EFI to Carb swap

[MUDICE1970]

I've got a '78, F-250, 4x4, 4-speed, with 4.10 gears, and 33" tires. The old 300 has got 246,000 miles on it and is getting real tired. I've got a '88 EFI 300 that's got 12,000 miles on a $1,500 re-build that I am gonna put in the PU. The old truck works hard 90% of the time it is being used so I am gonna try to get a little extra out of it. What I've rounded up so far is an Offy DP, Hooker 1 5/8" split header, a 390 Holley, and a recurved Duraspark with a MSD 6-AL box. The first question I have, is there a better cam than the Clifford 264? I was planning on running that cam with there cam kit (springs, locks, push rods, lifter). The second question, am I gonna run into any surprises going from EFI to carb other than not being able to run a mechanical fuel pump. Thanks in advance for the help. Later Vick

 

[Lazy JW]

Howdy and welcome to the forums!

I don't think there are any unsurmountable issues with swapping from EFI to carb but I have not done this myself so maybe someone else will chime in. A bit of port work on those EFI heads can be a good investment as they are pretty restricted in stock form.

That sounds like a lotta cam for a working truck, probably too much overlap for best torque. Are you towing heavy loads? What rpm range will you be spending most of your time?

I chose a short-overlap, high-lift cam from www.reedcams.com and am quite happy with it. Isky makes some good grinds for street use too, also Crane and probably a few others.

Those torque cams from Reedcams look pretty good to me.
Joe

 

[MUDICE1970]

Thanks for the input. As far as the loads I haul, to much for the brakes I got LOL. I put a 5,000# mud truck on the goose-neck all the time and haul it all over the country, but the weight isn't as much the problem as the thing setting so high in the air and catching a lot of air. ( It pulls like a parashute) On the rest of my loads trailor and load bumps 10,000# pretty often, plus the weight of the truck. As far as RPM's I stay between 1,800 and 3,200 90% of the time. It turns 1,800 at 40 MPH and 3,200 at 75 MPH. According to Cliffords the 264 cam starts pulling hard off idle, peaks out at 3,400 (I think), and still makes power to 4,200-4,400 (the best I can remember, I've slept since I looked at the specs). I was hoping to get by without pulling the head but if I have to I have to, how much will the stock ports hurt the bottom end grunt. Or would I be better off using a carb head? Thanks for the help. Later Vick

 

[80broncoman]

I happen to run a carb and Efi manifolds on my 80 bronco.
I use a efi head on mine.
Its really not much different. Running a efi head with a carb intake means
there are a few exh manifold bolt holes not used/

Sounds like a good combo to me

 

[63redtudor]

The mounting boss & the tapped holes are there for the mechanical fuel pump, all you have to do is make/drill a hole for the pump arm. If you look, you'll find the EFI cam even still has the lobe. Just an option.
Edwin

 

[80broncoman]

I'd keep the efi parts around, as you might change your mind later.
I'd especally keep the EFI Exh manifolds as they make a very nice replacment for old rusty, leaky headers.

 

[Anonymous]

Don't scrap your extra EFI parts. If you want to get rid of anything you don't want, I will probably take them.

 

[MUDICE1970]

Thanks for the input fellas. I'm a pack-rat and don't ever throw anything away. I know that I'll never use any of the EFI stuff but I alwys hang on to the left overs in case somebody needs them. Later Vick