Quadrajet Jets and Rods Question

[rwberinger4x4]

Hey guys,

Not sure which sub-category to post this in but I'll start here:

I've been running a Rochester Quadrajet S/N: 17058222 on an old Chevrolet 283 that finally gave up the ghost.  I've got a new, bare-bones 190HP GM crate 350 engine installed in the vehicle - so performance wise, it won't be too much different than the 283 - which was bored 30-over and running a mild RV cam.

The "tuneable" parts on the Carb show as follow:
Jet:73
Rod:41k
Secondary rod:DP

I can't find any information on the stock jets and rods for this Carb (checked Ethan's list, but no luck). 

The more important question is - will the jets and Rods that worked great with my 283 work on the new 350?  If this is the stock (or close to stock) configuration for this Carb - I'll give it a shot before I mess with anything.

Thanks, in advance, for any help or insight you can provide!

[Ethan1]

 Stock specs of that carb were .077" Primary Jets, 52K Primary Metering Rods, "K" Secondary Hanger and CH Secondary Metering Rods. Found on GMPartswiki.com.

[rwberinger4x4]

Thanks Ethan -

I swear I checked there and couldn't find it.  Is there any indication of what engine that was set up for? 

From a metering area perspective on the primaries, this means my carb is currently set up to be about 11.5% richer than stock at cruise, but 12.2% leaner at WOT. 

The bigger question is - any idea how this will translate from a 283 to a 350?  Is it worth even trying to run it on the 350?

[Ethan1]

 It was used on the G1 350cid, A/T, A/C, Fed. As far as your other questions go. I don't know. Cliff would be best to answer. It wouldn't hurt to buy the correct metering rods/jets and give it a try. Tune it. Do you know the specs on that rv cam? Trans? What's it going to be used for?

[rwberinger4x4]

The RV cam was on the 283, which had been rebuilt and bored .030 over (so it was really a 287).  Not clear on the exact cam specifications - it was in the truck when I bought it.  It had an Edelbrock SP2P intake - small runners for fuel economy, but just fine for what I'm driving.

The 283 is being replaced by the stock, base truck 350.  The vehicle is a 1975 Toyota Land Cruiser FJ40 with stock Toyota 4-speed transmission and 4.11 gears.  It's not going anywhere fast!  Really I'm looking for good off-idle response and as much fuel economy as I can squeeze out of a 4000lb brick.  With the 283 I had the secondaries ALMOST locked out entirely.

[rwberinger4x4]

Bummer - Looks like the CH hangers and 52K rods are both no longer available. 

I may just try to run it at is and see if it performs poorly. 

[Cliff Ruggles]

Not sure why the jets and rods were changed at some point in that carb.  Might want to check to see if it was every commercially "remanufactured" and has small main airbleeds instead of the large ones.

If the large MAB's are still in place call the shop and we can set you us with a much better jet/metering rod combination for what you are doing......Cliff

[rwberinger4x4]

Thanks Cliff,

This Carb came from Sean Murphy Inductions.  I believe it was built for the 283, specifically.  That would explain the rich (but small) primaries and the leaned-out secondaries.  The secondaries are wound up fairly tight.  When I was running it on the 283, it almost ran as a 2-barrel.  The secondaries would just barely kick in and "help" under load but on such a small engine they were barely necessary.  It worked pretty well, I got about 13MPG out of a 4000lb brick of a Land Cruiser.

I did give Sean a call - it sounds like he doesn't usually pull out the large air bleeds and put in smaller restrictions.   

I'm still a couple of weeks (probably months) from getting the truck running again with the 350.  I'm going to try and run the carb "as is," for break-in of the new motor, but I'm pretty confident it will be too lean at WOT under load. 

When the time comes I'll definitely be calling you for the jets and rods to get it dialed in. I also need to get your book!