High Altitude Adjustments, Car Bucks/Jerks and Shakes

[chad]

when was the last time you changed your fuel filter? A clogged filter can cause intermittent bucking.

'N I like bub's comprehensive ign, tune up 1st.
U may need to go barrow tools (italics) at the local big box store,
then a move to fuel system:

"...Distributor rotates CC fireing order is 153624
Autolite BF-82 plugs gapped at .034.
Valve lash setting is .016 hot for both intake and exhaust valves.
Basic Points setting gaped at .025 for best performance your looking for a Dwell setting of 39 Degrees.
Base timing is set to 4 Degrees BTDC for a Standard ( Stick) trans and 10 Degrees BTDC for a Automatic trans.
Idle RPM is 600 RPM for a Standard Trans and 525 RPM with an Auto Trans in Drive, parking brake set, AC if you have that is off
Fuel pressure is 4.5 PSI

To get most accurate tune up I always use of a tach / dwel meter especially if your Distribitor is still using the stock type points, and also a timing light. This is the procedure I have found works the best and quickly for me. Customized settings for your Pertronix.

A good tune up follows this order of work.
1. Set the plug gap to .045 with a Pertronix ignition.
2. Set the points basic setting to .025 after its runing set the Dwell Angel to factory spec of 39 degrees. This step is not needed with the Pertronix system. Skip this setting with the Pertronix
3. Now you need to set the timing to 12 degrees base timing vacuum line disconnected and plugged. You can also try more base timing to as much as 16 degrees but it if there is any hint of pinging when you try it then back off until it stops. Reinstall the vaccum line to the Distribitor.
4. With the engine warmed up good, set the valve lash to .016 on intakes and exhaust valves.
5. With engine warmed up good, Set the Idle mixture to its Lean Best Idle. ie set to highest idel RPM then turn the mixture screw in 1/4 turn to lean it.
6. Set the curb idle speed to 575 to 600 RPM if stand. Trans. Set idle RPM's to 500 to 525 RPM with an Auto trans in drive parking brake set, wheels chocked with block of wood, or you can have your daughter set on and hold the brake.
7. Repeat 5. & 6. To see if it improves anymore. When properly tuned these engines (warmed up) will restart without even touching the gas pedel.

You might also test your coils output with the volt / ohm meter as well as the plug wires and cap for their resistance readings that they are within spec.

Additionally while doing the tune up settings to the carb mixture and idle the engine needs everthing hooked up just as it will be operated! This includes having the Air Cleaner with a clean air filter installed and the PCV hooked up if your engine has one. If you want to use a Vaccum gauge then hook that up to the Intake Log below the Carb you would be looking for about 17 inches of vacuum at idle RPM..."

 

[63flcn]

Some updates and new issue.

Summary: car is running great at speed and all rpm ranges. Seems to have decent power too. Occasionally dying after idle.

What has been done:
Advanced timing to ~12 degrees, the mark goes from 10 degrees to 14 degrees and timing is set between the two. Was right about the 10 mark before.
New Pertronix plug wires
Autolite 46 plugs with .044 gap
Installed one size bigger jet to #60
Idle mixture screw still runs best almost all the way turned in.

Now, like I mentioned, the car is running and driving well. Has good power through RPMs, doesn't buck or hesitate under load like it was.

BUT, it is dying occasionally right off idle if its sitting too long. IE: I had it idling in the driveway for about 5min after driving and upon driving it again it was dying with an sort of throttle. Did the same thing when I went to get coffee and left it running. After getting it moving again for ~45 seconds it seems to level out. This was not an issue before.

Plugs as of a few minutes ago:

 

[bubba22349]

What's the float setting on your Autolite? Did you check the float out to be in good condition i.e. Not too heavy?

For lots of good info on the Autolite carb's check out the posts in the below link it goes into great detail and has many links on parts and rebuilding them. Good luck

Autolite carb's
viewtopic.php?f=1&t=79805&p=618064&hilit=Autolite+carb+info#p617634

 

[63flcn]

Carb is brand new, float level looks to be set properly and does not leak (tested when i received it and changing jets).

The stalling only happens after it reaches operating temperature and idles for a few minutes

 

[bubba22349]

Ok That's all good! You could try some thicker carb base gaskets or stack them up, about three to five of the thick ones will help or better yet you could make an insulating spacer for under the base of the carb. There was some Bakelite ones about quarter to 5/16 inch thick made in the past, and people have also used severial materials to do this such as aluminum, hard wood and the white plastic cutting boards with good results. You could also make a heat shield to set under the carb to keep the exsesive heat from soaking the carb's fuel bowl.

 

[63flcn]

Photo of my plugs with about 3 hours of 40-50mph driving and no stop and go.

Am I still too lean? These look white to me rather than grey.

Also, I'm not sure if you can see but #1 & #2 plugs, the porcelain center is swelling?

 

[chad]

I notice U keep ur eyes on the plugs. Try some new ones & a plug chop for best view.
White, looks too hot, but unless U have a plug cleaner - U keep reusing'em.

U did a good ignit tune 1st? (post #21)

 

[bubba22349]

Do you have another larger Jet size? If so try it, from the factory these carb's were jetted on the lean side by one or two sizes. Yes still looks lean should be a nice light tan color. What heat range plug are you using compared to the stock Ford plug number?

 

[63flcn]

I notice U keep ur eyes on the plugs. Try some new ones & a plug chop for best view.
White, looks too hot, but unless U have a plug cleaner - U keep reusing'em.

U did a good ignit tune 1st? (post #21)

These are brand new plugs, about 4 hours of 40-50mph driving on them, little stop and go with them.

Yeah Ive done everything in post 21 other than set the valve lash

 

[63flcn]

Do you have another larger Jet size? If so try it, from the factory these carb's were jetted on the lean side by one or two sizes. Yes still looks lean should be a nice light tan color. What heat range plug are you using compared to the stock Ford plug number?

Ive got one size richer, a #61 which is what was in the car when I got it. Ill put it back in.

I cant seem to find the heat range of the plugs. They are Autolite 46 Copper plugs gapped at .044.

 

[bubba22349]

The stock spark plugs were a Motorcraft BF-82 this is equivalent to an Autolite # 46 so yours are the stock heat range. The Autolite copper plugs are good plugs for their low price. On the Autlites the last number is the heat range. I would recommend that you also go down to a # 45 that's one range colder. Did the car start to improve were its any smoother now i.e. As far as the bucking, jerks, and shaking? Good luck on the tuning

 

[63flcn]

Put the #61 jet in and the car hated it. Could barely drive around town to get it warmed up and after doing so it didn't get any better after adjusting idle and mixture.

I put #60 back in and will play around with some other stuff

 

[bubba22349]

Ok did you try a colder plug yet? Did you try any of the ways to insulate the carb from excess heat, info was in the above post # 25?

 

[63flcn]

Ill go back and revisit that post.

I bypassed the heater (because its shot) so the coolant runs through the spacer and back into the block constantly. Any issue with that.

No colder plugs yet, Ill have time to get to the parts store later this week.

 

[bubba22349]

Yes you should try unhooking the heater hose for the carb spacer and then looping it back into the engine before the carb spacer. It would be a quick an easy experiment that turns the spacer into a carb insulator, this should help to get some heat out of the carb that you can do without during the warm weather. Good luck

 

[63flcn]

Unhooked the heater hose and routed it back into the block. Seems like its help the stalling issue, Ill be able to know more in the next few days when I get to spend more time driving it.

Swapped to Autolite 45 plugs. Overall this seemed to smooth everything out. Idle, acceleration are much more "clean" feeling. There is still an ever so slight bucking while cruising along and backfiring under deceleration in second/third gear.

The 46 plugs looked lean when I pulled them but the car did not like the richer jet.

 

[bubba22349]

Excellent that's some real good progress thats going in the right direction. Did you happen to reset the mixture screw to lean best idle and curb idle after installing the colder plugs? With each change these two should be reset.

From the reaction you got by disconnecting the heater hose to the carb spacer I think there still maybe to much heat going into the carb. Try some more of those insulating tips back in the above post # 25. By the way did you happen to put a new base gasket under that carb spacer when you installed the new carb? An old dried up gasket under there can be cracked or not be sealing good it can be a source of a vacuum leak that could also be leaning the engine out some. Check every other area of the carb base, manifold, and all vacuum lines for any possible vacuum leaks.

Another thing you might also check after the above items is the wet fuel level measurement and then try setting the float just a little lower (about a 1/16 to 1/8 of an inch) adjustment. After you get the carb to be cooler you could retry the bigger jet if the plugs still look lean. Try each thing separately to see which direct it goes you seem to be narrowing it down and getting much closer. Good luck Edited

 

[63flcn]

I am going to need to keep messing with it.

Drove it for about 2 hours straight this afternoon. 2 steps forward, 1 step back.

Went to fill up with gas about 10 min away. Let it warm up in the driveway and took off. It bucks in any situation now. I got to the gas station, shut it off, filled up and took off again. It completely died as soon as I gave it gas to merge into traffic. Sketchy.

Took my normal test route and has no power going up any inclines, where it did before.

Ill try the richer jet again and messing with the idle mixture screw.

Other than the LOOK of the 46 plugs, it felt like it was running strong.

Again, carb tuning is all new to me so maybe this all goes hand in hand. (colder plugs... richer jet)

 

[bubba22349]

Yes colder plugs and a little richer takes time to balance everthing correctly unless you have access to a Dyno to tune with this old school way is a slower process. Also harder because our fuels today makes it harder to read the plugs too. Also check my above post I was editing it as you were posting. Good luck

 

[63flcn]

Slow progress is still progress!

Switched to the richer jet and tried to tune it once warm. The car does not like the richer jet, seems like the #60 thats been in it is the sweet spot.

Also, I got a more accurate measure on the float (instead of the paper ruler) and it was too high by 1/8th of an inch. Set it to 1 3/32'' and it *seems* to have resolved the stalling/hesitation after shut off or long idle. Did a a few errands this evening in it where the same situation last week it would stall and die. Tonight it was smooth and started up real easy. So hopefully that's one more thing off the list.

Im going to put the hotter 46 plugs back in and see if the slight bucking and lack of power goes away. I was happy with the power it had then. 50ish mph over a 7500' pass with surprisingly easily, now it hates any bit of incline.

Should I gap them to .040'' instead of .044''? (where they are at, both sets)