Redline on 6.2?

[Vaughn MacKenzie]

I picked up a deal on a 82 Blazer I couldn't pass up with a Banks kit on it. The tranny has been modified on it too and the previous owner said the shift points weren't right on it.

I drove it to work this morning and decided to tromp on it after it was warmed up to see what it'd do. Well it rapped out in first gear and woulnd't upshift and by the time I decided it wasn't going to do that I was at 4600 RPM. It has an Autometer tach on it and gauging by the engine sound it's accurate (runs around 1400-1600 at cruising speed in town). I'm guessing 4600 might be a bit much for a 6.2.

Can the shift point be dropped by adjusting the kickdown cable? Not very familiar with GM drivetrains.

Thanks, Vaughn

[john8662]

I'd suspect that the tach is off, if it's an autometer tach it's probably got the sender for the tach mounted on the alternator via a big hose clamp.

The upshift problem is most likely due to either the TV cable out of adjustment (probably isn't the whole problem).

Or, the tranny was rebuilt and the rebuilder installed the wrong governor in the tranny for the 6.2, this has happened to me.

The 82/83 model 6.2 had the governor set at 4300 RPM in the injetion pump, the 84+ were at 4100.

So, unless the injection pump has been adjusted with less govenor weights, then it's not going to let the engine run 4600 RPM.

[Vaughn MacKenzie]

Thanks for the info John. I'm not sure if the pump has been messed with or not. The tach could be off, but by the way it sounded I think the tach is close. I have another 6.2L Blazer but this one revs WAY higher than it does. So yes it may have the wrong governor in the tranny. I'm going to try fiddling with the TV cable though.

How hard is it to change or correct the tranny governor?

Vaughn

[john8662]

Use extreme caution messing with a TV cable. You can burn up the tranny in the process.

How is the tranny shifting otherwise (besides at WOT)? Because if you are getting good shift points and it kicks down when it's supposed to, then it's likely not the TV cable.

My way of testing TV adjustment is to go for a drive. Come to a complete stop, take off really easy, you should feel the tranny shift into 2nd gear early. Once it shifts, punch it to the floor, the trans should shift back down to 1st, if it doesn't you're out of adjustment. A good symptom of a tranny out of adjustment is "hanging" before shifting, the TH700 behind a 6.2 usually shifts early and can sometimes somewhat lug the engine under really really light acceleration. when a tranny is waiting too much (say 2200 rpm) before a shift (especially first gear) its the sign (to me).

Hope this helps. I don't know much about the Gov replacement, I had the problem with a reman tranny that was still under warranty by a local shop (who I won't let rebuild another) and they finally got it fixed (after mechanic threw a wrench through the windshield). I got a new windshield (needed it too). But, they replaced the Gov because they finally admitted they installed the wrong one. I sold that vehicle though (afraid of the tranny)...

[NH2112]

I don't think the 82 would have a 700R4, wasn't the first year for them 1984?

If you have a TH400, replacing the governor is easy but adjusting the VRV (Vacuum Regulator Valve) on the pump is a bit tricky. The Haynes diesel manual has good instructions, though.

[BobND]

The 700-R4 WAS available in 1982.

[john8662]

oh yeah, 82 was the 1st year to get the 700 and the six point two diesel. Most blazers have the TH700, military being the TH400.

[Vaughn MacKenzie]

OK, back to the top. . . when driving normally the tranny doesn't seem to kick down very well, unless I mash the pedal down pretty far. Like if I slow down to about 20 then accelerate moderately it stays in high gear.

But if I'm driving along at say 45 or 50 and totally tromp it the darned thing shoots right from 3rd into 1st gear and revs past 4000 RPM.

The tranny is a 3-speed, it has been built a bit by the previous owner, but I'm clueless about GM trannys (and autos in general).

Previous owner says tach was calibrated and is accurate, BTW. But can you tell me if regularly rapping it past 4000 is OK or not?

Vaughn

[john8662]

Sounds like prev owner installed a TH350 (My mortal enemy) which is a 3 speed.

I don't think that rapping the engine that high is good practice, although it can be fun at times...

I'd find a tranny shop with a little more experience with the TH350 and describe whats going on with it.

Does anyone else on here have much experience with the TH350?

[Colorado Kid]

I don't have any ideas for your tranny, but I know that in Germany Hum-Vees and Military GM diesel trucks are run screaming along against the governor all day, apparently without harm. They burn a lot of fuel that way though.

[More Power]

The net horsepower ratings for these engines is at 3600-rpm. The various DB2 equipped 6.2's and 6.5's I've had would govern very close to that figure. The marine DB2 in the 6.5 Project is governed at ~3800.

The governor is adjustable, and may explain readings above 4000. Or it could have been assembled incorrectly. Personally, I'd get it down to 3400-3600...

Jim

[Vaughn MacKenzie]

It seems to make good power to 4000, then starts to fall off. But yeah for longevity I should get it tweaked down to 3800. Thanks guys. I am probably going to pull the pump at some point and have it worked over by the injection shop here in town, and also have them adjust it to the turbo motor's specs.

Vaughn