Slow Acceleration Problem.

[thisgunsays]

I have a 67 dodge dart with a nice rebuilt slant six. runs great but accelerates pathetically for a 225. It has a single barrel carb so i was wondering whether with minor adjustments itd accelerate much better or if i just need a bigger carb. I mean even my mothers made comments, so that right there lets you know its taking too long to pick up any real speed.

[mr-d150]

First thing: check your timing. The /6 has to be timed well to run well, but the problem is that the harmonic damper may have slipped.

so

Pull the plugs and bump the engine over with a remote starter button ( ignition off) till you feel pressure on your thumb from the no. 1 plug hole. Then I would put a socket and breaker bar on the damper bolt, insert a long screw driver into no.1 plug hole and turn it by hand, going very slow, till the screwdriver stops coming out when pushed by the piston (a wood dowel will work also and less likely to scratch the bore or piston).

Now the damper should be real close to the 0* mark. If not, you'll need a new damper or an after market one.

If good, then install the plugs, check the firing order of your wires (1-5-3-6-2-4) and start and warm the engine. shut it down for a few.

Disconnect and plug the vacuum advance line at the distributor, loosen the distributor hold down slightly and restart the engine after you hook up a timing light to either no1 or no.6 plug wires (no. 6 is exactly opposite no.1 in the firing order). Set your initial timing to 10* for 85 octane or 12* for 87 octane ( you can probably go 15* if you run 90+ octane).

Now tighten the distributor, reconnect the vacuum line and adjust your idle speed and mixture for a smooth lean idle. If done right, you shouldn't have to set the choke (cold engine) or pump the gas (warm engine) to start and you'll be rid of the long cranking time Mopars are known for.

Another possibility comes to mind: the rebuilder may have not adjusted the valves properly. Cold you can set them to 64 Hemi specs: 0.035" for both intake and exhaust to get you running, then set them warm at 0.010" intake and 0.020" exhaust. For a bit more performance subtract 0.002" from intake settings and 0.010" from the exhaust setting. Doesn't sound like much but it does make a noticeable difference.

Possibly, if the mechanic is a Chevy fan, he just cranked them down till they shut up and then added another quarter turn ... which means your valves aren't even seating when closed.

Budd

[thisgunsays]

Alright man, thanks for the advice. I'll try that out.

Appreciate it.

[mr-d150]

Originally Posted by thisgunsays

Alright man, thanks for the advice. I'll try that out.

Appreciate it.

Not a problem. Your welcome.

The slant is probably my favorite engine of all, bar none ... except maybe the Cummins ... and the Hemis ... and the big block Mopars ....




aw heck, if it's used by Mopar, it's gotta be good

and usually banned or factored out of competition with ridiculous restrictions.

Budd

[Dart 360]

If after you have done all those balancer checks and still not good, check the manifold vac. if it is low that could mean that the cam timing is out a tooth. I have come across several motors with these problems.
To awaken the motor further fit a 2 bbl inlet and larger exhaust system. Check out some of the previous threads on the Australian Pacer /6.

[Dick]

One bit of information that might help is did you own the car before the engine was rebuilt? If so, is the performance better or worse now than before the rebuild?

[princeh]

wow nice...i like this topic so much.....How to get laid
How to get girls ....

[Ray Bell]

I didn't get that from it at all...

But I did see that mr-d150 didn't give any kudos to the Hemi 6!

[tractorfix]

Check the throttle cable. Its probbly out of adjustment. Have someone push the pedal to the floor and then make physical sure the carburetor is wide open. Kickdown linkage can also prevent full carb opening. Tight valves are another likely cause.