Engine Timing 351C H Code /Carb Problem

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griffbl

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My H code mach 1 felt a little doggy to me when she arrived last month.  I have been working on little things here and there, like the correct inner fender battery bracket, adjusting the kick down rod for the FMX, getting the right exhaust tips on it, etc.  The engine was NOT missing, not smoking, started right up, etc.  I suspected engine timing was way off, as the ignition, plugs and wires seem fine, ignition is a petronix unit in which also seems fine, and, again, I did not see any black or white smoke, and it idles smoothly....but power felt way down.  Tried to backfire through the carb on me once under acceleration.  So, I got out my timing light, and the timing indicator showed timing to be very close to TDC. Too me, that seems very retarded!  I have always timed kind of by ear, by adding advance and then simply backing off a bit when you hear any signs on knocking or poinging.  So I dialed it up to 12 Degrees BTDC and the car seemed to wake up a LOT.  Laid a long black scratch on the hot pavement.  The car felt MUCH better.  NO pinging, or signs of too much advance.  Starter did not act burdened at all.  Honestly, I may try another couple of degrees more of advance up to 14 or so.  I am running 93 octane gas, and car is bone stock, save for dual exhaust.  I look and from what I can see, Ford recommended 6 Degrees BTDC.   So first question is is as to ignition timing:

 1) Is 12-14 degrees BTDC ok in your experience? 6 sounds crazy low to me!

Well, So I try to get her to idle and I immediately discover that idle speed is above the initial engagement of the curb idle screw.  I back off the solenoid enough so that it does not interfere any so as to remove that as even a potential issue for now.  Idle speed is probably 750-775 when she comes off of the choke / high idle.  Not super high, but too high if you do not even need to engage the curb idle screw for sure.

I start checking my reference sources, and I see a few things not quite right on my 2150 Carb...I notice that the accelerator pump rod is supposed to be at the inboard vs. outboard position near the pump, so I change that. I also see that the other end of the accelerator pump rod near the linkage is supposed to be in position #3, and it was set up on my car in hole #2, so I change that to position #3 also.  Then I notice the choke is WAY out of adjustment (see photo).  SO I change that also to one position rich, as the shop manual says.

Question Number 2:  2)Any suggestions for problems that might be making her idle high?

None of these things affect idle, as I would expect.  But the car has another annoying carburetor issue (the carb is correct for this car, and looks like a freshly re-built unit) that has been plaguing me: The throttle hangs up on fairly consistently, and sticks at a high idle type setting, or sometimes a bit higher.  It also returns to idle with another throttle tap.  I did have the A/T kick down rod adjusted (it now works properly, and this problem existed before that work was done and persists after.  I posted a pic below, and there is a small spring which is present but I do not know if it belongs.  I see several holes where a spring could be placed, but I am suspicious it is needed, or at the very least correct. 

So question number three is: 3) IS this little spring supposed to be there at all?

 I had purchased a new throttle cable, but when the problem went away before I had a chance to install it, I returned it to the shop.  My existing cable LOOKS ok, and I put a little spray silicone on the spring assembly.  I see no interference from anything like a floor mat, or anything else interfering with the linkage. The pedal seems fine, etc.  Cable LOOKS ok, but I know if the return spring is losing strength that is not anything that will look any different to my untrained eye.  I thought it might be something out of adjustment on the high idle cam etc., but I really did not want to get into that unless I had to.

For now, question 4 is: 4) Should I replace the throttle cable, or is there anything else I can check for a sticking throttle? IS there a chance the existing throttle cable return spring simply does not have the energy to return the throttle to idle on occasion?





 
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rvrtrash

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It sounds like you're well on the way to getting it set up correctly. I wouldn't replace the throttle cable just yet. With all linkage removed, does the throttle plate move freely? I would check to make sure the choke linkage is adjusted correctly, not just the housing. Also make sure your vacuum lines are correct between the distributor, manifold and carburetor. 12 deg of timing should be fine with good fuel. 6 deg was to pass emissions.

Steve.

 

TommyK

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The stock initial timing on a 351 2V is 6 degrees BTDC. The increased idle speed is being caused by the increased initial timing. If you have backed off the curb idle screw as far as possible and the increased idle speed bothers you, you will have to reduce your initial timing a little to find a happy medium.

Understand that any increase in initial timing results in an equal increase in total timing which if excessive can lead to engine damage. Once you have determined what your final initial setting is you should check total timing. If it is more than about 36 degrees the distributor should re-curved.

 

griffbl

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It sounds like you're well on the way to getting it set up correctly. I wouldn't replace the throttle cable just yet. With all linkage removed, does the throttle plate move freely? I would check to make sure the choke linkage is adjusted correctly, not just the housing. Also make sure your vacuum lines are correct between the distributor, manifold and carburetor. 12 deg of timing should be fine with good fuel. 6 deg was to pass emissions.

Steve.
Steve-

Thanks.  All vacuum lines seem as they should be.  Great idea to remove the linkage and check choke linkage.  Will do exactly that.  Any thoughts as to whether or not that small light spring that is in place is correct, or was added for some reason? I am thinking the latter at this point.

Best,

Brad

 

griffbl

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The stock initial timing on a 351 2V is 6 degrees BTDC. The increased idle speed is being caused by the increased initial timing. If you have backed off the curb idle screw as far as possible and the increased idle speed bothers you, you will have to reduce your initial timing a little to find a happy medium.

Understand that any increase in initial timing results in an equal increase in total timing which if excessive can lead to engine damage. Once you have determined what your final initial setting is you should check total timing. If it is more than about 36 degrees the distributor should re-curved.
Yes, I do understand as to excess total timing.  I do not think I am in an excess situation with 93 octane fuel, but I will monitor that, and check total timing at about 3000 rpm +/- as all advance SHOULD be in by that point.  I also should pull the throttle linkage and check the throttle plate adjustment.

Thanks again,

Brad

 
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That would be 36* mechanical, vacuum disconnected. There are different schools of thought on whether the vacuum source should be Timed Port off the carb or manifold port.

There has been much discussed on this subject of late, so a search might help you better, not that members mind chirping in whenever they can!!

I'm running a 71 4V, so it might be way different to your 2V, but here is where I finally found perfection.......... or close to it.

First off, you said you had a Pertronix module, but did you say what model? Take it from my experience, the P III is no good mechanically and has a poor plastic "bearing". It will move all over the place and your timing will drift. If that is what you have, chuck it and get a P II with the matching coil, then use 8mm spiral wound plug wires and I would use an Autolite 24 plug OR exact equivalent, NO platinum or iridium plugs either.

Mine is set at 16* initial + 20* on the crank for a total of 36* mechanical, then add in about 6* of vacuum timing. Mine is Timed Port as it doesn't need vac advance at idle up to 1100+ rpm or higher. To get the 20* on the crank, I reworked the slot plate by welding part of it up and re-cutting it to .410" or L10 (20*). I used an original Motorcraft heavy spring with minimal free play and a Mr. Gasket 925D. Works like a charm now. Distributors are all different, so be prepared to play with it.

Good luck, hope you find all your answers. Lots of far better help on here than I can offer, but that was just my experience.

Geoff.

 

griffbl

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2014 Ford F150
2018 Porsche Panamera


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My H code mach 1 felt a little doggy to me when she arrived last month.  I have been working on little things here and there, like the correct inner fender battery bracket, adjusting the kick down rod for the FMX, getting the right exhaust tips on it, etc.  The engine was NOT missing, not smoking, started right up, etc.  I suspected engine timing was way off, as the ignition, plugs and wires seem fine, ignition is a petronix unit in which also seems fine, and, again, I did not see any black or white smoke, and it idles smoothly....but power felt way down.  Tried to backfire through the carb on me once under acceleration.  So, I got out my timing light, and the timing indicator showed timing to be very close to TDC. Too me, that seems very retarded!  I have always timed kind of by ear, by adding advance and then simply backing off a bit when you hear any signs on knocking or poinging.  So I dialed it up to 12 Degrees BTDC and the car seemed to wake up a LOT.  Laid a long black scratch on the hot pavement.  The car felt MUCH better.  NO pinging, or signs of too much advance.  Starter did not act burdened at all.  Honestly, I may try another couple of degrees more of advance up to 14 or so.  I am running 93 octane gas, and car is bone stock, save for dual exhaust.  I look and from what I can see, Ford recommended 6 Degrees BTDC.   So first question is is as to ignition timing:

 1) Is 12-14 degrees BTDC ok in your experience? 6 sounds crazy low to me!

Well, So I try to get her to idle and I immediately discover that idle speed is above the initial engagement of the curb idle screw.  I back off the solenoid enough so that it does not interfere any so as to remove that as even a potential issue for now.  Idle speed is probably 750-775 when she comes off of the choke / high idle.  Not super high, but too high if you do not even need to engage the curb idle screw for sure.

I start checking my reference sources, and I see a few things not quite right on my 2150 Carb...I notice that the accelerator pump rod is supposed to be at the inboard vs. outboard position near the pump, so I change that. I also see that the other end of the accelerator pump rod near the linkage is supposed to be in position #3, and it was set up on my car in hole #2, so I change that to position #3 also.  Then I notice the choke is WAY out of adjustment (see photo).  SO I change that also to one position rich, as the shop manual says.

Question Number 2:  2)Any suggestions for problems that might be making her idle high?

None of these things affect idle, as I would expect.  But the car has another annoying carburetor issue (the carb is correct for this car, and looks like a freshly re-built unit) that has been plaguing me: The throttle hangs up on fairly consistently, and sticks at a high idle type setting, or sometimes a bit higher.  It also returns to idle with another throttle tap.  I did have the A/T kick down rod adjusted (it now works properly, and this problem existed before that work was done and persists after.  I posted a pic below, and there is a small spring which is present but I do not know if it belongs.  I see several holes where a spring could be placed, but I am suspicious it is needed, or at the very least correct. 

So question number three is: 3) IS this little spring supposed to be there at all?

 I had purchased a new throttle cable, but when the problem went away before I had a chance to install it, I returned it to the shop.  My existing cable LOOKS ok, and I put a little spray silicone on the spring assembly.  I see no interference from anything like a floor mat, or anything else interfering with the linkage. The pedal seems fine, etc.  Cable LOOKS ok, but I know if the return spring is losing strength that is not anything that will look any different to my untrained eye.  I thought it might be something out of adjustment on the high idle cam etc., but I really did not want to get into that unless I had to.

For now, question 4 is: 4) Should I replace the throttle cable, or is there anything else I can check for a sticking throttle? IS there a chance the existing throttle cable return spring simply does not have the energy to return the throttle to idle on occasion?



I have Been working on Problem # 3 this morning:

Well, I remembered that when after the kick down rod was adjusted at the transmission shop, the small unknown spring was just laying there unattached. The throttle was not sticking when I returned from the shop.  I re-attached the small spring after I looked at it again.  It had been located on a fixed point at one end, and it was on the tab for the kickdown rod on the other.  In hindsight, that is also coincidental, or maybe, not, with the throttle sticking.... So this morning I re-located the small unknown spring in the photo from the kickdown rod, to the throttle tab on the carburetor itself. That seems to make more sense.  Problem solved! Throttle not sticking now.  Honestly, that spring may not be necessary, or correct.  But for now I will leave it alone.  Glad I took the throttle cable back.  A fresh one may obviate the need for this little unknown spring, bor now it works! I might remove the throttle cable, and lubricated it if I can with a little spray lube of some kind if I can get any between the plastic sheath and the cable itself.

As to question #1:

Ignition timing is currently set to about 12- 14 degrees BTDC.  No pinging. No knocking.  Car WOKE UP! It will lay a long scratch from a stop, and seems to run as it should.  I am tempting to add a touch more advance until it pings, but I think I must be close at this point.  I am running 93 octane.

As to question #2: I did remove the throttle cable, as was suggested here so helpfully by RVRTRASH. The venturis seem fully closed at zero throttle, so I am thinking the carb is adjusted correctly there.  She idles only a touch high, but I think that is the price to pay for correct ignition timing in my particular case.  I may readjust the solenoid at this point so that engages to prevent Dieseling, as I call it, or with the A/C operation, which is not being used at this point. It is not Dieseling (i.e. trying to run a little after the engine is switched off).  I am going to change to a Sanden type compressor that is so much lighter, and provides so much less drag, before the A/C is used, as the OEM compressor does not seem quite right.

Progress! Thanks for everone's help!

Brad

 
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