4.2 carb help please - JeepForum.com

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post #1 of 16 Old 06-30-2013, 05:42 PM Thread Starter
supersport126
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Started to bolt on my "weber" 32/36 carb today and was surprised when it didn't fit. New carb gasket fits manifold but base of carb is larger. What am I missing here, an adapter? Weber was pulled off my 4cy via adapter

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post #2 of 16 Old 06-30-2013, 06:43 PM
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will your carb, with adapter, fit over the studs?

The gaskets that came with the Weber conversions did not fit at all well, so the scissors came out.

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post #3 of 16 Old 06-30-2013, 06:51 PM Thread Starter
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No, the base of carb is bigger bolt holes and all
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post #4 of 16 Old 06-30-2013, 07:02 PM
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Sorry, I was confused by your reference to having pulled it off a 2.5 "via adapter".

The Weber has a different bolt pattern and size from a Carter BBD and it will not fit without an adapter. There is an adapater available from Redline.

What are you going to use for an air filter? There is an adapter to refit the TAC on to the Weber, if you still have it.

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1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
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post #5 of 16 Old 06-30-2013, 07:07 PM Thread Starter
supersport126
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Adapter as in one barrel to two barrel. So would I still need a adapter if I wanted to bolt on a Holley 390 or motor craft 2100? Reason I ask I'd my 32/36 is gonna be too small for my build in the end, I was just bolt it on to get it running
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post #6 of 16 Old 07-01-2013, 02:19 AM
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Yes, you will still need the adapter, they are about $20. A Stromberg will fit but then you are off into a new set of issues.

The adapter for the 32/36 will also allow the 38 to fit in place of the Carter BBD.

What build are you doing that a 32/36 is too small?

BagusJeep lives in Bali.

1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
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post #7 of 16 Old 07-01-2013, 06:12 AM Thread Starter
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Check my threads
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post #8 of 16 Old 07-01-2013, 10:48 AM
uptillnow
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This is what the adaptor from a Carter BBD to a Weber looks like.
Bottom plate mounts to the Jeep manifold, top plate is a universal Weber bolt pattern.
I use and HIGHLEY recommend the Weber 38-DGES for your build.
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post #9 of 16 Old 07-01-2013, 11:33 AM Thread Starter
supersport126
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Does Redline sell "real" webers? Reason I ask is I bought my 32/36 new only to find out its a knock off
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post #10 of 16 Old 07-01-2013, 11:39 AM
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Quote:
Originally Posted by supersport126 View Post
Does Redline sell "real" webers? Reason I ask is I bought my 32/36 new only to find out its a knock off
Yes, REDLINE sells the Weber's made in Spain, with the Weber logo cast into the body, with made in Spain stamped on it.
Not the ones with the red W sticker, claiming it is a Weber.

REDLINE sells through distributors like Triangle A/S 800-572-3681, or,
Carburetors Unlimited 800-994-2272

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post #11 of 16 Old 07-01-2013, 11:47 AM Thread Starter
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Yea, I got the sticker weber lol. Thanks for the info
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post #12 of 16 Old 07-01-2013, 04:25 PM Thread Starter
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ok, so I ordered the kit needed, thank you for the help but to dig in a little deeper...

I found a calculation on CFM's vs. displacment: Max RPM x CID / 3456 = CFM

So with that said my 258 block bored over .30 would be around 262 CID and I think 4500 MAX RPM is about right So...262 x 4500 / 3456 = CFM rating of 341.

A Weber 38 is rated at 390 CFM, A Holley 390 is well 390 and the Truck Avenger 470 CFM. All too big according to a carb shop around here. They say to try and keep it under a bit. My 32/36 weber is actually rated at 325 which sounds like it would be perfect.

Any thoughts on this?
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post #13 of 16 Old 07-02-2013, 11:32 AM
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Quote:
Originally Posted by supersport126 View Post
ok, so I ordered the kit needed, thank you for the help but to dig in a little deeper...

I found a calculation on CFM's vs. displacment: Max RPM x CID / 3456 = CFM

So with that said my 258 block bored over .30 would be around 262 CID and I think 4500 MAX RPM is about right So...262 x 4500 / 3456 = CFM rating of 341.

A Weber 38 is rated at 390 CFM, A Holley 390 is well 390 and the Truck Avenger 470 CFM. All too big according to a carb shop around here. They say to try and keep it under a bit. My 32/36 weber is actually rated at 325 which sounds like it would be perfect.

Any thoughts on this?
Yes...
I do have some thoughts....
This CFM calculator is flawed.
The Jeep 258/4.2 engine came with a Carter BBD, with two 1 1/2" throttle plates. Your CFM calculator would claim this too big for your engine as well, yet Jeep engineers put it on many many Jeeps as original equipment.
The Weber 38-DGES is virtually the exact same size as the original Carter BBD carburetor with two throttle plates at 38mm each.
The 32/36 DGEV uses only one throttle plate (32mm) until 1/2 throttle position at which time the second barrel (36mm) STARTS to open. This is considered an ECONOMY carburetor and will work but take allot of tuning to make it drivable.

I use and HIGHLEY recommend the 38-DGES for stock, standard driving. Works GREAT and lasts a long time.

UPTILLNOW
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post #14 of 16 Old 07-02-2013, 12:17 PM Thread Starter
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Very good information I'm taking in here. At the minimum I will purchase a new 38, already have the adapter on order. I have another tread going and a 4 barrel carb is being suggested. I was looking last night and seen some 2-4 barrel adapters. Any thoughts on that?
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post #15 of 16 Old 07-02-2013, 12:24 PM
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Quote:
Originally Posted by supersport126 View Post
Very good information I'm taking in here. At the minimum I will purchase a new 38, already have the adapter on order. I have another tread going and a 4 barrel carb is being suggested. I was looking last night and seen some 2-4 barrel adapters. Any thoughts on that?
The "CFM" for a two barrel is calculated differently than a four barrel.
It is difficult to compare these "CFM" calculations and with that then match a carburetor that best suits your needs and engine build.

A whole bunch of people on this CJ forum have built many combinations. Some have worked and some have worked out better.

Good Luck
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