Author Topic: bypass air in throttle body?  (Read 4151 times)

Offline Tstates

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bypass air in throttle body?
« on: November 22, 2011, 06:11:18 AM »
I have a late model, 170 series quad that I have installed cliffs H.P kit on.  It works great, except the idle. So I pulled it off and inspected the idle circuit for proper setup based on the article in High Performance Pontiac.  My motor is a 400 H.P motor built with the Central Virgina machine shop recipe.
Once I measured all the components in the idle circuit I found everything up to spec as per the articles recommendations.  I was surprised that everything was sized larger than a stock quad.
That being said,  To get it to idle I was about 5 turns out on idle mixture and it is running very rich, strong fuel smell.  One thing I did have to change was the idle tubes, for some reason I had not changed those with the ones Cliff supplies in his Kit.
Also the only other thing I was unclear on was Bypass Air in throttle body?  My throttle plate has the hole in the base plate, but what confused me was; the article says to drill the hole through the plate.
Is that true?  Because my holes don't penetrate all the way through the plate??
Any help would be much appreciated.  Thanks in advance. ;D

Offline Cliff Ruggles

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Re: bypass air in throttle body?
« Reply #1 on: November 23, 2011, 03:47:35 AM »
What is the carburetor number?

Engine specifications?......Cliff

Offline Tstates

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Re: bypass air in throttle body?
« Reply #2 on: November 23, 2011, 10:36:43 AM »
Cliff, thanks for the reply.  Here are the specs.

Carb# 17058264, with your H.P kit and 073 jets and primary and secondary metering rods as per your previous recomendation. Dont remember the size??

comp cam; XE274H , 230/236@ .050
hyd. lifters
.060 over speed pro pistons, block zero decked, heads shaved, compression, approx. 9.5/1.
comp roller rockers; 1.52:1
ported heads to Ram Air IV size
2.11/1.77 stainless valves
Dougs headers, pypes 2.5" header back.
Performer intake, matched to heads.
Continental 2000 stall converter/ 3.73 rear gears.

Offline Tstates

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Re: bypass air in throttle body?
« Reply #3 on: December 02, 2011, 05:43:18 PM »
Hi Cliff, just wondered if you may get to my post soon.  I know you are a busy guy.  I appreciate your help.  I am ready to install the carb, but need your input first.
Thanks in advance. ::)

Offline Cliff Ruggles

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Re: bypass air in throttle body?
« Reply #4 on: December 03, 2011, 07:42:12 AM »
Nice carb, same one I use on my own engine.

Go to our book, use recipe #3 for the idle system.  That carb will NOT need any airbleeds enlarged, main or idle.  Just install larger idle tubes, idle down channel restrictions, and drill the throttle body for idle bypass air.....Cliff

Offline Tstates

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Re: bypass air in throttle body?
« Reply #5 on: January 10, 2012, 06:06:54 AM »
Cliff, I made the mods. I found the base plate bypass plugged, so that was easy.  Then did the idle circuit mods.  She idles very nice.  No longer have that rich fuel smell.
I purchased a new choke pull off from you, does it already come set to open faster, when I checked it it seemed to be close to the 2 second time. Just curious??
Again, thanks in advance.  Your recipe seems spot on for my application. :D 

Offline Cliff Ruggles

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Re: bypass air in throttle body?
« Reply #6 on: January 11, 2012, 04:24:41 AM »
The pull-offs we sell for that carburetor number will provide access to the restriction if you need to make the opening rate faster.....thanks...Cliff