Performance AMC blocks

[tarior]

What we need now is brand new, cast iron, performance engine blocks, heck Shafiroff is casting SBC blocks with a +1" deck height, MC ought to be able to do the same for us!

[1970amx]

That would be nice.

An all new AMC cast iron block with lots of meat so that we can take advantage of the large bore spacing. In my dreams I can see 500 cubic inch AMC motors in every Jeep and AMC car.

Of course this new block needs to sell for 1/2 the price of a new Indy aluminum block and have options for increased deck height and crank to cam bore spacing so it can go with a huge custom stroke crankshaft.

I want one.

[tarior]

Heck, I'm not even worried about making large displacement, the AMC V8 is a small block, after all. But I would like to see something with a little more deck height and be heavy duty enough to withstand sustained high rpm operation. You getting this, MC?

[Holeshot]

...and what exactly do you think is wrong with the 401 block design??

What do expect to achieve with the taller deck??

What do you think is so great about 500 cubes?

In case you didn't know, there was a ProStock racer named Shirley Shanahan (spelling?) back in the 70s, with '70s technology, that was turning 9.8 sec @ 139 MPH with a 2500+ lbs. AMX and an iron headed iron 360 inch AMC. Somewhere around 720 HP.
That's around 2 HP per cubic inch. Not too shabby for a stock-block, stock-headed, carbureted engine with a points distributor and no nitrous.

* 9.89@139MPH, 2520 lbs.
* 401 + .022" (4.187")
* Moldex 401 crank de-stroked to 3.26", 6.19" SBC rods, 302 SBC brgs.
* Piston specs????? (probably SBC)
* Offset guides, 2.165"IN, 1.86"EX,
* .628" lift, 324 duration.
* Pair of Holley 750 Double Pumpers.
* 40 lb. flywheel, 5.12:1 gear.

My '69 AMX was going 9.88 @ 128 with a 401/automatic and a single carb, no nitrous, and iron block & heads. That's well over 600 HP.


http://www.american-powersports.com/.../amx/mybbo.jpg

[Holeshot]

[1970amx]

Nothing is wrong with the factory block but it is only good for a limited amount of cubic inches.

I am running 9.80's now at 135.5 mph with a factory 401 block and Indy SR cylinder heads....so I am running faster and at a higher mile per hour than your example you are giving.

Why would I want the cylinder block you ask.....because I want more cubic inches than a stock block can supply. Cubic inches is horsepower and torque.

There is no replacement for displacement....and I want all I can get.

[Holeshot]

...and, there was a fellow named Mark Donohue who drove a Penske AMC to several TransAm championship titles, with iron AMC block and heads.

And there was a fella named Bobby Allison who raced NASCAR's top series with iron AMC block & heads. Underfunding allowed only one win, as I recall, but the AM engine went 500 miles at 8000+ RPM for at least a couple of seasons.

There was also a guy named Breedlove who drove an AMX with iron heads & block to 106 speed records, including a 189 MPH top speed record. In the early seventies. Carbureted & points ignition.

The AMC design is hard to improve on. All the aluminum "race" heads available, and fully ported & prepped iron heads still make as much (or nearly) power. Definately not cost effective horsepower gain to buy Edelbrock or Indy heads. The Edelbrock heads won't even take as large a valve as a stock head will.

About the only notable weak point is in the oiling system. That should be adressed in any high output build anyway. Waiting to see the Bulltear dry sump pan rite now.

[tufcj]

Shirley Shahan (Drag-on-Lady) ran an SS/AMX. These had specially prepped 390s, bored .030 over. They ran a cross-ram intake and dual quads. The heads were also highly modified with 2.080 intakes and 1.74 exhaust valves (even square ports). Still respectable with an all iron engine.

The Drag-on-Lady race car may be on display at the 2007 AMO show in Denver, and do some passes at Bandimere. We're still working out the details.

Bob
tufcj

[Holeshot]

First of all, you are not playing by the same rules that the example was, 70s ProStock. Very limited rules, only 360 cubes, stock chassis. Limited ancient tech. 2500 lbs min. No NOS.

Second, more cubes does NOT equal more HP in all instances.

Increased bore size actually makes peak HP go DOWN, while increasing torque.

The only benefits of more cubes are:
* You can use larger valves if you can build some heads with more distance between the valves (good luck).
* More torque.
* If you are going to use NOS, turbo, or supercharge, you don't need to rev as high to make th big numbers (like a small cube engine)

Smaller engines (can) rev higher than bigger engines and HP is made at higher RPMs. (why do you think the 302 Z28s were fast?) The limit is when the bore gets too small for the needed valve sizes. That's why the Japs went to 4 valve heads. I think there's several hundred front-wheel-drive four-cylinder cars that would make you load up and cry all the way home. I think they are in the high sixes now. So much for comparing apples to oranges.

The example of my AMX is a 3000+ lb stock chassis car with bolt-ons, and NO NITROUS, no non-amc rods, pistons, block, or heads. Adding 350 HP of nitrous could bring that ET down to the high 7s or low 8s, with traction & gearing dialed in.

I noticed you did not reveal how much your car weighs, or if it has a tube chassis, or how much NOS you are using, what rod/piston combo is. It would be faster with a smaller engine revving higher.

[Holeshot]

Argue with HRM!!!
-------------------------------------------
December 1971, Hot Rod magazine

Look at what AMC’s up to...again. Shirley and N.L. Shahan trade in their successful SS/D AMX for a team of all-AMC small-block Pro Stocks
By Steve Kelly *

One of Shirley Shahan’s brighter qualities is that when she steps out of
her race car, onlookers are often set to wondering how such a pretty, pert and fetching young lady is able to be at least as good as her male competitors. One of the reasons is that her car is well-maintained by her husband, H.L. Shahan. H.L. is the only moniker most racers know him by, and the initials certainly don’t stand for "Hard Luck". Back in 1965, Shirley took the H.L.-prepared Super Stock Plymouth to a Winternationals eliminator title. When the pair switched over to American Motors products in 1969, it wasn’t long before Shirley established new D/Super Stock records; and when they were broken, Mrs. Shahan set new marks for the same class in 1970. While Shirley is able to effectively get grease under her fingernails, she has found it best to leave the super-wrench work to H.L. And now, with a Gremlin and two Hornets running as a promotional
effort for AMC dealers, H.L.’s work has been aided by the talents of Paul Phelps and Louie Wlosinsky, both employees of Landrith Corporation, a small race car prep shop near Detroit. Dave Lan+ith, former manager of Hurst Performance, just happens to be one of the organizers behind the promotional program for the AMC dealers.

The AMC-dealership-backed drag team is meant to be a means of impressing potential customers in,each of the 21 American Motors sales zones. Naturally, a good amount of help was rendered by the AMC engineering department to make sure the cars perform as well as possible. The efforts have been rewarding. Best time-so far-on a Hornet is a 9.89-second e.t. and a speed of 139.52 mph. The Gremlin can’t get close to the Hornets, its best performance being a 10.01-second e.t., with a top speed of 137.20 mph. One of the advantages the Hornet body has is its longer wheelbase and greater rear overhang, which help to get the car off the line quicker, due to more and better weight transfer to the
rear. Ironically, when the cars are run "below weight" (i.e., below NHRA Pro Stock minimum), neither car runs equal to the times turned in at their legal Pro weight. The Gremlin can run with a weight of 2220 pounds, and the Hornets, owing to a lot of "metal thinning", come in at ten pounds less. Legal NHRA weight for the 360-cubic-inch-displacement American Motors cars is 2520 pounds. The Gremlin is used most often as a match racer for special outings, and the Hornets are put to work as showcase match
racers and as entrants in national events.

Except for wheelbase and body configuration, the Shahan cars are identical. The chassis work is quite refined. Front suspension is coil-spring-type, with each spring specially wound from .238-inch-diameter wire in a three-inch-wide coil. The left rear spring has five leaves, while the right has six. Each rear spring is 1% inches longer than stock, and they’re moved inward, for an increase in car height and also for tire clearance. The leaves now are shackled to the sub-frame rails, rather than bolted to their sides. Rear spring rate, at the wheel, is 145 pounds per inch on the right, 135 pounds per inch on the left. No traction bars are employed, and the rear axle housings are super-tough Danas with 9%-inch-diameter ring gears. The housings are narrowed 6% inches. Rear gears are 5.12:1,
axles are from Henry’s Machine and Detroit Lockers are used. The only change made to the front end, besides the new coils, is shortened upper A-arms so that each car rides with 7%-degree positive caster, meaning that only the outside edge of each front tire is pushed against the track. Shocks are Hurst/Gabriel, the rear ones located aft of the axle housing.

Steering units are from a ’65 Corvair (aluminum box), and there are lots of wheel turns from lock to lock to negate chance of driving a crooked "straight" line by accident. Air-heart disc brakes are fitted all the way around, front rotor diameter being 9~/y inches and rear 11% inches. Each car has a Line-Loc, but this is used mostly to warm up the rear
tires in the staging area. The brakes are one of Airheart’s "Pro Stock Kits", and the saving in weight is 16 pounds.

A stock six-cylinder model drive shaft has performed with no sign of twisting and no breakage. Transmissions are Borg-Warner Super T-10s, modified by Doug Nash and equipped with Hurst changers. Between each engine and gearbox is a 10'/y-inch Schiefer clutch (Borg & Beck style) and a 40pound steel Schiefer flywheel. Rellhousings are Lakewood hydroformed steel safety units.

The chassis have been highly detailed for the cars’ ten-second workouts, and the engines have been well-built by H.L., working closely with the AMC engine wizards in figuring out a few new techniques. For instance, only the concave surfaces of the intake ports were polished. The convex surfaces were left in stock finish. Factory tests showed a drop in horsepower when the entire port was mirror-polished. Even though the engines measure 360 cubic inches, they don’t share bore-and-stroke specs with stock AM 360 V8s. The bore now is 4.187 inches, an increase of .107-inch, and the stroke is reduced by .18-inch to 3.260 inches. The crankshafts are by Moldex, made from 401 AMC VS forgings, and have been Tuftrided. The journals have been cross-drilled for better oiling, and Federal-Mogul F77 bearings are used.

Bottom ends are reinforced with Milodon 392 Chrysler four-bolt-style main bearing girdles adapted to fit. (Reportedly, the switchover is fairly easy.) Compression is close to 13.7:1, and a new-design dome Venolia piston is now in use. Rod length, center to center, is 6.190 inches (stock is 5.875 inches), but this is not a Chevy rod despite its same length.
Twelve-point, 7/16-inch rod bolts are used on the shot-peened and polished, forged-steel Carillo rods that use bearings "adapted" from a 302 Chevy V8. Crane roller lifters run on cams of the same make, lifting .628-inch at the valve. Opening duration is 324¬?. Offset valve guides are used in order to use larger-diameter valves. This is a tricky maneuver, but worth the time and labor. Intake valves are 2.165 inches across; exhausts measure 1.860 inches, come from TRW and are suspended by dual (inner damper) springs by Crane. The 1.6:1 ratio rockers are Crane-made, forged-aluminum and needle-bearing-bushed. The relatively high compression dictated 0-ringing the heads.

The likeable Mrs. Shahan hasn’t been spending much time at home, nor has she been taking very long to traverse the 1820. No doubt a large number of her drag racing foes would prefer that she stay home with the laundry and cleaning, but chances of her trading a gear-shift handle for a vacuum cleaner are remote.
-------------------------
Rear weight bias for both Hornet and Gremlin should be about 54% to the rear for cars to run equal with same weight.

BELOW-Interior is free of nonessentials. It’s furnished with a blonde and S-W gauges.

ABOVE-Intake manifold is individual-runner type, specially fabricated by AMC. Two types of Holley carbs have been used: 4500 I-R and 4700 series double-pumpers. The 750-cfm-size double-pumpers work best at present time.
LEFT-Arrow indicates frame rework so that springs could be moved in for tire clearance and chassis lifting. Note the gusseted housing and Airheart discs.
BELOW-Shirley does her own wheel-lifting thing with 9.89 Hornet.