new engine start-up problems

[Brian King]

I agree - weak/improper ignition will allow the plugs to be wet.
Two ideas come to mind: either throw another crab distributor on there, or throw another intake on there (stock with a single carb.
Another distributor sounds easiest at this point.

[joe 1950]

Do you have good blue spark at the plugs

[glennpm]

Pull any plug. Ground the plug to the block. See if you have a spark from spark center electrode to the side ground electrode.

[Step-down]

For guys like myself I always start with a single carburetor, narrowing down the confusion and break-in.

[Chris Marshall]

Here's a long shot. A malfunctioning tach can cause all kinds of odd ignition issues. Disconnect the tach and give it a try.

[tubman]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by Chris Marshall

Here's a long shot. A malfunctioning tach can cause all kinds of odd ignition issues. Disconnect the tach and give it a try.

Maybe not such a long shot; I had this exact thing happen to me.

From my long experience with fouled plugs in snowmobiles, I don't think it would be a bad idea to buy a fresh set of plugs to try.

[Don]

Change out rotor,,easy to do,,had same problem but using single carb,,,

[Ggmac]

[QUOTE=Brian King;1934985]OK here is the latest:
-Unplugged the outer carbs and then covered their inlet with tape.
-Checked voltage at the coil and it's got 9 volts.
-Tried to fire again but it acted exactly the same.
-Cut the pressure regulator to it's lowest setting (.5 lbs) and even drained the bowls of the outside carbs.
-Just like last night, it goes from firing and sputtering for 10 secs to nothing on about a half dozen attempts.
-Plugs look wet, but not sure that tells me anything since it's pumping fuel but not firing - of course they're wet.

And no I am not running stainless from the firewall to the carbs. I bought one of Charlie Price's stainless lines that comes from the mechanical fuel pump (with the regulator in between).
Tape is not a good choice ! A little fuel oe vapor will cause the glue to go by by and the tape could be sucked into the motor . Did you disconnect the progressive linkage when first trying the tape ? If its not the tach causing problems I still think its TOO MUCH fuel . It starts normal and after 10 seconds it goe to crap , tells me its spark and plugs are ok for the first start up then it floods . Take the outer 2 carbs off , it doesnt take much to wash the cylinders out requiring rings or at least a rehone .

[Brian King]

I only used tape to cover the velocity stacks, not down on the intake where it could be sucked in. Besides, there are screens on the mouths of the carbs.

Worked on it some this weekend, though I let myself get distracted with other chores on a new build (ie: bleeding brakes, greasing zercs, etc.). But I did:
- completely disconnected both outer carbs from the fuel line
- checked the needle/seat in the center barb (not plugged)
- checked spark (looks to be good)
- disconnected tach
I too have to believe it is too much fuel. Tomorrow I'll pull the center carb and have a look.
I can't slap another distributor on there - had to machine this one to accept an altered spacer plate...this is what happens when you mistakenly put an early came in a later motor and the crab won't seat.

[JSeery]

Just taping the top of the outside carbs will not stop a fuel or air leak. You need to block off the manifold with something solid, like a thin metal plate. You can slip it between the carbs and the manifold.

[glennpm]

Hi,


Regarding "I can't slap another distributor on there - had to machine this one to accept an altered spacer plate... this is what happens when you mistakenly put an early came in a later motor and the crab won't seat"



Are you sure that you have your distributor mounted correctly with the rotor pointing to #1 on the cap for the power stroke? Not sure if your spacer would change how the crab tang mounting would be affected.


I had questions about finding #1 power stroke and there are good methods in this thread:


https://www.fordbarn.com/forum/showt...ht=TDC+glennpm

[Ggmac]

What Jseery said ! Leave the center carb , remove the 2 outer carbs by butting aluminum or something solid between the carb and manifold. By just taping the top of the carb you made it worse , now its just suckingfuel , unless you emptied the bowls and disconnected the lines . Reducing the fuel press isnt good enough.

[Brian King]

I gotta try and capture everything I've tried here:
-all 3 carbs disconnected from fuel lines
-spark is strong
-advanced the crab distributor
-checked and rechecked firing order
-rehooked up center carb only and it ran for about 30-45 seconds before finally succumbing to my tuning.
-backfired like a son of a gun. I could never get it to clear out.
Sooo..... it HAS to be ignition! Tomorrow I'll run a compression check to make sure we are ok there. For the life of me I can't figure out the backfire.

[glennpm]

"Are you sure that you have your distributor mounted correctly with the rotor pointing to #1 on the cap for the power stroke? Not sure if your spacer would change how the crab tang mounting would be affected."

[Brian King]

Checked and triple checked that the distributor is pointed at #1 when the thumb blows off #1 spark plug hole. The spacer should make no difference.
It acts as if the cam is off a tooth, to be honest. But not sure how I could have screwed that up during assembly - all you have ot do is line up the dots when installing the cam gear.
Hopefully the compression test today doesn't reveal anything.....

[glennpm]

Good Brian, thanks for the reply.

[Mart]

The fuel regulator set to 0.5 lbs might not actually be delivering any fuel. Set it to about 2 lbs.

[Brian King]

I took the pressure regulator off. Just a mechanical pump feeding directly to one carb.
Whether I had all three carbs or one on, or whether I had a pressure regulator or not, or whether I poured gas in from the top or pumped it in.....it all acted the same. Thus ignition(?)

[JSeery]

Another long shot, there were a couple of post about timing gears being mismarked. Not sure if they just thought they were mismarked or they actually were mismarked.

I don't remember, but have you run a compression test? A valve sticking might lead to a backfire.

Also, depending on the carb type, a backfire can damage the power valves and cause them to leak.

[glennpm]

He plans to run a compression check today from post #35