Other than Weber and Clifford, is there any aftermarket stuff such as roller cams and lifters for these motors? And fuel injection, too? 
CK5
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Any aftermarket support for 250 inline 6 motors?
- Thread starter thatK30guy
- Start date
Just a thought...
A 250 CID can be machined to use a 327 rod and Piston. Clifford stuff is good and a 6-71 works better.
IIRC the distributor from a 4.3 V6 is the same drive and length, making the TBI unit a possible junk yard upgrade for the fuel injection
A 250 CID can be machined to use a 327 rod and Piston. Clifford stuff is good and a 6-71 works better.
IIRC the distributor from a 4.3 V6 is the same drive and length, making the TBI unit a possible junk yard upgrade for the fuel injection
TARussell was big into 292's, he had a custom grind cam from Crane and a tbi kit from Howell. He also found some OE propane application pistons that bumped the compression up to (I believe) the low 9's.
The distributors on straight sixes use the same housing as the V8's did,they added an extention to the drive gear to operate the oil pump--so you might be able to make a 4.3 one work on a straight six if you wanted to cob up a home brewed fuel injection setup..............................................................................................................................................................................................................I always liked the 4 barrel intakes and headers they sold for inline engines years ago...but most 4 bbl carbs are just too big for them,a 390 CFM is about the max I'd go with..I made a adapter to put an Edelbrock 600 CFM on my 250 six in a '79 C-10 I had,I ended up removing the linkage that opened the secondaries,as it was actually bogging down when I'd boot it,it ran nice on just the primary barrels..but I had no hot cam,headers,etc too................................................................................................................I saw a few straight sixes at car shows in rat rods that had a turbo off a 231 Buick adapted to them,and they ran sweet..one guy I talked with said the 327 pistons are a direct fit on a 250 six,and also said he thought roller rockers for one might work on one too..he was going to try using a fuel injector setup off a straight six Ford 300 or Jeep 4.0 on his ,but didn't elaborate on how he was going to go about it...I think there are a few performance websites for chevy sixes online,if you google for them you'll come up with some I'm sure..
bigred88
1/2 ton status
I have an AMC 258 I6 in my Spirit. I'm getting ready for a high performance rebuild of it, so I've been doing a lot of research. I have no idea about the parts availability for the Chevy 250, but as far as the carbs go, the Holley 390 is a pretty popular one for a mild street engine (at least with 258s, but I figure for a difference of 8 cubes, the carbs should be about the same). Truck avengers (465 cfm?) are fairly popular too. There are guys that run 600 cfm carbs, but they tend to be more toward the drag race type- I think 600 is too much for a street engine. There's also plenty of guys I've seen mod one barrel TBI setups to work (or even multiple one barrel TBIs), I'm sure the same idea would cross to a Chevy engine. Obviously that's much more custom as opposed to readily available aftermarket, though.
There's a decent number of folks running turbos, too, from full on drag race applications running low 11's to daily driven J-10s.
There's a decent number of folks running turbos, too, from full on drag race applications running low 11's to daily driven J-10s.
I don't want to build a drag motor or any hopped up engine. The idea with the 250 and fuel injection is to see what kind of mileage I can get.
I used to have an '81 SWB K10 with the 250 in front of a 465 and 3.73 gears. The truck got 18 mpg on the highways easily, while riding 33's. I would love to have another SWB with a similar drivetrain but with the TBI to see if I could bump the mileage into the 20's somewhere.
With todays high prices of cars and trucks within 10 years of new, it just makes more sense to stick with old school rigs and modernize them to adapt fuel injection hence the reason I want to go back to what I used to have.
I used to have an '81 SWB K10 with the 250 in front of a 465 and 3.73 gears. The truck got 18 mpg on the highways easily, while riding 33's. I would love to have another SWB with a similar drivetrain but with the TBI to see if I could bump the mileage into the 20's somewhere.
With todays high prices of cars and trucks within 10 years of new, it just makes more sense to stick with old school rigs and modernize them to adapt fuel injection hence the reason I want to go back to what I used to have.
63chevyll
1/2 ton status
I'm a fan of the 250 s and 292s. Lots of people do tBI conversions.
People who.haven't driven them don't.know how cool and amazingly torquey they are.
I have a soft spot for I6's and 3 on the column
People who.haven't driven them don't.know how cool and amazingly torquey they are.
I have a soft spot for I6's and 3 on the column
Cool! Maybe I can push for 30 mpg with a 250 then!
I've converted 2 carbed AMC I6's to TBI fuel injection using the kit from Howell. Don't see why it couldnt work on the GM 250, I believe most of the parts in their kit are 4.3 parts. Best thing I ever did to those motors, On a stock Jeep I could get 20+ MPG if I tried.
For your home or for fuel?
It's about $4/gallon here in the mountains now, even in Denver it seemed to be similar to gas.
Irish1941
1/2 ton status
We built a few race 250/292/302 inliners.
Not a lot out there but what there is pretty good.Do yourself a favor and visit http://www.inliners.org/
Loads of info. Alot of B'ville stuff but some really cool daily driver EFI setups.
Also try http://www.stovebolt.com/
And http://www.patricksantiquecars.com/ Geared towards pre '70s sixes but still some good info.
TBI on 250/292 is very doable but the heads are the bad part. Without alot of work, performance suffers. EFI outflows the head.
Just a thought but South American GM had EFI 250 into the mid '90s.
Another tip: the 250 ran up to '84 in trucks and vans, which means you can get a 6 banger HEI that drops right in to 230/250/292 & 302.
Isky still grinds inline cams as do a few others.
Lots of old speed stuff on ebay. Try to find a Wayne head or Offy 4 barrel intakes.
Guy ran Bonneville 4 yrs ago (I think) with a Wayne head on a 302 GMC stuffed in a '87 Camaro and did 180 mph plus.
Let me know if need anything and I'll see if I can set in you the right direction.
Not a lot out there but what there is pretty good.Do yourself a favor and visit http://www.inliners.org/
Loads of info. Alot of B'ville stuff but some really cool daily driver EFI setups.
Also try http://www.stovebolt.com/
And http://www.patricksantiquecars.com/ Geared towards pre '70s sixes but still some good info.
TBI on 250/292 is very doable but the heads are the bad part. Without alot of work, performance suffers. EFI outflows the head.
Just a thought but South American GM had EFI 250 into the mid '90s.
Another tip: the 250 ran up to '84 in trucks and vans, which means you can get a 6 banger HEI that drops right in to 230/250/292 & 302.
Isky still grinds inline cams as do a few others.
Lots of old speed stuff on ebay. Try to find a Wayne head or Offy 4 barrel intakes.
Guy ran Bonneville 4 yrs ago (I think) with a Wayne head on a 302 GMC stuffed in a '87 Camaro and did 180 mph plus.
Let me know if need anything and I'll see if I can set in you the right direction.
1BEATK5
1/2 ton status
I have a set of high comp. Jahns pistons if you are interested.
My buddy in high school had a 68' camaro with a healthy 292 and a muncie 4 spd. That thing had tons of torque. Great engines. I've always had a soft spot for the inlines.
My buddy in high school had a 68' camaro with a healthy 292 and a muncie 4 spd. That thing had tons of torque. Great engines. I've always had a soft spot for the inlines.
I found a 250 HEI distributor in my garage recently ,hanging on the wall,complete with cap,coil,plug wires,etc, that I took out of either my '81 G-10 van or the '79 C-10 I had, that both had the "camel-humper" 2 barrel version of the 250 six,with the intergrated head ,when I swapped V8's into both of them.....I may have another one somewhere in the rubble in there too....................................................................................................I kind of regretted swapping a 305 into the '79 C-10,it was pretty cool with a 250 six and got better gas mileage than the V8,and wasn't all that much difference as far as power went.....the 307 I put in my '81 G-10 van was from a '73 Malibu,and that was a poor choice,but all I could find in my price range at the time..I looked for a few months before I found ANY V8 with a carb for sale,and that was in 2002!--it's the last year for the 307,and the first year they put EGR valves on them,and the lightweight low compression heads,that lowered the HP to 115!..and it was gutless compared to the older 307's I had that were 200 HP/300 ft/lbs torque..........................................................................................................I think the original 250 six had more torque than the '73 307 does..the van really became a slug when I had to swap another rear end in it after the side gear chowed the diff housing in the original one....I got a 2.73 ratio one for free,and it was bad enough with 3:08's in it--I should have held out for a 3:42 ratio one...now it'll wind up to 75 mph in second gear before it sounds like its anywhere near redlining!--but it bogs uphill and accelerates like a VW bus......gas mileage is not any better or worse than the 250 six was...the straight sixes were a lot easier to work on than the V8's and I put myself thru a lot of work for no real good replacing them with V8's...................................................................................................I really liked the 235 or 261 straight six my old '56 Chevy 3200 pickup had...you could start off in second gear (three on the tree) from a dead stop and that thing would just pull ,without pinging or bucking..you could lug that thing down to 10 mph in third and not have to downshift it..many guys who rode in the truck thought it had a 283 in it till I opened the hood...I drove a truck just like it with a 283 and my truck seemed better at pulling from low rpms ,despite the other truck having a SM420 tranny....................................................................................................I had a friend who had a '68 Firebird with a 292 straight six ,coupled to a TH400 tranny...he worked at an auto machine shop and got the engine free after a customer never returned after they rebuilt it...the car went pretty good,and it could bark the tires when it shifted into second gear...he built it for reliability more than speed,and I bet that power train was as close to bullet proof as you could get !.........................................................................................................Funny how the straight sixes we despised as youngsters as an "old farts engine" suddenly look quite desireable now,huh?....too bad so many of them got yanked out and scrapped,for no good reason,in our quest for more power & speed...
House would be below a dollar plus road tax for your truck. You know how to work it so I won't lead into it anymore. I was in Dillion not long ago and realize what the price of gas is compared to here (maybe .20 more) and at $4 you should be getting lube with it. They are quoting home contracts at less than a dollar for the winter right now.
Oh and I approve of this thread. I plan on a HOT 302 for my 1955 GMC.
Oh and I approve of this thread. I plan on a HOT 302 for my 1955 GMC.
Truer words couldn't be spoken here!
I started out with HP SBC's in my younger days and then bought the SWB with the 250 and never complained about the mpg but I always tried to do something to mess that motor up so I'd have a reason to upgrade to a V-8 and more power. Never could do anything. Then I sold that truck to buy some 33's on Weld wheels, brand new.
After that, I started bumping up to the BBC's and K30's. I never looked back after that but over the years I become more and more leary of the mileage and fuel costs out of these monsters and with each passing day, I kick myself more and more for getting rid of that SWB 250.
Hence is the reason where I'm at today at 42 and wanting to keep my old school status with these trucks but trying to improve mileage most importantly so I can drive further and longer without wasting time or money at the pumps.
Today while I still have BBC's and K30's, they've become nothing but toys. My DD is a '98 Jimmy with the 4.3 and it runs fine but its showing its age and wear at 165K+ on it and the tranny is getting worn. I don't really want to put anymore money into this car as I'd rather have another SWB with the 250.
greywolf
1/2 ton status
i miss my 250 i6 in my k10. i sold it to a kid and he ran it into the ground, 316k miles started everytime and now its a crossbreed of parts.
you told me not to sell it but i didn't listen and now i regret it
you told me not to sell it but i didn't listen and now i regret it
When I was of the age to buy my first truck I looked at a 1980 k10 with a 250/465/205. It was a reg cab step side with about 4" of lift. Pretty Janer but I loved how it looked. Always wonder how life would be different if I would have got it and not a z28.
I'm not intending to dampen any parade, but I think going to EFI just for the purpose of economy is kind of a wasted venture. At least that's what I think after going from a Q-jet to TPI/vortec heads/roller cam/roller rockers/headers etc. I definitely had high hopes of hitting 20-22MPG, and without a diesel (or a non-stock CID) I think that's near impossible in one of these trucks.
If you really get into it (lean cruise, more compression, etc) you can squeeze out at least 10% more economy, maybe. As well, compression on the low-grade gas is going to be somewhat limited by the combustion chamber, and I'm guessing the inline 6 chambers aren't the "new tech" stuff like Vortecs, which will tolerate at least 9:1 on 87. Had I known better at the time I would have understood quench, and would have figured my actual compression ratio when I put it together.
Unfortunately, I've seen the same freeway mileage with a carb (properly tuned) and EFI. I don't think off-road MPG is much different. There are other advantages of course, but it ends up being a pretty expensive endeavor, especially if MPG is the driving factor.
But, don't get me wrong, doing one-off stuff is fun, and for those that like to play with electrical stuff, EFI is it.
Dad's 454, everything being equal but the cam, intake and induction (stock TBI) at best is holding to the 10% "rule" I made up, and that's exclusively highway mileage.
If you really get into it (lean cruise, more compression, etc) you can squeeze out at least 10% more economy, maybe. As well, compression on the low-grade gas is going to be somewhat limited by the combustion chamber, and I'm guessing the inline 6 chambers aren't the "new tech" stuff like Vortecs, which will tolerate at least 9:1 on 87. Had I known better at the time I would have understood quench, and would have figured my actual compression ratio when I put it together.
Unfortunately, I've seen the same freeway mileage with a carb (properly tuned) and EFI. I don't think off-road MPG is much different. There are other advantages of course, but it ends up being a pretty expensive endeavor, especially if MPG is the driving factor.
But, don't get me wrong, doing one-off stuff is fun, and for those that like to play with electrical stuff, EFI is it.
Dad's 454, everything being equal but the cam, intake and induction (stock TBI) at best is holding to the 10% "rule" I made up, and that's exclusively highway mileage.
