Lets talk headers

[Jroch]

Gotta be careful trying to swap GEN II and GEN III heads - different deck heights, center intake bolt location (can be machined to work) and bolt dia. among other things - GEN II 7/16 bolts and GEN III 1/2 bolts... If you decide to use a GEN III head on a GEN II block - you will need to either have special gaskets made, machine work on the mating surfaces or a combination of both.

I'd still like to know what the casting numbers are on the block and heads - you may be luck and have one of those weird engines from 69 that were really a 360!

I can only hope CJ, I think I located the casting number? Located on the back of the motor top just before bell housing. to me it looks to be 3179063 I will post the picture of it also because the 9 looks like it could be an 8



I ran the Number on the net and got AMC 343 Engine casting number. figures yet another sign god hates me, gives me the love for the Jeeps and then blesses me with the purchase of one that has to be difficult

 

[Petescj]

How hard is it to get the correct exhaust manifolds? Is that the problem that you cant find any readily available?

 

[LongHorn]

How hard is it to get the correct exhaust manifolds? Is that the problem that you cant find any readily available?

2nd Gen AMC engines were never a factory option on a CJ.

 

[LongHorn]

2nd Gen AMC engines were never a factory option on a CJ.

The 1st factory V8 CJ came with a 3rd Gen AMC 304 V8 that came with Dog leg exhaust ports.

 

[Petescj]

I know that , Im just saying why not get replacements for the bad ones he has now. They fit , they just leak.

2nd Gen AMC engines were never a factory option on a CJ.

 

[Jroch]

I know that , Im just saying why not get replacements for the bad ones he has now. They fit , they just leak.

I haven't been able to locate factory one's as of yet, and the thought is if I am going to coin up I might as well try to enhance the performance. I went to an AMC forum and asked the same question and I got this response "Your manifolds is for the 360- 401 engine. (dogleg)
If the manifolds do not leak, keep them! They are as good as headers up to 6000rpm." So with that response I am wondering if I can use 360 headers?? I asked him to clarify his response but haven't heard anything back yet. Although that Forum is not about jeeps there seems to be a lot of good information on the motor a lot of guys are dragging the 343, maybe one of them will know some good tricks to get around my issue. If I can use 360 headers that opens up several options, it's just very frustrating

As always thanks for your help and insite

 

[Petescj]

You might be able to find someone who has a set here.

AMC ROCKS! :: Index

 

[LongHorn]

I haven't been able to locate factory one's as of yet, and the thought is if I am going to coin up I might as well try to enhance the performance. I went to an AMC forum and asked the same question and I got this response "Your manifolds is for the 360- 401 engine. (dogleg)
If the manifolds do not leak, keep them! They are as good as headers up to 6000rpm." So with that response I am wondering if I can use 360 headers?? I asked him to clarify his response but haven't heard anything back yet. Although that Forum is not about jeeps there seems to be a lot of good information on the motor a lot of guys are dragging the 343, maybe one of them will know some good tricks to get around my issue. If I can use 360 headers that opens up several options, it's just very frustrating

As always thanks for your help and insite

I guess, if it was me. I would pull the easiest one off & look at the ports to make sure.

 

[CJ]

Let's start again...

From the casting # you posted - you have a 343 square port 69 engine. You either have to get a set of factory manifolds or buy a set of early AMC GEN II headers because your going to have to cut and weld them.

The People at the AMC forum just took a quick glance at your question or it was not phrased properly - A 343 CANNOT USE HEADERS FROM A GEN III! Well maybe they can but they will leak and give all kinds of problems... Dogleg port are completely different from rectangular... )

The AMC forum saw CJ and knew that all V8 CJ's are from 72 and on so they talked about the dogleg heads..

Just pull a manifold and see if you have rectangular ports (I'm sure you do)? If so - you either have to jack a header or use manifolds...

You can put a GEN II head on and do all the machining / gasket work or not - it's up to you...

Sorry - but that is the way it is...

 

[Jroch]

Let's start again...

From the casting # you posted - you have a 343 square port 69 engine. You either have to get a set of factory manifolds or but a set of early AMC GEN II headers because your going to have to cut and weld them.

The People at the AMC forum just took a quick glance at your question or it was not phrased properly - A 343 CANNOT USE HEADERS FROM A GEN III! Well maybe they can but they will leak and give all kinds of problems...

The AMC forum saw CJ and knew that all V8 CJ's are from 72 and on so they talked about the dogleg heads..


Just pull a manifold and see if you have rectangular ports (I'm sure you do)? If so - you either have to jack a header or use manifolds...

You can put a GEN II head on and do all the machining / gasket work or not - it's up to you...

Sorry - but that is the way it is...

CJ you sound frustrated with me "sorry" When I posted the question over there I also posted the pics of the manifolds and I got few other responses This one was very interesting to me
"343 have rectangular exhaust ports. AMC 304 /360/401 have dog leg exhaust ports. You can use the dog leg exhaust on either. It appears you already have the AMC 304 /360/401 manifolds now. You can buy JEEP headers for a AMC 304 /360/401 and they will seal on the 343 heads, just like the manifolds do now."
With the information he provided and the statement "I have AMC 304 /360/401 manifolds on there now" YOU KNOW "slap to the forehead" I checked the block casting #'s maybe I need to check the head numbers it's possible someone switched heads along the road with this motor??

 

[CJ]

Hey JR! Not frustrated at all!

I just don't want you to get some thing that may or may not work...

Yes the DL headers will work with the rectangular port ones but have been known to leak... Just use a good thick header gasket (BTW - Did you know I ran an AMX 390 in my CJ for many years? What a pain in the !)

The guys at AMC forums know there ! LOL I go there every day..

I guess that I'm trying to say is that ... What do you want to do?

Do you want headers or replacement manifolds?

I want to get your CJ jamin and grinding! Heck - that is why I created this site! LMAO!

 

[Jroch]

Hey JR! Not frustrated at all!

I just don't want you to get some thing that may or may not work...

Yes the DL headers will work with the rectangular port ones but have been known to leak... Just use a good thick header gasket (BTW - Did you know I ran an AMX 390 in my CJ for many years? What a pain in the !)

The guys at AMC forums know there ! LOL I go there every day..

I guess that I'm trying to say is that ... What do you want to do?

Do you want headers or replacement manifolds?

I want to get your CJ jamin and grinding! Heck - that is why I created this site! LMAO!

Thanks CJ!

At this time my goal is to get the Jeep quieted down some, and the thought was that if I am going to have to invest I might as well try to get a little performance out of it. But from what I am hearing the manifolds I have are good up to 6000rpm and can handle a mild cam, which from what I was told from the PO it has?, I can here the cam at low RPM's so I believe it's in there. Although I think headers would be cool to have in there it sounds like they would be a waste of funds. So I think what I might do is bring the Jeep over to the local exhaust shop and see what they can do?
Of course your comments about the 390 makes me wonder what I have gotten myself into with this motor, but thats a another topic for when/if I hurt the current motor and need to look at replacing or rebuilding LOL.

As always the advice and input from you and everyone else if greatly appreciated!!!

Thanks

Justin

 

[CJ]

What a pain huh?

LOL

You know... Before we get into a bunch of - Why not take LongHorns and my advice and pull a manifold....

We can talk about the different possibilities for ever - but ....

 

[Petescj]