Personally I don't see the fuel mileage with the ,300 .final gear isn't 1to 1 like 350 or 400 then add switch pitch like my 65 has and mpg over60 mph sucks enen with 28 in tall tires. Best a race trans the way I look at it.
High gear is 1:1 just like the others. :TU: The ones I had were both '68's without the variable pitch converters (last year for it, and only year without the 'switch pitch' if I'm not mistaken) You can tell by the seat of your pants a difference. Taking off from a standstill it's a bit lethargic (with the 350), but once it winds up to about 30 MPH, it really turns on and pulls harder than the other transmissions. If you can get over the worse holeshot, the mid-upper speeds makes the engine feel like it has more power. The 455 had so much frickin power that the steep 1st gear didn't matter. A wide power band with lots of torque is the ideal engine for the ST300 trans in a street application.
:idea2:Looking at head gaskets for the sbb 340 and comparing them to the head gaskets for a 350,it looks like they may be interchangeable. If so,you can lower your compression ratio on the 340 by changing the head gaskets?(not sure if they're interchangeable,if anyone knows for sure please chime in)o No: If they fit,the .040" composite gaskets should drop your compression by about .5:1.Or TA has copper gaskets that are .020",.030",.040",.060",.080",and .125" thick,should be able to reduce compression with one of those for less than an engine swap.:Brow: Never tried it before,and don't know if it will work,but maybe a composite gasket stacked on top of a steel shim gasket might be a cheaper alternative to copper gaskets? Would be approximately .060" compressed thickness,and would drop your compression about .77:1. Doing any of the above,you will need to check pushrod length because Buick has non-adjustable valve trains. Combined with an overdrive of your choice,should give you the most economical "swap" to run on regular,and get better MPGs. Goodluck Derek
