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94 Mustang runs poorly since head replacement

1994 mustang 427 home built dragster, by lifetime mechanic. No shade tree here. This is my sons dragster, I have a 1995 ". ". ". ". " . Problem with my sons car. His car screamed on the old camfield heads except they water leaked terribly. Previous owner of these heads enlarged the ports to the extent that, they breached water jacket. We used steel apoxy to bridge these openings,which worked excedenly well, however, still water leaked to outside. So
For my sons Car,I bought him a set of high port trick flow race heads with increased cc for more explosion force. Problem: this car has never ran well since this conversion…WHY… No one can offer us an explanation. Our mechanist with 30 yrs experience has no concrete explination.this engine will barely explode on cyl 4 . Put it on dyno for seven hours without good results…produces 915 hp on 7 cyls. Our shop has tested compression. All cylinders produce 60 psi which is perfect for a blower mtr at idle. Produces 190 psi at throttle up. With 28 lbs boost. We have smoked this engine. No leaks detected nowhere. Bleed down is 5% within 1 hr. Camera through intake shows injector spray to be perfect. This race engine has new injectors. Dyno guys at fast track replaced five new plugs to cyl 4 . Engine supports new flame thrower coil for blower motors. Replaced this new coil off my dragster which runs perfectly. No noticible results. Both our engines runs 50 degrees timing on race fuel. I took all seven plug wires off except cyl 4. Engine barely fires on this cyl. This engine supports Norris cam. This engine is new. No worn out junk here.norris official tech states that their cam could not possibly be at fault. We are at our wits end here. Need help.

Old heads leaked. New heads perform poorly. So, it’s the head?

You have found your way to the wrong place. This is CarTalk, Not The Drag Race Forum. While there are some smart folks here, even some with drag race experience, I think you’d best look more for a hardcore drag racer’s or engine builder’s forum.

Personally, I’d be looking for a crack in the head in cylinder #4. It may only appear when hot. So a hot compression test and then a leakdown test just for fun. I’d also be running a dial indicator on #4’s valves and degree wheel to confirm the cam lobs on #4 are OK. Next thing, I’d pull the piston and rod out of #4 to take a look at the piston and rings. I’d also replace the plug wire on #4 and maybe the distributor cap just in case the spark is finding its way to another spot.

Just because the pattern is good doesn’t mean the volume is good.
I’d switch #4 injector with a different cylinder and see it the miss moves to new cylinder.

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