Stumped...need fresh ideas!!!

[car62]

been running same jets for 4+ years and never had an issue

[youngengines]

Seems like a lot of jet to me, unless a lot has been done to the carb. Rich will miss up high for sure. And, if there is any "pullover " going on it would be amplified. JMO

[Wrencherer]

Check the red flapper valve in the accelerator pump make sure it is not ripped also ceck the power valve

[car62]

we have 4 Kieth Dorton 350 carbs and a 500 carb....all carbs have been on the car,jets have been played with from 65-80 with no results other than 77 up loads up,we have used PV block and different power valves,every squirter from 21 to 31...4.5psi at carb with Holley Blue and Red with and without regulator.

[Headhunter]

Hydralic head? I'm thinking that maybe you have HLA that is pumping up and holding the valves open if it is Hydraulic. Oil pressure to high or pressure releif not working right? Last thing I can think of is fuel system. Either a colapsing/clogged pickup tube, clogged vent or bad fuel line. bad regulator.

[car62]

we have changed heads,3 different heads that all turned 7200+ when they were on other shortblocks,but just in case,went with new lifters and followers,set to .035 as we do on everything else...no change.

went through fuel system and replaced EVERYTHING (fuel cell,all lines,filter,fuel pump,fittings)...


again this is a miss that picked up last season just prior to mid season and has gotten worse and worse..id really be shocked if someone threw out an idea we havent already covered.

i also dont think a fuel issue is the cause for inside the intake manifold to turn black.

[Headhunter]

One common denomonator,,, the short block. that goes back to oil pressure maybe a cracked block or cylinder wall.

And yes a fuel system problem can on occasion cause that. You go lean and get pre-ignition causing hot spots on the plug, head and piston tops and when the fuel hits it it fires back into the intake igniting the fuel in the runners.

[Racedad]

A long shot here,but have you looked at the water pump?Rarely we see a loose or eroded impeller.Would fit with the symptom of sarting after a few laps on the track and gets worse.Coolant temp sensor in the block,maybe head area is hotter(too hot)?
Last time I saw it on a 4.0 Jeep,would run fine all day in the shop but overheat within a mile going down the road.

[car62]

headhunter and racedad...appreciate those 2 ideas...waterpump is something we have not looked at...we did have a different block in there,and upon pulling intake for tech,we saw some water droplets in intake runner #2...so we changed blocks....that was last season...i th9ink its time to pull out one of the backup bottom ends and put in there for next week.

[Milford Motorsports]

If I find half a fly in my rice,i'm sending it back!

[jatchis]

I'm not even sure rice is relevant to this conversation. We're talking about a Ford, not a Toyota ....

[steveshawjr]

we had a guy at our track wit ha wired issue like yours his turned out to be a bad crank. the crank had started to twist witch in turn was messing up cam timming and so on.. probly not you probelm but nothing seems to work so i thought id throw it out there.

[Dirtman29]

Probably a very long shot here, but have you checked inside the distributor cap for any moisture? Happened to me yrs. ago after cleaning up an engine compartment, car ran like crap after. Had water in the cap.

[car62]

yes,even changed distributors 3 times,modules,harness plug,rotor,you name it...the haunted mustang from hell!!!

[Dentman]

Sounds like you need to roll the car over a few times to shake it up a bit...
I had an enduro car that had a similar problem. It was traced back to a broken motor mount that was allowing the motor to move on accel causing one of the harness wires to ground out periodically and temporarily on the firewall. Perhaps you have an unsecured wire doing the same thing somewhere.
I'm a Toyota guy so don't hop on me, but maybe you have a worn crank keyway or pulley or something that is moving back and forth under accel/decel causing the timing to go out of range, then back.
On the Toy 22R engine, the timing chain tensioner relies on oil pressure. If the pressure drops from starvation in the turns (broken oil pick-up, broken gasket, slosh etc.) the tensioner can retract allowing the chain to whip and the cam timing to jump around. Perhaps you are having a similar issue, only it is causing your hydraulic lifters to starve for a few seconds and keeping the valves closed or partly closed.
Or perhaps the framistat is no longer attached to the connecticazoink. That would require a transplant...
Good luck with that. Hope this helps.
Dentman

[Dan32]

u tried changing the exhaust?? is it stoped up?