engine still pings uphill
Thread Starter
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Elder User
Joined: Sep 2015
Posts: 794
Likes: 19
From: between lost and found
engine still pings uphill
hello, I just completely rebuilt the motor for my 1977 F100, got it to pass smog (yes i live in the communistic country of Ca.....)
As long as i stay in-town and on flat ground the motor runs great, I can even do light highway driving as long as there is no steep or long inclines. there are no vacuum leaks, timing is set at 10 BTC spark plugs set at recommended gap
But when I think I've eliminated a cause, ie carb adjustment double check my timing I feel like I'm beating my head against a wall, I'm trying to avoid taking it to a shop and have some else turn the right screw 1/8 a turn and charge me for it at shop prices,
I'm no mechanic by trade but I have scarred knuckles from skinning them more than once
1977 F-100 custom shortbed step-side
302
3 on the tree
As long as i stay in-town and on flat ground the motor runs great, I can even do light highway driving as long as there is no steep or long inclines. there are no vacuum leaks, timing is set at 10 BTC spark plugs set at recommended gap
But when I think I've eliminated a cause, ie carb adjustment double check my timing I feel like I'm beating my head against a wall, I'm trying to avoid taking it to a shop and have some else turn the right screw 1/8 a turn and charge me for it at shop prices,
I'm no mechanic by trade but I have scarred knuckles from skinning them more than once
1977 F-100 custom shortbed step-side
302
3 on the tree
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Welcome to FTE
You'll need to do your homework and some sleuthing. In particular study engine distributor systems - mechanical and vacuum advance.
At a guess the distributor is probably worn out/gummed up and/or vacuum advance disconnected, vacuum leaks, etc. Or, did you replace the distributor as part of the rebuild? You'll need a timing light at minimum. I'd a mechanic's vacuum gauge too. Real useful.
You'll need to do your homework and some sleuthing. In particular study engine distributor systems - mechanical and vacuum advance.
At a guess the distributor is probably worn out/gummed up and/or vacuum advance disconnected, vacuum leaks, etc. Or, did you replace the distributor as part of the rebuild? You'll need a timing light at minimum. I'd a mechanic's vacuum gauge too. Real useful.
Thread Starter
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Elder User
Joined: Sep 2015
Posts: 794
Likes: 19
From: between lost and found
Welcome to FTE
You'll need to do your homework and some sleuthing. In particular study engine distributor systems - mechanical and vacuum advance.
At a guess the distributor is probably worn out/gummed up and/or vacuum advance disconnected, vacuum leaks, etc. Or, did you replace the distributor as part of the rebuild? You'll need a timing light at minimum. I'd a mechanic's vacuum gauge too. Real useful.
You'll need to do your homework and some sleuthing. In particular study engine distributor systems - mechanical and vacuum advance.
At a guess the distributor is probably worn out/gummed up and/or vacuum advance disconnected, vacuum leaks, etc. Or, did you replace the distributor as part of the rebuild? You'll need a timing light at minimum. I'd a mechanic's vacuum gauge too. Real useful.
just about everything under the hood is new (even the horn)
Cranky Old Guy
Joined: Mar 2008
Posts: 3,562
Likes: 6
From: Raphine, Virginia
Mixture screws won't be the problem, they are for idle only. Kinda sounds like vacuum advance is coming in too quick. Most of the replacement vacuum canisters have an allen screw adjustment accessed through the vacuum port controlling how much vacuum it takes to move the advance plate. You could try dropping to 8* BTDC or going up a grade in gas to see what happens. I know you don't want to make any drastic changes as you will need to retune come smog test time again. Good luck.
Cargo Master
Joined: Jun 2003
Posts: 2,982
Likes: 7
From: Somewhere Saskatchewan
hello, I just completely rebuilt the motor for my 1977 F100, got it to pass smog (yes i live in the communistic country of Ca.....)
As long as i stay in-town and on flat ground the motor runs great, I can even do light highway driving as long as there is no steep or long inclines. there are no vacuum leaks, timing is set at 10 BTC spark plugs set at recommended gap
But when I think I've eliminated a cause, ie carb adjustment double check my timing I feel like I'm beating my head against a wall, I'm trying to avoid taking it to a shop and have some else turn the right screw 1/8 a turn and charge me for it at shop prices,
I'm no mechanic by trade but I have scarred knuckles from skinning them more than once
1977 F-100 custom shortbed step-side
302
3 on the tree
As long as i stay in-town and on flat ground the motor runs great, I can even do light highway driving as long as there is no steep or long inclines. there are no vacuum leaks, timing is set at 10 BTC spark plugs set at recommended gap
But when I think I've eliminated a cause, ie carb adjustment double check my timing I feel like I'm beating my head against a wall, I'm trying to avoid taking it to a shop and have some else turn the right screw 1/8 a turn and charge me for it at shop prices,
I'm no mechanic by trade but I have scarred knuckles from skinning them more than once
1977 F-100 custom shortbed step-side
302
3 on the tree
Lead Driver
Joined: Sep 2003
Posts: 7,018
Likes: 210
From: SoCal
If you haven't already, check to make sure the EGR is working properly.
One of my old cars would ping badly after I disabled the EGR thinking I would get more power and efficiency. It sort of defeated the purpose of defeating the EGR; backing down the timing enough to stop the pinging caused the engine to run hotter, lose power and mileage. Things ran much better after I hooked it back up. Those 70's emission control systems were a real mess.
One of my old cars would ping badly after I disabled the EGR thinking I would get more power and efficiency. It sort of defeated the purpose of defeating the EGR; backing down the timing enough to stop the pinging caused the engine to run hotter, lose power and mileage. Things ran much better after I hooked it back up. Those 70's emission control systems were a real mess.
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Elder User
Joined: Sep 2015
Posts: 794
Likes: 19
From: between lost and found
Thank you
THANK YOU TO ALL WHO TOOK THE TIME TO OFFER A HELPFUL HINT
to TEDSTER9,STUART1,GFW1985, and XLT4WD90, THANK YOU
turns out (literally) I actually just needed to retard my timing by about 3 degrees
mistake on my part....once I did that I took it for a test drive
(for a couple of hours) lol truck ran great.
planning on a short trip to Ventura 100 miles from the house, this next week I'm really looking forward to really seeing how the ol' girl does
to TEDSTER9,STUART1,GFW1985, and XLT4WD90, THANK YOU
turns out (literally) I actually just needed to retard my timing by about 3 degrees
mistake on my part....once I did that I took it for a test drive (for a couple of hours) lol truck ran great.
planning on a short trip to Ventura 100 miles from the house, this next week I'm really looking forward to really seeing how the ol' girl does
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