The Stovebolt Site Forums The Shop Area The HiPo Shop Small Block 3000 RPM monster....and that's all she wrote !!!!

In my '53 3100 5-window I have a '69 327 block bored .30, forged flattop pistons, 70's 305 heads, edelbrock performer manifold w/600 edelbrock carb, Speedway HEI, block hugger headers with flowtech glasspack header mufflers, #42 AC plugs.

Now my problem: starts great, runs great up to 3500-4000 RPMs (don't have a tach) then spits, sputters, etc... doesn't die but have to bring it back under those RPMs to cruise. What am I missing here??????

So much to check, so much to talk about....so hard to say. That said I'd start with fuel. Check the fuel filter and the float level on the carb. Hopefully you have a good Edelbrock. I've never had one. Have several Carter AFB's and AVS carbs which are the ones the Edelbrock is based on and they are easy to work on and improve when needed. Edelbrocks not so much.

One easy check is to run it till it starts missing, stop and check plugs for lean fuel conditions. The carb and filter may be good but you could have crud in the fuel tank that's limiting supply.

Good luck, Ron

Check the fuel pump output- - - -it needs to be at least one pint in 30 seconds at idle speed. Also, run the same RPM in several gears to see if the miss/surge is related to engine RPM or vehicle speed (not likely). Id the HEI a stock type or some sort of aftermarket system?
Jerry

Does it pull strong up until 3500 rpm then quit? Does it quit at 3500 whether or not there is a load?

Could be ignition.
Old ignition wires bundled close together can induce cross firing at high rpm's ( haven't seen that in decades, but actually has several cases)
Point's bounce or sticking pivot. Even coil breakdown.

I would concentrate on the fuel first.It sounds that the engine want more fuel than the pump can deliver.Dirty filter, bad pump,crud in the tank.These have been mentioned of coarse.

Jerry,
Coil in cap, generic Speedway HEI. Probably made in china!

Thanks Ron, I'd say a fuel filter. Carb is new and fuel pump new Carter. Have not checked the filter...great point!

59 fleet,

pulls strong to that RPM. What do you think. Thanks.

BC52,

Thanks, same as Ron said. Will be checking fuel system tomorrow will let you all know. Thanks.

I will also check the screen filter in the tank. Have a stock tank in it. Tanks everybody, Ha Ha!

Jim,
New MSD 8mm wires, coil in cap HEI (Generic). Thanks for the return.

I think ignition not fuel if it pulls strong to 3500 and also won't cruise above same rpm

edit: weak valve springs but that is a stretch

Have to agree with 59 fleet. Sounded like ignition from the start, and an HEI coil in cap failure is far from rare.
Stick the original dist back in and do a test run.

What gauge wire do you have powering the HEI? Maybe you are using too small a wire.

HEI's either work or they don't- - - -it's very unusual for one to hit a certain RPM and crap out. An original HEI will start to spark scatter and miss at 5500-6000, but not below- - - -not sure about a rice-burner clone. Find the restriction in the fuel system- - - -filter, sock strainer in the tank, weak fuel pump, etc.
Jerry

I'm leaning to a spark problem. With A fuel problem it would fall on it's face & pick back up when you let up on the throttle. Make sure the HEI is not powered through the original resister. Check the spark plugs. Testing & idle ing can build up a varnish on the insulators with the gas we get now. That is quite possible with the cold plugs you are using.


George

Do you have an adjustable rev limiter in the Distributor ?

Hey 53TC,
The guys are right and it could also be the ignition coil.
Its cheap and easy to check.
have fun,
Bill

After reading the entire thread, since you have hei, check the rotor for center burn through. The plugs require more coil voltage as the combustion chamber temp increases and the coil buildup duration decreases. This takes only 5 min to remove the dist cap and remove the rotor. Look for small hole under the rotor center.

BnJ, it's been over a month since he has been here. Obviously he has left the building.🙀

fuel system clean and strong pumping. thanks.

fuel system clean and strong pumping. thanks.

nope!

still here, been sick. thanks for all replies.

thanks tennessee. actually re-did timing and it got much better, still tweekin it.

Just wondering if you've checked the gap on your plugs. May need to tweak the gap. Just saying. Good luck.