"normal" vacuum readings?
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From: Galveston... well, Santa Fe Texas
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St. Donor '03 & '06
"normal" vacuum readings?
I have a carb converted 84. carb is a big bore qjet (I forget the casting number, but it's off of a 75 vette) engine is otherwise stock, except the cats are gone and I'm running stright pipes with aftermarket mufflers.
it's running rich, and you can smell it when behind the car.
on my vac gauge, I'm getting 20 inches at idle, with a slight (1 in) variation at a regular interval.
I'm guessing that's a fairly normal reading?
or is the odor due to the lack of cats?
it's running rich, and you can smell it when behind the car.
on my vac gauge, I'm getting 20 inches at idle, with a slight (1 in) variation at a regular interval.
I'm guessing that's a fairly normal reading?
or is the odor due to the lack of cats?
Last edited by MonteHall; Nov 27, 2012 at 09:42 AM.
Tech Contributor
Joined: Aug 1999
Posts: 14,356
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From: At my Bar drinking and wrenching in Lafayette Colorado
For a stock engine with a stock cam that's a "normal" reading. Depending on cam and engine configuration, "normal" can cover quite a range.
The '75 Q-Jet is not a "big-bore" carb. It's the standard 750 cfm Q-Jet, and it will usually run lean unless there is some setup issue with carb or timing. Be sure to set the timing up correctly per my timing papers, and then you can tune the carb per the "Quickie Performance Setup" guidelines in my Q-Jet Setup paper. Both papers available by e-mail request if you need them.
Lars
V8FastCars@msn.com
The '75 Q-Jet is not a "big-bore" carb. It's the standard 750 cfm Q-Jet, and it will usually run lean unless there is some setup issue with carb or timing. Be sure to set the timing up correctly per my timing papers, and then you can tune the carb per the "Quickie Performance Setup" guidelines in my Q-Jet Setup paper. Both papers available by e-mail request if you need them.
Lars
V8FastCars@msn.com
Thread Starter
Team Owner
Joined: Feb 2001
Posts: 21,016
Likes: 0
From: Galveston... well, Santa Fe Texas
Cruise-In VII Veteran
St. Donor '03 & '06
For a stock engine with a stock cam that's a "normal" reading. Depending on cam and engine configuration, "normal" can cover quite a range.
The '75 Q-Jet is not a "big-bore" carb. It's the standard 750 cfm Q-Jet, and it will usually run lean unless there is some setup issue with carb or timing. Be sure to set the timing up correctly per my timing papers, and then you can tune the carb per the "Quickie Performance Setup" guidelines in my Q-Jet Setup paper. Both papers available by e-mail request if you need them.
Lars
V8FastCars@msn.com
The '75 Q-Jet is not a "big-bore" carb. It's the standard 750 cfm Q-Jet, and it will usually run lean unless there is some setup issue with carb or timing. Be sure to set the timing up correctly per my timing papers, and then you can tune the carb per the "Quickie Performance Setup" guidelines in my Q-Jet Setup paper. Both papers available by e-mail request if you need them.
Lars
V8FastCars@msn.com
isn't that indicitive of the larger bore qjets?
casting number is 7045223
Last edited by MonteHall; Nov 27, 2012 at 10:36 AM.
Thread Starter
Team Owner
Joined: Feb 2001
Posts: 21,016
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From: Galveston... well, Santa Fe Texas
Cruise-In VII Veteran
St. Donor '03 & '06
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,330
From: At my Bar drinking and wrenching in Lafayette Colorado
Lars
Last edited by lars; Nov 27, 2012 at 09:44 PM.
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
http://www.youtube.com/watch?v=xuqz5Bs96Tw
Dig the redneck accent! Be patient, the guy takes 4 minutes and 35 seconds to show us something that should take about 30 seconds, tops.
Keep the shiny side up!
Scott
Dig the redneck accent! Be patient, the guy takes 4 minutes and 35 seconds to show us something that should take about 30 seconds, tops.
Keep the shiny side up!
Scott
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,330
From: At my Bar drinking and wrenching in Lafayette Colorado
His video clearly shows the small bulge at the positions I indicated above. Note also that the 800 cfm carb he has is a Pontiac - not a Chevy. The Chevy 800's are very uncommon, and I don't think the '75 passenger car carb was a big carb. I'm going to check one of my spares to verify that, so I may stand corrected... I just checked a '77 Vette carb, and it's a 750..
Lars
Lars
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