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OLD TIMERS: School me on the Chevy 250 I6

posford

posford

Piece Of Shit Ford
Joined
May 19, 2020
Member Number
62
Messages
1,368
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NH
Yeah I know, there's a chance of tech in GCC, its better than the 50 daily political threads :flipoff2:

No the answer isn't LS swap it.

Back story is I've got a 67 M715 with a bad motor. I finally killed it after 3 years of fucking with it, I was digging piston skirt out of the oil drain hole :laughing:
It's got one of the oddball 230 Tornado OHC motors in it that has next to no part availability. I'm done fucking with these stupid things.
I've found a Chevy 250 from a 70 Chevelle that allegedly ran great. I know its not a super cool swap, but it keeps it an inline 6, while making parts actually available. Side benefit is I plan to let the wife's younger sibling use it as a senior project, so trying to make it as straight forward as possible and make sure I know what all the snags will be in advance.

What kind of quirks do I need to know about these things?
I'm seeing that starters can be a weird 3 bolt bellhousing mounted design. Plan is to use the SM465 I have with an 80s bellhousing, either mech or hydro, I have both. Should the block already be threaded for a block mounted starter, or is that going to require some fucking around? I have a starter for BBC with 168t flywheel, it should fit if I use a 6cyl 168t flywheel, right?
From the pictures it looks to be all original, should have 1bbl Rochester carb correct? Anything special I should know about those? Its old enough that it doesn't have the integral head/intake BS, so I could swap on an Offy later, but for now the plan is KISS.
Looks like power steering pump brackets are unobtainium, which is fine this thing still has Armstrong steering and Manuel brakes.

Anything I'm missing?
 
Should be a standard chevy starter. Trucks used the bellhosing mounted starter with the old cast iron bellhousings
 
electronic ignition upgrade is pretty sweet, once sibling understands points and dwell off course. PCV absolutely needs to work correctly or mosquito fogger.
6=8 has been building good stuff for those, long time.
https://cliffordperformance.net/
 
The combined manifolds like to rust out. They came with HEI which is nice and if you want to update to TBI down the road it's pretty straightforward to swap to an ESC era HEI module and lock out the advance. I swapped the dizzy from a 292 into my IHC BD240 to do this.

Anymore it's probably going to be easier to find complete gm L6's in boats. Lots of mercruiser 165hp 250's and 200hp 292's in 70's fiberglass boats that are getting scrapped.
 
yozsi said:
Random question, what carburetor did your 230 have on it?
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God awful Holley 1920, specific to these military trucks. I was down the rabbit hole of rebuilding the economizer body when the motor decided to end itself.
 
crisbee1 said:
electronic ignition upgrade is pretty sweet, once sibling understands points and dwell off course. PCV absolutely needs to work correctly or mosquito fogger.
6=8 has been building good stuff for those, long time.
https://cliffordperformance.net/
Click to expand...

I'll likely keep points, because I've never had much issue with them. I've got a Sears Engine Analyzer to tune the points/dwell and everything :grinpimp:
Good to know about the PCV, I tend to overlook them.
Clifford stuff is nice, but $$$
 
posford said:
God awful Holley 1920, specific to these military trucks. I was down the rabbit hole of rebuilding the economizer body when the motor decided to end itself.
Click to expand...

That's what I thought. I just redid the economizer on my 1920 that's on my slant six. Carb runs awesome now. Idle emulsion tube was all clogged the fuck up. Had to remove and replace all those little plugs that's on that metering block.
 
yozsi said:
That's what I thought. I just redid the economizer on my 1920 that's on my slant six. Carb runs awesome now. Idle emulsion tube was all clogged the fuck up. Had to remove and replace all those little plugs that's on that metering block.
Click to expand...

I threw mine in the ultrasonic a handful of times, giving it the air blast in between ultrasonic sessions. I disassembled a spare economizer and it wasn't going to go back together. I believe the slant 6 ones and the .mil ones are slightly different.

I spent 2 weeks fucking with it when the fuel pump seal failed, filled the crankcase with gas, and stupid me fed it a steady diet of starting fluid trying to get it to go and when it did, it was bad :laughing: not my most brilliant moment but I was exhausted from trying to make the POS run right.
 
posford said:
God awful Holley 1920, specific to these military trucks. I was down the rabbit hole of rebuilding the economizer body when the motor decided to end itself.
Click to expand...

I've never had the nerve, but did you see you can get holley 1920's on ebay for $95? Or universal 1-barrel carbs for $65? I've bought some ebay special chinese snowmobile carbs that worked well out of the box in spite of some pretty terrible machining but never though to look for automotive carbs till recently.
 
larboc said:
I've never had the nerve, but did you see you can get holley 1920's on ebay for $95? Or universal 1-barrel carbs for $65? I've bought some ebay special chinese snowmobile carbs that worked well out of the box in spite of some pretty terrible machining but never though to look for automotive carbs till recently.
Click to expand...

I hadn't seen that. Moot point now :flipoff2:

I fear that "universal" is just a poor chinese translation for "runs like shit unless you spend a ton of time tuning it, at which point buy a good carb" but then again that translation wouldn't separate fools from their money as easily
 
All I have to add is that I took a 250 from a late 70's Chevy van and replaced it for a broken 292 in a 64 C10 pickup years ago, had to fab some enginemount stuff on one side, and use a little flexpipe on the exhaust as I remember, no issues with the starter as I can recall, was a Powerglide though.
 
Gunwalls_Buckthorne said:
The tornado has parts on egge. I rebuilt one a few years ago.
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Piston set costs more than its worth, and the cam is pretty wiped thanks to pudding soft 60s metallurgy. If it was a resto, maybe, but this ol girl is pretty haggard

m715.jpg
 
posford said:
Piston set costs more than its worth, and the cam is pretty wiped thanks to pudding soft 60s metallurgy. If it was a resto, maybe, but this ol girl is pretty haggard

Click to expand...

Agreed, even rebuilt and new it was a hunk of shit.
 
I had a 250 in a ‘70 swb that I used to own. The 250 was kind of a fun, sweet running engine, at least until the the ring gear came off the flywheel on the highway and broke the block. It did have a standard block mounted starter. They aren’t real torquey, a Chevy 292 or gmc 302 might be better if you can find one.
 
Jackie Treehorn said:
I had a 250 in a ‘70 swb that I used to own. The 250 was kind of a fun, sweet running engine, at least until the the ring gear came off the flywheel on the highway and broke the block. It did have a standard block mounted starter. They aren’t real torquey, a Chevy 292 or gmc 302 might be better if you can find one.
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A gmc 302 would be a good choice.
 
posford said:
Piston set costs more than its worth, and the cam is pretty wiped thanks to pudding soft 60s metallurgy. If it was a resto, maybe, but this ol girl is pretty haggard

Click to expand...

Still a pretty cool old truck. I would put a V8 in it.
 
Jackie Treehorn said:
I had a 250 in a ‘70 swb that I used to own. The 250 was kind of a fun, sweet running engine, at least until the the ring gear came off the flywheel on the highway and broke the block. It did have a standard block mounted starter. They aren’t real torquey, a Chevy 292 or gmc 302 might be better if you can find one.
Click to expand...

Finding shit now can be a real bitch, the upside of the motor I'm looking at is it was running a month or so ago.

I'd prefer a Ford 300, but they seem to be unobtanium in a carb'd form. Yeah I could swap a carb intake onto a EFI motor but that seems like a waste of money
 
DMG said:
Still a pretty cool old truck. I would put a V8 in it.
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I've considered it, and its been done and well documented. I think it loses a bit of character with a cookie cutter 350 swap.
 
M92PV4U said:
A gmc 302 would be a good choice.
Click to expand...

Very expensive parts if you rebuild it or just water pump...Has the same clutch housing as the 216-261 Chevy that's different bolt pattern than the 230-292/SBC housing. 302 is a nice engine for pre 55 GM trucks
 
posford said:
I've considered it, and its been done and well documented. I think it loses a bit of character with a cookie cutter 350 swap.
Click to expand...

Then do a caddy 472. :flipoff2:
 
Allen Grove has the power steering pump mount with the alt mount $185
 
Truckedup said:
Very expensive parts if you rebuild it or just water pump...Has the same clutch housing as the 216-261 Chevy that's different bolt pattern than the 230-292/SBC housing. 302 is a nice engine for pre 55 GM trucks
Click to expand...

I didn't know that they had a different bellhousings, our water truck is a '53 and has that engine.

Do you happen to know if it uses the same distributor as the 216-261?
 
I have an Olds 455 sitting in my garage. I bet it wouldn't get much worse gas mileage than an overtaxed small I-6.
 
I run a hopped up 250 in my 63 Nova. Lumpy cam, ~9.5:1 compression, Offy intake & 4 barrel, cast headers, etc.

When you’re looking for bellhousing/transmission/flywheel stuff, treat it as a 2 piece seal small block chevy (pre ~‘87). Everything is exactly the same.

For example; I run a 97 T56 behind my 250 with a flywheel for a 2 piece main SBC, starter from 97 Camaro. Everything bolted right up. With 4.56s (currently setting up 5.14s) it is a really fun car to slam gears and hear that buzzin’ half dozen sing, especially autocrossing it. Probably have more into the 250 than a 350 or 383 at this point but I love it. Bonus: it takes more time to gap the spark plugs than install them.

Another source of parts is 12bolt.com. He has the cast iron “headers” and tons of parts for inliners. If you’re just looking for a basic motor, then the stock exhaust manifold probably won’t be holding you back too badly.

Edit: Your big block flywheel and starter should work fine. If the staggered bolt holes aren’t drilled in the 250 (because Chevelle) you can use a universal SBC/BBC mini starter and slide it to the second set of holes for the 168t big block flywheel.
 
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