My 401 teardown progress

[Holeshot]

I like those Ross pistons!!! Looks like valve reliefs specific to AMC. Are there two different part numbers so you don't end up with the big relief on an ex valve?

My experience with HDMD sucked!!! They ripped me for $100 (on about a $1200 purchase, the price went up $100 while my check was in the mail, they agreed to give me the previous week's price on the pistons), lied through their teeth repeatedly, called me a liar repeatedly, gave me bad feedback, and would NOT retract & give my $100 back until I retracted my complaints to Ebay. They even changed their ad to throw in "free" rings because they were so worried about my complaint to the FBI. They have either have someone on the inside at Ebay or someone doing some good html programming, because when they changed their ad to fight my claim, the sale a month or two earlier where I bought mine changed as well. I'll NEVER HDMD again. ALWAYS use PayPal!!!

[jeepsr4ever]

Hmm I havent heard of that either IIRC but no doubt AMC did some goofy stuff and new things are learned every day.

[Holeshot]

Did you ask ProMotion where they can borrow one from? I know for a fact they used one on my 390, I saw the machining bill (I don't think they lied). It is fairly common for a shop to not have the plate for AMC, my local shop "Shaker Racing" doesn't have one, so you have to know the guy who has it and get it from him or have him drop it off.

They really paid attention to detail on the assembly, there was a dab of orange RTV on the end of each valve to keep the keepers from falling off if the valves floated and the piston ever smacked one. The AMC design (depending on what kind of piston, stock style anyway) hits the valve totally square and will bend pushrods before the valve breaks.

One place where ProMotion DID mess up was in using grooved shims to shim the valves instead of spring seat cups & the shims UNDERNEATH of those seat cups. The small, pointy end of 2 valves had dug into the grooves of the shims and split & spit the shims & broke the ends off of the outer springs, one was broken roughly in half. Still was shifting at 7200 RPM & running damn quick, even with the 2 broken springs & one bad cam lobe from the shim shrapnel. That is why I now will ALWAYS use those spring seat cups, with the shims underneath.

I'm not sure if they did the porting & flowbench work there or farmed it out. It was a very nice job with each cylinder numbered and looking like the previous one, exhaust ports like mirrors. They also had the Torker extrusion honed and it looked amazing. I may have some pics, I'll have to dig.

It dynoed 518 on the HotRod Magazine chassis dyno they brought to Englishtown for the Power Tour.

I may be able to get my friend to send his for your use but he'd for sure have to have some security that it would be returned in a timely & undamaged condition, they are NOT cheap!!!

[Holeshot]

The part # of Ferrea 1.74" SS undercut & swirl polished exhaust valves:


The part # of DynaGear 2.08" SS undercut & swirl polished intake valves:


Here's what my compression ratio worked out to be, evidently the car's previous owner thought 9~1 compression would be ping-free, so he had PM put a dish in the pistons:

...ended up with close to 1/8" of clearance between the piston head & the cylinder head, .040"~.045" was what PM should have more vigorously insisted he run. Rarely does anyone argue with a customer about his engine, motorcycle, boat, etc.

[Holeshot]

Here's what one looks like:

[401 CJ7]

Hey holeshot, you should hop on AIM and we can talk there. My AIM name is in my profile.

He mentioned nothing about borrowing a torque plate. Are you sure you got it done there?

I'd like to see pics of your head and intake port work. Then talk about what else you had done.

[Holeshot]

If you must buy a kit, take a look at a reputable biz, like Flatlander Racing:

Stock kits:
http://www.flatlanderracing.com/rebuildkitsamc.html


HP kits with custom forged pistons (call 4 details):
http://www.flatlanderracing.com/hpkits-amc.html


They also have a Torker/Demon package deal with your choice of 650/750/850 Speed Demon for $659

I've never used a Demon but would not be one bit afraid to either.



They also sell Schnieder Racing Cams for AMC:
http://www.flatlanderracing.com/schcamsamc.html


They also have FelPro complete gasket sets:
http://www.flatlanderracing.com/felprosets-amc.html

Here's the first time I've seen the tall Milodon AMC valve cover ($61) listed:
http://www.flatlanderracing.com/milovc.html

Milodon AMC gear-drive for $375 (pays for itself compared to a $225 timing kit every 20k)
http://www.flatlanderracing.com/milotiming2.html
(be sure to inspect the oil delivery channels, most were mis-machined & eat distrib gears, EZ fix)

They even have stud girdles for AMC!!!
http://www.flatlanderracing.com/sgirdlesprostreet.html

& Venolia 401 pistons for $441 - those should be some great pistons.

Truly TOO much to list!!!!

Go to http://www.flatlanderracing.com/ and use their search engine on the word "AMC"

[Holeshot]

Another note on the AM V8 cams that won't come out the front:

Acording to my OFFICIAL 1971 AMC Technical Manual:
(a DIRECT quotation)

"The camshaft is supported by five steel-shelled, Babbitt-lined bearings which have been pressed into the block and line reamed. The camshaftbearings are step-bored, being larger at the front bearing than at the rear..."

So, either the blocks in question were bored by the break-time relief worker, on a Monday or a Friday, by a new guy, a dumbshit, or done that way for cam thrust control, I don't have any idea.

But I will also add that the 390 AMX (bought in about '88, prev owner had it stored for 10~12 yrs) that had the bw cam was 100% original, had the Grp19 cam & kit (& a very old "GatorNationals" sticker stuck to the dash), had 69k original miles on it, was 4-speed, PS, PDB, and weighed only 2,667, according to the title, which was based on the shipping weight.



And it pushed DAMNED easy, I can tell you!!! I pushed it in & out of my garages alone several times in the 8~10 yrs I had it.

I've had 2 other AMXs with identical options, both were over 3,200 lbs.

That weight difference would make the light one around six tenths quicker than one that weighs in as advertised. I never dragged it, but the lighter weight & cam would have it in the low 13s as tested by the magazines of the day (14.2 for a "stocker")

[Holeshot]

I think I would box up all the pieces and send them to Indy Head Service in Indianapolis. The shipping may cost a couple of hun but at least you would be getting a good job done.

Or maybe the real guru, Norm Brandes.

As far as the compression ratio, here's what Norm said:

"Brandes says AMC engines are not compression-sensitive, and he has run stock cast-iron heads at 11.25:1 without spark-knock on premium pump gas. "

So much for the naysayers.

I have an Indy Head Service labor price sheet here somewhere, I will try to find it, scan it, & post it, as soon as the 3-yr-old gets settled down!!!

[Holeshot]

Here's what Indy charges (a couple of yrs old) , for reference:




Here it is in a much larger size, easier to read:
http://www.american-powersports.com/...y/ihs_lab_.jpg