In another thread, I am contemplating using the air horn off a 750 qjet to mount onto an 800 body. When I pulled the 800cfm qjet apart the other day, I found two extra tubes sticking out of it (for a total of SIX tube-dealies) Is this some smogger air horn off a later model qjet? The number on the carb body is a 71 455 carb number... BUT the carb has been rebuilt since it was born in 71. So, now I am left with the task of ID'ing this thing. But I am still wondering if I could just bolt on the 750 air horn to the 800 body. Take a look at the pictures I posted on the last thread here: http://www.v8buick.com/showthread.php?s=&threadid=37607 Here is a single picture of the 6-holer air horn - uzzled: uzzled: uzzled:
i did that to the modified 800 on my 70 gs after one of those tubes that feed the fuel down the middle of the barrel came off,i had to replace the top, and i remember that that was the only difference in the top i got from one of my spare carbs, it worked and i didnt notice a difference in performance, it is still running fine.
i was told that it was a 750 but the 800 i orderer from Postons seamed to be the same . i swaped the airhorns and the only difference was that one had 4 tubed and one had 6. i never checked the numbers .
Hmmm...I've got a '71 800 with slightly warped air horn sitting around here - took it off a junker Centurian thinking "oooh good score." Was considering swapping it for the 750 currently running great on the car - that is until I found the warp. If you guys find out that a '70 air horn can swap onto an otherwise '71 carb please say the word.
That is exactly what I am wanting to do:laugh: I have a 70 carb(455) that I am wanting to swap the top onto a 71 455 body. I guess nobody has done this yet?
Adam, you are forgetting the fixed idle air bypass. They are air channels that lead from the top of each carburetor bore in the air horn, to a point below each primary throttle valve. At normal idle, extra air passes through these channels supplementing the air passing by the slightly opened throttle valves. This is so the throttle valves can be nearly closed at idle, which prevents nozzle drip. The fixed idle air bypass is only present on big block carbs(all 800's), and big block 750's
I did not know there was a fixed idle air bypass on the big block 750! I learn something new every day:TU: So theoretically, this will work just fine....co-rect?
Yup, All BB carbs have it, so in theory, it should work. If everything lines up and goes together, you should be fine.
I was wondering when that question would come up:laugh: Here's the story: The guy that bought my 73 Riv called me and asked if there was someone he could go to for a carb rebuild. I mentioned a few folks including John Osborne - but I also told him I had no problem doing it for half of what the other guys would charge him. And so guess who he picked.ou: I have one complete 70 455 (750cmf) carb, one complete 71 800cfm carb, and one 72 800cfm carb body to work with. The 71 carb air horn is shot - missing choke plate and has these weird 2 extra tubes coming out of it. The throttle plates are also locked up on it. I pulled it apart yesterday, and the whole thing is trash....even the body. So now I am going to do this: Use the 70 carb's air horn (top) with the 72 800cfm body, and the 70 throttle plate. This guy is an old friend of the family (I had no idea until he called me one night after he bought the car) so I have to make a good impression on him. Talk about being stuck between a rock and a hard place!:spank:
Six tubes. The extra set of tubes might be the (POE) pull-over enrichment circuit for later emissions carbs. This allowed the carbs to be calibrated leaner than the earlier carbs during idle and cruise.
Hmmm, my 76 and 71 were both missing these tubes. They're definitely 800 carbs tho. Maybe it's a Canadian thing uzzled:
Larry wasn't referring to the extra tubes...I don't think. My 71 doesn't have them (the one on my car). It looks just like the 750 air horn with 4 tubes.
Not sure what the tubes are, but all BB carbs have the fixed idle air bypass. So some airhorns may not be compatible with other carb bodies. Adam Why don't you ask the man, John Osborne, JOP455@aol.com
Here is his reply: And the assembly has begun:beer Thanks for solving another "Smartin" mystery question!:laugh:
So after I swap tops, and put the 800 in place of the 750, will I see as big an E/T drop as I got from putting on my new reproduction coolant bottle? :Brow: uzzled:
Adam, I did some reading on this one over the weekend. Are there 2 small (probably plugged) holes just below the choke plate on the rear wall that these tubes feed into? If so it's a POE. It's apparently a good thing to have for performance carbs...
Clint, yes, I have gotten the POE answer a couple times for those extra tubes. But that particular air horn is trashed. So I can't use it. Brad, I am expecting at least 2 seconds on the 1/4 times:laugh:
