Q-Jet Modifications

I recently had my engine rebuilt and it seems to run ok...just not what I thought it would be. I haven't made any changes to the carb and still have the stock converter. I was hoping to list the specifics of my engine build here in hopes of someone telling me what I need to do to the carb to get it to run optimally.

I have a 70 Buick 350
Bored .030 over
10:1 Comp Pistons
TA 212 cam
TA Stage 1 Intake
2 1/2 in headers
2 1/2 in exhaust
Petronix Points Eleminator
MSD Coil
Stock, never rebuilt 750cfm Q-Jet

Right now in order to keep the car from trying to stall under load I have to adjust the idle to about 1000 RPM and in drive it's sluggish from a dig. :sleep:

Is there a kit that I need to buy?

Thanks!

 

Thanks, I'll buy the book. But what hardware is recommended. I don't want to wait on the book and then have to read the book to find out what parts I need and then have to wait on the parts and then have to wait for the weekend to have time to work on it. I'd rather know what all I need and get this done this weekend.

Thanks

 

You can buy rebuild kits but ask for a master kit with all new parts

 

Or...send it to Ken and have him rebuild it for you......http://www.v8buick.com/forumdisplay.php?172-Everyday-Performance-LLC

Scott

 

You might not need any parts at all, other than the rebuild kit. l would get it running with factory rods and jets first after the rebuild, then make incremental changes to fine tune. Read the book, then make the changes. It sounds like your problems are all at low speed, whish is more around idle port sizing and accell pump working..

If your carb is original to that car, it has 69 jets and 44 rods on the primary side. I like the manual trans carb better with 73 jets and 44 rods - thats where I'd start if you want to stockpile parts. You'll also want to check the secondary air valve shaft and make sure you're getting 90% or better travel - if not, get one that does.

The secondary rods are kinda oddball -BS rods with extra long tips..It wouldnt hurt to start with a set of AY rods, although my 71 455 ran great with big/short rods, so what do I know...

All that said, Everyday Performance did mine, and I'm very happy with it.

 

For it to idle correctly after yor engine mods, your qjet will need some internal modifications in addition to the rebuild kit itself. you could contact Cliff, he has great parts and kits. You will probably need to open up the internal air bleeds for better idle. Specialty tools would be required for this part.

I don't have the specific information you seek. My tools and information are still in storage somewhere after my move, but I hope this helps you some. Cliff's book explains it well if you want to do it yourself. Ken, of course, does a great job also. In March, I should be back doing some myself.

 

I agree, Read Cliff's Book. It is the best reference available and it worked for my car.

 

Thanks everybody...Buying the book now. Just wish I had a back-up carb to put on there in the meantime. What do you all think about me pulling one off of a junkyard 350 and rebuilding it? There are 4-5 68-72 Skylarks at a place down the road I pull parts from every now and then.

 

Well, if you want to keep the car running while tinkering with the carb, by all means buy another core and rebuild it as well. I have 5 separate cores for my car, and I can tinker to my heart's content on them and keep driving. If the carb currently on my car has issues, I can swap it out for another in 5 minutes.

You'll also have the option to swap parts out and try different combinations from carb to carb until you get the engine running the way you like it. I'd agree with that plan.

 

I'd say get a extra core to tinker with, even if you have someone like Ken do your current carb - that way you can learn and not be afraid of screwing up, which is how I learned. As far as pulling one to use while yours is out for the rebuild, it's a crap shoot if a carb thats sat for 10-15 years will run at all.....

I'd grab the core, read the book while taking it apart, clean it up and put a basic kit form Cliff in it... then send yours out for the whole customization/resizing route..

 

i hope the 2-1/2 in headers was a typo?
also you put a cam in a engine,then left the stock converter in it,and now it wont idle
this should come as no surprise,you needto change the converter 1st
also what numbers did you come with to get at 10-1 compression?
is it really that high?
how much initial advance do you have in the distributor/
lots of variables here
good luck

 

As much as I dislike Q-jets, I wouldnt be so quick to point the finger at it.

Im suprised Larry didnt point out that your problems sound more like timing issues than carb issuesuzzled:

Having your vacuum advance coming in at idle will cause the same problem and turning your idle up will only make it worse.

If your timing is retarded and youre compensating by upping the idle it will cause the exact problems youre having.