Hello,
This is my first post.

I have been looking around at other threads to do with my symptoms, and tried a few things but so far I think there are multiple things causing my issues so thought I would start a post and get some opinions.

I have recently bought my truck and it has almost immediately started misfiring, and also hesitates, has a flat spot on the throttle, backfires and stalls.

I have checked the timing (which was out as the distributor wasn't clamped down properly) it is now set 5-6 degrees BTDC.
I have a hot spark electronic ignition conversion on the way.

The choke was stuck on, but has now been freed off.

The breather pipe from the rocker cover to the carb is missing.

I have put new spark plugs in (ngk wr5 set at .035) the old ones are black and sooty, and some were wet with fuel, others were a little oily on the threads.

Any initial thoughts would be greatly appreciated. I am currently waiting for the electronic ignition to arrive in the hope that will fix everything! Anything else I should be looking at though?

Thanks,
Dean

 

Dean, First and Foremost, welcome to FTE!! I am not an authority and since my 65, with the 390, has been in storage for the past several my tune up spec's are abit hazy. I recently brought it home and spent the past couple of days preparing the engine for running. Seem to recall that when I swapped from points to E.I, the plug gap increased to around .044, I went with Dura Spark ll, other EI tune up spec's may be different; in addition, in my case, I found running at around 10 degrees the engine better??

Couple reminders; vac. advance should be blocked when setting the timing; of course may depend upon Brand and type Carburetor; having said that, any change in timing requires readjusting the idle mixture, or vise versa. Expect to have the engine running tomorrow and the first item on my agenda is to check at what degree I set the timing? Anyhow, food for thought,; hopefully more knowledgeable member's will chime in with comments and suggestions? Again, welcome to FTE.

 

Welcome to FTE

Check that crankshaft damper outer ring has not slipped off its index. Common problem with vintage engines and makes timing marks totally inaccurate and cause for much confusion. Remedy of course is to replace damper, but for the moment set ignition timing using a vacuum gauge and see if that helps.

 

Thanks for the advice,
I will get a vac gauge and set up the timing that way.
I don't think the marks are too far out, I got piston 1 to about TDC by eye and the timing marks were about TDC too and the rotor was almost near lead 1. So I adjusted from there then set up with the lamp.

I would have thought it was close enough to not be missing even if it isn't spot on?

 

Hm, if you checked rotor position at TDC and marks were in the ballpark damper may be OK. Make sure for now spark is healthy - bluish white, not weak reddish yellow. Probably time for a carb rebuild.

While you're waiting for ignition components maybe treat the old gal to new spark plug wires. Also ensure good solid ground connections. New cables from battery, from frame and firewall to engine block. Grind mating surfaces down to bright shiny metal. I like to run a flat file at the boss where the distributor mounts to ensure good electrical contact. Better ignition means it will run noticeably smoother and warm up quicker.

 

My 390 is in a car, but same vintage, similar tuning issues. Most people I know with 390's and other vintage motors set the timing by ear or vacuum gauge. My timing marks are also close to where they should be, too, but the timing is right with much more advance than called for in the manual. So, yeah, it could still be pretty far off. (In all likelihood, you're running an ethanol blend for gas, not the 98 hi-test ethyl this motor expects.)

The stalling and dying could be the sign of a bad coil; I'd replace it, at least for testing.

Amen to a carb rebuild as well.

Good luck, and keep us posted.

~Steve

 

So, digging deeper.
One of the push rods has taken a beating. And it is definitely not straight anymore.

Any common issues on these engines that I could have?

 

Stale fuel? Just spitballin' though, need coffee.

 

Imagine that can account for misfire? Not an authority probly need to remove intake manifold and take a look at the lifters?

Recently towed my 65 w/ the 390 home after I had let it set in a field for the past 7 years, started right up but sounded like the piston were swapping holes.

May want to post question in the appropriate engine forum if member's in the 61-66 forum have no comments/suggestions?