choosing carb (77 f250 4x4)

gingerbreadman · May 16, 2005

as in this THREAD I bought a new truck. in short its a 77 f250 4x4 351m 4 spd 410 gears.

I need a new carb for it, its got a edelbrock intake on it so a 4bbl is in order.

I lean towards holley for there popularity.

What do you recomend for a carb for it? electric or manual choke? vaccume or mechanicle secondaries??? please school me on carbs here guys. truck avenger??

Gas mileage is a concern and so does carb price also this is by no means a hot rod.. Its my daily driver.

The autoparts store guys dont seem to have time to talk nor would I trust what they say so I just grabbed the holley catalogue so if you can give me part numbers of what carbs your talking about.

I always figured once this 351m goes out id replace it with 429 or 460 can I use the same carb for both engines??

-gbm-

6Stang7 · May 16, 2005

i'd go with an edelbrock because they are a more reliable carb IMO. I'd also get an electric choke with a mechanical secondaries.

gingerbreadman · May 17, 2005

T.t.t.

gingerbreadman · May 17, 2005

From my limited reasearch and knoledge im leaning towards this carb http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSC/0-1850C.html

anyone???

-gbm-

Gud T.B. Blown · May 17, 2005

i would recommend a holley 650 with vacuum secondaries for max mileage. if you want a carb to work for both a 351 and 429 you will need at least a 700cfm. the street avenger and edelbrock are both solid carbs right out of the box, the edelbrock being a lot cheaper. i would also go with an electric choke.

ForceFed70 · May 17, 2005

Well Josh... carb choice is very personal.

1st thing you need to do is decide on CFM. For best throttle responce and fuel economy, you want the least CFM carb you can buy without sacrificing much horsepower. In your case I think that would be a 600cfm carb. BUT, if you plan on doing any horsepower inprovements then you'll probably want to plan for the future and get something that will accomidate the higher fuel demands. Also.. I know you are considering a dual fuel system. Most dual fuel systems flow through the carb and thus the carb can restrict fuel flow. So you may also want to go a little larger for just that reason. So I'd be tempted to go with a 650cfm version even though it will hurt fuel economy and throttle responce a little. Your choice...

2nd thing is application. How serious are you about 4wheeling? If you want to get serious about wheeling, you'll want a carb designed for off-road. They handle steep angles much better than a regular carb. For example, my truck has the factory carb and every time I want to climb a steep hill, I have to make sure I'm running propane because with gas I get 1/2way up and then the truck sputters and dies from the steep angle. Really scary when your climbing a long steep hill and your truck has power steering and brakes.

3rd choice is make. Basicly edelbrock Vs holley. Here's how I see things... both companies make an excellent carb. But they are for different people. Holley's are great because they have lots of aftermarket parts, and are very "tunable". Great carb for getting the absolute maximum horsepower. BUT, most of us don't have the skills to do that. And this is where the edelbrock's come in.. they seem to be a great "pull it out of the box, bolt it to the manifold and go" type of carb. Depends on what you want.. in my case, I think I'm going edelbrock on my next carb purchase.

4th choice: Choke. Electric or manual. Manual you have full control over... electric it just works. I'd go electric..rarely have I found a need to manually control my choke.

5th: Vacum secondary vs. mechanical. I believe vacum is more fuel efficient. But I also think that mechanical is quicker to respond. If your truck was an auto, I'd say stick with the vacum. But with a manual it's a tossup. Since this isn't a race vehicle and your concerned about fuel milage, I think vacum would be your best choice.

So after all that, and what I know about you and what you want, I would suggest the following to you: Edelbrock Truck/offroad carb, 650cfm, electric choke, vacum secondary.

cougar694u · May 17, 2005

70_Nitrous_Eater said:
Well Josh... carb choice is very personal.

1st thing you need to do is decide on CFM. For best throttle responce and fuel economy, you want the least CFM carb you can buy without sacrificing much horsepower. In your case I think that would be a 600cfm carb. BUT, if you plan on doing any horsepower inprovements then you'll probably want to plan for the future and get something that will accomidate the higher fuel demands. Also.. I know you are considering a dual fuel system. Most dual fuel systems flow through the carb and thus the carb can restrict fuel flow. So you may also want to go a little larger for just that reason. So I'd be tempted to go with a 650cfm version even though it will hurt fuel economy and throttle responce a little. Your choice...

2nd thing is application. How serious are you about 4wheeling? If you want to get serious about wheeling, you'll want a carb designed for off-road. They handle steep angles much better than a regular carb. For example, my truck has the factory carb and every time I want to climb a steep hill, I have to make sure I'm running propane because with gas I get 1/2way up and then the truck sputters and dies from the steep angle. Really scary when your climbing a long steep hill and your truck has power steering and brakes.

3rd choice is make. Basicly edelbrock Vs holley. Here's how I see things... both companies make an excellent carb. But they are for different people. Holley's are great because they have lots of aftermarket parts, and are very "tunable". Great carb for getting the absolute maximum horsepower. BUT, most of us don't have the skills to do that. And this is where the edelbrock's come in.. they seem to be a great "pull it out of the box, bolt it to the manifold and go" type of carb. Depends on what you want.. in my case, I think I'm going edelbrock on my next carb purchase.

4th choice: Choke. Electric or manual. Manual you have full control over... electric it just works. I'd go electric..rarely have I found a need to manually control my choke.

5th: Vacum secondary vs. mechanical. I believe vacum is more fuel efficient. But I also think that mechanical is quicker to respond. If your truck was an auto, I'd say stick with the vacum. But with a manual it's a tossup. Since this isn't a race vehicle and your concerned about fuel milage, I think vacum would be your best choice.

So after all that, and what I know about you and what you want, I would suggest the following to you: Edelbrock Truck/offroad carb, 650cfm, electric choke, vacum secondary.

That was some pretty good info. I think the holley may even help more when climbing, with the float bowls on the front & rear. If you're climbing up a hill, the gas is pushed up against the jets in the front bowl. They have jet extensions for the rear jets that work like straws to suck up the gas, basically designed for wheel stands when drag racing.

Anyway, I found this calculator a while back when trying to figure out what CFM to go with on my car. Here it is:
((Max RPM/2)*Displacement)/1728

Since you're running the 351m, I'm guessing your max RPM would be 6500? Anyway, it works out like this ((6500/2)*351)/1728, then 3250*351/1728, then 1140750/1728, which equals 660 cfm. If you're only gonna spin about 5500 RPM, it brings it to about 560.

ForceFed70 · May 17, 2005

I've got a friend with a standard holley 4bbl. I believe it's a 4160. He has tonnes of problems with his bronco and hills. The carb goes super-rich and he leaves huge clouds of smoke. Much worse than the stock carb in my 85 GMC.

The newer holley carbs may be better for this. Either way I look at it, the truck/offroad carb's are only a few $$ more and worth every penny.

gingerbreadman · May 18, 2005

Thank you for the info nitrous, it explained things well too me. But a question I have is what is considered a steep angle??? would any passable loging road be steep enough to cause carb problems???

Are we talking rock crawling angles?

In my 85 on propane i never had a problem due to the propane but i wonder if my driving habits need the off road carb.

i due alot of off road stuff, fishing and hunting. but im not nuts like some of my buddies, Iv had my moments where im stuck on my bumper and stuff but i dont think I'll be like that with this truck

Its not pennies were talking here, its almost double for a off road carb, the holley truck avenger is about $600 opposed to $400 for a regular carb.

-gbm-

-gbm-

cougar694u · May 18, 2005

70_Nitrous_Eater said:
I've got a friend with a standard holley 4bbl. I believe it's a 4160. He has tonnes of problems with his bronco and hills. The carb goes super-rich and he leaves huge clouds of smoke.

It's probably coming out of the breather tube that sticks up for the front bowl. We used a peice of fuel line that made an upside down U and put it on both of them, then cut the top section off so it would still breathe.

But like you said, it's basically a matter of preference.

ForceFed70 · May 18, 2005

Hmm.. what angle is steep. Good question...

No, a logging road won't have what I would consider any steep angles, neither would anything that can be driven in 2wd.

Hmm... by "steep" I guess I mean something in the area of a 45* angle (or more) from level.

onlyme · May 18, 2005

f250

Thats cool I got a 1976 f-250 its pretty solid and sharp, mine is 2wd though with 3:54 gears and I got a 429 with a c6. Are you running 16.5 rims or 16, mine came with 16.5 i switched to 16'' all the way around.

gingerbreadman · May 18, 2005

onlyme said:
Thats cool I got a 1976 f-250 its pretty solid and sharp, mine is 2wd though with 3:54 gears and I got a 429 with a c6. Are you running 16.5 rims or 16, mine came with 16.5 i switched to 16'' all the way around.

Im gonna put a 429 in it when the 351m dies or sooner, 429's were built from 68-73 so Im pretty sure there all high compression and gas is expensive enough let alone running high octain, so when I rebuild the 429 have to drop the compression.

the P.O. told me it came with 16.5 inch split rims, they have been switched to 16's tho, the spare tire tho is a split rim, I wonder if it is 16.5??? have to take a looksee....

Ya its a beast. classic too boot. it suits me tottaly

-gbm-

gingerbreadman · May 18, 2005

70_Nitrous_Eater said:
Hmm.. what angle is steep. Good question...

No, a logging road won't have what I would consider any steep angles, neither would anything that can be driven in 2wd.

Hmm... by "steep" I guess I mean something in the area of a 45* angle (or more) from level.

Ahh I know myself, ill end up going back to my ways I'll probly spend the extra $$$ and get the off road carb.

holley makes a 670 truck avenger, but there like $600+

-gbm-

onlyme · May 19, 2005

f250

Cool, none of my 16.5's were split but i hated them so switched to 16's from 1972 up the 429 did have lower cr, mine has jsut 8:5:1 but its bene tweaked some.

gingerbreadman · Jun 12, 2005

I just got it.

I bought the holley truck avenger 670 cfm

I got it wholesale through my friends shop for $440 and only one tax.

Im reading the directions here and it pretty much states its extremly closely calibrated from the factory but it doesnt seem to hard to set up.

It says the primary and secondary jets are set for sea level, and for every 2000 feet above go down one jet size, I live at 1500 feet and spend alot of my time in the hills so i can see myself leaning it out one jet size, But obviously ill get it on there and check the plugs.

Do I need to install brand new plugs to see if its running rich or lean? the plugs in there are good but its been running rich for a while.

-gbm-

choosing carb (77 f250 4x4)

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