MTFCA Forum

Hi all,
I have tried everything I could think of to start this 21 engine. Background: the engine was rebuilt (I believe) before I bought it 2 years ago. I haven't gotten to try starting it till 2 weeks ago. Here's what I have so far:
all coils rebuilt
all new wiring harness
battery new but maybe fading a little
I rebuilt the carb with all new parts from vendors
the viton tip float needle sticks closed, so I put a little grease on it so it would move
ignition switch a little sketchy, but I got it to buzz
fresh high test gas
starter brushes are about 90 %

So I've drained the battery trying to start it. Several cylinders are firing, but it won't kick on. I jumped it from my 12 volt running van. I checked all the new wiring and all is secure.
Problems I see: after trying to start it, gas pours out of the carb. Also there is a puddle on top of the carb all by the brass Holley tag. It must be bubbling out of that vent hole. What could be the cause of it not kicking over? Several cylinders are firing. I can't tell which pistons are firing and which are not. Any suggestions to check the next thing? Thanks so much for any input.
John

First step: Fix your carburetor. The needle valve is not seating properly. If the gas has not already done so, clean out the grease you put in it.

Thanks. I only had a tiny bit of grease on the viton tip. Would the float needle (viton) have anything to do with the gas flooding out of the opening of the carb and pouring out of that vent hole below the brass name plate?

NY John T wrote: ↑

Thu May 04, 2023 4:10 pm

Thanks. I only had a tiny bit of grease on the viton tip. Would the float needle (viton) have anything to do with the gas flooding out of the opening of the carb and pouring out of that vent hole below the brass name plate?

That's definitely where your carb leak originates. Whether it's the tip itself, dirt in the needle seat, a damaged needle seat, a sticking float hinge, a leaking/sunken float, a bad float height adjustment, or ??? will remain to be seen.

Grease on the viton tip has transferred into the valve body and unless everything is THOROUGHLY cleaned, it will remain poluted and problematic.

Right now your valve is sticking open, as you have surmised.

when turned upside down, the float tab resting on the valve (DO NOT PRESS!!!), then the float should be essentially parallel to the carb bowl seat for proper richness throughout the RPM range without having to constantly fiddle with the spray needle.

THIS IS IMPORTANT: The float tab which lifts the needle must be arched such that at ANY position of the float, while it is lifting the needle, the contact area of the tab MUST be perpendicular to the needle...and when it is fully seated, the tab MUST be perpendicular to the needle. If your tab is basically an inclined plane, the needle will be thrown against the body and pinched there as it grinds its way up as the float lifts. This will keep the viton from seeking the hole and the stiction of the brass needle pressed sideways against the brass bore is all that is required to keep the needle from sliding home like it should. This fault is 99% of "failure to close" on this style valve. Get that tab right, and the world will be right.

DOUBLY IMPORTANT: Do not subject the Viton tip to Acetone or Laquer Thinner as that will have a great likelihood of swelling and softening the tip...it may not be visually obvious, but the continued failure to seal will be most obvious!

Thanks.
I think you all might have hit it on the head. The viton tip would stick in the valve when I lifted up the float. I thought, that's not right. Almost like the rubber slightly collapsed in the orifice and wouldn't release. I had another carb on another car with the same problem (sticking in the valve orifice), so I just changed back to the original metal tip that had been originally in the carb. I have no problems with that carb.
I do have the original needle from this rebuild, so I'll replace the viton with the metal one.
Question: Would the sticking (closed) viton cause the float bowl to fill up and overflow with gas? Or would the viton be shutting off the supply of gas? I'm confused.
Also, the air/fuel mixture rod should be open 3/4 to one and 1/2 turns, right? This wouldn't have anything to do with the flooding of the bowl, right?
Thanks so much. Today's my B-day and I thought "How wonderful, I'll get it started on my birthday and really celebrate". Not.
John

If you want it to leak, the old metal tip is the ticket!

If the float tab is bent as I suggested, a clean, undamaged Viton tip will seal very well. A flooding carb is from a valve sticking open or failing to seat fully and remaining partially open to some degree.

The usual disclaimer: all mechanical things fail, given enough time. Since the T has a gravity feed system, it is imperative that the gas tank sediment bowl shut off works, or better yet, an accessory 90 degree turn valve is situated immediately in the vicinity of the carb (and used!)

John,
If the float valve sticks shut you will get no gas into the carb, if it is stuck open the gas will flow out the top vent hole.

Initial needle setting is 1 1/4 open. Will start, but will be rich.

Hi alI
I FINALLY got the 26 Tourer started on Saturday after spending countless hours tinkering.
Several things resolved:
#3 coil box was not making contact with the box contact springs (I bent the springs to make better contact)
dirty old gas in the filter bowl and tank (I drained it out)
carb was flooding (float stuck open so I switched it with a known working carb)
dead battery (I even jumped it from my Sienna minivan)
wheels were on the floor (I then jacked them up)
not enough gas (I added hi-test)
did a compression test: compression was zero in #2 and low in two others (I added Kroil to start, then motor oil)
too much motor oil in cylinders which dripped down through the carb (I then cleaned out and got 40 40 45 40 in the cylinders)
foul language (I've since mended my ways)
rear end oil too thick and old? (haven't tackled that yet)
sticky ignition switch (I shaved the ignition plate, but didn't make a difference)
So.... at about 1:00 on Saturday, the engine roared to life. The engine was I believe, rebuilt. It seems so, as it sounds strong and steady.
I really appreciate all the suggestions on things to get the engine going. Without this forum, I would be nowhere with the project.
Next is to adjust the bands; as I creeped the car out of the garage but couldn't get it to reverse back in.
BTW: this will be the second carb where I switched OUT the viton tip for the metal tip!
Thanks so much,
John

John,

Doesn't it feel great when you finally get it going?!

Rgeardless of what style float valve you use, you should definitely have a fuel shut-off valve at the carburetor. (I guess you could crawl underneath and use the shut-off on the sediment bowl, but nobody wants to do that.) Bottom line: never trust the carb float to not leak when you least expect it. My carbs "never" leak, but I always shut off the gas when the cars are in the garage.

The rear end lube should be thick. As long as it can still flow and it's not gray looking, (signifying ground-up babbitt thrust washers), it's probably. Still, no harm in sucking it out and adding fresh.

I guess you could crawl underneath and use the shut-off on the sediment bowl, but nobody wants to do that.)

https://dauntlessgeezer.com/DG106.html

Thanks. I do have a carb shut off attached to the bowl filter on the firewall.
John

I'd like to second the suggestion of installing one of Scott Conger's full flow float valves (assuming it's a NH). It will improve fuel flow and should end your leaking woes. It certainly made a difference in my touring.