AMC 258 Intake Manifolds

[Granny]

This is a question for some of you engine experts. I am eventually going to put a Howell Injection on Granny 2 if/when I ever get her finished. The folks at Howell say I simply need a 2-bbl manifold off a 258 engine to make it happen. There are two different intake manifolds for a 258. The older style is made of cast iron and is connected to the exhaust manifold. The newer style is all aluminum, and is separate from the exhaust manifold. Does anyone have any thought as to whether one may be a better choice than the other? I have easy access to both styles.

 

[RenegadeT]

Are some of the older style 2bbl? Mine was 1bbl.

 

[paradisePWoffrd]

honestly I am not that familar with those manifolds specifically, but I would say that the seperate aluminum one would be preferable. Aluminum dissipates heat better, and since it is seperate, it should keep the intake charge cooler and increase effeciency (however slight it might be).

 

[Granny]

Are some of the older style 2bbl? Mine was 1bbl.

Yes they were... and this old dog didn't know that either. They were used at least as early as 1979, and possibly earlier, but not certain on that.

honestly I am not that familar with those manifolds specifically, but I would say that the seperate aluminum one would be preferable. Aluminum dissipates heat better, and since it is seperate, it should keep the intake charge cooler and increase effeciency (however slight it might be).

I fully agree with you on the heat dissipation, and I too wonder if it wouldn't be the best choice. However, I have heard varying tales of warpage problems with swapping aluminum parts so on the other hand I can't help but wonder if the cast would be the safer choice. Again Howell says either one is fine.

ThanX guys... anybody else care to chime in on this???

 

[Flex5]

Don,
The cast 2bbl intake helped the performance of the webber i was running greatly. It eliminated the need for the necked down adapter.

I have had some experience with Ofenhauser (sp) intakes for 250 chevy motors and they seem to work very well. Where we had problems was getting the monza 3 into one headers to seal up, partially due to the way the intake and exhaust manifolds worked together.

 

[Caver Dave]

Brother Don, FWIW...

My brothers 200K miler '84 CJ-7 is still running the AL 2bbl intake without any issues. The funny part about the AL intakes... they have coolant lines connected, likely more for pre-heating (emissions crap) than cooling the intake

If'n you'd rather spend $300 + your time to get the same outcome versus $1200 + time for the Howell... the BinderPlanet (formerly Binder Bulletin) has the defacto FI forum for these swaps! I've done 2 so far and was actually enjoyable. The main keys are to start with decent parts (if it looks like scrap, it probably is) and *only* solder/heatshrink the TBI wiring (shortcutting the process, using crimp connectors to save time will ALWAYS be rewarded down the road )

Also, if Howells kit doesn't come with the machined AL TB adapter pictured, go no further until it's replaced. The thin Holley/TransAdapt cast pot-metal junk WILL warp & you'll be chasing vac. leaks forever! I made adapters out of 3/4" AL to adapt the TB to the small 2bbl pattern before starting both swaps.

Taters "Timex" TBI

Moss' TBI Swap (the good stuff starts on Pg8)

 

[Granny]

Dave, I've had the do-it-yourself conversation with several different people and I'm still completely lost as to what all I would need to scavenge up, and what to scavenge it from. I have also come to the conclusion from some of those conversations that the do-it-yourself jobs can very quickly become a nightmare. Yes, the Howell is about $1200, but I have have heard nothing but good about these kits, and the support that Howell offers. That said, I am still looking hard toward that option as being the easiest to install and the most trouble-free.

 

[Granny]

Digging this thread up again... did Jeep (Chrysler) put a Holly 2-bbl carb on any of the 258/4.2 engines?... and is the Holly bolt pattern different than that of the Carters?

 

[flatblackzj]

here's a different combination to look into-use a 91 & newer 4.0 head and injection-strip out the harness, computer, sensors, intake, ignition and exhaust header from a newer XJ or ZJ and do a roll-your-own mopar MPI style kit. the HO cylinder head will gain some power and you can make it OBD I or II for diagnostics. a donor vehicle would probably come out cheaper than the howell, and if you want even more power, use the 4.0 block with your bottom end to make a 4.6

 

[RenegadeT]

here's a different combination to look into-use a 91 & newer 4.0 head and injection-strip out the harness, computer, sensors, intake, ignition and exhaust header from a newer XJ or ZJ and do a roll-your-own mopar MPI style kit. the HO cylinder head will gain some power and you can make it OBD I or II for diagnostics. a donor vehicle would probably come out cheaper than the howell, and if you want even more power, use the 4.0 block with your bottom end to make a 4.6

you don't even need the 4.0L head, you can bolt a 4.0L HO intake to a 258 head, continue using the 258 2-piece manifold. The HO head is supposed to flow better than the 258 though..but its not required for the budget MPI upgrade.

 

[Caver Dave]

Dave, I've had the do-it-yourself conversation with several different people and I'm still completely lost as to what all I would need to scavenge up, and what to scavenge it from.

Not that hard... Bill Hamilton has a complete list (depends on what functions you want to keep) on the BinderPlanet. If you change your mind, LMK!

I have also come to the conclusion from some of those conversations that the do-it-yourself jobs can very quickly become a nightmare

Agreed... but usually the "nightmares" come from lack of thought/planning on the frontside, followed up by "1/2 @$$" implementation (NOT following instructions to the letter, settling for crimping connectors, etc) on the backside. I've done 2 now... spent about 10 LONG days researching the options and a 3-5 months doing it right each time.

I understand the reasons for both DIY & Howell/Mopar routes... we simply had less $$ than time