FE 390 Backfires, no power and stall at low rpm's

[bobrod67]

I have a 61 ford Galaxie with a big block 390......She starts up fine and idles with no problem.....She does seem to backfire a little when you first start to drive around..but..at low speeds/RPM's she loses power when you accelerate...run pretty rough..will get a huge and loud backfire..

We went a on a Christmas light cruise through some neighborhood the other night it would backfire like someone shot off a SHOTGUN!!!!
The car stalled a few times too..but started right back up....at the slow cruising speed she ran like crap..If we stopped had to put her in park to keep her running...

Now once we get up to speed..like on the freeway or whatever...the car ran fine...no loss of power or backfiring....any thoughts????????????

[HOSS429]

what carb do you have ?

[ted dehaan]

Have you done a basic tune like checking the plugs, and plug wires, distributor cap, rotor, firing order, ign. timing and point gap is vary important the rubbing block wears down and changes the saturation and discharge time of the coil that means weak spark. very common problem on the old point type ign. sys.

[firebird77clone]

Bad diaphragm in the vacuum advance is my guess. Like Ted says, check everything.

[Rrumbler]

Plug wires.?..

.

[jerry clayton]

Your spark plug wires on the drivers side of the engine are in the wrong order-you've got #7 wire on #5 cyl, # 5 wire on #6 cylinder and #6 wire on #7 cylinder-this causes crossfiring and plug fouling at low speeds and kinda erratic at other speeds-leads to fouled plugs, valve carbon build up etc, etc and sometimes backfire will blow intake port gasket which will suck in oil to intake passage--------- and California gas on early engine?? your exhaust valve seats are goneeeeeeeeeeee

[bobrod67]

Edelbrock 1406

[bobrod67]

nope..all plugs are in the right order....valve seats are fine

[jerry clayton]

Bobrod----------The Fe engines out of the factoies had the plug wires in loom holder brackets on the valve covers and the passerger side 1,2,3,4 were in order-the driver side--to eliminate a crossfire between 7 and 8 had the wires in the bracket 7, 5, 6,8----many times I've repaired issues such as yours by correcting the wire location------
What makes you think your valve seats are fine????????40 years of unleaded gas???

And why do you have an Edelbrock carb on it????????

[jerry clayton]

another issue with older distributors------the mech rotating advance feature gets rusted/siezed up on the shaft-----------and if stuck in the advanced position during a tune up, timing will be retarded by mech and then when shaft does retard, timing will be so low that engine sluggish------and-------