No Acceleration under load

[chademinent]

Alright, i just finished rebuilding the top end on my 72 coronet wagon with a 318. I installed a Hughes Whiplash cam, lifters and springs, 360 heads with all new valves, guides, seats and valve job. Edelbrock RPM airgap intake, edelbrock 650 AVS 2, Mopar Performance timing kit and mostly Mopar gaskets, Pertronics Billet Flamethrower distributor with a custom curve for the cam. Now It idles beautifully and I can get timing set pretty close to where I need it (16 degrees initial) but when I put it in gear it drives but has no acceleration, I can get it up to 45-50 mph but it doesnt like going much faster. Ive been messing with the timing for a week now and nothing I do changes it. I'm not getting any backfire. I'm about to head outside to chexk my firing order on my wires, are there any other suggestions?

 

[1967coronet440]

When it’s on park or neutral does it rev normal or is there hesitation. Sounds like it could be a torque converter or trans issue.

 

[chademinent]

Revs normal in park and neutral. If I recall it had this issue before the rebuild...been a year and a half. I chalked it up to a bad acc pump on the old 2BB.

 

[65-440]

clogged exhaust ?

 

[oldbee]

Besides the above; what size cam? You may not be in it’s “sweet spot” yet? Kinda doubtful tho.

 

[moobster]

Sounds to me like a timing issue. Not enough advance.
Are you disconnecting the vacuum hose from the distributor when you set initial timing?
If so, maybe the outter ring on the harmonic balancer has moved.

 

[chademinent]

Exhaust is basically open headers right now so we can scratch that.
Yes I'm pulling the vacuum advance from the distributor and clamping it for initial.
Its a big cam, so I might just need to really sit down and dial in the timing, probably get a second set of eyes on everything too. Never hurts

 

[garrett1308]

A dirty carb could cause it. Not running on all cylinders can have the same symptoms as you have.

 

[66Satellite47]

Maybe a dumb suggestion, are you one tooth off on the timing chain? Just say"ng Sure is easy to do.

 

[Frank Mopar]

If it had the same issue before, my guess is it’s not the engine.

 

[Ranger16]

Maybe a dumb suggestion, are you one tooth off on the timing chain? Just say"ng Sure is easy to do.

Or maybe one tooth off on the distributor when you installed it? Also easy to do.

 

[Mike67]

Vacuum leak???

 

[Don Frelier]

Check the mechanical advance in your distributor. You should see the timing advance with a light when you raise the RPM's.
The advance plate may be stuck.

 

[idrivemopar]

If its running good and revs good in park or neutral, are you sure you are not driving with your emergency brake on, or have a stuck rear drum brake or front brake perhaps???? How good is the trans, maybe its slipping, has a bad disk pack or something cause it to lose power.

 

[Johnpat]

Put a vacuum gauge on it and see what happens
,If vacuum drops &stays there when at those speeds you have clogged exhaust.

 

[chademinent]

If its running good and revs good in park or neutral, are you sure you are not driving with your emergency brake on, or have a stuck rear drum brake or front brake perhaps???? How good is the trans, maybe its slipping, has a bad disk pack or something cause it to lose power.

Rolls fine in neutral can push it easily.

 

[chademinent]

Check the mechanical advance in your distributor. You should see the timing advance with a light when you raise the RPM's.
The advance plate may be stuck.

I'm on my second distributor. I think mechanical advance it a
Working fine.

 

[dvw]

If it's open exhaust it's not plugged. If it was timed with a light it doesnt matter what tooth the distributor is on. Leave 2 options I'd check. Lack of fuel delivery. Cam timing is off.
Doug

 

[chademinent]

If it's open exhaust it's not plugged. If it was timed with a light it doesnt matter what tooth the distributor is on. Leave 2 options I'd check. Lack of fuel delivery. Cam timing is off.
Doug

Yep, I think you nailed it. I still need to check my secondaries to make sure everything is working with fuel delivery (its a brand new carb). But Im now leaning toward being off a tooth on my cam timing.