[judge_jury_executioner_69]

what is diffrent on one of these vs. a regular carb ?

[judge_jury_executioner_69]

what is diffrent on one of these vs. a regular carb ?

[carbking]

Pressurized carbs have to be modified to handle pressure, or one has leaks. Normally, seals around throttle shaft, choke shaft, idle mixture screws, accelerator pump. Also, vent positions are changed to internal venting (ala marine units); baffles are added inside floats to prevent crush.

Jon.

[Tom Vaught]

Holley carbs can be build with nytrophile (solid) floats so they will not require float "baffles".

Holley carbs are internally vented in most cases these days so as long as you use a newer carb you will be fine there.

Holley carbs can be made to seal up between the metering blocks and the main body/ bowls by using marine gaskets or putting the carb in a box. Holley shafts have provisions for teflon sealing so no "o-ringing" is required.

Holley carbs have new NASCAR metering blocks which allow adjusting the jetting, emulsion circuit, and the power valve circuit so that you do not need to buy new parts each time you "screw up the calibration" Lots of people are building blow thru carbs themselves but one of the best companies today is CSU Carbs in california. Ask for Dennis or Kevin.

Tom V.

[carbking]

Gee Tom - one would think you were a fan of Holley carbs

The teflon does seem to work well, have never had much success with the O-rings on shafts. Carter used an "air seal" which worked very well.

Have had the polynitrophyll floats fail under pressures in the 18-20 psi range, but that was several years ago. The newer ones may be fine, don't know, as after we had problems, we went back to the "tried and proved" brass with the inserts.

Jon.

[Gus_Mahn]

There is info on a 7 second blow thru and lots of other good info here.
http://www.turbomustangs.com/forums/...93f&forumid=13

[Doug Christie]

Here's "Blow Through" Yahoo group I subscribe to.

http://autos.groups.yahoo.com/group/Carburetedblowers/

[Tom Vaught]

Quote by the YAHOO SITE:

"FLAMERS NOTE: If you try to discredit or belittle anything or anyone on this group for any reason, (1)your message will never reach the membership, and (2)you will be banned without further discussion. The Moderators"

Both Kevin at CSU and I were thrown off the site.

Kevin was removed I believe because he hinted that they were not making any power on the board.

I was removed for calling the moderator a "Tinkerer" which in the dictionary means a fumbling idiot vs someone who plays with stuff as a hobby vs a job (my defination).

I am a member of the Turbo Mustang board and it is a fine board.

Yes, Jon, I like Holleys (wonder why?) but I also like Rochester 2bbls,
AFBs and expecially Thermoquads.

I think you are the resource on afbs and thermoquads.

Tom V.

[judge_jury_executioner_69]

is this why everyone is using a holley on a blower motor ?

[carbking]

jje69 - Holley has made it easier, but not everyone uses the Holley. We have done dozens of Carter AFB carbs over the years for use with blowthrough applications.

Our largest group of customers were Studebaker people. Andy Granatelli (Studebaker) had a pretty decent blowthrough setup in the mid 1950's and early 1960's. This was replaced for convenience by an airbox arrangement (the carb set in a pressurized box, thus eliminating the need for sealing), in the mid-1960's. A company in socal is reproducing the airboxes, which makes for an easier (read less expensive) installation. Even with the airbox, floats still need modification.

As previously stated, had problems with the foam floats years ago with boost pressures around 18-20 pounds; so gave up on them. The newer ones may be better, don't know.

Here is a website that deals with early superchargers, and the modification of virtually any carburetor to use with them:

VS57 Superchargers

Jon.

[judge_jury_executioner_69]

thanks. i was toying around with the idea of keeping my 6X4's and throwing on a blower. i think it was a 6-71 or a 8-71. plus i bought another q jet on ebay so i can have a carb on my car when i send the other one off to get tweaked. thought about getting that set up for a blower ( if possible ). i have a set of big valve #16's that i just had worked on and havent even put them on yet. i dont like the idea of 10.5-6:1 cr and pump gas. but this idea went out the window when i emailed holley asking about a pontiac intake for a 6 or 8-71 and they said they dont have anything for my application.

[PONTIAC DUDE]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by judge_jury_executioner_69:
thanks. i was toying around with the idea of keeping my 6X4's and throwing on a blower. i think it was a 6-71 or a 8-71. plus i bought another q jet on ebay so i can have a carb on my car when i send the other one off to get tweaked. thought about getting that set up for a blower ( if possible ). i have a set of big valve #16's that i just had worked on and havent even put them on yet. i dont like the idea of 10.5-6:1 cr and pump gas. but this idea went out the window when i emailed holley asking about a pontiac intake for a 6 or 8-71 and they said they dont have anything for my application. <HR></BLOCKQUOTE>

I think your a little screwed up dude.
6-71 or roots blowers don't required blow thru carbs.
BDS makes Blower manifolds.
And I have run <span class="ev_code_RED">a few</span> blow thru carbs without doing all the "Trick" stuff people claim ya have to do to make one work.

Buy the SA design Blower book as it tells ya what ya need to do with carbs mounted 'over a blower'.

[judge_jury_executioner_69]

i dont knwo a thing abotu blowers. i was looking online for info on 6-71 or 8-71 blowers. was looking on ebay and seen a few holley blow thru carbs. so i assumed i needed a blow thru carb to run one. for now im just doing some research and find out what i need before i decide. i emailed holley asking them if they carry a intake for a pontiac to fit a 6,8-71 and got a reply saying they dont have anything for my application. so that makes me lean twards keeping my 16 heads and live with the higher cr ( for a daily driver ). if i cant find parts made by holley for a wiend then where can i fond them at ? ( sounds like expensive custom stuff )

[Junkyard Dog]

It's not custom. Go to the BDS web site and take a look. http://www.blowerdriveservice.com/

Have fun.

The reason the carb is not blow through on an 8-71 is that the carb is sitting on top of the blower, just like it sits on top of the intake manifold. In other words, the blower is after the carb, not before it.

In a centrifugal supercharger installation, the air is compressed and then blown INTO the carb. The result is that the carb mnust be modified to live with pressurized insides. You don't have the same concerns with the type of blower you are talking about. Go to the web site and take a look.

[BVR421]

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[BVR421]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> In a centrifugal supercharger installation, the air is compressed and then blown INTO the carb. <HR></BLOCKQUOTE>
Has anyone used a drawthru with a modern blower? It worked in 1937 for McCulloch but that was a 4lb boost. Does it not work as well to draw thru a modern carb or is it more a question of effcient pakageing with low hoods?

[judge_jury_executioner_69]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JunkYard Dog:
It's not custom. Go to the BDS web site and take a look. http://www.blowerdriveservice.com/

Have fun.

The reason the carb is not blow through on an 8-71 is that the carb is sitting on top of the blower, just like it sits on top of the intake manifold. In other words, the blower is after the carb, not before it.

In a centrifugal supercharger installation, the air is compressed and then blown INTO the carb. The result is that the carb mnust be modified to live with pressurized insides. You don't have the same concerns with the type of blower you are talking about. Go to the web site and take a look. <HR></BLOCKQUOTE>

thanks for the link