No secondaries??

[Mopar-Charger]

I have a mild 360 running a big cam its topped with a 750 holley.

I was adjusting my idle and I realized my secondaries never open? I tied the bracket arm so that the secondaries were closed, drove the car, then took the tie off and drove it again. Same results.

My brother had the idea to have something hold the secondaries open at about 20%. Drove the car and it got up and went like a mad man. :3gears:

I was looking online and everyone was saying it was low vacuum, punctured diaphragm, or too stiff of spring?


What do you guys think?

THanks,

Jake

 

[lewtot184]

probably a bad diaphragm.

 

[bm02tj]

Or the gasket to body is plugging the hole or leaving the hole open
but likely a bad diaphragm

 

[Mopar-Charger]

Sounds like a bad diaphragm.. I purchased a rebuild kit that comes iwth one. It should get here Wednesday. Thankgod I'm on Springbreak so i can switch it out and let you guys know how it goes. But thanks for the feed back.

 

[Mopar-Charger]

I purchased a rebuild kit, got the new diaphragm in and still no secondaries? or atleast they do not open all the way at WOT. What can i do about this?

Again I have a 360 +.500 lift cam, 750 holley, perf eddy intake, stock everything else. (new 2.02 heads soon).

If i manaully press the secondaries open during idle and partial throttle, it revs like a mad man. Without it, nothing.

Drove the car, lowend was crap then slowly caught topend and haulllled *** and kept it up through second. why is this?

Thanks,

Jake

 

[Deleted member 214]

Heavy spring in the vacuum pod = secondaries need a lot of vacuum to open. Lighter spring = less vacuum needed so they open earlier. Check what color spring you have.

White - Lightest
Yellow (Short Spring)
Yellow
Purple
Plain (Steel grey)
Brown
Black - Heaviest

 

[440beep]

I'm thinking about my Six Pack setup, but I'm assuming the 4 barrel might be the same way ---- check the vacuum hose to the secondary, any tears, leaks?

 

[Dibbons]

I have always dreamed of finding a way to monitor my secondary opening from the dash. Perhaps some kind of LED light panel or something that verify the status of the secondaries. One light at 1/4 opening, two lights at 1/2 opening, three 3/4 lites at 3/4 opening, and 4 lights at full opening. Might even be a marketable item. Most ideas I have I later find have already been tried or marketed, but never heard of this one. Maybe something patterned after a late model throttle position sensor? Anybody gifted with an engineering type mind like to try it for us?

 

[furyus]

Also remember that the secondaries won't open just revving it in park. It needs to be under load, as in driving. Keep going to a lighter spring until it starts bogging. Then go back one spring. You can get spring kits from summit.

 

[Mopar-Charger]

Also remember that the secondaries won't open just revving it in park. It needs to be under load, as in driving. Keep going to a lighter spring until it starts bogging. Then go back one spring. You can get spring kits from summit.

I purchased a spring kit, should be here friday.

As for the "leaks tears" I replaced the diaphragm, everthing else is inside the carb? Only hoses i have are booster and vacuum advance.

 

[Moparmatt72]

Mechanical secondaries always better lol I actually had a vacuum carb on my 440 with a isky 292 cam just put a nut and bolt on the slider and it pulls the secondaries open with out the need of vaccum

 

[Garys1969RR]

Also remember that there is a tiny donut shaped cork seal that goes between the carb and secondary vacumn pot. This is where it draws the vacumn signal from the carb into the top of the diaphram. It MUST be in there and sealed for it to work properly. Youre not alone in this, I have had many issues with the secondaries opening properly. They work well when set up properly. I would start with a white (lightest) spring and go from there.

- - - Updated - - -

You can see a small hole in the primary bore of the carb on the passenger side. As airflow increases past this hole, it develops vacumn that actuates the secondary diaphram. And another port in the secondary also increases vacumn as they open.

 

[Mopar-Charger]

I put the spring up from the white one, Yellow short? Drives good. You can really feel the secondaries open at about 3500-5000, my only problem now is the bottom end. Before that 3500, it moves like fat lady riding a bike. Should I go with the white spring? Advance or retard the dist, make it leaner?

Thanks,
jake

 

[Ron Ward]

Set your total ignition timing @ 36° BTDC @ 3000 rpm and then tune the carb from there.