302 engine issues.
Thread Starter
|
Elder User
Joined: Jun 2015
Posts: 664
Likes: 2
From: York Pa.
A few more thoughts as I think about this:
1) Already discussed, but I didn't see confirmation that you confirmed the integrity of your harmonic balancer. The "Positive Stop Method" would allow you to confirm when your piston is at TDC that your harmonic balancer is reading at TDC. If it has slipped then you are timing at the wrong spot.
2) In your initial post you mentioned timing was way advanced and once you retarded it, the backfiring and black smoke occurred. Have you tried running the timing up again just to see if that calms the backfiring?
3) Wondering if it's possible your dizzy is not advancing when you give it throttle. Can confirm with a timing light.
4) I think going to a smaller accelerator pump nozzle would exacerbate the problem. In my experience, stumbling off idle is because the engine isn't getting enough fuel for that transition from no load to load.
5) Spark is jumping to the wrong cylinder - possibly dist. cap or plug wires compromised.
6) If you have a smart phone and can post a video to YouTube with a link that would go a long way to help with diagnostics.
I know you've done a lot to confirm the timing, but going back to theory here the only way you can backfire through the carb is for the intake valve to be open when ignition occurs (someone correct me if this isn't the case - I think someone already said as much in the thread). I've seen others talk about a carb backfire under lean conditions but you clearly aren't running lean - I suspect this is because the engine is more susceptible to pre-ignition under lean conditions.
1) Already discussed, but I didn't see confirmation that you confirmed the integrity of your harmonic balancer. The "Positive Stop Method" would allow you to confirm when your piston is at TDC that your harmonic balancer is reading at TDC. If it has slipped then you are timing at the wrong spot.
2) In your initial post you mentioned timing was way advanced and once you retarded it, the backfiring and black smoke occurred. Have you tried running the timing up again just to see if that calms the backfiring?
3) Wondering if it's possible your dizzy is not advancing when you give it throttle. Can confirm with a timing light.
4) I think going to a smaller accelerator pump nozzle would exacerbate the problem. In my experience, stumbling off idle is because the engine isn't getting enough fuel for that transition from no load to load.
5) Spark is jumping to the wrong cylinder - possibly dist. cap or plug wires compromised.
6) If you have a smart phone and can post a video to YouTube with a link that would go a long way to help with diagnostics.
I know you've done a lot to confirm the timing, but going back to theory here the only way you can backfire through the carb is for the intake valve to be open when ignition occurs (someone correct me if this isn't the case - I think someone already said as much in the thread). I've seen others talk about a carb backfire under lean conditions but you clearly aren't running lean - I suspect this is because the engine is more susceptible to pre-ignition under lean conditions.
It's a project truck, I have been studying and learning and enjoying everybody's help. It has been fun and I know eventually we will get it worked out.
Thanks again to everyone.
Logistics Pro
Joined: Aug 2010
Posts: 3,717
Likes: 585
From: Chillicothe
I agree with posts 27 and 60. The balancer on my 95 302 LOOKS fine to the eye, but is actually off by almost 5 degrees. Definitely look up how to do the positive stop TDC test. Also, if you are using an adjustable timing light throw it away and get a standard one. The advance style leave much to be desired on accuracy.
Thread Starter
|
Elder User
Joined: Jun 2015
Posts: 664
Likes: 2
From: York Pa.
It's time for my Friday report. My neighbor came today at 2 pm as always and he immediately said we need to start the engine and pull the spark plug wires off the spark plugs one at a time to see if we have any dead cylinders. It turns out there were several that when pulled there was no difference in the idle = dead cylinders. My current plugs were recently purchased Autolite copper 26 plugs, the part that screws into the block is chrome looking. The plugs that came with the truck were Autloite copper 26 with a black body that screws into the block. We replaced the new plugs with the old used plugs and the engine came to life, the idle was stronger, the vacuum came up, and when we blipped the throttle the backfire was gone 
,that's huge. We did a little more dialing on the idle mixture screws and set the idle screw at 650 rpms and everything was sounding great and the vacuum steadied out at 19. We checked the timing and it is still set at 14 btdc, everything was still weirdly enough sounding good after weeks of frustration so we decided to take it out for a test run. We went on a couple mile drive and I'm pretty happy with the results, decent power and no backfires but there is a bit of hesitation when the throttle is given at times but thats minor and I think we will get that worked out next week as well. Thanks to everyone for all your interest and help, I'm very grateful to you all.
,that's huge. We did a little more dialing on the idle mixture screws and set the idle screw at 650 rpms and everything was sounding great and the vacuum steadied out at 19. We checked the timing and it is still set at 14 btdc, everything was still weirdly enough sounding good after weeks of frustration so we decided to take it out for a test run. We went on a couple mile drive and I'm pretty happy with the results, decent power and no backfires but there is a bit of hesitation when the throttle is given at times but thats minor and I think we will get that worked out next week as well. Thanks to everyone for all your interest and help, I'm very grateful to you all.
Lead Driver
Joined: Sep 2003
Posts: 7,016
Likes: 208
From: SoCal
Congratulations on solving a mystery; it must feel good.
It's possible that your recent plugs got fouled from originally running too rich. This happened to one of my engines that had not been run for a long time. I tried to to clean them up by burning the build-up off with a blow torch. They worked better, but still not quite as good as new, never-fouled plugs.
Your hesitation with throttle opening may be due to your attempts to lean out the carb. Maybe you can replace the new squirter its original, larger version.
I assume that you replaced the pump diaphragm when you rebuilt the carb? One of mine had turned stiff, and did not squirt much as I opened the throttle, resulting in stumbles every time.
It's possible that your recent plugs got fouled from originally running too rich. This happened to one of my engines that had not been run for a long time. I tried to to clean them up by burning the build-up off with a blow torch. They worked better, but still not quite as good as new, never-fouled plugs.
Your hesitation with throttle opening may be due to your attempts to lean out the carb. Maybe you can replace the new squirter its original, larger version.
I assume that you replaced the pump diaphragm when you rebuilt the carb? One of mine had turned stiff, and did not squirt much as I opened the throttle, resulting in stumbles every time.
Thread Starter
|
Elder User
Joined: Jun 2015
Posts: 664
Likes: 2
From: York Pa.
It's Friday and my neighbor and I worked on my truck. We hooked up the vacuum gauge and got busy, we first loosened up the distributor and advanced it to see how it would affect the vacuum and we were able to get the vacuum up to 21 but didn't like it advanced up beyond 14 btdc so backed it off a bit again to 14 btdc and played with the mixture screws and ended up with a very steady 20" vacuum reading and a 700 rpm at idle with my manual transmission. I have to say I'm very happy to have the engine running so well after all the frustration resulting from this change over. This truck is far from a hot rod but that didn't hinder my son and I from pretending that it was and having fun. I will let this thread fade out for now until I have more issues, thanks again for all the help.
I will let this thread fade out for now until I have more issues, thanks again for all the help.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Sounds good! Remember the vacuum reading is a true indication in this situation, without going over the last 2 pages, the suspicion is that the damper is lunched iirc, right?.
So in this situation the "14°" indicated on the damper is pretty much useless if that's the case, and should not be relied upon as the basis for deciding how much initial timing to dial in. Although 20" of vacuum at idle is right in there where you want it, and 14° sounds about where it would be.
The important thing is to see where the timing is at 3000 or so, where does it end up advancing, maybe 34° or 36° without vacuum advance connected. That's the key, the initial timing doesn't really matter too much. Set the initial wherever it needs to be to get there, once you have a damper that is known accurate.
Sent from my iPhone using IB AutoGroup
So in this situation the "14°" indicated on the damper is pretty much useless if that's the case, and should not be relied upon as the basis for deciding how much initial timing to dial in. Although 20" of vacuum at idle is right in there where you want it, and 14° sounds about where it would be.
The important thing is to see where the timing is at 3000 or so, where does it end up advancing, maybe 34° or 36° without vacuum advance connected. That's the key, the initial timing doesn't really matter too much. Set the initial wherever it needs to be to get there, once you have a damper that is known accurate.
Sent from my iPhone using IB AutoGroup
Thread Starter
|
Elder User
Joined: Jun 2015
Posts: 664
Likes: 2
From: York Pa.
Sounds good! Remember the vacuum reading is a true indication in this situation, without going over the last 2 pages, the suspicion is that the damper is lunched iirc, right?.
So in this situation the "14°" indicated on the damper is pretty much useless if that's the case, and should not be relied upon as the basis for deciding how much initial timing to dial in. Although 20" of vacuum at idle is right in there where you want it, and 14° sounds about where it would be.
The important thing is to see where the timing is at 3000 or so, where does it end up advancing, maybe 34° or 36° without vacuum advance connected. That's the key, the initial timing doesn't really matter too much. Set the initial wherever it needs to be to get there, once you have a damper that is known accurate.
Sent from my iPhone using IB AutoGroup
So in this situation the "14°" indicated on the damper is pretty much useless if that's the case, and should not be relied upon as the basis for deciding how much initial timing to dial in. Although 20" of vacuum at idle is right in there where you want it, and 14° sounds about where it would be.
The important thing is to see where the timing is at 3000 or so, where does it end up advancing, maybe 34° or 36° without vacuum advance connected. That's the key, the initial timing doesn't really matter too much. Set the initial wherever it needs to be to get there, once you have a damper that is known accurate.
Sent from my iPhone using IB AutoGroup
But again all is well for now and I'm happy with how the truck is presently running.
Cargo Master
Joined: Mar 2002
Posts: 3,132
Likes: 219
From: W (BY GOD) V
Why do you think that? Just wondering.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Cargo Master
Joined: Mar 2002
Posts: 3,132
Likes: 219
From: W (BY GOD) V
Oh, a lean condition (such as accelerator pump operation/adjustment) can lead to a lean backfire.
Cargo Master
Joined: Mar 2002
Posts: 3,132
Likes: 219
From: W (BY GOD) V
...sigh...So over torquing a fastener and stretching its' threads and its torque holding ability is an accepted method?
Goes along with the BFH and HOT WRENCH way of doing things...
Thread Starter
|
Elder User
Joined: Jun 2015
Posts: 664
Likes: 2
From: York Pa.
I'm sure you are right, but regardless the truck is running pretty good for now so I will enjoy it until I need to go back into the valve train and will be sure to get the proper torque and sequence done at that time.
Cargo Master
Joined: Mar 2002
Posts: 3,132
Likes: 219
From: W (BY GOD) V
Let me point out two things.
1) You need to re-check the inline fuel filter install
2) and a carbon fouled plug ain't gonna fire with a stock IGN.
No reply necessary unless you want to scold me...
1) You need to re-check the inline fuel filter install
2) and a carbon fouled plug ain't gonna fire with a stock IGN.
No reply necessary unless you want to scold me...
Cargo Master
Joined: Mar 2002
Posts: 3,132
Likes: 219
From: W (BY GOD) V
IMO
Another thing and I will be brief as I try to avoid on-line food fights...
Timing is everything. A balancer has to be verified as correct before any engine modifications are attempted, otherwise you will be beating your head (and wallet) against the wall.
Proper indexing is done with a piston stop, period. No coat hangers, no I think the valves are closed. If bad, you have that balancer rebuilt with an elastomizer and indexed correctly. You then have it pinned (I know, this is not a race car) to assure future integrity.
Then IGN and valve-train timing events can be be ascertained accurately. You also need to check at this point timing chain stretch/variance.
Concerning carbonation... ... carburetion...
There is no one fits-all carb. It needs to be dialed into the vehicle (not just engine). That TECH BOOK will get you started.
The HOLLEY WEBSITE has tons of info.
All of the above is IMO and your mileage may vary.
No reply needed unless I posted something incorrect and/or p!ssed someone off....
Timing is everything. A balancer has to be verified as correct before any engine modifications are attempted, otherwise you will be beating your head (and wallet) against the wall.
Proper indexing is done with a piston stop, period. No coat hangers, no I think the valves are closed. If bad, you have that balancer rebuilt with an elastomizer and indexed correctly. You then have it pinned (I know, this is not a race car) to assure future integrity.
Then IGN and valve-train timing events can be be ascertained accurately. You also need to check at this point timing chain stretch/variance.
Concerning carbonation...
... carburetion...There is no one fits-all carb. It needs to be dialed into the vehicle (not just engine). That TECH BOOK will get you started.
The HOLLEY WEBSITE has tons of info.
All of the above is IMO and your mileage may vary.
No reply needed unless I posted something incorrect and/or p!ssed someone off....