140 carb linkage..

[vaporloc]

Has anyone ever done away with the progressive linkage on a 140 and made all 4 carbs. work at the same time?? If so, how did it run? How did you do it? I was just thinking of trying it...

[Yenko117]

I'm thinking you'd want the secondaries to come on a little after the primaries, otherwise you'll dump too much fuel into the motor at a low RPM and it won't be happy. I do a little trick on my '66 and later linkage, by replacing the springs with lengths of metal brake line to make it a little more positive. You can always try to adjust the secondary rods up as much as possible and see how you like it.

Mike
YS-117

[4carbcorvair]

The rate at which the secondaries kick on due to the linkage, they come on quite quickly. They are designed to start opening at about 3/4 throttle and fully open at full throttle. The best linkage I had on mine was the linkage that a PO had installed. It consisted of threaded rods, and nuts. Double nutted on both sides of the secondary attachement point for positive on, and double nutted on the back side so they come off when the throttle is off, sort of pulls them off. I'm thinking about putting these back on as my stock linkage with springs always needs adjusting as they seem to turn themselves. I can tell when they are opening way too soon, as in at about 1/4 throttle as power is actually down. Engine seems to like it best when they come on at about 3/4 throttle.

[vaporloc]

The car I was talking about is my 65 140 vert. Anyway after thinking about it and reading your posts, I should probably just leave it alone. See when I had my 421 super duty pontiac with three 2's on it, I done away with the progressive carb linkage for awhile and remembered how good it ran.. Probably a little to much for a corvair.

[vaporloc]

I'm thinking you'd want the secondaries to come on a little after the primaries, otherwise you'll dump too much fuel into the motor at a low RPM and it won't be happy. I do a little trick on my '66 and later linkage, by replacing the springs with lengths of metal brake line to make it a little more positive. You can always try to adjust the secondary rods up as much as possible and see how you like it.

Mike
YS-117

Yea I know yesterday I said I wasn't going to mess with it.. Well today I did. I set it up so secondaries start to open at about 1/3rd. throttle.. Talk about a difference. I think I like it that way.. You can pull out like normal. Drive like normal but; with just a little more pedal you can feel it really coming on stronger then it use to. I'm going to drive it that way for awhile. I'll be keeping a close eye on engine temp and pull the plugs out to check them more often then normal.. So far so good.

[Yenko117]

Sounds like fun. We're covered in white s**t and salt here in VA, but as soon as it's clear I've got a 140 car that's itching for a little tuning - I may try that as well.

Mike
YS-117

[UNSAFE]

All six of my throttle plates open in unison with no hesitation

[mlevair]

I am jealous I only have one carb.

[vaporloc]

All six of my throttle plates open in unison with no hesitation

Yea and I can tell by looking at the engine, it is bone stock. GGGG

[Yenko117]

There is a legitimate difference between Kevin's motor and a stock set-up - it's the plenum beneath the carbs. Schardt tried to get it to work with a Weber, but it did not give good results. The stock set up with the shared plenum (manifold) has the ability to make all of that fuel available to just the one chamber (intake valve) that opens up first. That's my basis for a concern of having both carbs dump at the same time.

Mike
YS-117

[UNSAFE]

Mike wrote >>>>There is a legitimate difference between Kevin's motor and a stock set-up - it's the plenum beneath the carbs.Schardt tried to get it to work with a Weber, but it did not give good results. The stock set up with the shared plenum (manifold) has the ability to make all of that fuel available to just the one chamber (intake valve) that opens up first. That's my basis for a concern of having both carbs dump at the same time.<<<

Yea - a major difference . Michael LeVeque explained that to me some years back.

With my Webers on individual runner (IR) intake manifolds each barrel feeds only one cylinder with no mingling of the mixture .

With a stock 4 carb engine both barrels on one side are available to feed one cylinder at a time thru the plenum. Since only one cylinder sucks at a time it is actually allowing more cfms to be available to each cylinder than my six barrels of Weber carbs. --

---- But there is way more to it than just available cfm.

All carbs are not the same just like all EFI systems aren't the same but I'll save that for another day