1952-59 Ford UhOh, My 302 Suddenly Running Poorly

I recently installed some new gauges and cleaned up some wiring under dash and my 302 is suddenly running rough and stalling out. Any ideas how the two could be related? How should I approach troubleshooting it?

 

First thing I would check is the voltage going to the HEI with a volt meter you should get the same reading at the battery as you do at the HEI feed wire which should be 10-12 gauge. Was one of the new gauges a volt meter ? Does that gauge voltage match the other two readings ? Try disconnecting the volt meter gauge and see if the engine runs better.

 

Thanks Jeff, the voltmeter was one of the guages I replaced. I'll do those checks asap. When it started running bad, I replaced the plugs with Autolite APP45 double platinum's and mfgr recommends gap at 035. I've read that they perform better with HEI gapped at 050-055, is that correct?

 

That is what I gapped mine with HEI, .050.

 

i would check that spark plug wires are in order and firmly pressed onto the plugs. more than often 6 and 5 and/or 4 and 8 get wired wrong and the engine will run but really rough.

 

.035" gap on the plugs won't make it run rough. I would disconnect the present feed wire to the coil and feed it with a jumper wire from the battery temporally. If it still runs rough, it has nothing to do with your dash wiring project and you might want to recheck elsewhere under the hood.

 

I'm running .040" gap but I have 289 Hi-Po heads on my 302 the plugs are 18mm.

 

***uming you know that the firing order on an HO Is different than other 302’s.

 

Find the problem ? What was it ?

 

Tested voltage at distributor, 12v. Ran jumper to battery. Tested coil, .5 ohms on low side, 7000 ohms, still running rough and stalling. I'm starting to think maybe I picked up some bad gas. I'll add some gas treatment tomorrow. Anyone have any other ideas?

 

I forgot to mention, I also had the ignition module tested at Autozone with no issues found. I replaced it anyway just in case.

 

1. I would pull the fuel filter and see if there's any water in the fuel, and also check the float bowls for water/debris.
2. If not fuel related, check the HEI coil connections in the cap. They can sometime arc and carbon track inside.
3. As okie dokie mentioned, be sure your plug wires are hooked up for the correct firing order (HO and later GT 5.0's had different firing order from older 302's.

 

Fuel filter checked out good, HEI coil connections look good and firing order is correct. I'm at my wits end.

 

You have to determine if it is fuel or spark. I know you said the ignition module checked good, but do you have a spare distributor to put on to try? I'm grasping for things to try here, but you might try attaching your timing light pick-up on a plug wire and run the engine and look for an unsteady flash. Or get it running rough and spray starting fluid in carburetor throat to see if it smooths out for a second.

 

OK...so it was running good before you did some wiring...go back to what you did...check connections, grounds, wires around where you where working to see if you might have disrupted a wire end or something silly before you pull the motor or your hair out. a wire end is not secure...a spark plug end is not secure and voltage is needing to jump to make contact....something silly. Pull a spark plug wire and start it. Stop and try the next...and each one to see if you can locate the cylinder that is not firing properly. May just be a wire that has broken inside and is fighting for voltage. With you CD ignition - DO NOT pull them with your hand while it is running - unless you need to jump stat your heart!

 

Thanks 40cpe and 50sboy, I'll run through your suggestions tomorrow and report back.

 

Probably opening a floodgates of opinions here, but to. 40cpe's suggestion to try another distributor (I don't have a spare), what would be a good cost effective choice for Option 1: a cheap HEI to pickup as a diagnostic tool, and Option 2: a nice dependable mid price unit if I end up actually replacing what I have?

 

Mine is 5 years old plus: https://www.skipwhiteperformance.co...2-50-50l-hei-distributor-8502-blue-cap_89883/

 

Thanks Jeff,
Doesn't look like I can go wrong with the Skip Wite unit as a diagnostic tool, or a replacement unit. I have one ordered and on its way. As always, I appreciate the generous sharing of knowledge by yourself and all the folks on this forum. To all who have contributed on this subject, I'll complete the most recent suggestions and check back in. Thanks to all!!!

 

Not sure what year your 302 was but when you pull the old unit inspect the gears wear pattern,because there are two different HEI units (READ the text here) https://www.skipwhiteperformance.co...lete-distributor-long-shaft-6502-5-red_89697/ compare to the pictures there also.

 

I see that the unit he says is for a 5.0 roller engine has a longer shaft below the gear. When I converted a roller engine to carb/distributor back in the late '90s I used a '69 distributor and changed the drive gear to steel. I ran it that way for 60,000+ miles without any problems. Maybe I was lucky.

 

There is a fair amount of info on some of the Mustang forums regarding this,it seems some cases have to do with the oil pump drive shaft length so it may not be a bad idea to Google this issue so you know what to look for. You can check by putting white grease on the gear and installing the distributor that will show you the gear alignment NOTE: whenever you do a rebuild or replace a distributor you should replace the shaft they have been known to be a SBF "weak link".

 

what was it???

 

Don't know yet, at this point I've replaced plugs, wires, distributor, added Turbo 108 Octane Boost, Heet, and fresh gas. I cleaned the harmonic balancer and found timing marks, and added a timing cover timing pointer at 2 o'clock position. I brought it to TDC on compression stroke, and confirmed it was at TDC at marks relative to pointer with rotor pointing to #1 plug wire. I manually turned to 10* BTDC, and set timing with a light to 10* BTDC with vacuum advance line at distributor removed and plugged. I checked and confirmed all vacuum lines are good and no leaks. It runs good at higher rpm, but rough at idle, and stalls at idle. I hate to monkey with the carb, but I'm out of ideas.

 

Some other thoughts:
1. Pull and plug vacuum hose from brake booster to see if idle smooths out.
2. If you still have vacuum wipers, do the same with that vacuum hose.
3. Spray carburetor cleaner around intake gasket, base gasket, and carburetor body and see if idle changes any.
4. Check to be sure ground strap/wire is still connected between motor and frame, and body and frame.

 

Vacuum Leak!!

 

just got back on this today, and followed Fairlane 62's suggestions. I found some loose intake manifold bolts, and when I sprayed carburetor cleaner around intake gasket, base gasket, and carburetor body, it did smooth out just a little, and after I tightened the bolts it maintained at idle slightly better. At this point, I'm finding that it doesn't want to start unless I give it a shot of starting fluid, and then if I sorta feather the throttle for 3-4 minutes, it will maintain idle, but not nearly as well as prior to start of the issue. I' wondering if the mechanical fuel pump is failing to maintain consistent pressure. Any thoughts on possible fuel delivery issues? Note that early-on, I did pull the hose to the carb and cranked the engine with the hose in a container and seemed to be getting good flow.

 

There has been numerous complaints on a lot of forums about erratic fuel pressure,it's hard to find mechanical pumps that are not off shore made.You may have decent pressure at idle but not under load and vice versa. Installing a pressure gauge and regulator is a common cure some so called stock pumps are pushing over 10 psi drives the Edelbrock Carbs nuts they don't like anything over 5-5.5 psi.

 

Are you getting a good steady shot from the accelerator pump nozzles?

 

I'll check accelerator pump nozzle flow tomorrow. Any thoughts on going with an edelbrock electric fuel pump and pressure regulator?