1978 F150 / 4x4 / Manual Transmission

I bought a truck with a bad 351M engine. I have a new 400 coming in a couple months. I'd like to put a new carb / intake and distributor on with the new engine. Does anyone have some insight into the world of carbs for a 400?

Also, while we are at it, can you think of anything else that would be good to replace while I'm making the swap. I'll definitely do the clutch while it's out, but other than that?

 

Edelbrock performer intake /felpro valleypan tray
holley 600-650 cfm vac secondary
when getting clutch 400 to 351m is different if using same flywheel you want the 351m 11" the 400 is 12" same size flywheel but different bolt holes for pressure plate.

While in there
motor mounts
Trans mounts
good quality throwout bearing
Belts/ hoses
Rag joint (easy when nothing in the way)
have flywheel resurfaced.
Take a good look at ring gear while flywheel out replace if needed
balancer .....different 351m to 400
I joints while driveahafts are out.

Dizzy id go HEI (personally like simplicity better) DUI makes rhe best IMO

I'll add more as I think of stuff

 

I just rebuilt my 351M, I went with a Weiand intake and the Summit 500cfm carb, super happy with it, only issue is I ordered smaller jets as I'm getting 8mpg and it is running rich, so I'm going to drop down a few sizes to adjust for altitude (I'm at appx. 3000') and see if that helps, I think one of the things everyone does is over carburate IMO. GF's jeep with a 350/400 turbo had a 650 on it, always loaded up, mileage sucked, I had a Holley 390cfm I put on as a temp/test... it's still on there 3yrs later, mileage dbld as did driveability, and it still will get up and go like mad, just saying.

 

Is the difference between a manual choke and an electric choke a personal choice or does it need to fit the truck specifically?
Also, does it need an egr? There are no emissions tests in AR, but is it good to have anyway?

 

As previously mentioned....600-650cfm carb is optimum. I ran a Carter 625 on the 400 I had in my F150... puh-lenty of giddy up n go and got 10mpg doing it. Might also add that it was a 4x4 and I was running a Comp Cam 268 with headers and glass packs...several people asked me if it was a 390. Hahaha That always cracked me up.

 

I’ve used a used edelbrock 1407 which is a 750 for years on a 79 400 with a weiand intake. I still have it on a Pontiac car. It was an absolute champ. Even through me not knowing anything about tuning it and several things wrong with it it took my truck from 110 degrees to 15 degrees carrying all kinds of stuff and ran okay. It wasn’t a speed demon or a freight train but that’s not the carbs fault. Later on I rebuilt it and fixed many things wrong with it and learned how to use a vacuum gauge. It ran so so much better after that. The Pontiac car is a turd for many reasons not the fault of the carb but when I get it fixed I don’t doubt it will do the car good.

I found tuning the vacuum springs and metering rods pretty easy, and the kit to do that is only $80 or so. If you get a Holley, look into how expensive it’s gonna be to tune the carb to your motor. Whether it has vacuum or mechanical secondarys and if you need different parts to change them. Or things like accelerator pumps and springs. Small stuff like that might come up when you really start tuning it to your application.
Now I have a motorcraft 2150 on the same 400 It does the same thing with much less throttle
response, less intake noise, and more mpg. I’m sure it’s super reliable and resilient as well. But going from a 750 to a 350 theres a noticeable difference in throttle response and power but I don’t think it’s any real difference in overall available power. More that you can feel the 2 barrel is running out of steam but the 4 barrel is still trying.


I’ve had a manual choke in my truck for years. I know it’s a step back in technology from what our trucks are supposed to have but I got tired of fiddling with my electric unit and it’s super easy to use the manual choke.

 

The options for carbs is endless and boils down to how much you know (or want to learn) and how much you care. Both Edelbrock (carter) and Holley basic carbs are easy to tune. Edelbrock’s are less messy cause you don’t have to drain the float to change jets or the part throttle enrichment circuit (power valve for holleys and metering rods for Edelbrock). All edelbrocks also have secondary jets where as the standard holly 4160 (basic Holley) only has a metering plate.

The Edelbrock is probably easiest to bolt on and go with maybe a jet or two change if you want simplicity.

Now if you want to get way into it there are holleys that offer WAY more adjustment like screw in air bleeds and emulation jets. These things on an Edelbrock have to be drilled out to change.

Then there are the factory carbs that are still great. Holley 4180 carbs were some of the last factory Holley truck carbs before computers and they have some odd things but they also have primary annular boosters which give a pretty big increase in fuel atomization.

There is always also the option of a Quadrajet which when tuned right will probably get you the best mileage of any carb and they run great sideways when off road which is something most carbs suck at.

what ever carb you go with I’d suggest getting a “how to tune” book and working your way through it. Also don’t forget a carb won’t help a crappy or dead engine.

I currently have edelbrocks on my two Fords (79 F350 with a 400 and a 69 Bronco with a 351w) the F350 is going to be getting a modified Holley 4180 and the Bronco will be getting a Holley truck avenger 670. I also have a modified quadrajet that I will be trying on both trucks just for fun.

 

I put a Weiand 8010 / Demon 1901 (625 cfm) in my 400 way back in '21 and it just worked right out of the box. They make a tuning kit for it but I haven't had a reason yet to even think about needing it. I've been having so much fun enjoying the "get up and go" from this new sertup that I broke a valve spring!

 

2 more things thought about. Fuel pump if running mechanical.

If your dipstick goes thru side of pan (my 77 does) replace the gasket on the piece riveted to the pan. Requires drill out rivets then bolt back together. You dont want to remove the pan in the future in the truck. Its no fun with oil dripping in your face.

 

I’ve got to second the Demon carb. I’ve had great luck with them right out of the box and they are really easy to tune if you need to.

 

There's Holley then there's the search for the closest thing to a Holley. so the question is which Holley do you want ? the best answer to that is from Holley themselves .

Carb Selector (holley.com)

from those choices I'd go with a 4160 600cfm electric choke . the 4160 mainly because the single feed is so much better than the dual feed mess.

 

Quick fuel sl-1957e 600cfm, electric choke, single feed fuel vac secondaries, Some internet posters claim Holley ruined it, when they bought them. I'm not advanced enough to tell the difference.
I'm happy with it so far. But I'd follow the link above still to get an idea of what you want/need or don't need.

 

Keggar Kraig,
Me too, I had so much fun winding my balanced 429 with Crane valve train, I too broke a spring.
What saved my butt, is the Crane springs are dual. The round coil outside spring broke, and the inside flat-coil spring kept the valve in place so my engine didn't suffer any damage. yeay
I'm running a Holley 4160 model 3310 dual inlet.