383 W/no guts?

[mshelly]

My '70 383 B body with 3.91:1 Auto has no get-up-and-go.

All I know of the engine is what I can see externally. Edelbrock intake and 750 carb, chrome box electronic ignition and the large (maybe Jacobs)yellow coil.

The motor starts and runs well except for a seeming lack of low end torque, and loss of power at high RPMs.

From what I know of the previous owner the engine was rebuilt but no modifications were made.

Any suggestions of what to look at before a complete overhaul?

If I can't get this one to wake up, the '68 Imperial motor goes in!

[Streetwize]

383's are really good motors and with good rods and valvetrain have small-block like rev-potential. The reason they do (and the reason they lack bottom end) is the very short 3 3/8" stroke.

The motor you have is probably OK it just needs a good cam and some more Converter stall. I'd use a cam with around 224/230 I/E duration for a street 383 w/3.91's. Ultradyne/Comp and Hughes all have cams in this range. 110 works good, but 108 is a little choppier and helps mid range w/Automatics. A dynamic with 2800 rated stall would work good and a Performer RPM dual plane with a 650-700 double pumper with 31 shooters and a pink cam in #2 ought to make you think twice about yankin her out.

Wize 1

[Dr. Righteous]

If you can be a little more specific as to 'no get-up and go' might mean we might be able to help. If you are refering to a lack of power start with basics.
Iginition timing/advance, compression test, carb problems, ect.
A 383 is an outstanding performer and is a strong runner but not the torque monster a 440 is. But with 3.91:1 gears that thing should still come to life out of the hole.

[mshelly]

Dr. Righteous,

I guess the biggest problem is the loss of power at around 4000 RPM. Second is lack of low end torque. Even if the converter is a low stall, I would still expect some rubber with 28" tires?

I have as much initial advance as it will take w/o pinging using 92 octane.

I haven't swapped carbs. Could be this one is starving at high RPMs? It doesn't misbehave otherwise.

Thanks.

[66Dodge]

Make sure your secondary butterflies are fully open at WOT throttle position.

[rock bottom]

mshelly: The pistons used these days in stock rebuilds on 383s sit far below deck hieght giving low compression. This gives terrible low end response and lack luster performance through out when using the 906 open chambered heads. Check the cranking cylinder pressure on each cylinder, I would bet you are at 110-115 psi.The engine may be fine, just no squeeze for performance. Milling .040" off my 906 heads brought up the psi to 130-135 which then allowed me to use the mp .474" cam. If yours is a stock converter, get a looser one like Streetwise recomended.. IT WILL REALLY WAKE UP THE 383. If you are not running headers, the 750 carb is probably too big for a stock type 383. Those 28" tires are turning your 3.91 gears into much less, try some 26" (235-60/15s). I have done all the things just mentioned to mine and have cut almost 2 full seconds off my ETs.

[bbaspense]

I've been racing a low compression 400 (8 to 1) with a 484/292 cam and 3000 converter and 3.91 gears. I run high 12's in a 3700 lb Aspen. You don't need compression.........it does help but not necessary.

You seem to have the same problem my 440 used to have. Not enough fuel....my 440 would fall on it's face at 4000rpm....Go with an electric fuel pump.....

I run a 750 vacuum secondaries and it runs fine. Stick with the 750....or switch to a holley. Don't even think of a Thermobog....they're a headache in itself.

I would swap an MSD in place of the stock box. I dropped 2 tenths with this swap and mileage and streetability went up. Well worth the $$$$

Buy a MP performance distributor....it is set up with the fast curve.....Big Difference in bottom end.

[mshelly]

Thanks for the reply BB but look at the date. This post was a year ago! How did you dig this one up?

Since then I've discovered this motor had at least 3 strikes against it. First off a leak down test indicated the rings were not sealing well. Next the heads were bone stock -516s with the small valves and had at least one valve job which sunk them pretty well into the chamber. Lastly the pistons were about .060" down in the hole with an .040" gasket.

It was already .040" over, .010"/.010" and decided to retire it and start fresh. I've started collecting parts for a long rod 383 and am stuck now with finding a donor block. Got burned on a Pick-N-Pull block a few months back and am still trying to find one locally at a reasonable price. I can find 440s a plenty but 383s around here are like hen's teeth.

I'll be taking everyone's advise into account including your fuel delivery suggestions.

Thanks.