Project AMC-V8 / 5spd / AMC-20 MJ . . .

[AMC-MJ]

Ya well if I get rough that D35 will fail, the AMC guys say as long as I don't get rough with it the D35 should handle the 290 under commuting operation.

 

But they warned get on it or get rough with it the 290 will twist it off.

 

Now if I get the AMC-20 it'll already have 4.10s ;-) ! and the D44 will have 4.27s I like gear can't ya tell lol

 

The 290 has the same power curve as the 2.5 so I should try to keep around the same RPM/MPH ratio to, I really don't wanna have it gear to conservative as I do lots of slow road driving running 25-45mph tho some 55-70 driving is done not much.

 

 

Mike

[Pete M]

the more cylinders you have, then less likely it'll ever struggle at the low rpms. You'll have twice as many cylinders. It'll be fine. :thumbsup: I'm just saying, don't spend any time or money on a 35. that's all. :cheers:

[AMC-MJ]

Also got more tonnage to get rolling too, Now everybody told me my 6.5 wasn't doggy !

BS truck went great empty was a total dog under load even light ones . . .

 

I would rather not use the D35 at all, But if I had to temporally it would hold up as long as I drove it easy.

 

I'm used to my trucks getting up to speed just as fast empty as loaded, The recurring theme is they had the optional low gears and the optional stronger engine.

 

 

But anywho currently my AX4 I think is about to puke on me, howls n growls in 2nd, 3rd, and reverse . . . Now 1st is starting to whine and 4th grinds when you shift into it but not when you shift out ;-( !

 

Running out of time so I gotta do something soon

Mike

[MancheKid86]

i can't remember where it is,

but there is a post on this site where it tells you a type of gear oil (it may be motor oil)

to put it and stop it from doing that,

ask around I'm sure ull find it :thumbsup:

[Pete M]

you're thinking of the AX-15. the AX-4 takes plain ol' gear oil.

 

 

check to make sure your fluid is up to snuff. my peugeot had a nasty habit of leaking out the back and it would act up when low.

[AMC-MJ]

I started a thread for the AX4, let's chat about it there ;-) !

 

Mike

[jpnjim]

The 290 to 401 are all the same block as I under stand it, but there was 2 different deck hights the 290/343/390 were short decks with 9.0 and 10.2 compression ratios for the 290 and 343 the 390 was 10.2 through its full production run.

 

The 304/360/401 were tall decks they had 8.35-8.50 compression ratios, they were the answer to lower octane fuelk and exhaust emissions . . .

 

290 was replaced by 304, 343 was replaced by 360, and the 390 was replaced by the 401.

Now the 304/360/401 got the newer dog legged heads but the lack of compression hurt power.

 

The 290/343/390 still turned more Net power then the 304/360/401 in stock form.

 

BTW the was first used in 1966 model year, I hope this helps you !

 

Happy holidays

Mike

 

Mike,

Other than the 304,

1970 and 1971 V8's were still high compression engines.

 

And were actually the top horsepower years across the board for AMC.

(race spec SS/AMX's excluded)

 

 

1970 360/4bbl = 290 hp (vs 280 for the top 343)

1971 360/4bbl lost 5hp, to 285hp, due to a compression ratio drop from 10:1 to 9.5:1 (partway through the year)

 

1970 390 = 325hp (vs 315hp for 68-9 390's)

1970 Rebel Machine 390's = 340hp (Machine's had a special HP intake manifold)

1971 401 = 330hp (also would have been higher, but had a cr drop from 10.2:1 to 9.5:1 midway through the year).

 

1972 was the actual year they chopped compression ratio's (pretty much to 8.5:1 across the board),

and also went to the SAE Net horsepower ratings, making things look even worse.

 

Edit for clarity:

all GEN II AMC V8's (1966-1969) were short deck, rectangular port.

all GEN III AMC V8's (1970-1991) were tall deck, dogleg exhaust port.

 

The 390 was available in both GEN II (1968 & 1969) & GEN III (1970).

[AMC-MJ]

Ok well thanks for the education.

 

Mike

[jpnjim]

Ok well thanks for the education.

 

Mike

 

:thumbsup:

 

The early engine's were quite good,

it's just that the 70+ dogleg heads were much better.

 

Truthfully tho, even the rectangular port heads flow pretty good for the small bore engines.

 

I will say this,

if you plan to do any headwork down the road, beyond a simple valvejob,

you'd really be doing yourself a favor by finding some 70-71 304 heads to sink your machinework dollars into,

if you are going to invest the $$$, might as well start with the improved heads, and go from there.

 

 

FWIW, my first AMC engine was a Gen III (74) 304 2bbl auto,

and, for what it was, it impressed me,

till I got Gen II 343/4spd car.

 

The early engines were no slouches. :yes:

[AMC-MJ]

Ok, I just remember reading in hotrod about the 290/343/390 V.s. 304/360/401 were they dynoed them against each other and showed the gen 2 made more net power then the gen 3 V8s despite the better heads they noted the reason was the 10.2 comp v.s. 8.3-5 comp ratios.

 

They went more in depth on the 390 showing it was rated at 315 gross but actually turned 332 net horse power versus the 401s rated 215 to the 255 actual net horsepower.

 

The gust I got was for a strong build using OEM rebuild kits/parts. Was to run gen 3 heads on the gen 2 blocks and for the price of a simple rebuild one could have a very strong performer.

 

 

Mike

[jpnjim]

It depends on which Gen II engine you are comparing to which Gen III.

 

Gen II's used different pistons for 4bbl vs 2bbl engines.

with 51cc heads, you ended up with either 10:1ish, or 9:1ish compression ratio depending on which pistons were in the engine.

 

 

1970 & early 71 GenIII's also used 51cc dogleg heads with hi & lo compression pistons, as the Gen II's did,

so they also had 10:1 ish, or 9:1ish cr.

 

During the 71 model year, the 51cc heads were phased out for 58cc heads,

this dropped compression ratios to 9.5:1ish & 8.5:1ish respectively.

Swapping these heads onto Gen II engines would give you the same, reduced, 9.5ish, or 8.5:1ish compression ratio.

 

For 1972, the hi compression pistons were dropped all together, so combined with the 58cc heads, all 2 & 4bbl engines had 8.5:1ish compression ratio.

 

 

 

 

So, yes, swapping a high compression Gen II short block in place of a Gen III low compression short block could likely boost HP, even if the displacement dropped (304 to 290, 360 to 343, or 401 to 390).

But swapping a high compression Gen II short block in place of a high compression Gen III short block would more than likely cost you HP & torque, due to the loss of displacement.

 

Also 401 engines used a unique, bigger cam, while all other (non-California) AMC engines from 290-390 got the same (smaller) cam.

So swapping a HC 390 in place of a HC 401 short block would cost you both 11cubic inches, AND cam timing.

[AMC-MJ]

Again thanks for the education, the 390 came in 10ish & 12ish the 290 n 343 where 9ish n 10ish . . . Both in 2bbl and 4bbl applications again except the 390 which was 4bbl and 8bbl.

 

But AMC offered all the performance parts to make any of the 6 engines do as you wished.

Mike

[streetjeep2.5]

Got any weight specs for these engines in order to compare to the GM 350?

Also, what standard transmissions bolt to them (4x2 application)?

 

Editing my own post: Asked the weight question then found this:

http://www.team.net/sol/tech/engine.html

Ford small blocks are the best for weight in the "V-8's easy to find performance parts for" category. Buick 350's weigh about the same as the 289/302.

[MancheKid86]

can't wait to see pics :yes: :thumbsup:

[AMC-MJ]

Yes I am trying to figure out how to post some photos with my black berry lost my net at home, but engine is out of bed and on engine stand and sitting in the shed/ shop ! ! !

 

:-) progress is slow but progressing ;-)

Mike

[jpnjim]

Got any weight specs for these engines in order to compare to the GM 350?

Also, what standard transmissions bolt to them (4x2 application)?

 

Editing my own post: Asked the weight question then found this:

http://www.team.net/sol/tech/engine.html

Ford small blocks are the best for weight in the "V-8's easy to find performance parts for" category. Buick 350's weigh about the same as the 289/302.

 

Good reference,

but I'd take it with a grain of salt, since it's compiled from so many sources, and there are so many different configurations to each engine.

 

You could easily add, or subtract 50-60 lbs to any of those engine weights depending on how they're dressed (with, or w/o A/C compressor, exhaust manifolds, smog equipment, flexplate/flywheel, even the air cleaner assembly is heavy on some engines).

 

I'll say this,

the AMC block is heavier than a Small Block Chevy block,

and the AMC heads are heavier too.

 

Though the chart calls the AMC V8 @ 540lbs, and the SBC @ 575.

 

 

 

I don't know how accurate it is, but urban legend/lure,

and current BS usually has the Buick 215's (alum) as the lightest small blocks,

then Buick 350's,

Ford 302's,

SBC's,

and SB Chrysler LA/Ford 351W's.

 

AMC V8's & Ford 351C's are heavier still,

and once you get to Ford 351M & 400M's you're crossing over to 'medium blocks'.

 

Early AMC (gen I), Stude & International Harvester engines are sometimes called 'Medium Blocks, but really deserve their own category,

since they are small to medium cubic inch engines, but weigh more than some big blocks.

 

Early Hemi's were also 'pre-thinwall technology' engines like the AMC/STUDE/IH engines,

but with HUGE Hemi heads to add even more weight.

Mopar Poly's are equally big, heavy with small displacements & tough to categorize.

 

Lure then usually as the 400-455 Buicks as the lightest 'true' big blocks,

and Hemi's as the heaviest.

That leaves Mopar wedge B's & RB's, Pontiac's, Old's, Nailhead Buicks, early & late Caddy's,

BBC's, W head Chevy's, Ford FE's, Y's, 385 series, SOHC's, & Boss 429's to fight it out for position in between. :ack:

[AMC-MJ]

Ya well I personally like the AMC V8s you go from 290cid to 401cid factory with out them Siamese bores . . . Now after market I hear you can get 422cid ? Out of an AMC V8 . . .

 

Now I tried the mobile photobucket yup that was a failure nothing special just 3 shots of a 290 on an engine stand, Well I'm going as quick as money and time will allow :-( !

 

Mike

[jpnjim]

Ya well I personally like the AMC V8s you go from 290cid to 401cid factory with out them Siamese bores . . . Now after market I hear you can get 422cid ? Out of an AMC V8 . . .

 

Now I tried the mobile photobucket yup that was a failure nothing special just 3 shots of a 290 on an engine stand, Well I'm going as quick as money and time will allow :-( !

 

Mike

 

If you want to pop for an Indy block & billet crank, you can get a 500" AMC. :yes:

 

I forget what the biggest stock block AMC I've heard of was, but it was over 422". :thumbsup:

[AMC-MJ]

My progress photos added:

 

 

 

:cheers: Engines out of the bed, on the stand and in the shop/shed :cheers:

 

See i'm working on it ;)

Mike

[AMC-MJ]

Merry X-Mas MJ:

 

I got a set of scaled down "V8" badges for the MJ featuring the early model "V" and later model "8" to go with my project. Blending the vintage with the more modern . . .

 

 

Mike

[streetjeep2.5]

Now that v8 badge will be kewl! :drool: Gonna go right under the Comanche Badge on the fender?

[AMC-MJ]

Yup, one on each fender right under the "comanche" badges :)

 

Mike

[streetjeep2.5]

The length of an AMC V8; shorter or longer than a SB Chevy? I know the Ford SB is longer which makes it less of a desired swap. but the AMC?

[jpnjim]

AMC V8 has wider cylinder bore centers, and a much deeper aluminum timing chain cover

(that also houses the ft mounted distributor, fuel pump & oil pump) than a SBC,

so it is definitely longer than a small block Chevy.

 

 

I have a chart with L/W/H somewhere,

if I find it I'll post it.

[AMC-MJ]

Is that 88' a 2WD or 4WD ?

 

Mikey