Help! 1965 F100 dies/bogs/hesitates after 50mph

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chris401
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by chris401 »

RRTEC wrote:I often would rather replace parts and know they are "good". The stuff is so inexpensive my time seems more valuable than attempting to test a part. More money than brains? I would like to know "why" a failure occurs. Hence the post.
A hand full of us that posted free suggestions get paid well for our methods in the field. Use them to sharpen your "brains" and you'll be figuring these problems out in the time it takes to post.
Chris
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

I respectfully want everyone to know how much I appreciate the help. I do look at or check everything suggested. I just replace parts vs testing as I don't have all the tools and know how to test.

I am going to check fuel pressure though as my pump only has 500 miles on it. I also need to figure out why the truck runs hot. If they are related that would be fantastic. In the fall and winter the truck was a dream. This summer (hot) has been challenging.
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Toyz
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by Toyz »

RRTEC wrote:I often would rather replace parts and know they are "good". The stuff is so inexpensive my time seems more valuable than attempting to test a part. More money than brains? I would like to know "why" a failure occurs. Hence the post.
"The stuff is so inexpensive ----". If you are buying parts which hold any semblance to "knowing they are "good", I need to know your source. IME, most of the problem cases, especially on the internet; involves problems with "parts I just replaced"! The "HEI" is an excellent example; take a design even GM abandoned multi decades ago; make it with such "quality" that one can ship them stateside and sell them for less than $100.00; with a "lifetime warranty" on it, and carry on! Just an example; there are plenty more similar situations! If you REALLY want to know why something failed, then you test! I have a stack of "failed" and replaced Durasparks, for another example. Would you care to know the reason I keep them? Mostly because there is nothing wrong with them that wouldn't have been fixed simply by cleaning the connections! BTW, a static fuel "pressure test" by itself is next to useless/ IMO!
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RRTEC
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

I tend to buy my parts locally at Orielly.

Not sure what a static test is.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by chris401 »

RRTEC wrote:I tend to buy my parts locally at Orielly.

Not sure what a static test is.
Wasn't my intention to sound cocky. It is possible they all tie together. Assuming the gas cap isn't breathing, the pump will only pull so much vacuum. That's when the bowls run dry. If just enough fuel is trickling past the needle to keep it running your likely opening up the throttle more giving engine more air than fuel. Normal carburetor air fuel ratio is 12-13:1. When fuel starved your likely (a guess) around a ratio of 19:1 or higher. Lean would cause cylinder temperature to get high causing coolant temp to raise. If you have slower timing and/or calcium build up in the radiator the lean effects will be more drastic. A restricted fuel line will have the same symptoms.

That may not be your problem but it is a start.

Static Test: Look up what your fuel pump should flow in a minute. Divide by 4 and test for 15 seconds. Test warm fuel pump volume by pulling the plugs, ignition power and spinning the engine over. If volume is good try to duplicate the problem with a fuel pressure gauge between pump and carb. If problem reappears with good fuel pressure your problem is somewhere between your gauge and your boosters.


It is not likely your fuel is boiling while driving. Too much air flow through the engine and around the outside. Fuel boil typically occurs when idling stoped in hot traffic or carb heat soaked from sitting hot engine off without a good carburetor insulator.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

I ordered a new gas cap last week. My current cap allows fuel to spill out on hard corners when full...
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

Well it is very related to overheating. If I'm in traffic/at idle the truck starts shaking, running rough, idling low. The temp is over 200 unless I'm moving.

I must be lean, too far advanced, clogged, no fuel supply... Something.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by chris401 »

RRTEC wrote:Well it is very related to overheating. If I'm in traffic/at idle the truck starts shaking, running rough, idling low. The temp is over 200 unless I'm moving.

I must be lean, too far advanced, clogged, no fuel supply... Something.
If your timing has not been tuned put it in a safe zone. Plug off your vacuum advance and set your base timing at 15°. You shouldn't have over 35-40° total. That will isolate low timing as a problem. If it still overheats at idle the you need to get to a mechanic that knows small blocks. I do not know a whole lot about the 289. There maybe a head and head gasket combination that does not circulate coolant well or a block bored too thin. Your stock pickup cooling system should be plenty.
Chris
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

chris401 wrote:
RRTEC wrote:Well it is very related to overheating. If I'm in traffic/at idle the truck starts shaking, running rough, idling low. The temp is over 200 unless I'm moving.

I must be lean, too far advanced, clogged, no fuel supply... Something.
If your timing has not been tuned put it in a safe zone. Plug off your vacuum advance and set your base timing at 15°. You shouldn't have over 35-40° total. That will isolate low timing as a problem. If it still overheats at idle the you need to get to a mechanic that knows small blocks. I do not know a whole lot about the 289. There maybe a head and head gasket combination that does not circulate coolant well or a block bored too thin. Your stock pickup cooling system should be plenty.
Thanks for the advice. I will do that today. I have a 302 in the garage waiting to go in the truck and honestly it would have been in the truck already if it hadn't been for the fact that I tore my ACL and haven't been very mobile for the last 2 months. I am relying on my neighbors to help me get the adjustments made. Thank goodness for good neighbors.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

I replaced the cap today, and bought some block off caps for the vacuum ports.

To be clear, to set the static timing I will block the vacuum advance and set the timing at idle speed to 15 deg advanced?

Thanks again.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by 62bigwindow »

Yes. With the engine at normal operating temp. You may have to set it mildly warmed up and then check again if the overheating stops. Since it gets so warm idling.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by chris401 »

RRTEC wrote:I replaced the cap today, and bought some block off caps for the vacuum ports.

To be clear, to set the static timing I will block the vacuum advance and set the timing at idle speed to 15 deg advanced?

Thanks again.
Yes, as 62bigwindow said. If your dealing with an unknown timing curve leave vacuum plugged off till you figure out where everything is set. Some advances are non adjustable and too much or little. Say your total timing is 40° and your advance is 20° you will be in the next cylinder and in trouble.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

That makes a lot of sense. I have been having issues with timing. I followed the procedure to a T about 20 times since buying this truck and have never been able to get it right. It seems happier at further advanced. I have it set at 12deg advanced right now with the vac. Advance hooked up although it is much happier at 18-22deg... No detonation/spark knock although that seemed crazy.

One other factor I forgot to mention is that per some advice I received I had converted to a pcv valve instead of a vented cap. I have noticed that this seems to have upset the system somehow. I unplugged it yesterday and the truck idled better with that open vac leak where the pcv was. In plan to block that off too and put a filter back.

One last thing I noticed before removing the pcv hose is under heavy acceleration I hear a hissing/sucking sound. I have done a vacuum leak check via propane and a vacuum gauge and didn't have leaks.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by chris401 »

Check TDC balancer marks with actual piston TDC. Some balancers have a design flaw that allows the alternator belt to pull on the balancers rubber insulator causing timing marks move. I believe the early small blocks are one of them.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

I checked TDC with the new balancer I installed. It was correct on the power stroke. Of everything I am concerned that when the engine was rebuilt they clicked the cam timing gear incorrectly...
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by chris401 »

I suppose if a cam was retarded enough to pull exhaust back in it could be prone to overheating by trapping exhaust in the cylinder. More base timing will compensate some vacuum from a big cam or slow cam timing.

EDIT: I misspoke and changed my comment.

Another possible idle over heating cause could be a water pump timing cover miss match. I don't know if there are deeper impellers for certain years or not. Seems there is a small block guru here with a Yellow Unibody.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

Thanks for the tips. I locked the dizzy at 15 degrees with the vacuum advance blocked off. This gave my a total of 32deg advanced at wot with the mechanical advance. I plan on test driving it tomorrow.
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

I drove it around locally and it's done ok. I plan to venture about 40 miles of mixed today when I head to a dr appointment.

Other things I did to try and help the situation:

Added a coolant overflow bottle and bled the system.
Added a 2nd clamp to the fuel fill hose
Installed new vented gas cap
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by Mr. Jones »

RRTEC,
Just read both pages of your post,here's my take on it.Sometimes the most obvious solution is not so obvious......instead of wasting time and money throwing parts at it.Find yourself a good shop that still works on carbs and distributors,let them fix it you'll still get an answer to why......
I went thru a similar scenario with my one ton,I hated turning it over to someone else,but it now runs like it should.....KC to Salina and back close to 400miles no problems.....best money l've spent in years
Dan
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RRTEC
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Re: Help! 1965 F100 dies/bogs/hesitates after 50mph

Post by RRTEC »

Yeah I'm about there. It's still acting up. Nothing has solved it.

It's definetly fuel though. My last ditch is swapping the pump again. Back to the original that I swapped for no reason...
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