Engine Cuts Out

[ReMorton]

Request input on recent engine issues:

Problem: Flat spot at 1500 rpm, and cuts out briefly at approx 3000 rpm on hard acceleration.

Pulls hard between cutout and after cutout. Runs fine otherwise, although have experienced some run on after shut down.

Engine Details: Ford Racing crate engine 392 M-6007-C392 475 Hp; Holly
Carb; MSD Blaster HVC coil. Vehicle has 8700 miles.

Maint History:
- 3200 miles: replace worn distributor gear
- 5700 miles: engine cuts out at hi rpm, replace dist cap and rotor, rotor worn flat. Intake manifold gasket failure both banks, replace gasket
-8500 miles: Intake manifold gasket 'sucked in' causing vacuum leak; left side exhaust manifold gasket blown/burnt out. Replace both. Bronze distributor gear worn, replaced with steel gear. Throttle linkage worn and replaced. Suspect cutting out issue was not resolved before took delivery of used vehicle at 8700 miles.

Anyone care to sepeculate on cutting out (lack of fuel, Holy carb, MSD coil, electrical?)
Vehicle was recently purchased from Park Place, last set of replairs at 8500 miles still under warranty and will return for fix.
Thanks
Bob Morton SPO 2089

[Ant]

Is it cutting out at constant rpms at 3000 or as you progress through?
Might be carb accelerator pump displaying a flat spot. Borrow another carb and try it. Most likely fuel and if its good at high rpms then its unlikely to be the fuel pump.

Intake manifold shouldnt never cause any problems unless there is a mis match or not tightened properly.

[vector1]

if no air leaks then carb, could be lean or rich, i'd bet lean. specifics on carb?

[HighPlainsDrifter]

Hi,
The msd unit is going bad. It is multi spark to 3,000 rpm then switches to a single spark above that.
It will leave you stranded, i would use a different brand of spark box such as Malory.
run on is from alternator feeding voltage back to box, I would put a relay in that power line to alt.
good luck,
Perry.

[ReMorton]

I have a selection of rev limiter chips which came with the car for the MSD. Removed the current chip (tagged as 6000) and replaced it with one tagged 7000. Just took it out and the problem is gone. Good call and thanks for the tip, and saved me a drive town to Bellevue. If yer on this side of the border, I owe ya a beer..

Also, thanks to Ant and vector1 for the response..

[HighPlainsDrifter]

Hi,
Glad you found the problem.
I should mention to check the wires going to your coil. There should only be 1 wire on each side of the coil, a twisted pair from the capacitor in the msd box. Alot of problems can crop up if a 12volt wire is added, like in a standard ignition.
Perry.