I have a 76 360 with a reman 2barrel, stock exhaust manifolds.

I knew the timing was off because whoever had it before me hooked the vacuum advance to the wrong port, then turned the dist. to make it work alright.

So I put the new carb on, hooked the vacuum line up just to see, and it wouldn't even run, so i reset the timing back to 8 BTC and started fresh. I tuned the carb with a vaccuum gage( I'm 22 and slowly getting better at listening )
The engine seems to run best-smoothest, at about 20degrees advanced, but i left it about half that because i wanted it to be closer to stock. It runs damn good right now, but has a hard time starting. Do these engines(when tuned properly) run smooth, or a little lopey? I've never really messed with timing before so any help would be great. I realize there are other posts in searches, but they never quite answer my questions.

Just a thought, could the difference be the different timing set used after 1972, or more likely somebody screwed it up? Not sure the # of miles cause the speedo wasn't in the truck, but i do get some blowby out the valve cover vent, but none out the exhaust.

Thanks alot everyone. Anyhelp would be great. I'm just trying to learn all this stuff.
Brian

 

A stock 360 should have a rock-solid-smooth idle.

Is this thing rebuilt? Any chance someone put a more-radical cam in it?

20 degrees initial for idle, that sounds like my 11:1 390 with a pretty big cam.

You could have a vacuum leak, which can be covered up by advancing the timing way up.

What's your manifold vacuum at idle with 20 degrees advance?

 

thanks for the help

I seriously doubt the engine has had any cam work done or that sort of thing. stock manifolds and all.

the best vacuum i could pull with the dist way advance and the carb leaned down was 18, but i adjusted everything back a little so i don't know if it would have started.
The way it sits i'm pulling about 14-16 lbs of vacuum.
Sometimes when starting it will back fire, other times it cranks right over.
(nothing when you shut it off - doesn't diesel at all)

just trying to give you any info i can think of....

thanks again
Brian

 

Make sure the vacuum advance line is pulled off the dist. and plugged when you set the timing.

 

maybe the malancer has slipped. move it to tdc and see where the marks are.

 

Good point! Or the wrong harmonic balancer has been installed.

 

i did cap the vaccuum lines when i was timing it. i'll check the balancer though

with the 2 barrel, is there any lag if you just floored it from idle( like leaning for a second) or is the stock carb sized pretty well?

also - should i just adjust the dist until the engine runs at it smoothest/ highest rmp? then re-tune the carb? just wondering

Thanks again
Brian

 

Timing, idle speed and idle mix are pretty complicated to get everything setup right "by ear".

Check the balancer, that's a VERY good point.

Set the idle timing to 10 BTDC. Then, adjust RPM, and finally adjust the idle mix screws.

Then, recheck RPM (and timing!), change as necessary, and re-tune the idle screws.

Repeat until you lose your mind, or it runs right.

When you lose your mind, come back here and we'll try to help again

If you finally get it idling right, with 15-20 inches of vacuum, then drive it and see how it performs.

Before you really get into this, make sure the vacuum advance is working (pull the vacuum hose from the carb and suck on it - RPM should go up). Make sure the port you are using for the vacuum advance is "ported" vacuum - connect the vacuum gauge, you should have no vacuum at idle - hit the gas, the vacuum should come up (this is opposite of "manifold" vacuum, which I think you already know).

 

[QUOTE=ford390gashog]maybe the malancer has slipped.


opps that should be balancer not malancer

 

My 73 f250 runs so quiet I sometimes forget its running. Then my wife put 3 gallons of water in my tank. It ran like crap for about 3 months. I think I got all the water out. I rebuilt the carb and changed about 6 fuel filters. It kept backfiring I thought it was the carb, I checked the timing it was way off like it had jumped a tooth. I set my timing with truck in gear vacuum line removed and plugged. Now it runs like a scalded dog. Wow what a difference!

 

Your wife trying to convince you to get rid of the truck?

 

Naw! I had a gas can that I kept water in for breakdowns. I guess it was partially my fault. But funny thought anyway!