25 replies to this topic

[tsn007]

Hi Guys,

Is a rochester too big for a mild 253 v8, reason i ask is that i am having trouble tuning the carby

Does any one know what jets etc i should be using

The car just isn't responsive in 3rd or 4th gear.

any advice?
thanks

[yel327]

It's the standard carb for 253 from 1980 onwards. Copy the WB metering rods out of the parts catalogue. Only one pair changed from memory from the 308.

[TerrA LX]

Is it going again?

[TerrA LX]

Hey T??

[makka]

what model Rochy is it?

Run AN secondary metering rods, they are standard 308 rods, make sure that the secondayr flaps have a bit of tension on them or else it will bog down.

[Rockoz]

Did a comparison years ago with a quadrajet and a 350 Holley. Both cars were VB 253 manuals.
Holley was marginally quicker off the mark.
Quaddy was marginally better mid range.
Couldnt really check top end but in lower gears there wasnt anything in it.
Big difference was fuel usage.
Opinion at time was quaddy was too much carb for 253.
Ended with both cars with 350 Holley

[TerrA LX]

Pity you didn't try a Holley 465, would have been interesting to compare the results.

Herne

I did.
Both were set up for the motor with jetting and metering, mild 253, throated heads and cam to match.
There was not much in it by way of seat of the pants or speed in each gear but the holley was noticeably crisper so the holley went back on.
My personal preference is for the holley, for the ease of jet selection etc etc etc as the rochester is a pain to reset the float and chasing metering rods can be hard.

Edited by ALX76, 13 March 2009 - 08:42 PM.

[REDA9X]

I ran a quady from a VH on my SS 253 with a Brock aircleaner and it was fantasic. When I bought the car it had a 350 holley and ran like a dog all the time, used lots of juice. I put a WW stromberg on and it wasn't as responsive, but better on the juice. I later put the stanard red pollution manifold for a 308 on fitted the Rochestor and the car was the best of both worlds, good on fuel, but went well when pushed. I later turfed the M20 for an M21 and that made it even better. It was regularly more than a match for standard 308's, and every idiot who wanted to race in their VN V6's. It was a mild 253 with 40" flattops, X rods, a nice cam and electronic ignition, but it still had the standard exhaust manifolds but with a nice exhaust.

[TerrA LX]

Some say the "Quaddy" was too much or the 350 holley was a dog but you can not compare apples to oranges, both carbs to be compared must be in the best serviceable condition and tuned to the motor to compare as it can make a world of difference.

[Redslur]

VH Commodore onwards with a 4.2 had the quady, great carby when set up right. I would only ever use a Holley to go fast. My 300+hp 308 ran really well with a quady and never missed beat!

[Struggler]

I love the Q jet !!!

Admittedly the Holley is a lot easier to tune and ultimately will make more power in some applications but the Q jet is a great street and mild race carb.

As for the 253 applications, you just need to tighten up the sec. air flap tension to get it to work properly on the small engine. Get Purple LC to reco it for you and let him know its for a 253, it will be unbeatable.

JMHO

[REDA9X]

Purples the man with the Rochestor is he? Maybe I should get him to fix the one on yellows car.

[rodomo]

the amount of air that gets into the motor is massive, the engine idles at around 900 - 1,000rpm, and thats even with NO idle screw LOL

You realise something is wrong? Don't you?

[TerrA LX]

Missed you on the weekend Tony.

[tsn007]

Hi Terry


what about this weekend sometime?

tony

[rodomo]

ALX76: Your place or mine "big boy?" ....................................

[TerrA LX]

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[TerrA LX]

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Still with us T?