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carb suggestions anyone?

554 Views 15 Replies 6 Participants Last post by  z50k2
I'm wondering if anyone can give me a suggestion for a good carb. to put on a 1976 cj-5 with the 304. I am also wondering what I should be getting for approximate gas mileage with this truck running 31x10.5 tires, headers and no lift. Any help would be appreciated..Thanks!


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If you have the stock 2bbl intake then the stock carb when properly tuined works well, as long as the throttle shaft bores dont leak

a little more ooomph can be had by bolting on a 2bbl Holley 2300 series of the 390 CFM persuasion...
the Holley is about $200 new ( I think, its been a while since i bought mine)
find a used one off of a Ford truck, mercruiser FORD V8s used them also..

NW Arkansas
Thanks for the input OzarkJeep!

Don't have any carb suggestions but from all I have heard and from my own experience the most you'll like get for mpg out of a 304 is about 15 mpg. I know there are probably some exceptions but for the most part anywhere from 9-13 is the norm. I'm lucky to get 10.5-11 out of my '77 CJ-7 w/31x10.50's, TH400 and full-time Quadratrac transfer case. I was told that the design of the engine block is just not fuel efficient. I have tuned/tweaked mine for over a year now and 12 is the best I've squeezed out of it and that was only once. Good luck,

/wwwthreads_images/icons/smile.gif Fratt.....don't forget to "tune" the tires. It is VITALLY important to "size" the tires to the inth degree. We have a little fixture that stands on the concrete and has an adjustable pecker to set to just slide over the top edge of the metal rims. We check it after driving to warm up the tires, and on good concrete....adjusting the air pressure for PERFECT sizing. If you don't do that, the QT slurps up HP when the clutches bind-slip-bind-slip well, you get the idea. On our SNOJEEP, we disabled the clutch action to get it totally "open center" for tricky snow driving like our 242 case in the '97 ZJ, which is superior in snow. We have an altitude-compensated 2150 Motorcraft carb, and have NO IDEA what our CJ gets since it is still in pieces! We are shooting for the moon though, sweeping out all the corners for fuel mileage./wwwthreads_images/icons/wink.gif

I never believe any statistics unless my moonguys /wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/wink.gif made 'em up themselves.
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My old man just upgraded his early 70's bronco intake/carb. It had a two barrel, possibly a Holley, will check if you want me to.
I think he's going to throw it away, needs rebuilding but it ran good as a daily driver. Let me know if you want me to check in to it?

Big Ed
'88 YJ, 4" susp, 3" body, 33's, 283 Chevy V8, TH350, 4.11's, D30, D35c
Post deleted by jeepgoddess
ok.. boys. i dont want to hear crap about gas milage.. i am running a 401, witha holley 500 2 barrel.. am lucky to see double digits.. if you are that worried about gas milage.. stay with the stock carb.. if you want to have some fun.. then thro on a big holley.. 500 or up.. my friend is running a 600 on his 304 but he also has a 292 cam.. and so forth.. i would go with a 500.. but that is me.. and i always say.. (you will just have to look at jeepgods profile to figure that out)..
the jeepgod.. on his womans puter..

Jeepgod's girl... .
500 is about right for your 401, WAY too much carb for a 304, Im running a Holley 2bbl 500 CFM on a stock 360 and its pretty thirsty...

the Guy with teh freebie carb from a Ford truck mught have a great deal if its a Holley carb, Id bet its the motorcraft 2 bbl though.. they are pretty common/cheap used


NW Arkansas
Too much? i never heard such a thing.. lol.. that 500 came from my 258 i will have you know.. and that was just right for her.. it depends on what you want that 304 to do.. and what if anything you plan to do with it. always go big.. leaves room for improvement.

Jeepgod's girl... .
Assuming you could even buy/build a 258 bottom end to handle it, a super fire breathing 258 would have to turn about 10,000 RPM to ever fully utilize 500 CFM

a 401 at 5000 only uses about 550 cfm, didnt we go through this a few weeks ago?

NW Arkansas
Yes we did just go through this last week.
What didn't get mentioned,
1. Like Tex said, most people don't have a clue what the final drive is on their vehicle, but complain about no power, and bad fuel milage anyway.
2. On large engines, like 300 CID and up, I usually recommend a four barrel carburetor.
Trying to keep vacuum up and Venturi/ port velocities up at low speed with a huge two barrel throttle body hanging open is a real pain. Just not enough air flow control.

A correctly tuned vacuum secondary Holley will give better throttle response, better drivability, higher vacuum, and if you keep your foot out of it, better fuel milage.
(...I have never been able to keep my foot out of it...)

(That's why all of the 300 CID, two barrel, six cylinders got less fuel milage than the 302 CID, V-8's with a four barrel)

Just an observation...

When a fool and a wise man argue, Onlookers can't tell the difference...
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when I went through the carb/intake selection process, I didnt get your advice TeamRush ( it was several years ago)

but the general Consensus ( then at least) was the 2bbl gave a little better bottom end than a progressive 4bbl, but Ive never understood that since the primaries would be smaller in the 4bbl?

all I can say it runs VERY VERY good, Immediatly after bolting on the 500CFM it made the autolite 2100 feel like it had about 4 positions, idle/ wide open/ and 2 spots non-evenly spaced in between, and the top end was way more noticable power.

Keep in mind It was pushing through an automatic tranny then, im wondering now if I could benefit from a small 4bbl since Im going to a 4 speed stick in the latest application...

NW Arkansas
I really don't have a clear answer for that one.
I know what the normal manufacturers usage guides say, and I know about the experiences we have had with tow vehicles, but I really don't have a lot of experience with customizing Jeeps.
Mine has just set in the drive way for years untouched. It had a small block ford, that was scrapped, in it when I got it, and we put a small block chevy/ TH-400/ QT back in from a junkyard donor. I was involved in a project at the time, and the shop guys did the install, and I haven't really looked at it from that point on.
I do have been getting some ideas now...... You guys are full of them.....

Check the final drive ratio. If you don't know how, the easiest way is to measure around your tires. The three things you will need to know:
X amount of inches around your tire
Y rear gear ratio
Z Transmission drive ratios, especially the high gear. (1:1 in most 4 speeds)
Can't find my formula book...... Damn. It must be at the shop.
I'll get back to you on the formula...
Anyway, if you know the final drive ratio, you can make much better informed decisions on everything about your power train.
Match Carb, Cam, Intake, Exhaust, Gear Ratios, Wheel & Tire Size, Ect,

If you aren't going to rev a 300 CID engine more than say, 3,500 RPM ever, then a little 350 to 400 CFM carb would be just perfect. And Holley makes several that 2 and 4 barrel carbs that size.

Most people don't know that the late 60's and very early 70's 350 CID neck snappers only had 410 to 530 CFM carbs.
Even the big block chevys in the first A bodies only had a 530 CFM, and that was to feed a 427 CID engine!
The biggest carb chevy put out on normal production cars was 780 CFM, and that was what NASCAR used for years.
(I know about the LS-7 and LS-8 engines, and they weren't normal production, neither were Yenko or like cars)

I have a really nice selection of HUGE carbs (only used for a few hours) that people bought and couldn't make work.
I can't keep any good used 350 to 650 carbs here. 750 & 780 CFM carbs seem to be popular again also.
I saw a guy last summer that trailered a show car in here, had a RV style torque cam (exactly what a show & go car should have) and two Holley Dominators on a tunnel ram bolted to it! Seems the chrome shop plated shut all of the passages in the venturi body and metering blocks... I think the float bowls & fuel lines can be salvaged, and the tunnel ram is nice.
Anybody want to buy a small block chevy tunnel ram with two 1150 dominators bolted to it? I'll give you his phone number....
(I have to say, that polished tunnel ram and chrome plated carbs really look good setting on his poker table in the garage! Real impressive! Looks like the table is going 200 miles an hour!)

When a fool and a wise man argue, Onlookers can't tell the difference...
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yeah, I know all about the final drive ratios!!

my 3.54 gears, will soon be dumped for 4.09s to compensate for 33 inch tires, Ill drive the CJ everyday when the weather is nice, well rotate between it and my MGB, and also take it rhough lots of trails, rocks and rivers around here everychance I get, so im really trying to make too specific of a vehicle for 2 really wildy different uses..

Im Hoping hte 33 inch tires will be enough in conjuntion with 4.09s to keep the 360 in its narrow little power band..

then Ill rely on the T18 granny first for fun in the woods..

Ive got an edlebrock 4bbl manifold, and carb available to me, I might try it out and see how it works out!!

thanks for the help!

NW Arkansas
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Goddess I am with you...Although I am new to this board and have not had the time to read a lot of the other messages, I believe a 401 can take up to a 700cfm carb. I just built a 401 and it has a 600 cfm Holley. My 304 was tired and needed a rest. It did however, perform well with the stock 2bbl and did not skip a beat at any RPM..I also agree with you about fuel economy. Jeeps were made for a lot of things,and one was not for fuel economy,especially due to it's streamline shape..ha ha...seeya...

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