Big Block seems to slow
- Thread starter 360Duster75
- Start date
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mopowers
Well-Known Member
If it's bogging off the line, there's your 13's right there. Sounds like it may be time to tune the carburetor.
PRH
Well-Known Member
Around 35 years ago a guy I used to work with bought a mid-70’s polara that had a well used 400 in it.
Someone had put some oddball aluminum intake on it(don’t recall what, but I hadn’t seen one before that), and a Holley 4bbl.
They had convertered the car to points, and it was running like crap, popping thru the carb, etc.
They thought it needed a timing chain.
They didn’t want to fix it so he bought it for dirt cheap money.
I told him I thought it acted like a bad condenser.......so, a few dollars later and a new condenser and it was running fine.
He drags a somewhat beat up Duster home from the junk yard, and puts the drivetrain from the polara in it.
It had a single dig 2.76, the 400, and there were some rusty fenderwell headers in the trunk of the Duster, with holes already cut out for them...... so they were installed.
The 4bbl Holley ended up being a 390cfm unit.
It went mid-14’s like that, if you walked it off the line.
If you just mashed it, the one tire would spin almost forever.
I don’t remember the speed, but I don’t think it was as good as the OP’s 361.
Someone had put some oddball aluminum intake on it(don’t recall what, but I hadn’t seen one before that), and a Holley 4bbl.
They had convertered the car to points, and it was running like crap, popping thru the carb, etc.
They thought it needed a timing chain.
They didn’t want to fix it so he bought it for dirt cheap money.
I told him I thought it acted like a bad condenser.......so, a few dollars later and a new condenser and it was running fine.
He drags a somewhat beat up Duster home from the junk yard, and puts the drivetrain from the polara in it.
It had a single dig 2.76, the 400, and there were some rusty fenderwell headers in the trunk of the Duster, with holes already cut out for them...... so they were installed.
The 4bbl Holley ended up being a 390cfm unit.
It went mid-14’s like that, if you walked it off the line.
If you just mashed it, the one tire would spin almost forever.
I don’t remember the speed, but I don’t think it was as good as the OP’s 361.
360Duster75
Well-Known Member
So the issue is stock cam(if not stock not much bigger) big intake and big carb. Probably going to go down to a 600cfm from the 750 that’s on it and see if that helps more. But at this point I’m
Just glad I got it to where it actually runs decent.
It's not being hurt by the 750 if it's working correctly. You can try a different intake and smaller cam. Or, more converter and gears. Either way. I think 14.4 is a great baseline with a lot of opportunity.
360Duster75
Well-Known Member
It’s getting way to much fuel in it. Put the accelerator pump on lowest point and helped it out but not a whole lot. Going to pull the jets and see what they are and go smaller if needed to see if that helps.
Tuning is key. One thing is when buying a set up like you did, you never know what or where the previous owner had things set. You might want to look at shot nozzle, accelerator cam. I run 750 double pumper on both my 360 small blocks. They even run a better 60 ft better with the DP than a 600 eddy, or Holley vacuum secondary.
360Duster75
Well-Known Member
That’s what I’m wanting is a double pumper. Got it to where it’s way better after I adjusted the flap on the secondaries and made the whole difference. It doesn’t completely die when I floor it from a stop now just slow. Gears will fix that issue and probably a performance ignition box.
360Duster75
Well-Known Member
Got it to where it comes off the line nice after a lot of tuning last night and today but now I have popping in the exhaust at around 3k Rpm. Chasing that issue now but slowly getting better. This car was held together with boogers and bubble gum I swear.
360Duster75
Well-Known Member
13.89 @ 100mph now. New plug wires, plugs and distributor cap, with a little more tuning woke it up tremendously. I’m happy with it now but it still a weird car because it doesn’t run on the ignition box since previous owner had points setup in it. But going to keep it like it is and build a nice 440 or 360 small block for it not sure on the direction yet.
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