Is this qjet ok for 400hp 10.5:1 Chevy 350?

[Camaro350]

Hi, I am building an engine for my '70 Camaro. I am replacing a matching # 250hp 350 with a daily driver motor but want to stay with a Qjet carb. 

New engine specs: ~10.5:1 compression, 3.48 standard stroke, not sure about cam yet but probably an Isky Mega 221@0.050 lift, 108 LSA. Rear axle is 2.73, TH350 tranny.

The carb: http://www.smicarburetor.com/products/sfID1/28/sfID2/9/sfID3/32/productID/18

[omaha]

yes that will work but don't be surprised if it needs some tuning

[novadude]

Why not just find a good core and build one yourself using parts from Cliff?  This way you'll know what you have, and you can tailor it to your application.  As said above, any "out-of-the-box" carb you buy will likely be coming apart anyway.  Why not just start with a cheap core and DIY?

FWIW, a 10.5:1 355 with that cam won't need a ton of help except with the idle circuit.   I am running something similar (355, 9.6:1, 217/225 108 LSA roller), and my car idles great and runs well with a carb built close to Cliff's "recipe 1" specs (slightly larger idle down channel restriction).

[Camaro350]

Thanks,  I ordered the book they sell here as well. I am open to build myself but I probably should have mentioned I live in Sweden, not easy to find used qjets over here that's already "in use". Enthusiasts who like to cruise are quite fond of qjets I believe.

So I figured that even though I get one ready 2 go, I'm probably gonna take it apart before use anyway.

[omaha]

yes I think you might be ok with the carb the way it is. However, with the info in the book you should be able to get it "spot on" if you need to.  Might need some idle work but not much

[Ethan1]

Why not just find a good core and build one yourself using parts from Cliff?  This way you'll know what you have, and you can tailor it to your application.  As said above, any "out-of-the-box" carb you buy will likely be coming apart anyway.  Why not just start with a cheap core and DIY?

FWIW, a 10.5:1 355 with that cam won't need a ton of help except with the idle circuit.   I am running something similar (355, 9.6:1, 217/225 108 LSA roller), and my car idles great and runs well with a carb built close to Cliff's "recipe 1" specs (slightly larger idle down channel restriction).

 I agree. If you can find one over in Sweden, I would go ahead and build it to your specs using Cliff's book.

[Camaro350]

Thanks! The way you put it makes me believe there's lots of good info in that book. Can't wait to read it.  In the meantime I'll be looking for a core or one that needs some work.

[Camaro350]

Hi again, have another question ofcourse, how about this intake manifold? I like the advertised "multi" powerband design, don't know how true that is, but I want to build something different than the usual Performer type dual plane manifold.

http://www.summitracing.com/int/parts/ofy-5744/overview/make/chevrolet

Any answer highly appreciated!

Kim

[Shark Racer]

I'd go with a Performer RPM (if you can get it under your hood) or the ZZ4 intake. The ZZ4 intake fits better than the Edelbrock or Weiand spread bores I've tried.

[Camaro350]

Got the book today. Good read. Very interesting and a few hallelujah moments as well. 

I read a little on the net about divided single planes like the Offenhauser and it seems they may not be the best solution for a daily driver not pushin 7000rpm. I can fit most intakes under the hood as long as it's dual plane, even high rise dual plane ones if I used a dropped base airfilter assy. Will probably go for the ZZ4 one or a similar, thanks.

[novadude]

As said, the 7104 Performer RPM Q-jet or the ZZ4 manifold both perform very well with a Q-jet on a set-up like this.  I've ran both - the ZZ4 on a 327, and the 7104 on a 350.

[Camaro350]

Plans have changed a little, and I've ordered a core to play with from ebay, carb #17080260, think it's a BOP carb and it looks to be a 800cfm air horn.
 
http://www.ebay.com/itm/true-800-cfm-Rochester-quadrajet-carburator-spread-bore-off-1980-z28-camaro-/291092063629?_trksid=p2047675.l2557&_trkparms=gh1g%3DI291092063629.N19.S2.M-996.R1.TR4&nma=true&si=6jLxsK1XJzigW%252B2%252BgWFTbhNMhoo%253D&orig_cvip=true&rt=nc

I had a little money over so I went ahead and made an offer for one of these as well, just in case I mess up the used core I'll still have something to bolt on that should work ok:

http://www.ebay.com/itm/390787928765?_trksid=p2047675.m570.l4467&_trkparms=gh1g%3DI390787928765.N19.S2.M-982.R2.TR4

Reason for the "850cfm" carb is that I'm building a 421 sbc. Already have a prepped 4.155 Dart SHP on the way.

[Cliff Ruggles]

I'd stay clear of any "remanufactured" or catalog carburetors.  I get them in here all the time, and they are most often a MESS.

There is absolutely no such thing in this hobby as a generic "stage" 1, 2, 3, etc carburetor that you can pull out of the box and be calibrated exactly for what you are doing.

Most will run poorly, if at all.  Expect to do some custom tuning in several areas if you go that route....FWIW....Cliff

[Camaro350]

Thank you Cliff, I understand.

I read your book and had that in the back of my mind when I ordered it. It will be opened up and checked/calibrated, I just figured a "new" carb might be a good clean base, with all new linkages, pull offs, set screws etc etc. 

I also have a #17057502 sitting on the original 350 and thanks to your book and that I find the layout/design of the Qjet really interesting, I'm really looking to learn these carburetors.

[Cliff Ruggles]

I actually like getting some of those in here, nicely plated.  Then I "gut" them completely out and put in much better parts and correct tuning components.  Nothing wrong with starting out with a nice clean foundation, and much less labor intensive than working with an old rusty core.....Cliff