I get a fair amount of vibration from my 3800 -- interesting if that is to be expected -- thought I had some latent issue...

 

There is a count balancer in the 3800 II. When everything is working right 98% of the general public will not notice the vibration. It is very minor. The 4.3 was a bigger problem. We had customers trading in their 1 year old S10 (2.8) for the new 4.3 and some of them where pisses about the Vibration in their new truck that their one years old truck did not have.

 

How much different is the gas mileage between the 2 engines? I have a 95 3.4 and I managed from 30 to 32 mpg on the highway for an 18 hour drive. And if I drive conservatively I can manage around 24-27mpg city driving.

 

The 3.4 will get that on hwy if it's running correctly.

 

. When Buick designed a 90° V6 based on their 90° V8, they initially used a simple three-throw crankshaft laid out in the same manner as the V8 with pairs of connecting rods sharing the same crank pin, which resulted in firing intervals alternating between 90° and 150°. This produced a rough-running design which was unacceptable to many customers.
Around 1977 Buick upgraded the engine for smoother operation. It still had the same three throw crank but used a split-pin design which produced a 120° firing interval by staggering adjacent crank pins by 15° in opposite directions, simulating a six throw crank and eliminating the uneven firing. This made the crankshaft somewhat weaker, so if you intend to make a lot of power, the old type crank will be a better choice

 

^ Sure nice to have the Z28Pete encyclopedia on the board!

 

You mean WikiPeteia, don't you?

 

LOL.

Also at lemontime, the 3800 will get about the same mileage as you said your 3.4 does.

 

I get 30-31 MPG in my daily driving. Most of the 3.4 owners are saying 27-28 is their best.

 

Yeah I made sure I documented my miles and fuel used on the long trip because I was curious at what my actual mileage was since my 3.4 had 240 000 km on it at the time of the trip. At the low end it was 30 and the high end 32. And if I do city/highway as I did for the first month of the summer with my new job, my mileage ranged from 27-29mpg