Progressive 94's (For Max)

Butch11443

Butch11443

Senior Member
I'm running 2 94's on an Offy intake with common plenum. Do I need to get rid of the PV in the slave carb. I've got an AF gauge built in and a vacuum gauge. The PV vale is a 7.5 in the rear carb and a 5.5 in the front slave carb.
The main jets are 51's in rear and 48's in front.
Thanks for any ideas.
Butch
 
IMO your going about this all wrong. Diff PV's,diff.jets,progressive linkage,ask the guys that have used this route. ken ct.
 
I'm not a 94 guy... They pissed me off 45 years ago.
From what I've heard though, you probably need to start with 4.5 powervalves and .050 jets in both carbs and ditch the progressive linkage.
 
Thanks Max. 3.5 or 4.5 PV are correct and lose the progressive linkage. Jets i would suggest in the range of .046-.047,sorry about that Max,going by previous builds. There easy to change if need be. OMO ken ct.
 
Was after an opinion was all. I usually run 48 jets in both carbs, 7.5 PV in front carb & 5.5 PV in rear. I run 3 deuces on a y-block w/ slave carbs and works great.
Butch
 
I run 2 - 94's Isky 88 Cam 49 jets and 2.5 power valve in both carbs. Both carbs are full time too not progressive tried that route didn't work. Couple old timers that run a lot of flathead told me plug the power valve in the rear carb and I am going to try it soon. Friends behind me say when I am climbing a hill in the power circuit they smell raw gas. I get 19 mpg on the highway.
 
Generaly You do not have a slave carb with two carbs . They both act together. With three ( which is an easy way to drown a flatty) a primary carb and two secondary is the norm.
I would image very poor fuel distribution with one carb at the front as a main carb and a rear coming in as secondary . Heck just listen to advice and rejet both carbs to around low 40s with low PVs to act as a pair and your motor will thank you. I have done two carbs on a y single manifold and found poor distribution.
We run a primary 97 on a 272 y block with secondary 97s that come in about 3000 rpm economy is good and they really kick in .
 
Butch,

You didn't mention the displacement of your engine. I am running dual 94's with 4.5 power valves, 50 jets and direct linkage on a 265 ci 8CM. Works perfectly. I expect this combination with slightly smaller jets would work well in a 239 ci engine. Richard
 
Do you guys run a mechanical advance or no advance at all ?I have heard that you don't need to run any advance .I got a 2 deuce manifold and 2 97's I want to install ,but not sure about the advance part of the set up .
This would be for a 53 flathead .
 
joe plumber said:
Do you guys run a mechanical advance or no advance at all ?I have heard that you don't need to run any advance .I got a 2 deuce manifold and 2 97's I want to install ,but not sure about the advance part of the set up .
This would be for a 53 flathead .
Click to expand...

Joe,

I use the original style (load-a-matic) distributor connected to the venturi port vacuum coming off of one carb. The distributor has been modified to advance with a lesser vacuum signal by removing the springs from the breaker plate and re-installing a single spring of lesser tension. A vacuum of 1-2 on a gauge will advance the plate. Works great. Richard
 
joe plumber said:
Do you guys run a mechanical advance or no advance at all ?I have heard that you don't need to run any advance .
Click to expand...

You need advance to improve power, performance, and reduce heating. It will run without advance, but SO much better with a properly set up distributor.
 
Experimenting with distributor advance and Air fuel ratios has given us an idea of what the engines of different degrees of modifications like. Especially in the area of economy. The Flathead is one of those engines that seem to run pretty good when way out of tune, at present a well modified 276 with L-100 cam, 500 CFM 4bl and gets 20mpg in average trip. In doing this we had to go beyond what we thought was just OK. For an example we are now running a 16:1 AF in cruise, however we do this because we have a Vacuum advance that can burn a lean mixture, while the Machanical advance allows the engine to develop full power under hard acceleration. All this in a 3500 lb car.
I creadet Richard fro m Fl for designing all the instrumentation necessary to preform these tests, along with the cost involved. And he offeres this free for the asking.
 
Going to change back to my original setup. 48's front & rear and both carbs together. Was experimenting with mileage was all. I did find out if a run a 7.5 on one carb & a 5.5 on the other it get rid of any hesitation when running light throttle when cruising. I get around 18 MPG with this setup. Also get good reading on AF gauge.
Butch
 
FYI The progressive setup ran perfect. I need to find another carb to blank out the base and rebuild it like I want for a slave carb. It was where it belonged with the AF gauge and produced good vacuum.
Butch
 
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