Newbie question, is there a way of taking a newer FI 5.0 HO and make it into a carburated engine? Thanks.

 

Yes, but why would you want to?

Post the details of what you are working on and why you want to make this move and you will get some better responses.

 

1955 F100 project. Want to keep it simple, no computer, wiring harness, sensors. I am aware FI is the way to go but I wanted to keep it old school.....

 

Easy then. Peel off all the EFI stuff. Get a pre efi distributor and either stay with Duraspark or go Pertronix.

Select a manifold: dual plane for Plain Jane running, or a single plane for high performance. Billions served, stockers, exotics etc. Avoid the tunnel ports ones as they won't fit and are probably a million bucks.

500 CFM for Plain Jane, 750 if you want to set records. Vacuum secondaries or mechanicals if you are running 4.56 gears.

Search this forum for more complete discussion, but the bottom line is take off the EFI, bolt on the carb stuff, nothing much else to change.

 

Two things to look out for are: does the donor engine have a roller cam or flat tappet? It's important as you will need to match the dist. drive gear to the type of camshaft the engine has. Roller cams are steel, flat tappet cams are cast iron. Second is what kind of fuel pump you plan on using. If an electric one then go for it. If you want to use the "old school" mechanical fuel pump you need to change the timing cover to one that has the correct boss for the pump and add an eccentric cam to the front of the timing gears to drive it.

 

It's far easier to just go with a low pressure, low volume electric fuel pump here. Something like a MrGasket 12S is what you want. Simple to wire (run a hot wire to the ignition ) and no regulator needed. What you want in an intake is a high rise dual plane like the Edelbrock RPM, Weiand Stealth or the old Ford C9OX, Shelby Cobra high rise or their newr incarnation, the Ford Racing A321. All these perform from idle to 6000 rpms, top them with a 450-600 cfm carb (going bigger on cfm's will cost you in street manners) If it's a true HO 5.0, leave the cam as is but augment the lift with a set of full roller 1.7 rockers to increase the lift at the valve by .030. These will also shed the friction in the rocker fulcrums by using roller trunions.

 

I'm in the process of doing exactly this. I just ordered my bumpstick yesterday too. just be sure to order a cam with a 110lsa or smaller. I got a complete donor motor for $325 from a salvage yard with GT40P heads. I spent $1100 at the machine shop BTW. I'm anticipating about 335-350 flywheel HP with this combo. O, and I'm going to do the FiTech Throttle body EFi. It was on sale last month for $725 after rebate, normally $795. I'm running a 600cfm on my current 1971 F100 - 302 with decent results.

 

Picking a cam with an LSA of 110 or lower isn't a good way to go. You're sacrificing bottomend and streetability for a few HP numbers on the topend. Wider LSA cam's work great with carbs as well as EFI.

 

I have to agree with "baddad" on this. A LSA of less then 110 deg. will make for a "lumpy" idle. Of course if that's what you want then go for it but if you want good response off idle and good drive ability stay above 110. A stock Ford 5.O HO FI cam is a good street cam that will still make good power. With headers and the 1.7 RR's and better then stock (Ported) E7 heads you can made around 300 HP. GT 40's or the P's will add another 30 peak HP.

 

I had a few conversations with Comp Cams and they told me multiples times that they would not recommend a carb with more than 110LSA in a carberated application. I figured they know their ****. My personal decision to go with TB-EFI was a late decision on my part. Maybe that would have allowed me to go 112 or 114 with their recommendations. I'm doing:

Camshaft Type: Hydraulic Roller
Duration Exhaust: 278
Duration Intake: 272
Duration at 050 Exhaust: 225
Duration at 050 Intake: 219
Engine: 221-302 / 351W
Firing Order: 1-3-7-2-6-5-4-8
Intake Centerline: 106
Lobe Separation: 110
Engine Manufacturer: Ford
RPM Range: 2000 to 6000
Valve Lift Intake: .544
Valve Lift Exhaust: .533

 

I've actually run EFI cams with carbs. The guy you were talking too was probably flipping burgers the week before you talked to him. My Comet's 331 with a 3x2 carb setup is running a Ford Z303 cam in it (112*LSA) I've also carbed an Explorer cammed 302 (116 LSA with the stock F4TE roller cam) Both run like they've got a EFI setup feeding them. And run a B303 in a 5.0 with a carb (112 LSA) Also had friend's run an HO cam 5.0 with carbs(115.5 LSA) All performed great. Comp for some reason in stuck on the old bugaboo that carbs need lots of overlap to perform, when the reverse is true. You may give up a few HP numbers at the top of the rpm scale, but you gain far more response at the bottom with a stronger vacuum signal at idle and off idle that allows the carb's circuits to respond faster to changes in the throttle.

 

The old school carb guys are just like guitar players.. it's all about "that sound" and they don't care if it doesn't actually work with everything around it.

 

Also a LSA below 112 makes it more difficult to tune carbs in. The reversion pulse messes with vacuum signals, and this is where the "Dump that vacuum secondary carb and put a mechanical double pumper on it" mentality came from. Mismatching cams to the engine combo.

I learned the hard way taking Comps advice, car ran good really did but felt like it was leaving something on the table. Pulled the 268he out and swapped in a similar grind with a 114 LSA with the same 268 duration AND the idle calmed and it pulled harder through the midrange which is what you want in a street vehicle.