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1966 coronet 440 383 4spd/ rebuilt is a dog need suggestions

dave n

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kids are older now and don't require as much attention. so i talked my wife into a old mopar for me. I purchased a 66 coronet 440 4 spd 383 car two years ago. Over last winter i rebuilt the 66 383 and it's a dog. from top to bottom; 600cfm eddy, weiand dual plane, 250 heads (close to 906) open chamber heads, 287 grind mutha thumbr cam, 3.55 gears and kb- 400-30. this winter i hope to correct the hp the car deserves to run. I'm not sure if i used the wrong push rods 67 and down i believe use different lifters and rods which i did. the distributor newer nonpoint with no curve easy options changing that.
just looking for some suggestions i dont have alot of $ to throw at it this winter.
 
first off, take a compression test, did you degree in the cam? this might tell us where your at.
 
plained on starting this weekeend static compression; the cams 107 Ls not sure what com should be?
looking for cam card i believe 4 degrees
 
that tight lobe separation on the cam won't mix well with cast exhaust manifolds. 383's are very easy to screw up.
 
Shooting from the hip here. Is that cam for low compression? If you have at least 9.5 compression ratio you can, on the cheap order a K6401 cam from summit and make sure to degree it when you put it in.($117.00 cam and lifters, delivered).

Was the block or heads decked? Could be that your valves Aren't closing all the way. Would have to shim the rocker shafts if needed. A compression check should answer this question.

Do you have at least 2" dual exhaust? Make sure the passenger side exhaust baffle isn't stuck closed. Or if needed remove it .

If the pushrods have the same size tip on both ends it is the 68 up design. The early ones have a small cup in the lifter and a corresponding small tip on the pushrods (nothing positive about using 67 and down). It's better have the ones with the large tip on both ends as lifters are easier to come by.
Check that you don't have a small cup lifter with a big tipped pushrods in it.

You should have with the distributor vacuum advance disconnected and plugged at the carb 12-14 degrees advance, at idle. Then rev the engine up to 2000-2500 while checking the timing again, you want 36-38 degrees total advance. A cheap trick is to remove the heavier of the two distributor mechanical advance springs this will give a quicker total advance. You may need to get a timing tape for your balancer to get a good read. Saw once where the flat blade on the distributor wore down in the oil pump drive slot and caused my timing to be very erratic.

Last make sure you don't have a vacuum leak.

The tire companies are counting on your car running right to keep them in business.

Let us know how you make out.
 
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383's are very easy to screw up.

^^^^ This

Very easy to build a low compression overcammed 383, which unfortunately gives 383s a bad rap.

Were the heads milled? CCs of combustion chambers? Was the block decked much? What head gaskets are you running?
 
A Comp Cams 280H advanced 4 degrees is a great cam for a mostly stock street 383
 
^^^^ This

Very easy to build a low compression overcammed 383, which unfortunately gives 383s a bad rap.

Were the heads milled? CCs of combustion chambers? Was the block decked much? What head gaskets are you running?
 
it has small tube headers. the machine shop that assembled the motor stated 10:1 cr used the .40 replacement head gasket. i ask them to use a .20 shim if needed to get 10cr tomorrow I'll start checking cylinder psi, vacuum leaks again i know I'm just missing something silly appreciate the help
 
back in the day I ran [email protected]"/.480" lift hydraulic in my 383 and it was the best over all cam I tried, but I did have small tube headers.
.
I had one in a completely stock (except for headers) 9:1 motor and that thing hauled ***! I had it in my '66 D100 with an 11 inch converter and 323 sure grip.
 
Book spec on 66 383 is 10:1

I had no trouble (except dialing in a carb) running a 284-484 cam in a 70 9.5:1.
Headers and stock converter 3.55 SG

I did degree the cam and had to use an offset button to get it in spec.
 
...BTW I'm collecting data on factory 383 66 Coronet 440 cars.

In case you didn't know, they only made 1679 of them.

If you have any pics to post and would like the VIN/tag/buildsheet documented, I'd be interested.

Yours would be the 4th 4 speed car of 18 currently in the DB.
 
Is it a factory 383 car?

There is also some confusion on 1966 VIN engine codes.

There is an error in the 1966 service manual and a single page addendum correction that was mailed out after the manual was published.

The correct engine code for a 1966 383 4 barrel was "G".

The VIN should start with WH23G6 (If it's a 2 door HT).

Also of note is that there were no 383 2 barrel motors installed in 1966 B body cars.
 
it has small tube headers. the machine shop that assembled the motor stated 10:1 cr used the .40 replacement head gasket. i ask them to use a .20 shim if needed to get 10cr tomorrow I'll start checking cylinder psi, vacuum leaks again i know I'm just missing something silly appreciate the help
if you look on the KB website you'll note that you probably have 9:1 compression. a hydraulic cam with 74 degrees overlap isn't ideal. of course there could be other things like fuel issues, timing mark on dampner off, etc, etc.
 
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