231 oddfire

[76luv]

i have a 1 ton chevy drivetrain powered by the 231 odd fire. my first time out was over the weekend and discovered that i may either have a problem w/ the carb, torque conv, and or the powerplant being not enough. i am running 38.5 tsl's and 5.38's in the axles w/spools front and rear, and a stock 205 behind a th400.
the problem was when in reverse with the wheels turned full either direction, i would give it gas and it would bog way down and eventuallly die. and getting it started wasn't happenin
do i need a higher stall converter, a better offroad carb like the truck avenger (but is only offered in 470cfm and up) or do i upgrade the motor.
anyone runnin the 231 odd fire please comment. thanks matt

 

[mbryson]

Interesting. I had a '76 Regal or Century or something with that motor. It was quite impressive in that mid-size car for 6 cyl. I'm thinking it would work great as a buggy motor in stock form. If you've done a few little performance mods, it should be downright OK. I'm fairly confident that had a Quadrajet on it, but my memory of that car is a little fuzzy. (a lot of memories from that era of my life are a little fuzzy )

How are your plugs looking? That should tell you if the carb needs some tuning or not. If the carb is OK, make sure your dist. advance is working as well.

 

[bryson]

A TH400 takes something like 50 horsepower just to turn the pump and internals(or something close...)

So, I'd guess that leaves you with 80 hosepower or so...? Trans may be a bit much for that engine... TH350 or 700R4 may be a better match. Even a manual maybe?

 

[Jinx]

A TH400 takes something like 50 horsepower just to turn the pump and internals(or something close...)

So, I'd guess that leaves you with 80 hosepower or so...? Trans may be a bit much for that engine... TH350 or 700R4 may be a better match. Even a manual maybe?

That was my first thought... the th400 is bulleproof, but it robs power...

and the story sounds like you are powering out...

 

[Jinx]

That was my first thought... the th400 is bulleproof, but it robs power...

and the story sounds like you are powering out...

sorry forgot to add that the spools with the wheels cranked are probably causing a bind that contributes to the powering out.

 

[jr4x]

What did your oddfire come out of?

225's & 305's = oddfire
231's & 350's = evenfire

Points dist = oddfire
HEI dist (unless swapped in) = even fire

IMO you dont have enough power to turn what you need to turn. A 4.3 may be a better plant for what you are doing. Or a t-18, t-19, t-98, sm465 4 speed with their 6.~:1 first gears or sm420 with its 7.20:1 first.

 

[76luv]

i bought the truck with the engine in it, so the swap was already done. Was told it was important to know that it was a 231 and was an odd fire not the even fire after a lot of research (trying to hook up some msd stuff) i found that the dist shaft has 3 lobes not 6 (good indication it is an odd fire) and the block is stamped 77' the guy cleaned it up to excelllent shape (polished intake, water pump, pan etc.) so i trust that when he said it is a 231. however could have been a 225 bored out but acording to http://home.off-road.com/~merls_garage/oddfire.html there were few 231 odd fires built, so this could be one.
anyway. the motor has some upgrades, but apparently not enough, i've wanted to do a 383 stroked... but this motor looks to good.
well thanks for the info and i'll check those plugs, i just signed up w/ RME and am impressed. thanks for your help

 

[Jinx]

second side thought, have you checked your ATF level? that could lead to the not moving, but not necessarily the powering out...

 

[76luv]

ATF level is good (b&m trickshift) , and i am running a hayden cooler w/ a
pusher style fan.

 

[Jinx]

ATF level is good (b&m trickshift) , and i am running a hayden cooler w/ a
pusher style fan.

Then thats really throws up back to engine, drivetrain bind, and realistically gear ratios...

I am trying to remember what the reverse ratio in a Th400 is I know 1st gear is 2.48. I believe a chevy np205 is around 2.05-2.08 I would have to check the novak site to be sure.

I would be thinking about a loMax kit (3 to 1 or 4 to 1, I can't remember) for the 205 before I started playing with torque converters.

keep posting we can figure this out.

 

[mbryson]

i bought the truck with the engine in it, so the swap was already done. Was told it was important to know that it was a 231 and was an odd fire not the even fire after a lot of research (trying to hook up some msd stuff) i found that the dist shaft has 3 lobes not 6 (good indication it is an odd fire) and the block is stamped 77' the guy cleaned it up to excelllent shape (polished intake, water pump, pan etc.) so i trust that when he said it is a 231. however could have been a 225 bored out but acording to http://home.off-road.com/~merls_garage/oddfire.html there were few 231 odd fires built, so this could be one.
anyway. the motor has some upgrades, but apparently not enough, i've wanted to do a 383 stroked... but this motor looks to good.
well thanks for the info and i'll check those plugs, i just signed up w/ RME and am impressed. thanks for your help

The odd-fire 231s were built from '75-77 or something like that. After that, Buick went to the even fire 231 which does share some parts (most?).

Logical sounding link that sounds similar to my experience/knowledge
http://home.off-road.com/~merls_garage/oddfire.html

 

[76luv]

k so i did some research and some thinking.
First off i went to novak and figured out my crawl ratio: anywhere from 42 to 50, depending on the torque converter. Ya i could do the lomax but if im going from 2.05-1 and upgrading to 3-1 that isn't goin to help me as much as i would like. most serious rigs are at minimum 60 and as much as mid 100's.
What i could do is a klune-v underdrive which (if i did the 4 to 1) would give me not only 4H and 4L but also KV4H and KV4L and a max crawl ratio of around 212. Probably to high, and i really don't know how affective my brakes would be, but here's my next ? , Does the tire size have anything to do with decreasing or increasing the crawl ratio?
The point has been made to me that it does, but im not really sure that it would be Noticable.

 

[BCGPER]

Sounds like what every one of us that ever wheeled a Toyota has gone through. You can stack gears behind that weak engine and get by, but keep in mind everything you add is robbing more power. I had my Toy set up at 108:1 if I remember right. Did ok off road, but not great and anything out of low-low range was a struggle.

If I did it again I'd take all that money I had put into gearboxes, and do a cheap TBI 350 swap and be happy on both ends.

 

[76luv]

Beautiful, thats just the kind of advise i need and want.
Someone who's been there And dealt w/ that.
I appreciate it.

 

[bryson]

Tire size absoulutly affects crawl ratio, but you are right in thinking that it may not be that noticeable. Stepping down from your 38.5s to 35s or 37s would be fairly noticeable on the street in high range, but once you've compounded gears in low range, you would probably notice very little benefit.

I agree with BC also... you can throw all the gearing you want at it, but the more you do, the more dedicated to "low range only" you become.