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#1
05-26-2004, 03:14 PM
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I just tore down my buddies Edelbrock #1904 Q-jet. I was surprised at the differences. Maybe these are common with very late model Rochesters.??? The fuel bowl is different than what I've seen before. The power piston and primary rod hanger is completely different. They moved the primary jet location. They are farther apart. The power piston bore is closer to the rear. The primary bores are very large compared to the 750 Rochester that I have. The Edelbrock primary venturi measures around 1.220" vs. around 1.095 for the Rochester. That's as close as I could measure with my dividers and dial calipers. I will try to post the pictures I took.
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#2
05-26-2004, 03:14 PM
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I just tore down my buddies Edelbrock #1904 Q-jet. I was surprised at the differences. Maybe these are common with very late model Rochesters.??? The fuel bowl is different than what I've seen before. The power piston and primary rod hanger is completely different. They moved the primary jet location. They are farther apart. The power piston bore is closer to the rear. The primary bores are very large compared to the 750 Rochester that I have. The Edelbrock primary venturi measures around 1.220" vs. around 1.095 for the Rochester. That's as close as I could measure with my dividers and dial calipers. I will try to post the pictures I took.
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#3
05-26-2004, 03:33 PM
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Here's a try.
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#4
05-26-2004, 03:34 PM
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Another.
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#5
05-26-2004, 03:35 PM
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And another.
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#6
05-26-2004, 03:42 PM
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Edelbrock chose to use the late model side inlet Chevy style castings for their RPM and several other models of "high performance" q-jets. They are nice castings, quality control is "spotty". We get quite a few of them in here for custom tuning.
Last year at Norwalk I ran one for most of the event. It was the RPM "850" cfm version. It ran within .02 of my 1978 Pontiac q-jet, so they are basically equal in performance potential.......Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#7
05-26-2004, 04:53 PM
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Cliff,
How does the size of the primary venturis on the Edelbrock compare with the Rochester 800 primaries? I've never owned an 800. |
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#8
05-28-2004, 12:53 PM
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The Edelbrock q-jets have the same primary bore size as the 75 and newer front inlet factory q-jets (non ECM). They do however use the single main airbleed castings that require a "teardrop" shape gasket where the main primary fuel supply passage meets the airhorn. They have no performance advantage whatsoever over a late style "800" cfm factory carb. I've ran the "850" cfm Edelbrock RPM q-jet back to back against my own 1978 Pontiac q-jet and for all practical purposes they are identical......Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#9
05-30-2004, 03:57 PM
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I agree with you Cliff on quality control, you can get a good one, and next one is iffy.
They are also about $100 more than a very comparable "800" cfm late chevy carb. Very easy to do secondary rod changes however.
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http://www.stockappearingdrags.com http://www.stockappearingdrags.com Come on get off that lawn chair and drive that car like it was meant to be driven. 69' 400 RAIV Judge Conv... 12.86@107 Factory Stock 69' 400 RAIV Trans AM .....12.48@110 Factory Stock 69' 400 RAIV Judge HT..... 13.07@104 Factory Stock 73' 455 SD Trans AM........13's?? not run yet 66' 455 GTO Convert.........12.20@112 non original 63' 421 SD Catalina...........restored fast as h*ll |
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#10
05-30-2004, 04:30 PM
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I'm not sure where the Edelbrock q-jets are manufactured? I heard that Webber made them under contract. Last summer an RPM q-jet was sent here for custom tuning. Despite the owners best efforts after purchasing the $100 Edelbrock tuning kit the engine had a bad hesitation any time he went to full throttle. We got the carb apart and started checking it over. One accellerator pump hole in the airhorn was not drilled and both rear fuel supply holes to the pull over system were drilled off center and completely missed the fuel passage coming up from the outer brass tubes!......Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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