oddfire crank in newer 231 ?

Hey guys.. I bought a car with a buick 231 recently.. and plan to pull it out, and possibly use it in my Jeep. My idea is to overhaul a new motor for the jeep.. using the 225 oddfire crankshaft in the 1980 231 block.. using it's pistons, rods.. But I need to know if the crankshaft mains and rod jornals are the same size ? I have a good set of heads and qjet 4bbl intake manifold for this 231 block. Also, swap in the oddfire camshaft... or a new one.

What do u guys think of this ? Will it work ? the main reason I want to do this is because of the heads and intake manifold I have for the 231.

 

I went though my books.. and got the engien specs for both motors...

225 bore/stroke 3.750x3.400

225 main 2.4993-2.4997

225 rod journal 1.9998-2.002

231 bore/stroke 3.80x3.400

231 main 2.4995

231 rod journal 2.2487-2.2495

Looks like the crankshaft will go in fine, but I'll have to hang the 231 pistons on the 225 rods or, get .05 over 225 pistons ?

I also took a look at the 252 buick v6.. same thing as the 231, just a bigger bore of 3.97 early, 3.95 later. But I doubt the extra 21 cubics is worth the effort ?

 

This is purely a guess but I bet it will work but with some seal compatibility headaches possible --I don't know.

IMO, don't mix and match and eliminate self imposed punishment, frustration, and negative cash flow

The 4.1 was a good engine but nothing to get excited about. It does have the hard-to-find rolled fillet crankshaft that was used in Grand Nationals (compatible in all even-fire RWD 231's). Even in a naturally aspirated application, the bottom end is exceptionally trustworthy. Some turbo guys switch to the 4.1 block for the additional bore because 3.8's can't be safely bored to 4.1 specs. Is it worth it? technically yes but I think it is more a personal preference and bragging rights thing.

 

Swapping Cranks

oh yes--all

a Dauntless odd-fire and say a 1975 Buick 231 odd-fire are the same except for Bore-- .050 difference.

A 1977 231 odd-fire (the very last month of the manufacture) odd-fire is different in many ways though-- a hybrid of an even-fire and odd-fire with Oldsmobile V8 rods and pistons, different heads, intake, block casting, one piece cam/gear and soforth. I have seen a few in wreaking yards taken 1/2 apart and looked at the guts--- and they would be the most rugged odd-fires of all.

 

yes to all ?

Another thing to add is.. the oddfire in my jeep is a 1966.

steve, intresting about the 77 oddfire motors. What do u think about my oddfire crank in a 80 3.8 block ?

I am assuming the rod lenths are the same between blocks and hopefully the pistons will go on the 66 oddfire rods. So, I dont see why this wouldnt work.

I read somewhere the newer heads wont match up the old oddfire 225 blocks very well. So thats why I want to use the newer block. Otherwise.. I'd use the 225 block.

 

80 even-fire

Well Dan,
An Odd-fire crank 225 (dauntless) will NOT go into an even-fire block.
A 1980 even-fire engine is basically the same dimensions on the outside as an old dauntless-- but the machined surfaces, deck hights and main bearing spacings are different for the guts.

The last odd-fires in 1977 might work---or might not have cranks that fit-- into RWD 3.8 liter Buick V6s, But I do not know for sure.

BTW some builders have converted Chevy V6 4.3s to odd-fire engines using special cranks though. --- Pretty $$$$$ though.

If you weld some of the water passages in later even-fire heads, and re surface them putting later heads on a 225 dauntless is possible.
I talked to machinists about it who said the there are milling problems due to the welded areas-- which wreaks the milling/plaining machines blades--- so I would have to pay $$$$ to them to do it.

There is a whole world of engine building in the even-fire world of Buick V6s--- the Stage II and Buick V6 Turbos and ...

its a matter of $$$$--- that is 10s of thousands of dollars for a custom engine, verses the few hundred dollars for a strong running dauntless, or a early even-fire.--- or do a even-fire Chevy V6 4.3 liter -- or a TBI 4.3---- or a couple of thousand for a Vortex 4.3 Chevy V6. Or adapt a FWD Buick 3.8 fuel injected like the Australians put in Toyotas and Rovers.

But it you do not have an odd-fire you loose that "rumble" sound and primal soul fulfilling life-force affect of a dauntless.

 

For the kind of money you are talking to put this hybrid engine together you could just spend a few hundred dollars and port / polish the original Dauntless heads and put a good RV cam in and make at least 200hp, upgrade the oil system a little and have a very good strong running engine, if you want to make power with the Dauntless v6 talk to nickmil he has done several of these up to 400-500hp without doing what you are trying to do. Trying to mix and match these parts you will end up with a fortune in a motor that is really not much better than what you started with would have been with only a rebuild and a few good mods.

 

from what i have read, the 225/231 are the same block only (thats on the novak site) .050 bore diff and large ports in the heads. http://www.novak-adapt.com/knowledge/buick_90_v6.htm
some intake manifolds wont line up with the smaller port sizes, but if you used the large 231 heads with the large port intake it will work. from what i have read and been told, they are the same heads or are very close and are interchangable. so, late model heads/intake with oddfire came/crank/dist all on the 225 block should work nicely.

also, the 3.8 has a smaller deck height than the buick 350. the rods are alot shorter (almost 1/2 "). i have both, the 231 oddfire and the dauntless 350 and the 350 even "looks" bigger from the outside. 231= 3.4" stroke/350= 3.85". pistons are the same tho. the speed pro pistons are the same part number between the 231 and the 350 so you can order the compression you want to match the cam/4bbl.

hope this helps you make a descision. but the 225, with its smaller intake runners, will make alot of low end torque for rock crawling (higher intake charge velocity) but will lack on top end. the large ports will suffer on lower end power, but make it up on the highway. a cammed up 225 with the 4bbl and 9:1 speed pro pistons will rawk. my old roomie had a 225 with a carter (edelbrock) 500 on it and it would light those rear tires up.

 

Thanks for the replies

No, I'm not looking to spend $$$. I was just hoping between the 2 motors the parts were well interchangeable. I guess this isnt the case.. I do like the idea of putting the newer heads/intake on the 225 block. I'll look into that more.

Has anyone swapped newer heads/intake on a 225 block ?

I have a set of 85 GN style 3.8 heads and a stock 83 regal 4bbl qjet intake I want to run. I think it will be better than my current setup. 225 heads with an 4bbl offenhauser intake with square to spreadbore adapter for the qjet i have. Also, the exhaust ports are square and supposly flow better on the newer heads.

 

Dan. You might want to pick up a copy of Pat Ganahl's V6 Performance. About $20 or so - amazon/ebay/etc. My understanding is that trying to use newer heads can cause sealing problems as the shape of the water passages changed quite a bit.

 

maybe i need to get one aswell..=)
rowdy j

 

i had read smokey yuniks book on building v6s and have not found anything that says head gasket leak problems on 225 - 231 head swaps.
the biggest thing i read on turbo regal boards is to use the headgaskets correct to the year of the heads as alot of revamping of heads on 84-85 and newer heads for turbos. maybe early 79-81 heads will work right..
also if the heads are 84 or newer you have to get correct year head bolts for heads .some are beveled ,some use once "torque to yeild"
and the newest version the block has sunk threads and different length head bolts that will bottom on a earlier block so heads never get torqued properly.i have 79 heads and turbo with manifold i want to try.
should be stout. :stout:
hope it works for ya.
andy

 

You might want to go to this thread and just pick up another 225.

http://www.earlycj5.com/forums/showthread.php?t=14748

I want it, but too expensive to ship. May be alot closer for you and cheaper in the long run overall. Just a thought.

 

all the even fire :v6:'s I've com across had the #5/6 journal off set. thus makeing a crank swap ether full of $$$$$$ or impossible. save the coin, get a newer block (231/252ci).