1966 f250 Engine missing when warm
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Freshman User
Joined: Jan 2012
Posts: 43
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From: Los Angeles
1966 f250 Engine missing when warm
I'm still battling the engine "cutting out" problem.
I have rebuilt the carb.
new coil
new points and condensor and cap
new wires/plugs
I have a new phelonic carb spacer to try and rule out heat to the carb.
Gaskets seem correct
PCV valve and hose, though older, seem fine.
Replaced a passenger exhaust gasket (it worked for a minute and now has the same pip pip pip leak...Twisted stock manifold??)
There seems to be a problem with the points.
I have ordered a Pertronix 1281 electronic ignition upgrade (stuck in a late UPS shipping container over the Memorial day weekend, thank you very much ups)
The engine it missing spark after it gets warm. And after driving a few minutes, it simply progressively gets worse over the course of a minute and eventually dies.
We had messed with this at the carb shop for 2 hours. Had the carb all appart again and narrowed down the issue to points possibly. Replaced the points with an older spare set and it seemed to run great. We set the timing to 10 degrees.
Then on the next truck trip it acted funny. I replaced the old points with new points (.017 gap) and no love. Runs ok when cold then craps out.
Has anyone encountered this type of behavior?
This is a 1968 390 with a 2 barrel. The truck is a 66.
Thanks for any help
I have rebuilt the carb.
new coil
new points and condensor and cap
new wires/plugs
I have a new phelonic carb spacer to try and rule out heat to the carb.
Gaskets seem correct
PCV valve and hose, though older, seem fine.
Replaced a passenger exhaust gasket (it worked for a minute and now has the same pip pip pip leak...Twisted stock manifold??)
There seems to be a problem with the points.
I have ordered a Pertronix 1281 electronic ignition upgrade (stuck in a late UPS shipping container over the Memorial day weekend, thank you very much ups)
The engine it missing spark after it gets warm. And after driving a few minutes, it simply progressively gets worse over the course of a minute and eventually dies.
We had messed with this at the carb shop for 2 hours. Had the carb all appart again and narrowed down the issue to points possibly. Replaced the points with an older spare set and it seemed to run great. We set the timing to 10 degrees.
Then on the next truck trip it acted funny. I replaced the old points with new points (.017 gap) and no love. Runs ok when cold then craps out.
Has anyone encountered this type of behavior?
This is a 1968 390 with a 2 barrel. The truck is a 66.
Thanks for any help
Fleet Mechanic
Joined: Apr 2012
Posts: 1,275
Likes: 134
To check if the condenser, the next time it quits, pop the cap, crank the engine over, if you have good fire at the points, pull a plug wire, put a known good plug in it and crank it again. If no fire the condencer is bad. If no fire at the points, coil is bad.
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Freshman User
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From: Los Angeles
Thanks, I just checked that. Got what looks like consistent fire to the points and with the cap back on and a grounded plug, got fire to the spark plug.
It is really missing bad now and parked in the driveway with little capacity to move. Also backfiring and stinkin the place up.
I notice the Amp meter is really jumping up into the max range when it is trying to idle.
i'll check the plugs tomorrow. I'm using Autolite 45s with .035 gap
It is really missing bad now and parked in the driveway with little capacity to move. Also backfiring and stinkin the place up.
I notice the Amp meter is really jumping up into the max range when it is trying to idle.
i'll check the plugs tomorrow. I'm using Autolite 45s with .035 gap
Fleet Mechanic
Joined: May 2012
Posts: 1,724
Likes: 1
From: peru kansas
instead of pertronics
for similar price you can pick up an electronic dizzy for a 390 shove her down the throat and rule out those issues real quick like i have heard quite a few horror stories of those pertronics set ups out here in kansas they are great until they crap out and then your stranded til new parts get shipped in but those ignition boxes are cheap and plentiful
Senior User
Joined: Jun 2005
Posts: 274
Likes: 0
From: Wichita, KS
Double check that you have no air leaks underneath the carb and phenolic spacer, and between the spacer and manifold. Spray carb cleaner around it to see if it changes the idle. I had a similar issue- ran great when cold, crappy when it warmed up. New gasket underneath the carb fixed it.
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Freshman User
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From: Los Angeles
I tried to do the carb spray thing. Kinda tough when you are by yourself and the truck wont stay lit. I'm pretty sure it is tight there. I am getting a new pcv valve hose an PCV to be certain. And will pick up a few gaskets.
I'm waffling on the Pertronix purchase. Maybe a diz for the same price would resolve any bearing or vacuum advance issues as well.
Weird how this went from running fine, doing high-fives at the carb shop, thinking we found the culprit with the points to not being able to get out of the driveway after 20 miles.
I'm waffling on the Pertronix purchase. Maybe a diz for the same price would resolve any bearing or vacuum advance issues as well.
Weird how this went from running fine, doing high-fives at the carb shop, thinking we found the culprit with the points to not being able to get out of the driveway after 20 miles.
New User
Joined: Jul 2010
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I'm battling the same issue. I've got a '70 F250 with a 390 and 2bl. Runs fine and holds idle when cold and holds idle in park when hot, but drive it around for a little and it starts idling rough and stalls. Starts right back up. I've put a reman. carb in, new fuel lines, pump, filter, checked everything for vac leaks from the brake booster to the trans vac modulator, new coil, etc etc. When it's running it's strong but get it hot and it just wants to sputter and die. Let me know what you find out.
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Posting Guru
Joined: Oct 2007
Posts: 1,144
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From: Sedro-Woolley, WA
My 78 FS Bronco, "Grim", is doing a similar thing.
Internally stock block, stock ignition, Edelbrock performer intake & 650 performer carb.
I strongly suspect I have set the carb up poorly but I'm no expert in that department.
Internally stock block, stock ignition, Edelbrock performer intake & 650 performer carb.
I strongly suspect I have set the carb up poorly but I'm no expert in that department.
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Freshman User
Joined: Jan 2012
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From: Los Angeles
Apparently there is some "cross talk" between wire 7 and 8. I think you are supposed to have 7 inbetween 5 & 6 in the loom, to keep it away from 8 which may cause misfire. I just upgraded to an electronic distributor from twperformanceparts.com. Works great so far. I also replaced my carb gaskets and replaced the carb spacer with a phenolic spacer from this guy items in gm302396427 store on eBay!
As well as secured the new pcv valve and hose.
will give it an official test this weekend.
Thanks for all of your help.
As well as secured the new pcv valve and hose.
will give it an official test this weekend.
Thanks for all of your help.
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