Rebuild or replace

[Mv7fd]

Most of you have read about the problems I've been having with my truck last night I pulled the top end of the motor off and looked at the lifter it is trashed and the cam is junk as well. So now I'm wondering what is better to do should I get a new gm long block and put the new stuff on it or just replace the cam and lifters and put the new carb and intake and stuff on the old motor. This motor has a little over 100 thousand miles on it. I'm really torn on what to do

[Mv7fd]

And which carb to go with and should I 600 or 750 cfm I want electric choke

[rich weyand]

Buy a new 350/260hp crate engine, and put a dual-plane manifold and long-tube headers on it. Maybe put a better cam in it. Comp 12-235-2 is a good choice. Several others as well. 12-234-2. 12-300-4.

A 350cid engine at 5000 rpm sweeps 350*2500/(12*12*12) cfm, or 500 cfm. With a volumetric efficiency of 1.00, which a normally aspirated engine will not achieve, you could pump a maximum of 500 cfm through the engine at redline. Carburetors work best near their flow rate maximum, when stack velocity, swirl, and atomization are best.

So a 600 cfm carb is plenty.

That said, a Qjet with electric choke is the best carb for the 350. It's sort of the peak of carburetion technology, while still having a large following on the net that can help you tune it. There are some low-volume aftermarket carbs that some people like, but I would stick with the Qjet.

[tucsonjwt]

If you have the $$$, I always say go with a new crate motor and sell what pieces you can off the old motor on CL. I also always recommend a manual choke, especially in cold climates, but each to his or her own. I like a professionally rebuilt Qjet and stock everything if possible.

[imjeff]

Before recommending a motor it's only right to ask what you want from the truck. It's easy to make recommendations about spending someone else's money to get what they want, but what are YOU looking to get out of it?

Jeff

[Mv7fd]

A daily driver if I need it to be and a wood hauler and a trailer if I need to

[J Knight]

I would run a compression test, if all is good and no knocks I would throw a new cam and ride.

[Mv7fd]

I'd have to put it all back together to do that

[rich weyand]

With 100,000 plus miles on the odometer, I wouldn't put money into the old engine unless I was going to totally rebuild it. At that point, I think you are money and time ahead on a new crate engine. You can rebuild the old one in your spare time and sell it later.

[Mv7fd]

That's my thought and hopefully i'll be able to get half way decant gas mpg out of it

[rich weyand]

On a 79 K with a stick? I'd figure 14 highway, and 11 or so city, depending on axle ratio and tires.

[jetmech85]

If your bores and crank are good then an overhaul without much machine work would be less than a crate motor. I've seen small blocks with 200,000 miles with excellent block and crank then I had one that needed boring at 90,000. Have to have major machine work and new pistons, turn crank, etc. then a crate motor is the way to go. I am usually forced to go with the overhaul because I can do it a little at a time. Hard for me to come up with the cost of a crate motor at one time. Will end up costing as much or more but my only option.

[Mv7fd]

so i ordered everything tonight i got the stock gm crate motor and the edelbrock performer intake manifold non egr and i'm using the stock qjet carb since i just had that rebuilt a month ago. i hope this set up will work well together. and will i need an adaptor for the carb to mate up to the intake. the carb is a 2701

[rich weyand]

Depends on which intake you got. Some will take either carb directly.

Which Edelbrock part number is it?

[Mv7fd]

Eel-2701

[Mv7fd]

Sorry edl-2701

[rich weyand]

Depending on where you ordered it, you can return it. Jegs, Summit, Amazon all take returns. Or you can refuse delivery when it arrives.

The Edelbrock 2101 is the identical unit, BUT it accepts either the Qjet or Edelbrock carb directly with no adapter nonsense.

[Mv7fd]

Will an intake manifold make that much of a difference over stock

[rich weyand]

Originally Posted by Mv7fd

Will an intake manifold make that much of a difference over stock

A good dual-plane manifold? Yes. Long-tube headers, too.

The easier it is for the engine to pump, the more mixture you get, and the more torque/horsepower you get. The induction system and exhaust system matter a lot.