300 intake & Carb question
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300 intake & Carb question
I am going to do the modified intake & carb. modification to my 300 and I can't decide on the combination that would be the better of the two I am considering.
I am looking at a single plane Offie 'C' with a Holley 2-bbl 500 CFM carb vs an Offie dual plane with a Holley 4-bbl 390 CFM carb.
I also plan to do the EFI exhaust manifols with the Walker 'Y' to a turbo muffler and single pipe out rear. (No Cats)
This will be an everyday driver and I need fairly good mileage and want good reliability.
Any thoughts on which is best would be helpfull.
Thanks.
I am looking at a single plane Offie 'C' with a Holley 2-bbl 500 CFM carb vs an Offie dual plane with a Holley 4-bbl 390 CFM carb.
I also plan to do the EFI exhaust manifols with the Walker 'Y' to a turbo muffler and single pipe out rear. (No Cats)
This will be an everyday driver and I need fairly good mileage and want good reliability.
Any thoughts on which is best would be helpfull.
Thanks.
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Joined: Jul 2002
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From: East Freetown, MA
Good start
Are you doing anything with the heads, or cam? If not I would probably even think about using the 350 2BBL Holley, also if not I would reconsider using the stock exhaust manifold it bolts right up to the Offy and makes a much better everyday manifold, especially in the winter, this is cause it heats the intake manifold. I have fooled around alot with these engines, but just my 2 cents. Single out on the rear is your best bet, these engines don't need that much exhaust they run better off the back pressure.
Good Luck,
Chris
Good Luck,
Chris
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From: GANS
I'd probably go with the holley 390. You generally get a little better gas mileage with a 4bbl, as long as you keep your foot out of them [all 4 barrels, that is]. I used headers, but I got a clifford intake that had the coolant ports to hook up through your heater hoses. I never had trouble with cold weather (live in Western PA), or with vapor lock in the summer.
I went with an edelbrock 500CFM 4bbl, clifford intake & headers (back in 98 the headers were a lot cheaper), and I got around 16-17mpg (with 3.50 gears, with 2.47s i got 12
)
I went with an edelbrock 500CFM 4bbl, clifford intake & headers (back in 98 the headers were a lot cheaper), and I got around 16-17mpg (with 3.50 gears, with 2.47s i got 12
)
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I am concerned about the cold weather aspects of running. I live in west central Indiana and we do get some short but very cold days most winters.
I was not aware that Clifford made a manifold with heating connections - That appears to be something I need to look into. I had planned to build a air intake bypass box for one of the EFI hedders to help with carb ice up. I think a heated manifold would be easier and most likely better when it's really cold.
I was not aware that Clifford made a manifold with heating connections - That appears to be something I need to look into. I had planned to build a air intake bypass box for one of the EFI hedders to help with carb ice up. I think a heated manifold would be easier and most likely better when it's really cold.
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From: GANS
I don't have the dyno numbers, but it raised my top speed from 85 to 105+, I could haul over a ton @ 80mph without hitting the 4bbl, with 3.50 gears, acceloration was good. My guess was probably about 40HP with all the stuff I did. If I was going to do it again, I'd put a different cam, and shave the heads and deck the block for 10:1 compression for some serious power.
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From: Metamora
bremen242, what ignition setup did you use, DSII, did your truck originally come with the computer controlled carb? If your truck came with the computer, did you keep all of that stuff? I'd like to upgrade my 86 also, but since it is computer controlled (TFI module on distributor, feedback carb) I'm assuming that I would need to replace the ignition system (with DSII) if I replace the carb. Also, what did you do with your emissions systems (EGR) with the Clifford, were you able to retain them?
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From: GANS
I had an '84 with TFI/EEC IV. I ran the computer for about a day until I realized it wouldn't run very good. I had an '82 Bronco I pulled my DSII dizzy&module from. I ditched all the emissions. Fortionately, no one was checking where I lived at the time. If I was to do it with emissions, this is what i would do:
1) make sure your testing stations aren't total a&&&&les about have _all_ emissions equipment. (most all carb'd trucks fall under high emissions by default, so really as long as your truck's mixture is tuned perfectly, you'll pass emissions everytime)
2) I'd modify a Ford 4BBL egr plate and plumb exhaust from a header
3) get a 2-to-1 high flow CATCO cat from Summit (2-2" inputs, one 3" out) and run the headers into that.
1) make sure your testing stations aren't total a&&&&les about have _all_ emissions equipment. (most all carb'd trucks fall under high emissions by default, so really as long as your truck's mixture is tuned perfectly, you'll pass emissions everytime)
2) I'd modify a Ford 4BBL egr plate and plumb exhaust from a header
3) get a 2-to-1 high flow CATCO cat from Summit (2-2" inputs, one 3" out) and run the headers into that.