Carb idle circuit issues

[Roscobbc]

The wiper door just opens and closes on start up. Been chasing it for a while, but you get fed up upside down under the dash not achieving anything. My friends got a smoke machine but we did do the rear mains crankshaft oil seal in the spring which was a priority so maybe cure the door leak over winter. Thought the door vac button thing under the grill I changed would sort it but will have to chase elsewhere. I did find one aperture not plugged that was a while ago and sorted that. I'm with you Tim on a vac leak throwing the idle out. I was going to get the feeler gauges out to let you know how much the blades are open but then remembered its cylindrical chambers so no hope. On the positive side I've got no dieseling on shut down that was an intermittent problem. I've got a barely used gasket so will swop that as that could be a possible leak as it's been on and off a few times for various things while I've had it. I'm going to wind the sec throttle stop in half a turn while I got the carb off again. I got a few I guys local I know if I run into a brick wall but it's always more satisfying fixing it yourself and learning the process.

You don't need the wiper door (or headlamp doors for that matter) - why not plug the vacuum sources that feed them - simply take them out of the equation while your are sorting the carb. Perhaps consider sourcing a complete quality carb rebuild kit and respective base gasket IF the carb has been sitting dry for any length of time. I've been faffing around with yank motors for nearly 50 years and the very first things I would do with a newly bought car (if the service history was dubious) was - carb rebuild kit. New oil and filter. New dizzy cap, rotor arm and points. New plugs and HT leads. Set-up timing. New thermostat (and as neeeded, antifreeze and fan belts). One simply couldn't rely on previous owners maintenance schedule (if any). Some of the above you can discount........but not the carb rebuild. Its not a difficult job.........or borrow a 'known' working carb from a friend........simply take the carb out of the equation.

 

[Chuffer]

Can’t be helping, depends how small but look at how little the area is that’s open in the carb at idle and then compare it with your leak. Even a little intermittent leak can give you enough air to change the rpm by a few hundred. Same with carb gasket, are all the vac tubes on the Holley in use or plugged with no cracks, there’s usually 3.

When I overhauled my vacuum head light system and cured the minor leaks the engine / carb ran a whole lot better .

 

[CaptainK]

That's on my to-do list too - disconnect and cap the headlight and wiper vacuum to see if I can cure the minor issue I have on mine occasionally (it bogs pulling pulling away from 0mph unless you pull away slowly and up to 5-10 or so mph, then you can accelerate faster. Sometimes its fine, sometimes it horrid. It doesn't bother me, I don't really do burnouts or launches in it etc.

 

[Chuffer]

That's on my to-do list too - disconnect and cap the headlight and wiper vacuum to see if I can cure the minor issue I have on mine occasionally (it bogs pulling pulling away from 0mph unless you pull away slowly and up to 5-10 or so mph, then you can accelerate faster. Sometimes its fine, sometimes it horrid. It doesn't bother me, I don't really do burnouts or launches in it etc.

It`s amazing how things improve when you are not trying to suck all the clouds out of the sky .
I well remember back in my steam loco fireman and driver training days that a vacuum was described by some wag as " f**k all in a pipe " . Priceless !!
The relevence being that the brakes are vacuum operated . No vacuum = No movement .

 

[Roscobbc]

Vacuum sucks! - I've had mid 60's Fords that have vacuum operation for anything we would normally expect to be electric ie. vacuum central locking - vacuum seat back release on a two door coupe - vacuum operated air vent operation in rear parcel shelf. A decade or two earlier and it would have been pumped hydraulic operation for windows.
TBH I thing that vacuum operation has a lot going for it - its simple - it last-out well if you consider that our Vettes have lasted-out 50 years and most of us don't have issues with the headlamps.

 

[Chuffer]

Vacuum sucks ! I thought that was the whole point of it ! Didn`t we just love the vacuum operated wipers on Ford Prefects etc . I had an early 60`s Thames 15cwt van in my yoof and at speed the wipers moved as fast as a royal wave but nearly flew off the screen as you came off the gas !
Totally agree with you Ross about vacuum systems being simple . They did sterling service for well over 100 years on the railways as a continuous braking system from the loco right through the length of the train applying the brakes to every wheel . Keeping the hoses and seals in good order meant a totally fail safe system that worked very well .

 

[Roscobbc]

Vacuum sucks ! I thought that was the whole point of it ! Didn`t we just love the vacuum operated wipers on Ford Prefects etc . I had an early 60`s Thames 15cwt van in my yoof and at speed the wipers moved as fast as a royal wave but nearly flew off the screen as you came off the gas !
Totally agree with you Ross about vacuum systems being simple . They did sterling service for well over 100 years on the railways as a continuous braking system from the loco right through the length of the train applying the brakes to every wheel . Keeping the hoses and seals in good order meant a totally fail safe system that worked very well .

And extremely powerful if need be.........be reminded never to get your fingers in the way of the headlamps closing - even the wiper flap closes with a rather discerting clang.........

 

[Chuffer]

And extremely powerful if need be.........be reminded never to get your fingers in the way of the headlamps closing - even the wiper flap closes with a rather discerting clang.........

Vac can be very powerful indeed. The flexible connecting pipes between locos and carriages known by railwaymen as the ` vacuum bag` are very thick , very bulky and very strong and if one fails big time and implodes the resulting bang sounds like a canon going off !!

 

[sublimemike]

You don't need the wiper door (or headlamp doors for that matter) - why not plug the vacuum sources that feed them - simply take them out of the equation while your are sorting the carb. Perhaps consider sourcing a complete quality carb rebuild kit and respective base gasket IF the carb has been sitting dry for any length of time. I've been faffing around with yank motors for nearly 50 years and the very first things I would do with a newly bought car (if the service history was dubious) was - carb rebuild kit. New oil and filter. New dizzy cap, rotor arm and points. New plugs and HT leads. Set-up timing. New thermostat (and as neeeded, antifreeze and fan belts). One simply couldn't rely on previous owners maintenance schedule (if any). Some of the above you can discount........but not the carb rebuild. Its not a difficult job.........or borrow a 'known' working carb from a friend........simply take the carb out of the equation.

The carb got rebuilt as the guy even sent me the kit , when it first landed on the boat as it was all over the place - 2000 on tickover as the air filter base was pressing on the accelerator pump , rear calipers leaking , fuel guage , not working, clock bust, tacho scatty , oil leaks etc etc etc . I don't buy the cam is too much as the original owner told me he drove it on a parade , after a while it overheated - viscous fan , no shroud, that was before the last guy fitted the lecy one. Just gone through running carb dry on the mopar...float overfilling , needles jet seals needing changing out etc. I'm no expert on carbs but the vac issue needs investigating and I'll plug wipers/lamps

 

[sublimemike]

PCV grommets gone hard - not sealing. Hose to carb has cracking. Could be vacuum probs.....new grommets ordered from Ulimate spares america. tweaked sec idle stop in half a turn.

 

[Forrest Gump]

PCV grommets gone hard - not sealing. Hose to carb has cracking. Could be vacuum probs.....new grommets ordered from Ulimate spares america. tweaked sec idle stop in half a turn.

The pcv valve grommet itself would not give you a vacuum leak because it’s downstream of the valve. If the hose is split or the pcv valve itself is stuck open then you would be losing vacuum.

 

[sublimemike]

Yes, maybe relates to wiper door leak I'll see. Another box ticked . Hopefully get out for a run and timing light on motor later this week. Good think is I've an elecy fuel pump so easy to prime fuel bowls.

 

[Roscobbc]

The pcv valve grommet itself would not give you a vacuum leak because it’s downstream of the valve. If the hose is split or the pcv valve itself is stuck open then you would be losing vacuum.

PCV valve is dead easy to check. Simply remove and shake it - if it rattles it's moving. Replace - run up engine and hold finger over end of valve to check suction from hose connection on inlet manifold or carb base.

 

[sublimemike]

Will help to stop oil weep on rocker cover if nothing else

 

[sublimemike]

Timing running 11 degrees initial . Think I need to push it forward to 12. Header gasket gave up so have had to wait to get one - all done. Transfer slot on carb looks a bit big. Others say it should be a square relative to the amount opening. I think I wound it out too far on first go so have reduced. Good thing I've found is you can adjust with a hex key from underneath rather than taking carb off. Anyone know what the right size - is for the hex key 5/64 inch ? On the guages 2.3mm seems to work. Try finding a hex key that size

 

[Oneball]

Have you checked the vac advance in the dissy is working?

 

[sublimemike]

Not touched the dizzy yet. There is a vacuum port on the side of it. Next step was going to be release the clamp and give it a little twist to get 12 advance

 

[sublimemike]

Like I say carbs aren't an area I've messed with before except setting floats and stuff so not an expert but great to have help

 

[Oneball]

I’d bung another 5 deg on see what happens. But defo check the vac advance is working. If the car ran ok before but doesn’t now it failing would explain a lot.

 

[Roscobbc]

If that engine has a 12.5 compression (static presumably) it's odds on that it will have a hot cam. Generally hot cams love a high initial advance. To perhaps prove the cam..... when idling gradually advance the distributor a couple of degrees at a time.....if the engine picks up speed and idles more smoothly you it may show you the way forward.....if the engine tends to overheat on idle it will also help it to run cooler.