Engine 258 1 bbl to 2 bbl conversion

[bcstringer]

Howdy Jeep-CJ Community,
I've been reading your posts for years via various google searches, but now that my Jeep re-build has started, I'm running into some issues only you experienced CJers can likely help with. My 1972 Jeep CJ5 (v1.0) was my grandfather's and he taught me how to drive it well before I hit puberty. After he passed, my Dad got it and he and I restored it in 1993-94 as project v2.0 for me to drive as my first vehicle in high school. It's been sitting under my parents' house for nearly 30 years and even got completely flooded by Lake Travis in TX.

I just can't let this heirloom die, so almost 30 years later I'm bringing it back to life with project v3.0. I'm replacing the frozen AMC 232 i6 with a stroked AMC 258 i6 / 4.2l and the T-14 with a T-18 . I'm upgrading to a 2 bbl Holley Sniper EFI so need to upgrade the stock 1 bbl intake to a 2 bbl intake. I can't find any late '70s model 2 bbl cast iron intakes out there that will marry up with the stock exhaust manifold so I'm going to use an early '80s model 2 bbl aluminum intake with a detached header.

1) I will block off the EGR with a plate, but what do you do with the vacuum ports and water jacket?
2) Has anyone out there with a '70s 1 bbl intake done this conversion to an early to mid '80s 2 bbl intake before that can walk me thru a clear step-by-step?
3) Are there threads or plugs out there that I can purchase to make this easy?

Thanks in advance for any help! Glad to be here with you all in the CJ Matrix.

Thanks,
Cody

 

[CJ]

Howdy Jeep-CJ Community,
I've been reading your posts for years via various google searches, but now that my Jeep re-build has started, I'm running into some issues only you experienced CJers can likely help with. My 1972 Jeep CJ5 (v1.0) was my grandfather's and he taught me how to drive it well before I hit puberty. After he passed, my Dad got it and he and I restored it in 1993-94 as project v2.0 for me to drive as my first vehicle in high school. It's been sitting under my parents' house for nearly 30 years and even got completely flooded by Lake Travis in TX.

I just can't let this heirloom die, so almost 30 years later I'm bringing it back to life with project v3.0. I'm replacing the frozen 232 with a stroked 258 and the T-14 with a T-18. I'm upgrading to a 2 bbl Holley Sniper EFI so need to upgrade the stock 1 bbl intake to a 2 bbl intake. I can't find any late '70s model 2 bbl cast iron intakes out there that will marry up with the stock exhaust manifold so I'm going to use an early '80s model 2 bbl aluminum intake with a detached header.

1) I will block off the EGR with a plate, but what do you do with the vacuum ports and water jacket?
2) Has anyone out there with a '70s 1 bbl intake done this conversion to an early to mid '80s 2 bbl intake before that can walk me thru a clear step-by-step?
3) Are there threads or plugs out there that I can purchase to make this easy?

Thanks in advance for any help! Glad to be here with you all in the CJ Matrix.

Thanks,
Cody

Glad to have you here and I'm happy we have helped you before.
Here are some thoughts but we have others who have more I6 knowledge than myself.

1. You can plug the unused vacuum ports. The water ports on the intake help reduce fuel puddling in the intake.
2. I've not done one but others have. Here is a start -->> https://jeep-cj.com/community/threads/77-258-4-2-intake-manifold-conversion.7385/ *** -->> https://jeep-cj.com/community/threads/1-barrel-to-2-barrel-4-2-conversion.25305/ **** -->> https://jeep-cj.com/community/threads/manifold-swap-258-i6.59633/ *** --->> https://jeep-cj.com/community/threads/258-4-0-head-swap-results.8500/
3. Not sure what you mean.

 

[bcstringer]

Glad to have you here and I'm happy we have helped you before.
Here are some thoughts but we have others who have more I6 knowledge than myself.

1. You can plug the unused vacuum ports. The water ports on the intake help reduce fuel puddling in the intake.
2. I've not done one but others have. Here is a start -->> https://jeep-cj.com/community/threads/77-258-4-2-intake-manifold-conversion.7385/ *** -->> https://jeep-cj.com/community/threads/1-barrel-to-2-barrel-4-2-conversion.25305/ **** -->> https://jeep-cj.com/community/threads/manifold-swap-258-i6.59633/ *** --->> https://jeep-cj.com/community/threads/258-4-0-head-swap-results.8500/
3. Not sure what you mean.

Thanks CJ! I'll take a look into those threads. #3 I guess I'll just try to find some threaded plugs that will fit. Cheers

 

[CJ]

Thanks CJ! I'll take a look into those threads. #3 I guess I'll just try to find some threaded plugs that will fit. Cheers

I also contacted @elwood blues about this. He said when he gets home he will dig up what info he has saved.

 

[gert]

Lol, if your in still in Texas you dont really need the water port, its for cold weather up north if you dont want to plumb it, i never had a problem with mine not having it


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[gert]

Definitely share lots of pictures we love Jeep porn


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[bcstringer]

I also contacted @elwood blues about this. He said when he gets home he will dig up what info he has saved.

Thanks CJ!

 

[bcstringer]

Lol, if your in still in Texas you dont really need the water port, its for cold weather up north if you dont want to plumb it, i never had a problem with mine not having it


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Thanks gert, I'm not in hotter-than-hell TX anymore, but still in a somewhat warmer climate in Southern CA. The original v1.0 of this Jeep was Avocado Mist Metallic. Here's some photos of the black v2.0 before and during the rebuild.

 

[elwood blues]

Howdy Jeep-CJ Community,
I've been reading your posts for years via various google searches, but now that my Jeep re-build has started, I'm running into some issues only you experienced CJers can likely help with. My 1972 Jeep CJ5 (v1.0) was my grandfather's and he taught me how to drive it well before I hit puberty. After he passed, my Dad got it and he and I restored it in 1993-94 as project v2.0 for me to drive as my first vehicle in high school. It's been sitting under my parents' house for nearly 30 years and even got completely flooded by Lake Travis in TX.

I just can't let this heirloom die, so almost 30 years later I'm bringing it back to life with project v3.0. I'm replacing the frozen 232 with a stroked 258 and the T-14 with a T-18. I'm upgrading to a 2 bbl Holley Sniper EFI so need to upgrade the stock 1 bbl intake to a 2 bbl intake. I can't find any late '70s model 2 bbl cast iron intakes out there that will marry up with the stock exhaust manifold so I'm going to use an early '80s model 2 bbl aluminum intake with a detached header.

1) I will block off the EGR with a plate, but what do you do with the vacuum ports and water jacket?
2) Has anyone out there with a '70s 1 bbl intake done this conversion to an early to mid '80s 2 bbl intake before that can walk me thru a clear step-by-step?
3) Are there threads or plugs out there that I can purchase to make this easy?

Thanks in advance for any help! Glad to be here with you all in the CJ Matrix.

Thanks,
Cody

Sorry I'm late! That is a sweet looking CJ, it's good to hear you're not letting it die!

Let's start with the intake manifold question. '80 and older AMC 258 i6 / 4.2l /AMC 232 i6 engines had cast iron intake and exhaust manifold, and they physically bolted together. My understanding is that the theory was the heat from the exhaust manifold helped heat up the carb when it's cold. Anyway, 2bbl or 1bbl, this is what it looked like.




1980 and new manifolds are two separate pieces
intake;


exhaust;


They still bolt "together" on the head, but they're not physically bolted together like the earlier versions are. That's also why the newer version has the water ports, to heat up the intake manifold using coolant. The cool part is there's no difference in mounting holes or anything. It's also a lot simpler, a lot, to use a header with an '80 and new intake manifold than it is with the older version, if you're looking into going the header route.


Vacuum, I've got 2 diagrams. The first one here shows a CTO and an EGR, I deleted both of those on my as well.



So, I created this disaster of a diagram in paint

You "should" be able to just use the Holly Sniper in place of the carb here, I doubt the Sniper has a "bowl vent", that's the light blue line, so you can delete that one too. For vacuum source, I have stock fitting that goes in the hole above where the PCV valve sits in the pre-'80 exhaust manifold. That's going to be your biggest thing is finding a vacuum source for your PCV system.

 

[bcstringer]

Sorry I'm late! That is a sweet looking CJ, it's good to hear you're not letting it die!

Let's start with the intake manifold question. '80 and older AMC 258/232 engines had cast iron intake and exhaust manifold, and they physically bolted together. My understanding is that the theory was the heat from the exhaust manifold helped heat up the carb when it's cold. Anyway, 2bbl or 1bbl, this is what it looked like.




1980 and new manifolds are two separate pieces
intake;


exhaust;


They still bolt "together" on the head, but they're not physically bolted together like the earlier versions are. That's also why the newer version has the water ports, to heat up the intake manifold using coolant. The cool part is there's no difference in mounting holes or anything. It's also a lot simpler, a lot, to use a header with an '80 and new intake manifold than it is with the older version, if you're looking into going the header route.


Vacuum, I've got 2 diagrams. The first one here shows a CTO and an EGR, I deleted both of those on my as well.



So, I created this disaster of a diagram in paint

You "should" be able to just use the Holly Sniper in place of the carb here, I doubt the Sniper has a "bowl vent", that's the light blue line, so you can delete that one too. For vacuum source, I have stock fitting that goes in the hole above where the PCV valve sits in the pre-'80 exhaust manifold. That's going to be your biggest thing is finding a vacuum source for your PCV system.

This is awesome, thank you! My plan is to definitely use the newer 80's aluminum intake with a header system. Thanks for the diagrams! I'll refer to them when I start that process.

 

[gert]

Man thats a sweet looking Jeep, i look forward to seeing it come together


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[Manic Mechanic]

Sry I'm late to the party work has been kicking my butt. I'm running a AMC 258 i6 / 4.2l with the 2 barrel sniper. I actually use the water ports on the intake for the EFI coolant sensor. You will need a one to two barrel adapter and the throttle cable from a V8 Jeep I would also recommend a GM HEI distributor if you go headers just make sure you install the 02 sensor 4-6" past the collector and have zero exhaust leaks

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[gert]

Man thats a pretty
Motor


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[Manic Mechanic]

Thanks I try

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[Lumpy Grits]

OP, just be happy you don't have to pass Ca. SMOG!

 

[Manic Mechanic]

Ya from what I understand the sniper EFI is not ca smog legal yet

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[bcstringer]

Sry I'm late to the party work has been kicking my butt. I'm running a 258 with the 2 barrel sniper. I actually use the water ports on the intake for the EFI coolant sensor. You will need a one to two barrel adapter and the throttle cable from a V8 Jeep I would also recommend a GM HEI distributor if you go headers just make sure you install the 02 sensor 4-6" past the collector and have zero exhaust leaks

Thanks @Manic Mechanic for the info and pics! I'll look into using the water ports on the intake for the EFI coolant sensor instead of another area. The used but good condition '81-'86 aluminum intake part #EF3237858 I bought has 2 barrels so should marry up to the 2-barrel Holley Sniper EFI now instead of using a 2bbl-to-1bbl adapter. I bought the Holley Hyperspark distributor and Hedman 6-into-1 HTC Headers part #99616. I'll make sure to install the O2 sensor 6" past the collector per your and Holley's recommendations.

Why a throttle cable from a V8 Jeep in particular? Will existing not work?

Here's some updated pics of build so far in order:
1. New stroked AMC 258 i6 / 4.2l engine painted '69-'73 AMC Blue Metallic Ditzler PPG #13730 (original AMC 232 i6 engine completely seized up. The Jeep was flooded by Lake Travis and water was in EVERYTHING: engine, oil pan, Transmission , Transfer Case , axles, gas tank, etc. Since no power steering and no power brakes, I stayed with an I6 in lieu of going with a V8. The stroked AMC 258 i6 / 4.2l with Holley Sniper EFI specd to get over 200hp over the original AMC 232 i6 's 100hp, but I'll believe it when I see it!
2. Dana 30 front end rebuilt w 4.56 gears upgraded from original 3.73
3. Dana 44 rear end rebuilt w 4.56 gears upgraded from original 3.73
4. 2bbl aluminum intake manifold '81-'86 #3237858 upgraded from original 1bbl cast iron intake manifold '72-'74 #3191690
5. New T-18 4spd Transmission upgraded from T-14 3spd Transmission , new bell housing
6. Jeep on lift and front and rear ends and suspension off. Currently grinding, rust treating, and coating the underside.
7. View of the underside. Not many rust holes to patch. Just a few small ones under the passenger storage box area.

 

[bcstringer]

OP, just be happy you don't have to pass Ca. SMOG!

I was so happy when I read that after moving from TX to CA! Just 4 years newer and I wouldn't be able to do any of the upgrades like the Holley Sniper EFI, Headers, etc. I don't have to have a catalytic converter as well for '72! I feel bad for the '76-'86 CJers in CA.

 

[bcstringer]

Ya from what I understand the sniper EFI is not ca smog legal yet

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CA Smog test and inspection requirements go by vehicle year. '76-'86 CJs have to have smog tests, but '44-'75 CJs do not. I got lucky with a '72. I've always wanted to have a CJ6 or CJ7 in addition to my heirloom '72 CJ5 so I'm definitely staying under that '76 mark if I do.

 

[bcstringer]

Thanks @Manic Mechanic for the info and pics! I'll look into using the water ports on the intake for the EFI coolant sensor instead of another area. The used but good condition '81-'86 aluminum intake part #EF3237858 I bought has 2 barrels so should marry up to the 2-barrel Holley Sniper EFI now instead of using a 2bbl-to-1bbl adapter. I bought the Holley Hyperspark distributor and Hedman 6-into-1 HTC Headers part #99616. I'll make sure to install the O2 sensor 6" past the collector per your and Holley's recommendations.

Why a throttle cable from a V8 Jeep in particular? Will existing not work?

Here's some updated pics of build so far in order:
1. New stroked 258 engine painted '69-'73 AMC Blue Metallic Ditzler PPG #13730 (original 232 engine completely seized up. The Jeep was flooded by Lake Travis and water was in EVERYTHING: engine, oil pan, transmission, transfer case, axles, gas tank, etc. Since no power steering and no power brakes, I stayed with an I6 in lieu of going with a V8. The stroked 258 with Holley Sniper EFI specd to get over 200hp over the original 232's 100hp, but I'll believe it when I see it!
2. D30 front end rebuilt w 4.56 gears upgraded from original 3.73
3. D44 rear end rebuilt w 4.56 gears upgraded from original 3.73
4. 2bbl aluminum intake manifold '81-'86 #3237858 upgraded from original 1bbl cast iron intake manifold '72-'74 #3191690
5. New T-18 4spd transmission upgraded from T-14 3spd transmission, new bell housing
6. Jeep on lift and front and rear ends and suspension off. Currently grinding, rust treating, and coating the underside. Also will replace all body to frame bushings.
7. View of the underside. Not many rust holes to patch. Just a few small ones under the passenger storage box area.

@Manic Mechanic I guess my photos didn't attach so attaching again