1985 F350
460ci 7.5L
4spd BW

I have a Holley (Summit) 650cfm carb with electric choke. New plugs, wires, cap, rotor, ignition coil, ignition module, and just replaced all of the gaskets/seals above the heads.
It cranks, and cranks, and cranks....sometimes it misfires and sprays fuel out of the carb.
It ran well before I pulled the engine to replace the gaskets

I am out of ideas.... Please help.

 

Did you pull the dist as part of the re-gasket job?
Hope you have all the old parts you replaced as new parts have been known to be bad out of the box and give 2 or 3 being bad you will go hairless in no time.

You say sometimes it "misfires" lets start at the beginning and get the motor on TDC and check that the timing marks line up with the piston at TDC on the compression stroke.
You have to make sure it is the compression stroke then make sure the rotor is pointing to #1 plug wire.
If it is not and you pulled the dist. you will need to pull it and drop it back in so the rotor points to #11.
Then recheck the plug wire firing order.

Lets see what happens from there
Dave ----

 

Thanks Dave.
I pulled the motor so I could replace the oil pan gasket, and I removed all of the Smog pipes from the exhaust manifold.
Before I started loosening bolts, I turned the motor to TDC and marked the distributor. It should have been easy......

I have since used a boroscope to make sure that Cyl1 is at TDC, the crank lines up and the distributor is pointing at #1.
I have tried rotating the distributor 180° and it doesn't like that. Hard cranking and backfiring. (I have repeated this process several times.)

This past weekend I took the carb (summit M2008 600cfm) off and did my best to clean and inspect it.
I made sure the fuel/air mix screws were 2 turns out from the bottom. The curb idle I have tried at no engagement, all the way to lots of engagement(throttle open). I get a strong stream of fuel out of the primaries when I press the throttle but I can't get any fuel out of the secondaries....probably gonna need vacuum for that to work, but I thought I could manual pump it after the primaries were wide open??

I have verified all 8 plugs are firing.
Even if I spray starting fluid down the carb and crank it, I'm not getting any combustion.

I'm so confused.

 

I just replaced my ignition coil for an OEM style.
Didn't change anything.
I'm going to replace the ignition module, just to cross off every possibility, but the module is newer....maybe 6-9 months. And it was working fine when I parked it.

 

You can't look at the piston and determine TDC. The piston comes up twice in a complete cycle, once to fire and again for exhaust. You have two choices;

1. Turn the engine with the #1 sparkplug out, and you thumb over the hole. As you are turning the engine, the marks will come around. If you are on the TDC mark, and air is trying to push your thumb off the hole, that is the mark you want. If you keep turning the engine, the mark will come around again and it will not push air around your thumb because air is leaving through the exhaust valve.
or
2. Pull the valve cover off on the pass side. Watch #1 cylinder valves as you turn the engine. The mark will come up and both valves will be shut. That is TDC. If the mark comes up and one of the rockers is opening one of the valves, that is not the one you want.

 

What he said you have to make sure that #1 is at TDC as it will never start any other way.
Once at TDC and you try to start with a little gas down the carb you can turn the dist. a little each way to see if it dose anything to try and start.

The carb unless it is a double pumper, and I dont thing yours is, you will not see fuel squirt on the secondary side.
Dave ----

 

Should the next step in the cycle be intake opening or exhaust opening?

I just pulled the valve cover.
The Dist is pointing to #1 after the intake valve Closes and before the exhaust valve Opens.

 

There are 4 steps
1- intake valve opens and pulls in the air fuel mix as the piston is moving down. INTAKE
2- before the piston get to the bottom the intake valve closes and the piston starts back up. COMPRESSION IT IS AT THIS POINT YOU WANT THE TIMING MARK TO POIN TO TDC AND THE ROTOR POINTING TO #1 IN THE CAP
3- just before the piston get to the top spark happens and the air fuel mix fires. POWER
4- just before the piston get to the bottom the exhaust valve opens and as the piston starts back up it pushes the spent air fuel mix out. EXHAUST

So when turning the motor over you are looking for the intake valve to close. Keep turn the motor till the timing mark lines up to TDC. VALVES SHOULD NOT BE OPENING OTR CLOSING AT THIS POINT.
Now pop the cap and the rotor should be pointing to #1 plug wire in the cap. If not you will have to pull the distributor and turn it so when you drop it back in it points to #1. Remember the shaft will a little when going in so you will need to go past so when dropped in it lines up.
If the valves are doing anything when timing mark is at TDC make 1 more full turn and check the valves.
Dave ----

 

Are the plug wires in the correct firing order ? It differently sounds like the timing is off.

 

I kept looking for it, some of the books I have tell you when you are at TDC #1, that a certain other cylinder the valves will be rocking. In other words if you turn the engine a little bit back and forth past #1 TDC, another set of rockers on the engine will be alternating exhaust/intake. See if that is true on your engine. I am thinking it's #4 cylinder but not sure about that.

 

Which is why, it's so easy to be "180 out". Been there done, that on my 340 back in 1975.

 

Yea I think when the intake valve starts to close look for the timing mark to show 0 TDC
Dave ----

 

Well.... that all sounds good to me.
I just replaced the distributor.

I confirmed the intake valve #1 had just closed before reaching TDC. Exhaust valve has not begun opening.

Distributor is pointing at #1.

I have replaced all components to starting/firing.
I'm positive the ignition timing is correct.

....I guess I'll pull the timing cover and double check the crank timing. I replaced the chain and installed "straight up" timing a couple thousand miles ago.
Am I missing something relating to the straight up timing versus the factory 8° retarded?

*I'm so frustrated as it was running(poorly) and I drove it out of my driveway with a bad intake manifold gasket. I replaced the gasket and now it won't start. WTF

 

https://www.google.com/search?q=1985...hrome&ie=UTF-8

Maybe that will help.

If it ran well before, then is it possible you have a vacuum leak from the gasket under the carb ? As you say, you placed all gasket above the heads. Why did you take the carb off the intake ?

It has to be something simple.