Tired motor

[PeteG41]

Hey guys, just some questions for the experts. Finally got my dream car about a month or so now and getting some things done. Just rebuilt the carb, and after doing so found out the fuel pump was shot. So spent the morning yesterday replacing that. Jeez they don’t make that top bolt easy to get to.
Changed the oil while I was at it since the filter seemed partly in my way. Whatever gunk was around the drain plug was hiding the fact it’s stripped, so now I’m getting a slow leak out of there. What’s the easier fix for that? The idle is a little bit all over the place, but completely smoothes out at 2k rpm’s. Then it will go from about 1k, drop to 650-700 like it’s going to die, and then the rpm’s bounce back up. I was told this motor was rebuilt back in 2015 or so, but something seems off. 99k original mile but has been sitting for a bit. I’m checking the timing tomorrow and hopefully that solves a lot of it, but I’m not too optimistic unfortunately. I thought about running a can of Berrymans down it so try and wake up the top end, maybe a stuck valve or something. I’ve recently been getting a decent amount of smoke, assumed it was just burning carbon buildup from some shots of carb cleaner spray. Any input is greatly appreciated.

 

[1973 Mach-1]

Frankly. It sounds like one cylinder doesn't have compression. Check the timing, but I wouldn't go adjusting it until I checked everything else.
I'd disconnect one plug at a time to determine which cylinder is the problem. If you can find it, pull the plug and check it, gap and whether there are any deposits.

 

[PeteG41]

Frankly. It sounds like one cylinder doesn't have compression. Check the timing, but I wouldn't go adjusting it until I checked everything else.
I'd disconnect one plug at a time to determine which cylinder is the problem. If you can find it, pull the plug and check it, gap and whether there are any deposits.

Yeah I ran a compression test before I bought it, but considering it was one of those “rentals” from orielly it kept giving me problems. I got 148-151 on 5 of them. Then the gauge was crapping out. The plugs are all new, and honestly the ones that were taken out all looked fine. Nothing burned or oil soaked

 

[RIBS]

For the oil pan stripped drain bolt, I used Helicoil…. It seemed like it wasn’t going to work, but it holds fine….if your idle is all over the place, I would rebuild carb if car is new to you, oh duh you did that….change fuel filter, and check for vacuum leaks….my newly purchased Mustang had a mangled Edelbrock intake and carb install, once I got that redone and reseated and carb rebuild my engine came alive! Like others said. Check all the external stuff, tune up, ignition, fuel delivery…

 

[PeteG41]

For the oil pan stripped drain bolt, I used Helicoil…. It seemed like it wasn’t going to work, but it holds fine….if your idle is all over the place, I would rebuild carb if car is new to you, change fuel filter, and check for vacuum leaks….my newly purchased Mustang had a mangled Edelbrock intake and carb install, once I got that redone and reseated and carb rebuild my engine came alive! Like others said. Check all the external stuff, tune up, ignition, fuel delivery…

I’ll look into that for sure. Don’t really like hemorrhaging oil right after a change. Carb is rebuilt as of last weekend, and just swapped the fuel pump. After the rebuild I was getting 0 fuel to the carb. Fuel pump seemed to be the original so it was for sure worn out.

 

[RIBS]

FYI you can check for vacuum leaks by spraying small amounts of carb cleaner around, if it’s pulled in through a leak the idle speed will change….

 

[PeteG41]

FYI you can check for vacuum leaks by spraying small amounts of carb cleaner around, if it’s pulled in through a leak the idle speed will change….

For sure! The only problem is getting it to idle decent enough to be able to do that. I can feather it but from bouncing all over the place its tough to get it steady enough to leave. I’ve capped unused vacuum ports, but I would imagine I have a couple I can’t see

 

[Steve McMahan]

That engine is not running on 8 cylinders. Have you done the pull one plug wire at a time to see which cylinder(s) are not contributing? And buy a compression tester. HF has them and they’re good. My past experiences with someone else’s rebuild is a pushrod might be bent of off its rocker; maybe I’m off mine?

 

[Hemikiller]

Oil drain plug can be quick-fixed with an oversized drain plug. Factory is 1/2", most auto parts stores have single, double and triple oversize plugs.

Go back to basics. Do the compression test again, get a good gauge this time. Procedure from Ford shop manual below. If you have relatively even compression across all cylinders, then you can start troubleshooting individual systems.

 

[PeteG41]

That engine is not running on 8 cylinders. Have you done the pull one plug wire at a time to see which cylinder(s) are not contributing? And buy a compression tester. HF has them and they’re good. My past experiences with someone else’s rebuild is a pushrod might be bent of off its rocker; maybe I’m off mine?

I haven’t done the individual test. I was hoping I could get it to idle a little smoother before, so I could actually do that. I’ll be doing a compression test this week, with a functioning one. I was hoping to avoid pulling off the valve covers but might be pretty necessary

 

[PeteG41]

Oil drain plug can be quick-fixed with an oversized drain plug. Factory is 1/2", most auto parts stores have single, double and triple oversize plugs.

Go back to basics. Do the compression test again, get a good gauge this time. Procedure from Ford shop manual below. If you have relatively even compression across all cylinders, then you can start troubleshooting individual systems.



View attachment 64507

Much appreciated. With that first step, should I just feather the throttle until she warms up? The first time I did it cold, all the plugs out. I know you can do it cold but for truer readings. But I will have an actual functioning gauge this time.

 

[Steve McMahan]

Either way will work because that engine video is telling.

 

[will e]

I tried to follow the firing order from the video but wasn't able to do so. Double check your firing order. If that doesn't clear out the problem then pull all of the spark plugs and do a full compression test.

 

[PeteG41]

I tried to follow the firing order from the video but wasn't able to do so. Double check your firing order. If that doesn't clear out the problem then pull all of the spark plugs and do a full compression test.

Yep I double checked that, but will do it again just to completely rule it out. If it was something that simple I will be kicking myself

 

[71ProjectJunk]

It does seem like you are only running on like 6 cylinders.

 

[JJU9507]

I once had coil primary wires reversed, creates massive retated timing.

 

[Ron Tanzi]

First things first, as others have suggested: a compression test is in order. Do this with all the spark plugs out and the throttle wide open while cranking the engine. If the engine sat for a long time it is possible you have a valve or two sticking in it's guide(s). I have seen it happen. The next step would be to pull the valve covers and check the valve spring heights and confirm that a pushrod did not become displaced. You have to reverse engineer the problem and what could have caused it. The ignition wires did not rearrange themselves or just go bad while the car was sitting around (unless of course critters ate some of them).

Ron

 

[PeteG41]

It does seem like you are only running on like 6 cylinders.

F word haha not the things I like to hear, but I have no reason to disagree. I was optimistic that once I got things moving in there again she would come back around. Although I am still holding out hope.

 

[PeteG41]

First things first, as others have suggested: a compression test is in order. Do this with all the spark plugs out and the throttle wide open while cranking the engine. If the engine sat for a long time it is possible you have a valve or two sticking in it's guide(s). I have seen it happen. The next step would be to pull the valve covers and check the valve spring heights and confirm that a pushrod did not become displaced. You have to reverse engineer the problem and what could have caused it. The ignition wires did not rearrange themselves or just go bad while the car was sitting around (unless of course critters ate some of them).

Ron

Will be doing the compression test again this week with a full time functioning gauge. Probably a dumb question but if I have a dead cylinder or 2, whats my next plan of action? I am a "carport mechanic", so pulling the motor is far above my paygrade. Is it possible the timing is so far off that its running this poorly? Popping the valve covers off wouldn't be the worst thing, I am sure the gaskets are pretty shot anyways based on the transmission leak that just started.

 

[PeteG41]

I once had coil primary wires reversed, creates massive retated timing.

I'll make sure to check that today!