I am thinking of changing to a 4bbl carb and intake. What cfm carb for a '79 F250 4x4 does the forum think. Thanks for the help.

 

Your choice depends on what you prefer.

Intake:
If you are looking for a new aftermarket intake, I would suggest an aluminum dual plane manifold. The dual plane gives you more torque. If you want something cheaper then get a stock manifold from the salvage yard. Unless you have a built motor you probably wouldn't notice the difference from stock to aluminum, I would say go with the stock one and save a couple hundered bucks.

Carb.
I've used Holley and Edelbrock. In my opinion Edelbrocks are more reliable and require less tuning and tweaking. I have a 600 cfm Edelbrock on my 73 390 and I love it. I've had several Holleys and I was constantly adjusting them. But I know some guys would die before giving up their Holley carb. So it is up to you.

That's my 2 cents worth.

 

I forgot to mention the engine size. It is a 351M.

 

David save your money, I doubt that you can tell any difference.
John

66 F100s
In the still cool hours of the night, you can hear chevys rusting away.

 

I wouldn't say that I would die before giving up my holley but I have run A couple and have come to this. I had a model 1850 single feed and was always screwing with it. I switched to a dual feed 650 double pumper and was quite pleased with it. My opinion is that dual feed holley's cooperate a little better. Holley has way more adjustments such as fuel/air mixture, floats, accelerator pumps, ect.. and also can have internal parts changed and modified such as jets. This makes tuning for hardcore performance more precise than the Edelbrock which is basically a slap on, adjust the two screws and away you go. I have nothing against their carbs. I had a friend put one on his 76 f-250's stock 390 to replace the tired old stock holley, and for his application it suited him just fine. Holley is also a fairly easy carb to rebuild compared to an edelbrock which someone told me is based on a quadrajet design. Although if you are a hardcore and have lots of money to donate to a serious street machine, Barry Grant carbs stand pretty tall. I beleive the reason for the price and reliability that comes with carbs is because they are individually hand made and not on an assembly line or automated manufactured. Although BG does make a carb called the Street demon which is priced about 100 bucks more than the same model holley (compared to double the price.) I was thinking about trying one of these out for myself just to see if they really are what they claim they are. That is if my 650 fails me. I'm not telling you whats better or what to buy but trying to give you a refrence of carbs from what information I have been given. Although John might have the best advice unless you plan on building your engine for more performance. Just my 78 cents.

 

Guys one of my biggest disappointments was adding a 4 barell to my 352. I think the FE is a heck of an engine, but a 2 barell can deliver all the gas needed, to a stock engine.

John

66 F100s
In the still cool hours of the night, you can hear chevys rusting away.

 

David, about three months ago, I did what you are thinking about. 1978 351m 4x4. I put on a Holley 600cfm with an Edelbrock Streetmaster intake. I bought the intake used for $60. After I put it on, I found out the streetmaster is a single plane intake for higher rpms. I would have to recomend not using a Streetmaster. I am keeping my eyes open for a Performer 400, as it is a dual plane torker intake. I have a very mild cam, one up from stock. I ripped off all of the vacuume crap on the engine also. I put on some cheap Dynomax headers and some Purple Hornies glass pack mufflers. I already had the Holley 600 in the garage. I only put about $200 into this project. I highly recomend doing this to your truck. I have twice the power that I used to, and now you can hear it too. It makes driving my truck fun again. By the way, I was getting 10 mpg, now I am getting 10.5mpg. Good Luck!

 

BB you say you spent $200.00 to get 1/2 mpg increase. How long do you think it will take to recover the outlay?

I'm glad you found all that reserve hidden power.

John

66 F100s
In the still cool hours of the night, you can hear chevys rusting away.

 

I am also thinking of this switch. I have some questions, any help would be great.
As far as a manifold I was thinking used, I am not sure; did they ever make a stock 4v intake for the 351m or is aftermarket the only way to get a 4v intake?
Also I will go with the new style holley, (I have had very good luck with it on my cougar with 289)
I'm thinking 600cfm vac. but would a 650cfm dbl.pumper over carb. a stock 351m?

Thanks in advance,
Brad

 

I couldn't swear to it but I think my Dad's 78 Lincoln MK 5 w/ 400 in it has a 4barrel. The 400 intake should interchange with the 351M since they are the same engine family.
BBT

 

Jowilker,
With my two twenty gallon tanks, I can recoup my $200.00 investment after only seventy one fill ups. Sounds real tempting now doesn't it? Are you sure we can't change your mind about four barrels and intakes?

 

Depending on your driving style, you may not see much of a power advantage. The back two barrels will only kick in when you put your foot in it. The front two barrels, I believe, are actually smaller than the two barrel carbs. Anyway, the 4 bbl looks nice and sounds great when you have your foot down, but you can also see your gas mileage go down hill. In fact, I'm surprised that the one post stated he got better mileage. Once again, that's driving style. You should be able to get added HP and some torque with the 4 bbl though, especially between 1000 and 5000 rpms.

Also, typically, the intake ports in the heads are smaller than the factory 4 bbls, so you will not get the full response that the larger ported heads will give. You can re-capture some or most of that loss by porting, polishing, and matching the intake with the head.

Also, it would help if you opened up the exhaust with headers, high flow muffler, and larger exhaust pipes. Once again, you can overcome some of the restrictive stock components by porting the exhaust chambers and opening them up a little.

'82 F150 w/351W (orig 300 I6)
Slik

 

blue, I got compairison trucks 2 66 F100s. I made my first 2 to 4 barell change 20 years ago, didn't see anything there at all, thought the carb was at fault. Now back to today my red 66 has a tired 352 with a big ol hammer inside slapping the hell out of a wrist pin. It has a 2 barrel, Cruse-O-matic and 3.00 rears. My blue 66 has a fresh 352, with an Edlebrock performer kit, cam, intake, & carb, headers, elec. ign. C6, & 2.75 rears, you know a real goody package.

Don't get me wrong the fresh setup is sweet, but I can park that one and climb into the old beater, and I'm here to say it aint bad. If you had them on tracks with meters and clocks, I'm sure olblue would win out, but the ole beater would be there looking.

In short, I have been there, & done that, and just aint convinced that headers and 4 barells are worth the money, time, and energy, on them big ol truck motors. [img]/dcforum/Images/happy.gif[/img] IMHO


John

66 F100s
In the still cool hours of the night, you can hear chevys rusting away.

 

How many miles are on the engine? If it's more than 85k, you stand a slight chance of turning that motor into an oil burner. The rings are seated based on certain forces in the motor. I saw a lot of guys in high school hop up their parents' high milage hand me down cars with bolt-on parts, and a few started smoking within a month or so. It's the combination of different driving habits as well as more power out of a tired motor.

Also, you won't get full advantage of that carb and manifold unless you change the cam and exhaust system too. Don't go overboard. It's more important to have a well matched setup.

If you DO go ahead with this:

1. The carb should be NO more than 600 CFM. Have it jetted for your motor.

2. Go with a dual plane manifold.

3. Don't expect much.

I hope this helps.

-Jim

'76 F-250 4X4
<a href="/pictorial/big/1976_f250_2.html">/pictorial/big/1976_f250_2.html</a>

 

I've got a 79 F150 4x4, 400 c6 3.50 gears. I have installed comp cams 268 magnum, edlebrock performer 400 intake, edlebrock 1406 600 cfm carb, mildon timing set set at 0 degrees, Three angle valve job,milled heads down .015 headers, running mobil 1 5-30. I get 11.5mpg on the highway at 75. 10 mpg all around driving. 9.5 pulling my 1700lb boat. I can also run on regular unleaded if I'm not towing

I drag raced my wife (1998 f150 5.4 triton)
I was pulling a 700lb trailer and she could barely pass me. My truck also weights in at 5200 lbs.

This set up has made me very pleased.