Anybody running a helmet distributor w/o vacuum?

[SoCalCoupe]

Anybody running a helmet distributor w/o vacuum?


Don't know if backing the vacuum retard all the way out is good enough or if I'd need to remove the piston and spring as well.

[38 coupe]

I run stock with vacuum. I like to run the spring and piston with the adjuster backed all the way off then turned back in just until I feel a little bit of spring tension. I find this keeps the advance stable at idle speeds.

[SoCalCoupe]

Originally Posted by 38 coupe

I run stock with vacuum. I like to run the spring and piston with the adjuster backed all the way off then turned back in just until I feel a little bit of spring tension. I find this keeps the advance stable at idle speeds.

I like that approach. I'll ply around with it to see if I can find the point where "I feel a little bit of spring tension."

[Lawrie]

Lots of folks say that it has no effect with modern fuel
My 33 with a 99a engine, it sure does, if you set the timing with a lite at 4Deg before it goes like a rocket , but with the vacuum brake screw out it will ping on hills, so I run it about half way in and its great, the low grade fuel here is 91 octane .
So my advice is leave it in.
Lawrie
Lawrie

[koates]

I run my stock 34 Ford original engine with about 3 or four threads showing on the tension bolt beyond the lock nut. That is about the original factory setting for the helmet distributor. I also set my dist up on a bench type timer, Australian made Servex type. Never have a problem and it goes like a train. Of course if you have a modified engine then you are on your own and may have to have a modified ignition system. I am a lover of stock cars and engines. Regards, Kevin.

[custom_lettering]

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I have a rebuilt distributor from Michael at Third Generation and he recommended NOT running it. The motor runs amazing.

[35fordtn]

I always recommend one turn of tension and not running vacuum. I have lines on my cars and have the lines pinched. The exception is if you get pinging like Lawrie has. On today’s fuels I’ve never had pinging unless it’s a super high compression 4-1/4” motor. But obviously still possible

[flatjack9]

Originally Posted by 38 coupe

I run stock with vacuum. I like to run the spring and piston with the adjuster backed all the way off then turned back in just until I feel a little bit of spring tension. I find this keeps the advance stable at idle speeds.

The piston is retarded at idle, so no contact on the plate.

[tubman]

Originally Posted by flatjack9

The piston is retarded at idle, so no contact on the plate.

"retracted"?

[flatjack9]

Yup retracted. I'm a little retarded.

[Lawrie]

Question for the distributor experts.
One thing I found on my spare distributor is it ( like all my distributors) has wear in the housing where the vac brake piston works,It lets a lot of air(vacuum ) past on my test bench, I use a hand vac pump and it will only pull the piston up if you keep pumping the pump, it will not hold a vacuum and the piston just drops back .
I know that on the engine it has a continuous supply of vacuum,but my thinking is this will run the two cyls that supply it leaner.
Maybe I need to leave the bore in the housing and make a new piston that is unworn.
Any thoughts on this.
Lawrie

[Zeke3]

Lawrie, I am no expert, but I watched the video of Bubba rebuilding a helmet distributor several years ago. He generously coated the vacuum piston with the red grease he uses to lube the distributor so the cylinder and piston would have been sealed pretty well; I don’t think much vacuum would bleed by.

[Lawrie]

I do the same but the grease will get sucked in in no time flat,
Just think, 50 mph, 35 C air temp for 400 miles , Im sure the grease wont still be there.
Lawrie

[38 coupe]

Originally Posted by flatjack9

The piston is retracted at idle, so no contact on the plate.

True. Hmm, don't know how I didn't think of that before. Turning the adjustment in until I feel a little spring pressure does seem to stabilize the idle. Now I wonder if I'm biasing my observation since I expected to hear the difference. I'll have to experiment next time I'm messing with a front mount distributor.




Lawrie, I use red grease on the plunger as a lubricant to keep from wearing the bore more. I have not seen any difference in the spark plugs of the front two cylinders on the left side of the engine. I also have not noticed any meaningful difference in wear of that bore between distributors, but I haven't measured for differences either. I'm curious if you have seen anything specific on this.

[Lawrie]

Well , thats a thought, I have not seen any difference in the plugs either.,
I will take a closer look at them next time they are out.
Lawrie