3.8L BuickV6/914 Conversion, Took my first prolonged ride... Options

[dbledsoe]

this morning. Got into commute traffic to the muffler shop down the road from where I work. About an 18 mile drive, country roads and into downtown Boise... with open headers. (IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/stromberg.gif) that sucker's loud when pulling away from a stoplight. Definitely got the looks from the other asleep at the wheel commuters. (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) Every thing was hot straight, and normal with the engine/drivetrain... but there is some vibration. Must not of got the engine balance quite right. Oh well, just have to get going on building the 4.1L Buick engine and do a better job of it, plus throw more hot rod stuff in that engine. (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

[drgchapman]

I put a Buick v-6 into a vega about 25 years ago....it vibrated too

[Phoenix-MN]

When you had the engine balanced, did the machine shop balance everything? The even fire V6 is an externally balance engine so all parts are neccessary to do a correct job (front balancer, crank shaft, pistons and rods, fly wheel, and clutch pressure plate). If done properly the V6 will be a smooth running engine.

Paul

[dbledsoe]

QUOTE (Phoenix-MN @ Oct 18 2005, 05:50 PM)

When you had the engine balanced, did the machine shop balance everything?  The even fire V6 is an externally balance engine so all parts are neccessary to do a correct job (front balancer, crank shaft, pistons and rods, fly wheel, and clutch pressure plate). If done properly the V6 will be a smooth running engine. Paul

Paul,

I didn't have the balancer or the pressure plate and I'm getting convinced that the machine shop wasn't all that knowledgable about the Buick V6. But that's my fault for not doing a bit more research before hand. I've learned a lot building this conversion and am getting started on building the 4.1L and hope to have it done by spring, then I'll swap them out and tear down the 3.8, which will then likely go into my white 76 914 (my next project).

Don

[dmenche914]

Buick V6 are not he most smooth engines, even the even fire type. On my 914 / Buick 3.8 l conversion I wnet crazy with vibration until I found the prior owner did not intall the "special" conversion pilot bushing int he flywheel. Im my search for a solution I pulled the tranny to look a the flywhell, I thougt it was good, as I saw the original Buick pilot bushing pressed intot he crank shaft, little did I relize at the time that the tranny drive shaft is not long enough to reach the stock Buick pilot bushing. Only later On pulling the tranny again did I notice the problem, ordered the correct buching from Kennedy or renagade and got it going much much smoother.


good luck

[Slowpoke]

How bad is the vibration? I built a 3.8 from parts one time and had the machine shop give me 3.0 balancer by mistake. Damn, that thing went through rod bearings like you could not believe. Look to make sure it is an external balancer. But, I agree, they do vibarate some. Buick tried to eliminate it with motor mounts. If you are not using a stock mount or like replacement, you will notice it more.

Nice car by the way.

Peter

[dbledsoe]

QUOTE (dmenche914 @ Oct 18 2005, 07:42 PM)

Buick V6 are not he most smooth engines, even the even fire type. On my 914 / Buick 3.8 l conversion I wnet crazy with vibration until I found the prior owner did not intall the "special" conversion pilot bushing int he flywheel. Im my search for a solution I pulled the tranny to look a the flywhell, I thougt it was good, as I saw the original Buick pilot bushing pressed intot he crank shaft, little did I relize at the time that the tranny drive shaft is not long enough to reach the stock Buick pilot bushing. Only later On pulling the tranny again did I notice the problem, ordered the correct buching from Kennedy or renagade and got it going much much smoother. good luck

I got the Kennedy pilot (roller) bearing with my conversion kit bought from them so I don't think that's the problem (installed according to their instructions), but that's a good thought to keep in mind.

[914GT]

Great to hear you got it out on the road. Sorry to hear you're not completely happy with it though, but you're still looking ahead to the future. Maybe when you get the exhaust on it you'll be in a better position to really evaluate the vibration. I'm sure you're already convinced that it's an engine balance issue, but maybe another check of the motor mounts or inadequate clearance to the body at some point is worth the time. Maybe also double check your belt tension on the water pump/alternator in case there's some strange vibration going on there. Anyhow, great looking job and I'm sure you'll get the bugs all worked out.

[dbledsoe]

QUOTE (Slowpoke @ Oct 18 2005, 08:48 PM)

How bad is the vibration?  I built a 3.8 from parts one time and had the machine shop give me 3.0 balancer by mistake.  Damn, that thing went through rod bearings like you could not believe.  Look to make sure it is an external balancer.  But, I agree, they do vibarate some.  Buick tried to eliminate it with motor mounts.  If you  are not using a stock mount or like replacement, you will notice it more. Nice car by the way. Peter

Peter,

It's kind of odd but the vibration is at its worst at one particular RPM. The bad part is I can't tell you exactly what the RPM is because my tach, while working with the MSD ignition box, is not correct. The vibration, according to the tach, is at its worst at 3K rpm, but I know it isn't 3k rpm as the tach appears to read somewhere in the neighborhood of 1 and 1/3rd to 1 and 1/2 greater than the actual RPM. Idle shows an RPM of 1200 and the engine is barely keeping itself going without the alternator light coming on. At an indicated 60mph I'm showing 4K plus RPM, and I know darn good and well that it ain't going 4K rpm at an indicated 60mph from the original Type IV engine RPM! Be that as it may, above or below 3K RPM (indicated) it smoothes out.

I did not get an original 3.8L balancer with the engine so ordered one from "GM Parts Direct." Only thing is, it appears identical to the balancer that came with my 4.1L Buick V6 in terms of the offset balance built into it (of course that was after the fact). Once I received it my thought was that a 3.8L balancer should have a smaller offset weight than a 4.1L due to the larger bore diameter i.e., greater reciprocating weight to offset. Unfortunately the balancer didn’t come in time to meet the machinist schedule, who assured me there wouldn't be a difference anyway, (IMG:http://www.914world.com/bbs2/html/emoticons/bs.gif) and I went for it because I am more familiar with many years of building small block Chevy engines and their harmonic balancers, which aren't a balancer at all (except maybe on the 400 inch smb Chevy) they are actually a damper.

I am using standard Buick replacement rubber motor mounts (not made in the USA, but made in India... and like what the fuck do Inidans know about Buick motor mounts (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif))? And Porsche sport mounts at the transaxle end, all rubber (elastometer) based mounts.

Thanks for your thoughts, they are truly appreciated.

Don

[LvSteveH]

Late model even-fire buicks should be as smooth as any other modern engine. The rumors about vibration are left over from the old odd-fire version in the 70's. I've got a 3.8L that runs very smooth, no hint of vibration at all. Keep in mind that it was balanced properly when built for high RPM use. There are a couple shops that specialize in the 3.8, may be worth working with them to get it just right. The Grand National motor is nothing more than an even-fire 3.8L, having only a stronger crank, and lower compression pistons. Your 4.1L should already have the turbo crank in it. I’ve got a 4.1L that puts out around 250-275hp, should be pretty peppy. Have fun.

[Phoenix-MN]

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif)
The owner of the shop where I had my machine work done personally races a turbo Grand National. He came highly recomended by the local boys.

[dbledsoe]

OK, here it is. Proof positive that my 914 conversion really does run. Look!!! It is somewhere other than my house, or on jackstands. This was taken in front of my in-laws house in Boise. Oh yea, that's me. Took the wife out to dinner in it and gave her a minor demo of its power as we were trying to cross Broadway Ave. after leaving the resturant. She was definitely impressed... I could tell by the tone of her yelling at me to "SLOW DOWN!!!" (IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/monkeydance.gif)

[dbledsoe]

My thoughts (for the winter) of ducting air through the fog light holes to the radiator didn't work. First trial run with the bumper installed had the engine temp approaching 210 degrees within 2 miles of driving in 70 degree weather. That led to a hasty cut (IMG:http://www.914world.com/bbs2/html/emoticons/sawzall-smiley.gif) in the glass bumper, which cured that problem.