I love this board! I have the Holley 390/Offenhauser 4 bbl/split headers on my 1984 E150, running with a 3.9l (240 ci). Personally, the whole experiment has been a mistake. Due to the climate that I live in (really cold in the winter), even with running a hot plate under the carb and re-directing it's intake through a pipe to the air around the exhaust manifold ( a cover that I had to make), it takes too long for the carb to warm up. I also had to design a mount for the bracket that holds the throttle cable. As for the idea of using a 2 bbl carb on this intake manifold, you have to purchase a conversion plate and the one(s) that I've tried tend to warp too easily, thus you're dealing with vacuum leaks and back-firing through the carb. As well, because of the size of the intake manifold, I've had to cut parts of the engine cowling (the "doghouse") away in order to accomodate the carburator. THEN there's the problem of getting the air cleaner to mate to the new larger hole of the 4 bbld; once again I had to invent an adapter to fit.

For gas mileage, when it's running properly, I get about 250-275 miles to a tank. At the end of the day, I would say: stick with the factory setup, especially if you live in areas where the winters are a bit harsh.

 

Also, can anyone suggest something to use on the Offenhauser manifold other then the Holley 390? Mine is giving problems which make it sound like it's running too lean. I've tried putting kits into the carb, setting and checking the float level on the primaries and sealing all surfaces (hot plate to manifold, hot plate to carb) to ensure that no vaccuum leaks are causing the backfiring problems through the carb.

 

not to butt in, but if anyone gonn get rid of their 390's or intakes or BOTH give me a PM, id give some cash for them

 

I have a '75 F-250, with a tricked out C6 trans, and 3:31 rear gears. I am running a 78 4.9 with p&p head, over-size valves, mild Isky cam, MSD 6a ignition, Edelbrock 500 carb on an Offy DP manifold, with Hedman headers, zero emisions, and I recently got 15 mpg on a trip.

Currently searching for a Gear Vendor overdrive, and hope to be pushing 20 mph with it installed, hope to.

<a href="http://s659.photobucket.com/albums/uu316/bobbyrogue/?action=view&current=P1010237.jpg" target="_blank"><img src="http://i659.photobucket.com/albums/uu316/bobbyrogue/P1010237.jpg" border="0" alt="Lokar throttle cable"></a>

 

I've owned a number of Fords and it seems to me they tend to be cold-blooded. My current ride is no exception. We don't get as cold here in Spokane as you do in Regina but I plug in a block heater if temps are going to be down near the low 20'sF or less and I plan on driving right away in the am. As far as the backfire goes, definitely check the timing. Carbs get blamed for problems that are 95% something else like ignition and the jets are absolutely the last thing to change when one is down to the fine tuning.

Nice, clean install F-250!

 

I run a water heated carb spacer on mine. Works like a champ, especially if I plug in the water heater a few hours before I drive it. Love that engine. works way better modded. I would never go back to stock.

 

since your truck is an 86 the first thing i would do is the duraspark II ignition upgrade,and get rid of that feed back setup.that would be your main culprit for you bad mpg's,and you will have to do the conversion if you change the intake and carb any ways .

 

I run a mildly modified 2150 on my truck. I used a 4 to2 adapter plate to mate it to my Offy. I also have a stock ford heated carb spacer (thanks Scott!) and I have been getting around 14 mpg with4.10 gears and 36" tires.

My personal experiences with the 390 are that it isn't that good. I have more driveability and impercievebly less power with the motorcraft 2150.

 

scottfreeman - do you have a picture of the water heated spacer? I need something for this winter and that's about all I could use. Was it hand made or something you bought?

 

Message for Ranger GT2; I have a spare water heater space that I could sell you, if you wish. I purchased mine (2 of them) from ebay. Let me know...

 

I finally had a chance to actually check the mileage I'm getting since I changed out my engine. I have a 82 F100 with a 300 six and 4 speed trans and the 4th gear is a O/D. The motor has a 390 cfm holley, offenhauser dual port intake and long tube headers. My son and I drove 160 miles and only used 8.5 gallons. Which is a little over 18.5 MPG. Not bad for an old truck.

I still have a few things to do to try and help increase it. I have a unilite distributor and I have to clean the carb and put new gasketas in it. I also want to try and change the jets to see if it will help any.

I'm hoping to get 20 mpg out of it before I'm done.

 

Looks nice but why did you abandon the 4100 for a Carter?

 

great thread! I've got a 65 f100 w/ a 240. 80 mile round trip to school everyday is not fun with this kind of mileage, so I'm definitely looking for some ways to increase mileage. I have an electric fan I need to hook up, but that's about it and I'm kinda broke, along with the rest of the world. now I was looking at the offy/weber 32/36 2v combo, what's yall's opinion on that setup?

I really should do a rebuild on the engine... it's got either 200000 or 300000 on it and likes to blow oil everywhere...

 

I not sure that I have ever heard of that set up. What type of offy intake are you talking about? The offy C series?

You definetly want to rebuild your engine if it is getting that many miles and it is blowing oil out. Either you have a clogged PCV valve or it is time for the rebuild.

Nice looking truck.

 

The H/W 2v is popular with the small block 6 crowd...170-250 engines. Check out this Forum: FORDSIX PERFORMANCE &bull; View forum - 144-250 "Small Block" Six Performance

The problem with any particular 390 might be internal leaks due to warped metering block. IIRC, a machining operation called "fly cutting" to true up the surfaces is the recommended fix.