance? Appreciate any guidance you can give me.
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I would say the stock fuel pump is not enough for your combo.
I would try an after market FP like a carter or holley mechanical. I don't think your FP is up to the task of what you've got there. GT. |
Well all I can say is if you take it to a track and it runs anywhere in the 12 second range you are getting all it has. Some internet hero will say I am wrong but they never go any faster at the Pontiac events I go to. I race a guy who has a similar motor in a 80 gp that goes 11.80 with a lot of porting and converter. Rod
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I had an old girl friend that had the same problem!
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Quote:
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Yep, that's what she said!
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My 63 with 421 and 716 non ported with dual plane 2x4 offy with "750 cfm", solid lifter 248-252 @ .020 with .484 lift would run 12's. Stock fuel pump with and electric in rear. Put on 980 sd heads and a Pontiac 859 2x4 and runs low 11's. I am wasting my time going down the strip with out the fuel pump on. Only run 3/8 lines. All stock under the hood with closed exhaust. Street car
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Well if you say that at 60 mph the ingine stars to get lazy look at your rpm range and see at what range start to fall . I think your 1.52 rockers arm are the problem I think you need to step to 1.65 and let that engine get more air
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