AMX 390

put an ad in the wanted section, they are out there. To me only the 70 390 seems like the prices are high.

The best factory heads would be the later model heads. If building any AMC V8 I would use those instead of early heads. 

1969

The AMX 390 is a legendary 'muscle car' engine and for that reason there are very likely people who've tended to store them away for all their potential and future collectability.

Likewise, there are people who are willing to make sure they accomplish an authentic restoration of these very rare vehicles that originally came with these powerful big CID torque-maker engines.

*One of the 'big magazines' back in the day (I think it was Road and Track) tested the '68 AMX and they had a 'big husky formidable looking' American Motors engineer there at the testing ground who was quoted for saying '...the AMX 390 was designed for 8000 rpm...' (although no factory made engines were built with the more expensive necessary parts that would allow the engine to turn 8)

IMO? ...naw, you don't need to fret over sleeving an engine; sleeving 'done right' is a race engine builder's trick to strengthen the cylinder bores against flexing and thus to make more cylinder pressure by gaining better ring seal.

See Darton Sleeve's website: all current Top Fuel engines are sleeved! = that should tell you something positive about sleeving blocks!

Enginetech, out of Dallas Tx, currently sells HD 'race' sleeves for American Motors 390/401 engines (this part interchanges with '63-'67 Cadillac 390 engine) -these are centrifugally cast? (makes the iron grain more consistent, for increased structural rigidity) and 1/8" thick (opposed to standard 3/32" thick sleeves)

*What you will need to look out for is a sleeved block that has been weakened by throwing a rod, then repaired by installing a sleeve(s).

In this case, the damage to the block is concealed, but very plausibly lost some of it's original structural rigidity. ~that's what to look out for!

I would also advocate sleeving (if it's doable) all damaged 390/401 blocks because their rarity and will serve to keep the legend alive for cars that are not going to visit the racetrack -they'll still make a great powerhouse street engine; big CID simply makes big power.

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The AMX 390 is a legendary engine and definitely worth the effort to build.

This statement is not merely my own AMC-biased opinion, rather it is a provable statistical truth that American Motor's '69/'70 SS AMX held the most annual wins in it's drag racing class for a long, long time ...'till about '92, (for about 25 years after AMX production ended!) when finally Chevy Camaro was able to accumulate enough wins to take AMX's crown.

-AMC AMX won it's NHRA SS/D ? drag racing class about 10 times, then Camaro took it when the finally won 11 annual events.

This is a lightweight 540 lb. 390 engine that has an automatic power to weight ratio advantage from the get go, juxtaposed to 700 lb. Chevy 396 'big block'.

If you wanna build one, be smart & educate yourself, and get a copy of AMC's book named "Performance American Style" -written by actual AMC engineers, where good advice and good engineering never goes out of style.




Edited by amcenthusiast - Apr/20/2019 at 11:46am

Enginetech, out of Dallas Tx, currently sells HD 'race' sleeves for American Motors 390/401 engines (this part interchanges with '63-'67 Cadillac 390 engine) -these are centrifugally cast? (makes the iron grain more consistent, for increased structural rigidity) and 1/8" thick (opposed to standard 3/32" thick sleeves)

AMCenthusiast: