I've got an 85 D100 Custom with a 318/727 that I drive daily. My trips to work consist of 3 miles @ ~50mph then 15-20 mins of 80+ mph and then the same on the way home. I'm doing a little freshening up on the 318 and I have an Offenhauser 6129 intake and a 4bbl thermoquad to go on stock heads. I also have some hooker headers and was planning on trying to find a stock 340 cam. Is this a crappy setup or will it get me down the road better than the tired old 2bbl/318 setup that needs love now? Keep in mind these are parts I already have and I'm not just seeking out this new combo

 

fat -

Your thinking ain't that bad. In the late 70's I had a fairly similar set up, but with a few important differences. I got a pair or 340 HP heads, and used a slightly hotter cam. The TQ was on an Eddy Streetmaster with an adapter, and used the same headers. I gotta tell ya, the combination was pretty quick and still a good street/highway driver.

So you're not that far off base, in my experience, but match the cam to the other stuff, like the rear gears. Also with the cam, think new lifters, timing chain and maybe springs. Any head upgrade, including a refresh and porting will help. Despite popular opinion, a good porting job will get you pretty close to aftermarket heads (at least according to Edelbrock).

Archer

 

Welcome and Merry Christmas.

That 6129 is a Dial-a-Flow rated at 1500-9000 rpm, 600-850 cfm, adjustable with 3 different inserts or "turtles", and for a square bore carb not a spreadbore like the Tquad.

I like the carb and headers, Edelbrock Performer or the Streetmaster too.

I would look for an OEM cast iron that will be easy to find, inexpensive and one of the best manifolds from Chrysler.

We ran a Comp Cam XE256H in our 318 truck with fantastic results.

 

I agree with Coronet. I don't know about the Offy, it sounds like more of a high RPM manifold. You do NOT want a 360 manifold. The smaller "318" Performer would be good as would a stock factory 360 TQ manifold WHICH THE FACTORY used on some 318s

DO NOT put 340 heads on that, unless you are going to also do something about compression. You would have to mill those head, and the intake, and add taller pistons.

I can guarantee you that a GOOD low RPM manifold, headers, and the appropriate cam AND A DISTRIBUTOR RECURVE will make that into an impressive runner.

Don't go too big on the cam. "340 ish" is good.

 

Thanks for the helpful input fellas. Hope you are all enjoying your holiday