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  #1  
Old 09-05-2007, 07:27 PM
Jodaddy Jodaddy is offline
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258 performance upgrade questions

82 chero 258/t176/208 120k original tfi upgrade
I would love some more top end ponies but as it seems I don't think the 4.0 head swap would be in my best interest as I have quite a bit of blow by and I would rather not cook my rings just yet. the engine doesn't smoke out of the tail pipe but it does smoke out of the valve cover. anyone out there running an aftermarket intake and if so with which carb. what about headers? what kind of gains will I see and is it worth the money? Oh yeah if you have anything that might help me in this quest I would be happy to buy it within reason( not really looking for a stroker)
thanks
Joe
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  #2  
Old 09-05-2007, 07:35 PM
Ristow Ristow is offline
 
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have you flipped yer air cleaner lid over yet?
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  #3  
Old 09-05-2007, 07:40 PM
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Cecil14 Cecil14 is offline
 
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To be honest you're really not going to benefit from much more. The best thing you can do at this point is carb, get either a Motorcraft 2100 (1.08 bore) for the cheap side or a weber for the more pricey. I run the MC2100 and love it. Flat out one of the best 2bbl carbs ever made, even if it is a ford.

A header will gain you next to nothing since the 258 head flows so horribly to begin with. The exhaust manifold will never be your bottleneck with a factory 258 head.

That's really about it. Without a major teardown the only things you're really going to benefit from are a good ignition (TFI or HEI) and carb. Obviously a good exhaust will help but don't bother spending money on a header.


aa
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  #4  
Old 09-05-2007, 08:32 PM
Jodaddy Jodaddy is offline
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what is gained by flipping the lid? I tried to read something about modifying the aircleaner for ten hp but I couldn't open the webpage. what about a k&n air filter? waste of greenbacks or golden ticket?
thanks
Joe
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  #5  
Old 09-05-2007, 08:37 PM
Ristow Ristow is offline
 
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nuthin',it's what high school kids used to do,thinking it gave them "big power" by letting more air in.in reality it did nothing but let hot air into the intake.old joke.

guess i'm getting old...
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Ristows right.................again,




Quote:
Originally Posted by Fasts79Chief
... like the little 'you know what's' that you are.




Quote:
Originally Posted by Fasts79Chief
I LOVE how Ristow has stolen my comment about him ... "Quoted" it ... and made himself famous for being an ***hole to people. Hahahahahahahahahha!


→ Where the kids hang out...

fsjbuilder.org come for the mindless chat,stay for the hand drawn emoticons.

It's like you're unraveling a big cable-knit sweater that someone keeps knitting...and knitting...and knitting...and knitting...
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  #6  
Old 09-05-2007, 08:59 PM
Jodaddy Jodaddy is offline
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inserting laughter.......



.......now!
the internet takes most of the fun out of sarcasm. Especially when you're stupid. btw I did flip it over but I didn't want to feel like I wasted the 5 bucks I spent the other day on a new snorkel so I put it back proper. Now if only I can remember to poke ristow in the eyes if iever meet him.
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  #7  
Old 09-05-2007, 09:37 PM
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Kali Kali is offline
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what size tires are you running? you likely have 2.73s gears in your axles, so if you have a tall tire that could really make a 258 seem weak.
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  #8  
Old 09-05-2007, 10:43 PM
Jodaddy Jodaddy is offline
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3:31's with 215/85/16's. I want to be able to climb a hill without downshifting or lugging the engine. I have found 2 reasonably priced 2100 conversion kits on the 'bay both that flow 350 cfm. Is this too much for the stock intake and head?
thanks
Joe
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  #9  
Old 09-06-2007, 06:44 AM
yankeedog yankeedog is offline
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350 cfm is about right. you will probably never use it all,but you shouldnt be overcarbed with that.
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  #10  
Old 09-06-2007, 06:48 AM
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Cecil14 Cecil14 is offline
 
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Be very leary of 2100 "kits". There is absolutely nothing special to putting that carb on except the little 1"x2" plate you have to make for the throttle. Took me all of about 10 minutes.

No one really knows how much the 2100 flows. I have yet to see anyone actually flow test one and produce charts. 350 sounds pretty close and that is about perfect for a stock 258. I ran 45 jets in mine on the 258. Think I'm running 47s now with the 4.6L.


aa
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  #11  
Old 09-06-2007, 11:32 AM
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tgreese tgreese is offline
 
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No evidence, but I doubt an factory 2V carb flows 350 CFM. The 2100 carb was used on the Ford 260/289/302 as well as the AMC 304, and at 300 cid, you'd have to be running 4032 RPM to pull 350 cfm at 100% VE. Seems unlikely that a car for the street would be tuned like that. I think the extimates of well under 200 cfm for the 1.08" venturi 2100 are more realistic. A cfm spec is mostly ad copy for aftermarket carburetors - it's of some use though, since it gives the aftermarket purchaser an idea whether the carburetor they pick has a chance of running on a specific engine.
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  #12  
Old 09-06-2007, 11:57 AM
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Cecil14 Cecil14 is offline
 
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Quote:
Originally Posted by tgreese
No evidence, but I doubt an factory 2V carb flows 350 CFM. The 2100 carb was used on the Ford 260/289/302 as well as the AMC 304, and at 300 cid, you'd have to be running 4032 RPM to pull 350 cfm at 100% VE. Seems unlikely that a car for the street would be tuned like that. I think the extimates of well under 200 cfm for the 1.08" venturi 2100 are more realistic. A cfm spec is mostly ad copy for aftermarket carburetors - it's of some use though, since it gives the aftermarket purchaser an idea whether the carburetor they pick has a chance of running on a specific engine.

I can certainly see the 1.08 being around 300cfm. That would make all kinds of sense from a mass production stand point. You make one carb that can be scaled to a TON of different engines. You can get it down to run good on a 3.5Lish motor and up all the way to a 360+. Then of course they made the bigger ones that were basically the same carb bored a bit more to run on stuff as big as the 400 and up. Smart companies made as few different parts as possible to keep costs down. Why do you think SJs didn't change much from '62-91.


aa
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  #13  
Old 09-06-2007, 07:37 PM
Jodaddy Jodaddy is offline
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I found a 1.21 2100 that boasts 350 cfm. Does this sound like what I am looking for.
thanks
Joe
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  #14  
Old 09-06-2007, 07:46 PM
Ristow Ristow is offline
 
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Quote:
Originally Posted by Jodaddy
Now if only I can remember to poke ristow in the eyes if iever meet him.


good thing i always wear my shades......







......(they have bi-focals too......y'know,cause i'm old...... )
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Quote:
Originally Posted by Hankrod
Ristows right.................again,




Quote:
Originally Posted by Fasts79Chief
... like the little 'you know what's' that you are.




Quote:
Originally Posted by Fasts79Chief
I LOVE how Ristow has stolen my comment about him ... "Quoted" it ... and made himself famous for being an ***hole to people. Hahahahahahahahahha!


→ Where the kids hang out...

fsjbuilder.org come for the mindless chat,stay for the hand drawn emoticons.

It's like you're unraveling a big cable-knit sweater that someone keeps knitting...and knitting...and knitting...and knitting...
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  #15  
Old 09-06-2007, 07:46 PM
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Cecil14 Cecil14 is offline
 
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The 1.21 is going to be a bit big for your motor. I'm still running the 1.08 on my stroker and it's plenty big enough.


aa
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  #16  
Old 09-06-2007, 07:50 PM
Jodaddy Jodaddy is offline
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Also wondering, if I understood right that I could just take the 2150 off my 360 and bolt it on the 258 intake and fab a throttle bracket. would this be just as good as the 1.08 or 1.21 2100 set up?
thanks
Joe
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  #17  
Old 09-06-2007, 07:51 PM
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scantar scantar is offline
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Quote:
Originally Posted by Ristow

guess i'm getting old...


Yes you are! And I'm not ageing one day older until you catch up!
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  #18  
Old 09-06-2007, 08:41 PM
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Stuka Stuka is offline
 
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The 'smoke' from your valve cover is steam, and its caused by condensation. Which is generally caused by lots of short trips. Its a common isue with 258's that I have seen on a lot of rigs.

On my 258, I have a 2.5" exhaust from the manifold back (noticable top end gain over the stock 1.75"), a Weber 32/36 DGEV carb (I love it, great milage, good power, HUGE improvement over the stock BBD), Full TFI ignition upgrade, again, ran a lot better (and it actually had a fresh tune up when I did the change over).

The 2100 is a great carb, and they can be found easily. It wont give you the milage of the weber, but it does give more top end power (higher cfm than the 32/36, although the 36/36 would out perform the 2100). But mostly, its a whole lot cheaper.
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1981 J10 AMC 258 with TFI and Weber 32/36 DGEV Carb with a BJ's Aluminum Radiator, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 TSL's, BJ's Offroad Rear Bumper.

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  #19  
Old 09-06-2007, 09:36 PM
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Cecil14 Cecil14 is offline
 
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Isn't the collector on the 258 manifold 2.25"? I know the one on the 4.0L is. That being the case there's no point in going any bigger, you'll always have a 2.25" bottle neck. Even so, however, that would be a huge improvement.

Yah, while the weber would be awesome it does cost a good chunk of money. Sometimes you can find them on the bay for a pretty good deal.

And yes, you can take the one off your 360 and drop it on. Ones off a 304 typically work better, though. You need to watch the size of the carb off the 360. I've seen both 1.08s and 1.21s on 360s. You also need an adapter plate (think mine was $12 or so...) to put the 2100 on the factory intake. Then the air cleaner and throttle piece and you're set.


aa
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  #20  
Old 09-07-2007, 12:07 AM
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Stuka Stuka is offline
 
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The collector is 2.25. However, its only that size for about 1". The rest of the exhaust is about 19ft long if you count all the bends and such. By going a step larger, I cut down on back pressure for that length of pipe.
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1981 J10 AMC 258 with TFI and Weber 32/36 DGEV Carb with a BJ's Aluminum Radiator, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 TSL's, BJ's Offroad Rear Bumper.

1975 Cherokee *Sold*
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2005 KJ Limited 3.7, 42RLE, NP242
2008 JK 3.8, 6sp, NP241, 2.5", 33's, 4.56's
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