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My 258 build

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billd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: May/14/2018 at 4:11pm
The 2100 powered many small V8s just fine for many years - think of the AMC 290......
So it would be a fine choice.
The 81 and later exhaust is a good choice as it's divorced from the intake and has smoother flow.
the Offy intake - the dual plane - is better than a large intake as it will keep the air speed up and aid torque at lower speeds.
the 258 was a great torque engine - proof is in the thousands of Jeeps and Eagles that used it.

Don't sweat the clutch - even with a built 258 you aren't going to have to worry about the same problems higher HP engines have. I have a stock clutch in my Eagle and that's a HEAVY car with a mild build I-6 and I beat on it as far as the drive train.

I used a split pattern Comp xtreme energy cam in my build and like it. I had to watch vacuum so kept the LSA down the maintain vacuum for injection.
Warning - some of those Comp xtreme cams will make your valve train sound like a small truck engine. Mine does - because the ramps are fairly radical - the open and close the valves more quickly - that's how they move more air without extreme lifts. Open wide faster, wait until the last second, drop it shut.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ollie Quote  Post ReplyReply Direct Link To This Post Posted: May/14/2018 at 6:25pm
My 258 build will use a 904 with lock up torque converter. Ford 7.5 with 2:73 gears. I hope for 26 mpg @ 70 mph w/AC. I getting 22.5 to 23 mpg @ 70 mph with my 232, 727 and same rear end and no AC.

Having AMC Fun,
Ollie
1966 American Convertible -- "The Rambler"..SOLD
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: May/14/2018 at 6:35pm
My baby Eagle with the 4.0 does in the twenties routinely - I need to update my spreadsheet - I've not put in the stats and numbers for a year now, but last I checked, I had a time it hit upper 20s - like 27 or so.
I track it over TIME so it's not based on a single fill or two with the car pointed up hill or down hill, different weather and driving styles, etc. - it's more fair that way, an average over weeks and months, town and highway, summer and winter.

Remember, air resistance goes up exponentially at speeds over something like 60 mph so if you can get that mileage at 70, it will be FAR FAR better at 60.
A 904 with lockup is a good choice - light, and locked like a stick at speed.

I figure my Eagle does GREAT considering the weight is well over 3,000 pounds, the front is fairly flat and not shaped like an arrow, and the air gets UNDER the car and catches on the suspension and transfer case, etc. - unlike modern marvels where they have literally closed off the lower end to prevent almost all drag from air UNDER the car.
Air hitting the flat areas under the car are like holding a cup out the window...... it's a big scoop under there. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: May/14/2018 at 8:41pm
The 2100 also was used on engines up to 400s. Ford and AMC used the 2100...for years.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: May/15/2018 at 5:53am
Lots of sizes of the 2100 -- from 190 to 424 cfm. You want 240-287 (1.01, 1.02, 1.08... 02 is 245 cfm), maybe 300 (1.14), for a 258, with the smaller for a stock replacement just a tad bigger than the 195 cfm BBD. There is a 351 and 356 cfm (1.21/1.23), those would be good for a really built one. Don't think I'd go any bigger in a 2V, and wouldn't use the two bigger ones on a street engine. Iskjy makes a 256/262 cam that would be a good split cam, but the 256 or 262 Supercams work well. Only the smallest of the Comp Xtreme cams is really usable, but Comp will cut one of the others with a bit less lift if asked. Just don't use the Comp recommended springs, as they are HEAVY!! Mopar Performance or Crane springs (no more than 300#) can be used with regular oil. With the Comp or any spring over 300# (the Crane spring is like 310#, but still ok) you will need to use off-road oil or a high pressure additive like ZDDP.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: May/15/2018 at 5:56am
My J-10 was an 83 base model, 2.78 gears and four speed from the factor. Was made for gas mileage. Just had to slip the clutch a bit taking off, but then it had 100K on it when I bought it, and about 10K was in low range pushing snow around the last few years before I got it -- all in low range.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DaemonForce Quote  Post ReplyReply Direct Link To This Post Posted: May/15/2018 at 7:20am
Originally posted by billd billd wrote:

Air hitting the flat areas under the car are like holding a cup out the window...... it's a big scoop under there. 
Wait what? Where are your armor plates? They serve a dual purpose that helps reduce drag.
Originally posted by farna farna wrote:

Only the smallest of the Comp Xtreme cams is really usable, but Comp will cut one of the others with a bit less lift if asked. Just don't use the Comp recommended springs, as they are HEAVY!!
This just reminded me what a ridiculous issue the valvetrain parts are for this engine series. I can't believe how bad this and always an issue with top names that like bundling complete cam kits to the consumer. I go out of my way to avoid Comp and order a set of Crower lifters. Sometimes springs if I'm suspicious of stock quality.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote hoosieramc Quote  Post ReplyReply Direct Link To This Post Posted: May/15/2018 at 8:52am
The new Holley Sniper 2300 would be neat........


http://youtube.com/watch?v=rXUJPeCqWlQ


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Stormogdis Quote  Post ReplyReply Direct Link To This Post Posted: May/19/2018 at 5:25pm


Got the Hornet home yesterday
Got powersteering, AC and powerbrakes
A frech battery and some fuel in the carb it fiered right up after sitting for 10 years
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: May/21/2018 at 5:40am
Great find, especially in Norway where even Hornet must be rather rare indeed!!
Frank Swygert
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