I worked at plymouth dealer in 1970. These 6 packs had a bad problem bogging with the yellow springs. We had better results with the long brown or short black springs. You do good work. Good information.
You had it right, those are in fact kill bleeds in the secondary carburetors, they are larger in the 440 carbs than they are the 340 carbs, if they weren't it would make the carburetors open much faster due to the difference in cubic inches. I have in fact put a vacume tee in line to create more of a leak to slow down the secondaries, we did this on a dyno to control our secondary opening. I used a needle valve from an aquarium to control the amount of leak, it worked quite well
Thanks for all the good info . I wish I knew some of it back in 1979 when I had a mint 340 duster with 6 pack set up . It would stumble at high rpm . I suspected an air leak somewhere. Hey , I was only 18 at the time . Again , great videos
I am sure you are 100% correct, but the throttle blades on the outboard carbs open 3/4 of the way on the one I have in the shop presently. This is 47 yrs old and it came in with a backfire out the intake problem. Both pods are blown. Thanks again
If those outboards are opening mechanically then some thing is wrong with the linkage. If you open them mechanically you will get a lean condition and the back fire will go through that port I was telling you about and take out the diaphragm. The back fire probably took out the power valve in the center carb. Good luck. if the customer wants them done send them to me.
I just watched your video for the first time. I was having trouble with my 440 6 barrel and wanted to learn some more about it. On the secondaries I opened up the diaphragm pods to see if the rubber was ripped. The rubber was fine but I noticed that the ball bearings were missing, I believe it supposed to have one ball bearing in each pod. Should I replace this ball bearing or is it OK without it? Thanks Ed
Hi Ed DO NOT PUT CHECK BALL in the secondary pod. It will block the vacuum port and they will not open. Every rebuild diagram for Holleys shows that check ball. There are only certain vacuum pods that use it None for Six Pack Or Tri-Power. I talk about that in one of my videos. Thanks for watching. Harold
Hi Herald, I have a couple questions? I wish I saw this video three years ago, after spending so much money on all these rebuild kits tying to chase my problem, but I think you explained it. Fist off I have a 1969 corvette 427 tri power, but I'm guessing the operation will be the same being its not a 440 6 pack, and still Holley. What happens with my carbs, is when the engine is cold, it runs perfect after sitting for a week, but once the engine gets hot after driving for 20 minutes, the car starts to stall at intersections, and will not maintain an idle, unless I hold the rpm above 1500. If I shut the car off and let it cool for 15 min, then it seems to start and run fine again. so when you explained in the other video about the power valve orifice section slowly filling up with fuel, because the metering block starts to warp, would this be why I am having these problems? Also it seems all the bowls leak down over night, and fill the engine with fuel?Any input will really be appreciated.Darren
Hi Darren I can see the center carb leaking fuel into the intake after the engine is off sitting. If the body and metering block are warped the fuel will leak into the power valve vacuum chamber and into the intake manifold. The out board carbs should not leak in to the intake because the vacuum hole is not drilled all the way into the chamber. I have seen some that were. But very few. The 440 has no hole even partly drilled like the Tri Power. You seen my video on the vacuum test. If you have a mity vac you can do the same test. I offer a restoration service $480.00 + shipping back to you. I resurface the bodies and take the warp out of the metering block. Everything is plated to the factory look. Here is my email chucknorbid@gmail.com Harold
Ah, ok thanks, I may just take you up on that, I’m at my wits end, after so many rebuilds. I’ll hang onto your email, and will let you know if I decide to get you to rebuild them properly. Thanks
Know anyone that has these metering plates for the 340 Six-Pack and do they have two different numbers for the front and rear like the 440 set-up ? Would the 340 set-up be the 34R-6153b #41 Thanks
The linkage does not open the outboard carburetors. It does close them. The vacuum source from the center carb comes from a port in the body throat just below the venturi. This feeds the outboard carburetor vacuum pods which opens the butterfly's.The outboard carburetors also have the same port in the body to assist with vacuum to the pod. The linkage will not allow the secondary's to open until it reaches a amount of the center carb opening. if the pods have a bad diaphragm the carbs will not open. Hope this helps.
