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View Full Version : 258 Intake/Exhaust Manifolds.....


76'kee
11-16-2003, 11:36 AM
My OEM exhaust manifold's falling apart and I'm looking for a replacement. A buddy of mine gave me a complete set-up (intake/exhaust/carb), my question is about interchangability. My 258 came with a 1bbl carb, the new stuff I have has a 2bbl and what appears to be a different bolt pattern for attaching everything to the head. I have no idea what year his came off of, are there differences in designs......? I'd have to guess upgrading to a 2bbl would bring performance enhancement with it. Can I use it, or adapt it, or do I have to continue the search for a compatible exhaust manifold?

Zorm
11-16-2003, 11:42 AM
what year is you FSJ? are you sure you have the 258 or the engine that came before it? 232 or something like that.
As far as different bolt patterns for the intakes, how are they different?
Is your old intake/exhaust connected under the carb??

porkchop
11-16-2003, 11:47 AM
I am not sure why they would be a different bolt pattern. His must be from a 232 or a 230. The 258 all had the same pattern. Do you have any pics? You need to drive that chero out to the house. When you going to stop by?

Zorm
11-16-2003, 11:51 AM
I was woundering the same thing porkchop, I was under the impression that all 258s even the ones put in Wranglers up till 88/89 were all the same.

76'kee
11-16-2003, 12:21 PM
No pic's, no digi cam.....
I'm sure I have a 258, I ran the casting numbers when the Jeep was given to me just in case.
My current intake has more mounting bolt holes than the stuff I got from my buddy. He say's they're off a 258 he had in his CJ, I can't validate it though.
My old set-up connected under the carb, that's where my problem's at. The stud's pointing upward's sheared off, so I drilled them out and tried to tap, but the iron's so old it crumbled under the pressure. I put in a new gasket, used some Thermoweld in the old stud holes and tightened them down best I could, but I have a terrible vacuum/exhaust leak that's driving me nuts..... I like the idea of a 2bbl carb upgrade if I can get this to mount up and work properly. If I remember correctly - I've had a few rum & Coke's tonight - the current stuff on the Jeep share a common bolting point with the intake/exhaust to draw them tight against the head. The newer stuff doesn't have that in common.
PC - I've been working the past few weekends, and will again this coming Sunday. I hear your BBQ rib's are a national icon and something to experience before death. I need to catch up to you and show off the free rig. My kid's into the 715's and bugging me to check yours out, especially after I showed him your rebuilding photo's.

[ November 16, 2003, 06:22 PM: Message edited by: 76'kee ]

427CometGuy
11-16-2003, 12:23 PM
As the proud owner of a 76 vintage 258 with an 83 vintage engine, I can assure you bolt patterns changed around 1980. Pre-80 will not bolt up to post-80, and vice-versa. Intake bolt and exhaust bolt patterns are not the same.
My 76 came stock with the 1 bbl Carter crapulator, and my 83 engine came stock with the 2 bbl Carter crapulator.

Just TRY to find upgrade exhaust/intake parts for a 76 258! Difficult.

Good luck with the parts!

Dave

76'kee
11-16-2003, 12:39 PM
I was running through the internet trying to figure this out and found something referencing a difference between pre and post 1980. Thanks 427, I'll get back into search mode and see what I can come up with for parts.....

Stuka
11-16-2003, 12:45 PM
79 and older 258's are different then 80 and newer 258's. The head being one part that has quite a few changes. Internals are the same though.

Zorm
11-16-2003, 02:44 PM
I got two 258 heads if you need them one takes 1/2 head bolts and the other takes the smaller size, can't remember the size just now.

porkchop
11-16-2003, 09:03 PM
Cool, this weekend I am going to head up to Raleigh. Just let me know when you want to swing by. I am plan a party and WOT at the house for the 6th. Hopefully you can make it then.

76'kee
11-16-2003, 10:56 PM
Thanks for the offer on the heads, I'll pass for now in the hopes of finding an exhaust manifold.... which is turning into the proverbial needle in the haystack....

PC - Duty schedule permitting, I'll certainly try to make it!

tgreese
11-17-2003, 12:55 AM
Originally posted by 427CometGuy:
As the proud owner of a 76 vintage 258 with an 83 vintage engine, I can assure you bolt patterns changed around 1980. Pre-80 will not bolt up to post-80, and vice-versa. Intake bolt and exhaust bolt patterns are not the same.
My 76 came stock with the 1 bbl Carter crapulator, and my 83 engine came stock with the 2 bbl Carter crapulator.

Just TRY to find upgrade exhaust/intake parts for a 76 258! Difficult.

Good luck with the parts!

DaveDave may be referring to something else, but as far as I know, the cylinder head patterns from the 1960(?) 199cid to the 1990 258cid are all the same.

AFAIK there are three main intake manifolds that will fit on that block: early 1V (Carter YF, iron), early 2V (Carter BBD, iron) and the late 2V (Carter BBD, aluminum). Don't know about the early 1V, but the early and late 2V exhaust manifolds have the same outlet location.

The late 2V manifolds started in 1980 or 81 and accompanied an overall lightening of the 258 engine. Differences between early and late include:
1) Early manifold has four bolts between the intake and exhaust, and has an exhaust diverter flap that heats the intake manifold for cold weather starts. Late manifolds use an electric heater in the underside of the intake manifold.
2) Both early and late bolt on as a unit. The EGR gas path is internal in the early manifolds, but uses an external tube on the later manifold.
3) The accelerator cable mounting bracket on the early manifold mounts to the intake-to-exhaust bolts. On the later manifold, the bracket mounts to bosses cast in to the intake manifold (not entirely sure it doesn't bolt on somewhere else too).
4) The mounting holes on the front of the exhaust and intake manifolds are the same, but different brackets are used becasue the late exhaust manifold has a more streamlined shape.
5) The late manifolds weigh about half as much as the early manifolds.

I mounted a set of manifolds on my '77 truck that were removed from an '85 CJ-5. Here's the old (old style) manifold:

http://www.nmr.mgh.harvard.edu/~reese/oldmanifold.jpg

Here's the new-style manifold in its place:

http://www.nmr.mgh.harvard.edu/~reese/underhood.jpg
hth :cool: Tim

[ November 17, 2003, 07:01 AM: Message edited by: tgreese ]

Brule_Cherokee
11-17-2003, 01:10 AM
Tim, I have another interesting manifold, it's a 258 2V manifold that looks just like the first picture you posted (old style) except the carburetor mounts exactly opposite of the one pictured. In other words whereas the MC2100 you show faces toward the front of the engine, on mine it faces the left fender. I've never seen another manifold like this and nobody can tell me what it's from. The carb works just fine mounted like this though. Makes linkage a cinch to connect too. Here's a {very} crude image of what Im talking about showing cylinders 1-6 and the alignment of the carb in relation to the engine.

[0 0 0 0 0 0]
-----oo-----

tgreese
11-17-2003, 01:12 AM
BTW neither of these manifolds has many bolt holes - most of the bolts are bridged between the intake and exhaust using a large hardened cup washer. I was lucky that a kind soul at a wrecking yard gave me a few extras that I needed to install this new manifold.

tgreese
11-17-2003, 01:34 AM
Originally posted by Brule_Cherokee:
Tim, I have another interesting manifold, it's a 258 2V manifold that looks just like the first picture you posted (old style) except the carburetor mounts exactly opposite of the one pictured. In other words whereas the MC2100 you show faces toward the front of the engine, on mine it faces the left fender. I've never seen another manifold like this and nobody can tell me what it's from. The carb works just fine mounted like this though. Makes linkage a cinch to connect too. Here's a {very} crude image of what Im talking about showing cylinders 1-6 and the alignment of the carb in relation to the engine.

[0 0 0 0 0 0]
-----oo-----Huh. I'd guess it's from a car, but that's really a WAG. Don't know that much about the BBD 2V carb, but usually the placement of the float pivot (left-right v. front-back) makes a big difference when climbing hills.

tgreese
11-17-2003, 02:52 AM
Originally posted by 76'kee:
My OEM exhaust manifold's falling apart and I'm looking for a replacement. A buddy of mine gave me a complete set-up (intake/exhaust/carb), my question is about interchangability. My 258 came with a 1bbl carb, the new stuff I have has a 2bbl and what appears to be a different bolt pattern for attaching everything to the head. I have no idea what year his came off of, are there differences in designs......? I'd have to guess upgrading to a 2bbl would bring performance enhancement with it. Can I use it, or adapt it, or do I have to continue the search for a compatible exhaust manifold?Back to Jacksonville's question - if it's a 2v iron manifold from a AMC Jeep I6 (see the picture), it will bolt on to the cylinder head, no problem. It's the details that could cause trouble.

How much of the 2V setup do you have? If you have the carb, linkage, brackets, air cleaner, throttle cable, EGR valve, etc. then it should be easier. Check the location of the exhaust output vs. your existing manifold, the locations of the threaded holes for the accessory brackets (like power steering), and so forth. The changeover year for SJs to 2V was '77, so if you use the 2V manifold you may need a throttle cable from a '77 SJ in order to reach the new linkage.

If you decide to replace the stock manifold, I'd take the broken manifold off and try to match it to a junk yard manifold. I'm fairly certain that the 2V exhaust manifold will not mate with the 1V intake manifold, but I believe that any AMC 1V I6 exhaust manifold with a carb heater flap will work. Look in Gremlins, Hornets, Jeeps and such of that era. I used a 1V I6 manifold from an AMC car on my '75 Jeep 258 long ago - bolted in perfectly.

hth :cool: Tim

[ November 17, 2003, 08:56 AM: Message edited by: tgreese ]

Brule_Cherokee
11-17-2003, 03:26 AM
Also, if you're looking for a bit of a performance boost and a definite reliability boost over the Carter BBD, go for the MC2100 2 barrel swap (as pictured in Tim's post above). I did this on my CJ and it is miraculous. I went from the Rochester YF 1bbl to an MC2100 and the performance increase was noticeable. The 2100 is very simple to rebuild and mine does very well on inclines. An adapter is required, I can't recall the part number at the moment, but it's a common part that costs around $20. Search on google or any search engine for MC2100 swap and you'll find a load of information.

76'kee
11-17-2003, 12:38 PM
First of all, thank you for all the input here.
Fortunately, the newer set-up is complete, everything from the manifolds to the carb, including linkage, EGR tube, choke and all the gizmo's. It's not identical to the 2nd photo at the mounting bolt holes. My current set-up's like the 1st, except a 1bbl design.
I'll spend some time on Saturday pulling the old and test fitting the newer 2bbl design. I'll have to do some serious searching for a throttle cable if my current one's not compatible. My biggest concern is hooking the exhaust collector to the manifold. The current set-up is a straight bolt up, the newer has an angle, but I think I can work around it all.
I'll let you know how it all goes later this weekend!!!!

[ November 17, 2003, 06:43 PM: Message edited by: 76'kee ]

Cecil14
11-17-2003, 01:49 PM
If your cable won't work I know bj's offroad has some cables, may be able to get what you need from them.

Anthony

tgreese
11-17-2003, 10:54 PM
Re the cable, I think it's available from NAPA. It's listed on the Turner 4WD site too. Shouldn't be hard to locate.