350 2bbl, worth 4bbl swap?
 

The 350 in my 73 C60 dump truck has a 2bbl manifold and carb. As I'm working on the truck I'm realizing this would be a great time to swap manifolds, I just have questions as to if it's worth it. I know the truck 350s are low compression small valve engines made to run hard for a long time. I was considering a Performer EPS manifold, made for torque in the range the engine will be running, and I have a spare 1406 carb laying around.

Anyone have experience in this swap? Are there any real world gains to be had from going 4bbl or will I just be dropping my mpgs?

Merry Christmas!

Re: 350 2bbl, worth 4bbl swap?
 

Anyone? I know for most vehicles it's a no brainer but I just wondered if anyone had real world experience in a heavy truck like this doing the swap.

If this would be better in another section of the forum mods please feel free to move it!

Re: 350 2bbl, worth 4bbl swap?
 

I would do this swap.

I would choose a Quadra jet.

Re: 350 2bbl, worth 4bbl swap?
 

I'm really considering it. I have enough Amazon gift cards saved up to do it for basically free so that really helps too.

I'd go with a Q-Jet but I have a really good 600 Edelbrock on the shelf. I've had good luck with them performing well on stuff that sits intermittently like this truck will.

I'm also considering some headers. It's got rams horns now, I'd go for long tubes but with the PTO I don't think they'll be too easy to fit, passenger side would dump right into it. Maybe a set of shorty headers or mid length...

Re: 350 2bbl, worth 4bbl swap?
 

I'll bet there's no noticeable difference in performance.

Re: 350 2bbl, worth 4bbl swap?
 

This is also a very real possibility that I'm considering. On one hand, conventional car guy wisdom automatically tells me that more airflow in and out equals more power output. But on the other hand I don't know if it'd be enough to justify the modifications.

I'm hoping someone who's had the experience of swapping intakes and carbs on an old small block will be able to provide a record of their real world gains or lack thereof.

Re: 350 2bbl, worth 4bbl swap?
 

I doubt you will feel any difference other than in your wallet. I swapped the engine and transmission from a 1972 C50 into my 49 Studebaker 2R16A. The two barrel carb was missing. I had two choices from parts I had sitting around; either use an even SMALLER two barrel intake and carb from a 1968 El Camino that came with a 307, or use a 68 intake and Qjet from a 1968 Chevy 350. I opted for the two barrel and have never regretted that decision. I am a big fan of Qjets (set up correctly) in cars. But really no need in a big truck. I do not drive on the highway often; only to get sod, gravel and dirt. But when I do, I am doing 4200 RPM at 65 mph because of the 6.66 rear axle. Those big secondaries on the Qjet would be open ALL THE TIME.

I ran a Q-jet in that 68 El Camino and it ran flawlessly. Had a 3.31 rear axle and a 4L60E auto overdrive trans. Got great mileage when I wasn't towing. I have the exact same manifold and Qjet in my 57 Chevy and it runs great. But I am sticking with the two barrel in my big truck.

Re: 350 2bbl, worth 4bbl swap?
 

Thanks for the info!

I have had the same line of thought on the swap myself, that with 8.50 low/6.50 high gearing I'll be running with the secondaries open a LOT of the time.

I think that unless someone can tell me otherwise that it's a worthwhile swap, I'll leave the 2bbl alone and just make sure the truck is tuned up as good as possible and see how things go. I do think I'll open the exhaust up with true duals just to help it breathe a little, that was an option from factory. Currently it's got a y pipe and stock single exhsust.