Intake/exhaust opinion

[jakeh937]

So first off engine is 74 AMC 232 i6 . Comp cam and springs. More of a woods/mountain jeep. I cleaned up my intake manifold and found that one of the lower bolt hole ears is chipped off. Will that effect clamp pressure and create an intake leak?

I thought about upgrading intake/exhaust but I am unsure what people are running and what seems to be the best bang for the buck for different situations the vehicle will be operating in.

Any suggestions?

Thanks!


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[elwood blues]

Yes, with a broken off ear on your intake, you could be sucking in air causing a lean situation.

Honestly, your options are pretty Limited . Clifford Performance or Offenhauser are your only 2 options for aftermarket 199/AMC 232 i6 /AMC 258 i6 / 4.2l intake manifolds. Both of them go for between $300 and $400.

I replaced the stock 1bbl intake manifold on my AMC 258 i6 / 4.2l with a 2bbl intake from a 1980. I don't remember the exact years, but your '74 should be the same set-up. You could use up to a 1980 intake manifold, the 199/AMC 232 i6 /AMC 258 i6 / 4.2l should all be the same. After 1980 the intake & exhaust manifold's are different and I'm not 100% sure if they'll work on your AMC 232 i6 .

 

[jakeh937]

Yes, with a broken off ear on your intake, you could be sucking in air causing a lean situation.



Honestly, your options are pretty Limited . Clifford Performance or Offenhauser are your only 2 options for aftermarket 199/AMC 232 i6 /AMC 258 i6 / 4.2l intake manifolds. Both of them go for between $300 and $400.



I replaced the stock 1bbl intake manifold on my AMC 258 i6 / 4.2l with a 2bbl intake from a 1980. I don't remember the exact years, but your '74 should be the same set-up. You could use up to a 1980 intake manifold, the 199/AMC 232 i6 /AMC 258 i6 / 4.2l should all be the same. After 1980 the intake & exhaust manifold's are different and I'm not 100% sure if they'll work on your AMC 232 i6 .

That's what I figured, it'd leak. That's interesting. I'm not to sure if stock 74 AMC 232 i6 came with a 1bbl or 2bbl? The one on it was a 2bbl. I have access to a 79 AMC 258 i6 / 4.2l , so those intake/exhaust manifolds should bolt right up?


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[elwood blues]

That's what I figured, it'd leak. That's interesting. I'm not to sure if stock 74 AMC 232 i6 came with a 1bbl or 2bbl? The one on it was a 2bbl. I have access to a 79 AMC 258 i6 / 4.2l , so those intake/exhaust manifolds should bolt right up?

From everything I've read, the only differences between the 199/AMC 232 i6 /AMC 258 i6 / 4.2l was bore and stroke. Some minor external parts stuff, waterpumps,but otherwise the blocks are the same. So, yes, the '79 intake/exhaust manifolds should bolt right up to your '74 block.

Sorry, that was a little wordy to just say yes

 

[jakeh937]

From everything I've read, the only differences between the 199/AMC 232 i6 /AMC 258 i6 / 4.2l was bore and stroke. Some minor external parts stuff, waterpumps,but otherwise the blocks are the same. So, yes, the '79 intake/exhaust manifolds should bolt right up to your '74 block.



Sorry, that was a little wordy to just say yes

No such thing. Can't ever learn to much info! Thank you for your help. Do you by chance know what the performance gain is over running an aftermarket intake/exhaust is over stock? And do you get say an aftermarket intake does running the stock exhaust make that pointless?


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[elwood blues]

No such thing. Can't ever learn to much info! Thank you for your help. Do you by chance know what the performance gain is over running an aftermarket intake/exhaust is over stock? And do you get say an aftermarket intake does running the stock exhaust make that pointless?

You're welcome! From what other's have said here on this forum, the performance gains are noticeable with an aftermarket 4bbl intake manifold. Mostly in throttle response and MPG gains. The most common and most readily available is the Offenhauser 5999DP intake manifold, it's a dual plane manifold for use with a 4bbl carburetor.

https://www.summitracing.com/parts/ofy-5999dp



The 5999DP is designed so that it will bolt up to your stock exhaust manifold.

I don't know what kind of performance gains you're looking to get? The gains I got going up to a 2bbl intake and a Motorcraft 2100 carb were impressive both throttle response and MPG. But honestly, an intake and exhaust upgrade are only going to get you so far, the AMC L6 is a low HP high torque engine.

 

[jakeh937]

You're welcome! From what other's have said here on this forum, the performance gains are noticeable with an aftermarket 4bbl intake manifold. Mostly in throttle response and MPG gains. The most common and most readily available is the Offenhauser 5999DP intake manifold, it's a dual plane manifold for use with a 4bbl carburetor.



https://www.summitracing.com/parts/ofy-5999dp







The 5999DP is designed so that it will bolt up to your stock exhaust manifold.



I don't know what kind of performance gains you're looking to get? The gains I got going up to a 2bbl intake and a Motorcraft 2100 carb were impressive both throttle response and MPG. But honestly, an intake and exhaust upgrade are only going to get you so far, the AMC L6 is a low HP high torque engine.

I was looking st that exact one and looking at the price as well. I'm not to concerned with hp numbers. I'm more gearing the engine to be torque in the low rpm range. I plan to use this rig in the mountains and hills so torque over hp and better throttle response and mpg. I have heard nothing but awesome things from mc2100 carbs on these engines. Now here is the stupid question.. you had said you went with a 2 bbl intake and mc2100. So if I took the intake and exhaust off that 79 AMC 258 i6 / 4.2l I have and threw on the mc2100, that'd be the setup your running and most likely the best for what I'm looking to do?


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[elwood blues]

I was looking st that exact one and looking at the price as well. I'm not to concerned with hp numbers. I'm more gearing the engine to be torque in the low rpm range. I plan to use this rig in the mountains and hills so torque over hp and better throttle response and mpg. I have heard nothing but awesome things from mc2100 carbs on these engines. Now here is the stupid question.. you had said you went with a 2 bbl intake and mc2100. So if I took the intake and exhaust off that 79 AMC 258 i6 / 4.2l I have and threw on the mc2100, that'd be the setup your running and most likely the best for what I'm looking to do?

Yes, that's what I went with. You need an adapter to match up a Motorcraft/Autolite carb up to a stock AMC 2bbl intake, I think there's even one for the stock 1bbl intake too if you dig around on Summit racing. I like the MC2100 carb, they're easy to work on, there are still places to find parts and rebuild kits for it. I really like the throttle response above a stock carb, and they do fairly well for a carburetor off road. I have no experience in mountains or steep hills with mine, it's pretty flat here where I'm at on the east coast, and mine spends more time on the road than off.

 

[jakeh937]

Yes, that's what I went with. You need an adapter to match up a Motorcraft/Autolite carb up to a stock AMC 2bbl intake, I think there's even one for the stock 1bbl intake too if you dig around on Summit racing. I like the MC2100 carb, they're easy to work on, there are still places to find parts and rebuild kits for it. I really like the throttle response above a stock carb, and they do fairly well for a carburetor off road. I have no experience in mountains or steep hills with mine, it's pretty flat here where I'm at on the east coast, and mine spends more time on the road than off.

Awesome! I'll look at those manifolds when I get a chance. I greatly appreciate your help! Thank you!

As far as linkage with the carb, what did you do/use?


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[jakeh937]

Yes, that's what I went with. You need an adapter to match up a Motorcraft/Autolite carb up to a stock AMC 2bbl intake, I think there's even one for the stock 1bbl intake too if you dig around on Summit racing. I like the MC2100 carb, they're easy to work on, there are still places to find parts and rebuild kits for it. I really like the throttle response above a stock carb, and they do fairly well for a carburetor off road. I have no experience in mountains or steep hills with mine, it's pretty flat here where I'm at on the east coast, and mine spends more time on the road than off.

And also what did you do with choke? Did you keep it manual or go electric?


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[elwood blues]

Awesome! I'll look at those manifolds when I get a chance. I greatly appreciate your help! Thank you!

As far as linkage with the carb, what did you do/use?

And also what did you do with choke? Did you keep it manual or go electric?

You are very welcome, I love talking CJs and carbs! The linkage was a pain, but I made it homeade from a couple of universal kits I bought at Autozone or Advance Auto or wherever it was. My stock carb was the 1bbl Carter YF, POS!!! It has a pull down linkage, where the MC2100 has a pull back linkage, like a Holley carb does. It took a little redneck engineering and welding a pair of vice-grips to the parts by accident, but it's not that hard to make. I went with an electric choke, my '78 had an wire ran to the carb for the automatic Transmission kickdown, which I didn't use anyway, so I ran that to the choke. I prefer to run an electric or climatic choke over a manual choke, that's just my preference, I feel that I would forget to turn off a manual choke and flood the engine all the time.

 

[jakeh937]

You are very welcome, I love talking CJs and carbs! The linkage was a pain, but I made it homeade from a couple of universal kits I bought at Autozone or Advance Auto or wherever it was. My stock carb was the 1bbl Carter YF, POS!!! It has a pull down linkage, where the MC2100 has a pull back linkage, like a Holley carb does. It took a little redneck engineering and welding a pair of vice-grips to the parts by accident, but it's not that hard to make. I went with an electric choke, my '78 had an wire ran to the carb for the automatic Transmission kickdown, which I didn't use anyway, so I ran that to the choke. I prefer to run an electric or climatic choke over a manual choke, that's just my preference, I feel that I would forget to turn off a manual choke and flood the engine all the time.

Hahaha sounds like something I would do haha. Maybe you might know, I haven't tinkered to much on this subject, but I'm basically swapping in the engine and tcase from a 74, a ford np435 Transmission into a 79 CJ5 . So as far as a wiring harness, do I get one for the 79 or get one for a 74?


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[elwood blues]

Hahaha sounds like something I would do haha. Maybe you might know, I haven't tinkered to much on this subject, but I'm basically swapping in the engine and tcase from a 74, a ford np435 Transmission into a 79 CJ5 . So as far as a wiring harness, do I get one for the 79 or get one for a 74?

That's a little above anything I've ever done, I would say you'd want the harness for the '79. It's always easier to not use something, like the Transmission kick-down circuit or air-conditioning circuit, than to try to add them in later.

Big but here, I've never attempted something like that.

 

[jakeh937]

You are very welcome, I love talking CJs and carbs! The linkage was a pain, but I made it homeade from a couple of universal kits I bought at Autozone or Advance Auto or wherever it was. My stock carb was the 1bbl Carter YF, POS!!! It has a pull down linkage, where the MC2100 has a pull back linkage, like a Holley carb does. It took a little redneck engineering and welding a pair of vice-grips to the parts by accident, but it's not that hard to make. I went with an electric choke, my '78 had an wire ran to the carb for the automatic Transmission kickdown, which I didn't use anyway, so I ran that to the choke. I prefer to run an electric or climatic choke over a manual choke, that's just my preference, I feel that I would forget to turn off a manual choke and flood the engine all the time.

Hahaha sounds like something I would do haha. Maybe you might know, I haven't tinkered to much on this subject, but I'm basically swapping in the engine and tcase from a 74, a ford np435 Transmission into a 79 CJ5 . So as far as a wiring harness, do I get one for the 79 or get one for a 74?


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[jakeh937]

That's a little above anything I've ever done, I would say you'd want the harness for the '79. It's always easier to not use something, like the Transmission kick-down circuit or air-conditioning circuit, than to try to add them in later.



Big but here, I've never attempted something like that.

That makes sense. I guess I could then use that circuit for the electric choke. How does that work if you don't mind me asking? Like ur circuit. How does that work becoming an electric choke


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[elwood blues]

That makes sense. I guess I could then use that circuit for the electric choke. How does that work if you don't mind me asking? Like ur circuit. How does that work becoming an electric choke?

I just checked that circuit to make sure that it only was powered when the key was on, I checked with a multimeter, and then I double checked it on a wiring schematic in one of the books I have. There was nothing else on that circuit, it was designated to be used with the Transmission kick-down, so I just high jacked it.

 

[jakeh937]

I just checked that circuit to make sure that it only was powered when the key was on, I checked with a multimeter, and then I double checked it on a wiring schematic in one of the books I have. There was nothing else on that circuit, it was designated to be used with the Transmission kick-down, so I just high jacked it.

How does that circuit control the choke if it's powered all times with key on? I'm assuming power turns choke on, so what would kill the choke?


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[elwood blues]

How does that circuit control the choke if it's powered all times with key on? I'm assuming power turns choke on, so what would kill the choke?

On the inside of the electric choke is the coil, it's a bimetallic strip that will coil up tighter when heated up and will uncoil when it cools off. So, when you turn the key on, electricity starts running through the coil, heating it up, the longer the key is on, the tighter the coil gets, turning off the choke. Then you turn the key off, no more electricity running through the coil, the engine cools off, and the coils unwinds, turning the choke on.

 

[jakeh937]

On the inside of the electric choke is the coil, it's a bimetallic strip that will coil up tighter when heated up and will uncoil when it cools off. So, when you turn the key on, electricity starts running through the coil, heating it up, the longer the key is on, the tighter the coil gets, turning off the choke. Then you turn the key off, no more electricity running through the coil, the engine cools off, and the coils unwinds, turning the choke on.

WOW! Total mind blown hahaha. That's awesome. Makes complete sense now. Do you have a problem with how long/short the choke stays on or is it pretty proportional to the engine heating up? If that makes any sense


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[elwood blues]

WOW! Total mind blown hahaha. That's awesome. Makes complete sense now. Do you have a problem with how long/short the choke stays on or is it pretty proportional to the engine heating up? If that makes any sense

I don't have any issues, getting it set up is pretty straight forward. How to adjust it is usually in the directions with the carb rebuild kit. Once the engine warms up, the choke gets turned off, so it doesn't matter how long the engine is on/electricity is supplied to the choke, once it's off, it's off. It's usually pretty right on as far as the engine cooling off an needing to apply the choke when I start the engine back up after sitting and cooling off too.