Overdrive is dogging, what are my options?

[savagek5diesel]

Hey guys, I've got an 83 jimmy, 6.2, and i live in northern california... lots of mountain highway driving. But even on level highways my overdrive can't maintain 65 without jumping from 3rd to 4th constantly. Not to mention by the time i hit the hills... 3rd gear just loses spead all the way up. It's sad when i'm following big rigs trying to catch a draft going up the hills. Would new diff. gears help this? I'm just running 33 inch mud terrains right now with stock ride height.

 

[bigblock454]

What is your current gear ratio?

 

[Can Can]

New gears might help. Like bigblock asked above, what are you currently running? With 33s, 3.42s or 3.73s would keep you in the higher end of the power band, which would help on the hills.

When's the last time you changed out your air filter. A dirty filter is the #1 enemy of diesel performance. Even a filter that is moderately dirty will reduce your power dramatically....FWIW, I swap in a new air filter twice a year.

I also think it's worth mentioning that 6.2/700r4s are kind of weak on big hills to begin with. There's some pretty extreme climbs up here as well and on most of them I'm forced to keep the truck in D. I don't lose speed too often but the ol' 6.2 sure does struggle at times.....

 

[savagek5diesel]

Right now i'm pretty sure the truck has it's original ring and pinion, 3.07's or something like that. I have a 4inch K&N air filter on it that is only 4 months old and i've already cleaned it twice. New ring and pinion sounds like the way i'm gonna go. Probably something in the 4. something range because i plan on a lift and 35-36inch tires in the next 6 months.
Whould a propane injection kit be a good idear for this kinda situation, as well as for off-road use. Like the full-throttle actuator set up? If so, does anybody know where i could look online to find a setup for a 6.2?

 

[bigblock454]

Propane does not help in an NA configuration, you just can't get enough air into the engine. If your gears are really 3.07 then 3.73s sound like the way to go depending on your future tire size. The facotry C-Code 6.2 were pretty weak, swapping over some J code heads and intake would help some. A decent intake and exhaust would probably allow for a slight increase in fuel amount while keeping acceptable EGTs, install an EGT gauge and do some testing.

I am guessing your air cleaner lid is standing off the base by 1" with that 4" K&N? A cool intake charge is very important in any engine. I would either buy a 3" element or modify the air cleaner assembly, all the air going into the engine should be cool from infront of the radiator.

How many miles are on your engine?

 

[savagek5diesel]

My engine just turned 98k miles. About the intake manifold and heads... i can get my intake port matched to the gasket size holes for dirt cheap, I have some friends in a machine shop that will do it for free if i buy them a pizza or lunch or something. Whould this help out significantly, or is the J coded heads and intake the best way to go. If so, what kinda price range am i looking at?

 

[82dieselburb]

I had the same problem on my with my transmission.B&M makes a new sleeve that goes in the 3-4 shift valve in the transmission they cost around $35.It keeps the trans from down shifting out of 4th untill 3/4 throttle.It worked great for me and was easy to install.I picked up my J code intake off ebay for $50 .There is not that much differance between the J &C code heads .If you want to upgrade you heads ,I would get some 6.5 heads,they are a much better design.If you really want some improvement do what I did a get a banks turbo and stinger exhaust.Now I got some power,it was a huge improvement. /forums/images/graemlins/burb.gif

 

[tRustyK5]

I noticed an improvement in power after port matching my intake...hard to put a number to it though.

Off topic a bit...how did your 65 Skylark end up with a 430? Shoulda got a nailhead (401, 425) or the 300 or 340 small blocks. the 430 wasn't intro'd until 67. /forums/images/graemlins/smile.gif Any pic's?

Rene

 

[bigblock454]

I would cruise ebay for parts, i often see 6.2 and 6.5 heads listed. Usually a rebuilt set of heads is close to $500, maybe $100 for the intake, $100 for gaskets and new TTY head bolts, $50 in antifreeze and 2 days of work. For the $750 you would be 1/2 way to the banks turbo kit that would get your exactly what you want.

 

[savagek5diesel]

i bought my 65 lark with the original 300sb in it. But, i have great luck with motors. 5 days later the motor blew on the way to school. This was my first car by the way. So i called the guy i bought it from because he was going to do the 430 swap but ran out of denero, so i took the big block off his hands and did it myself. I have some pics, but the car is still in the works and i still have to scan them. But i'll post em in my gallery eventually.

 

[tRustyK5]

Cool, I'd lovge to see some pic's! /forums/images/graemlins/thumb.gif

My first car was a 65 Wildcat 2 dr. 401 nailhead, TH400 with the variable pitch convertor, 3.23:1 gears and factory posi-track. Big, but fun as all get out.

Rene