[Fast Eddie]

The 340 was definitely under rated at 275 H.P.

An interesting thing is Chevy built a specific 1969 LM1 combination to compete against it in NHRA.

The 1969 LM1 was a 350 4 bbl under rated at 255 H.P. and is still competitive today.

1969 Nova and Camaro SS models had the 300 H.P. version as standard equipment.

Only lighter non SS cars got the 1969 LM1 package to compete against the light 340 Darts etc.

LM1 cars got Muncie 4 speed trans rather than the Saginaw normally used in cars less than 300 H.P.

Most also received 12 bolt rears instead on the 10 bolt units found in non SS cars.

The 1969 LM1 was discontinued after about Feb 1969 and was replaced by the 350 2 bbl. 250 H.P.

Interesting history!!

Thanks
Randy

I did some of the original dyno development on the 340 when I was running the dynos at Chrysler. The 4 bbl 340 running under lab gross conditions (no air cleaner, deep sump pan, max spark and F/A, cold intake manifold, no accessories, and lab exhaust) would make in the range of 320 to 330 HP at 6000 rpm. The 275 HP advertised number was for NHRA Stock classificationn to make it more competitive.

 

[Fast Eddie]

The 340 six pack would have had even more power if they added a little more to the mold to eliminate the pushrod bulge in the intake port. And maybe a little bit more cam. 340's made a lot of power without spending a lot of money.

There was no real manifold development for the 6-pack. .................

 

[Fast Eddie]

I had a 68 340 4 speed fastback and it would pull to 6K.

We would run power runs to 6000 rpm on the 340" but it peaked at 5600 rpm. We ran power runs to 4800 for the 318" but it peaked at 4400 rpm. We always ran the power runs at 400 rpm increments and would shut down when the power fell off at the next speed after the peak.

 

[Fast Eddie]

The 360 never got a good rep mainly because it came out in the smog days.
If you were on a limited budget and you were hopping up a 70's A body would you go with a expensive 340 or go with the 360.?

The main issue with the 360 was it had a production cast crank,,,,,,,,,,,,,,,,,,,,

 

[Fast Eddie]

If I remember correctly the 1971 and 1972, 340 and 360 engines were equipped with 3418915 heads, so-called "J" heads, because of the cast-in J in three locations (backwards in one place) on each head. These were either equipped with 1.88 inch/1.60 inch valves, or 2.02 inch/1.60 inch valves, and have "open" chambers with volumes of 65-73 cc.

Police sedans were equipped with a high performance 318 engine, which was equipped with 360 heads and a 4 barrel carburetor (Thermoquad through 1984, Quadrajet from 1985)??

 

[Fast Eddie]