Engine Keeps Stoping ideas and help Please

[mattathome]

Hi,

Having a few troubles with my 138 in my FB. Originally I had a fuel supply problem. Changed the fuel pump, but pretty sure the braided fuel line to the fuel pump was the problem . Replaced with fuel hose and clamps and instantly the fuel bowl filled with fuel and was pumping fuel into a clear filter. All of which it would not do before.

So onto the next problem.I will try to explain in my uneducated non mechanical speak.

The car will idle no trouble and can be revved. But if I drive it , the motor starts to miss/stutter at a constant half or more throttle. I can simulate this in the shed by reving hard and or holding at half throttle or more until it starts to break down. It eventually stops as it did out on the road yesterday. Some times it will fire back up to idle but will not rev, just stalls.It does not backfire if that is important.
But where do I start? If i pull off the air cleaner and press down the throttle linkage I get a good spray into the throat. On the side of the road , I removed the fuel filter and pulled the top off the carby to see if there was fuel in the float bowl , which there was. The float also moved freely.
So I am tending to think fuel is ok. But really unsure.

As for ignition system, I have no idea of these at at all, It seems to idle smoothly , is there something else I can check. Maybe its the leads or plugs? These are of unknown age and I am happy to replace these as a matter of course. The NGK website tells me to use BP5S plugs with 0.8 gap. Is that 8 thou ?Is there something else I should use?
Leads any suggestion there? I cant seem to find any info on what to replace them with. I have a supercheap in town and a repco.

Points and distributor I am clueless about , cant seem to find much info there on what to do?

Any help would be appreciated. This FB has been baptism into the olden mechanical world. I could take it to a local mechanic, but if I can work through these problems with help, hopefully I can then drive with confidence that I could get it going on the side of the road.

Regards
MATT

[Craig Allardyce]

Sounds like you may have a blocked main jet or discharge nozzle. I'd pull the air cleaner and look down the throat of the carby whilst bringing it up very slowly on the revs from idle.
If its ok you should start to see fuel discharge (being drawn out of the discharge nozzle by air speed in the venturi) from the main jet nozzle at about 3000 rpm. The carby should go from idle circuit through progression circuit and then on to main metering smoothly when doing this check. If you can see fuel coming out of the nozzle then I would go looking for a ignition problem. Try checking your timing and point gap (dwell) and see what you find there.
I would also check to see if there is no crap in the bottom of the float bowl around the main jet inlet. Could be something floating around in there and is getting sucked into the jet at high fuel flow conditions
What's your float level set at? Check and make sure you've got no manifold vacuum leaks.

[Dr Terry]

Plug gap 0.8mm = 0.032" (32 thou).

Do what Craig has suggested first, but I'd have the dissy checked out also, because contact points can cause many similar dramas.

Dr Terry

[mattathome]

Thanks Craig and Dr terry,

I looked down the throat of the carby. I could not see any fuel coming in anywhere. It would stall unless I gave it a pump and a squirt would come in. So I took apart the top of the carby took out the fuel bowl and there was a lot of junk in there. I didnt have a tool to take out the main jet , so sprayed a bit of CO spray down the jet and some junk come out the bottom into the bowl. Clean all that out. Reassembled ,reinstall the filter and started. Went straight away and idled ok. Looked back down the throat and I could slowly build revs until the the main jet started pulling in air. I tried to simulate the fault as before but she kept running. Just took her for a quick spin and seems to be revving better. Still not perfect but does seem better.

Another step forward, I think I will get a kit put through the carb as precaution and that will be one less thing to worry about moving forward.

But will do Plugs and leads as well. So any input there would be appreciated. Then to tackle the black art of points and timing..


So Thanks again Craig and DR Trery

Regards
MATT

[Craig Allardyce]

Good stuff Matt.
I'd probably strip the carby totally less throttle shafts and have it chemically cleaned. Once the alloy has corroded (if it is that way) the remnants of that process will be all through the carby well beyond the float bowl. Once cleaned have it blown out and rewashed. Blow through every little hole you can find and recheck all drillings for blockages with some fine wire if in doubt. Once that's all done go through and check all jets, power by pass, accelerator check valve, emulsion tube, main jet, etc. for blockages and correct operation. Past that reassemble and set up as per the book (accelerator link position, float level), fit and adjust idle mix and set idle speed ad all should be good.
If you've got a factory workshop manual there are very good diagrams in it of how the carby is structured internally so you can work out all the drillings and circuit flow paths.

[Brian Westlake]

My old 59 Fairlane had this. Car would idle but would not take load or driving. It gave symptoms like fuel starvation but seemed to have fuel in venturi. It ended up being the condenser and this has happened about 3 times in the last 3 decades that I can recall. This may be a F ORD thing only therefore unrelated, but it sure had me stumped the first time.
Tony F ordsAsWell.

[mattathome]

There was definitely no fuel looking down the throat, having said that I could not get it to run for long enough. But a quick stab would give a a squirt and it would keep running . After it would idle and rev up until I could see fuel in the main jet. Plus I did get a big bit of crap come back out the jet tube.

I had this with a AU falcon once it would idle and drive but brake down under load. Going over the Gateway bridge in Brisbane is NOT the best place to break down. It was leads that time.

Hopefully I will get a chance to take it for a decent run this arvo.

MATT