Defender Source Forum banner
Cancel

GM - Chevy 250 Engine Conversion

177285 Views 782 Replies 86 Participants Last post by  Steyn, 
rdavisinva
Starting a separate thread on the 230 & 250 inline 6-cylinder engine conversions.
This engine conversion will bolt in and out of a 90/119/130 without vehicle modifications, like the 292 making it an easy, inexpensive weekend conversion.
Since the 230 and 250 blocks are 2" shorter than the 292, and the ancillary mounts are different, this thread should eliminate any confusion with the 292.

Why convert?
The performance and ease of conversion are remarkable and well-suited to a Defender-style vehicle.
After driving small diesel for over 15 years and having to deal with high maintenance and poor performance coupled with reliability issues it was time for something better.
We built conversions for the Diahatsu 2.8 TD, the Iveco 2.8 and 3.1 TDI, and the OM617, and drove Land Rovers with 200 and 300 TDI engines.
These mechanical diesel are generally loud and smoky while the GM inline 6 is smooth and so quiet, you often don't hear it idling or driving.

The Chevy 250 was used in cars, trucks, and vans, and had many industrial uses being manufactured from 1962 to 1990.
A good used GM inline 6-cylinder engine typically sells for under $500 and is usually less than $250.
The cam is driven by metal timing gears eliminating the need to change a timing belt or timing chain.
The GM High Energy Ignition (HEI) systems are extremely reliable and were used on military vehicles without issue when submerged.
Parts are inexpensive with over-the-counter support from any local parts store.

There were several different versions of the 250 engine with different cylinder heads.
Some of the heads had a separate bolt-on manifold, while other versions had the inlet manifold integrated into the head casting.
Both versions will fit into a 90/110/130 using our conversion kit.

If you want Electronic Fuel Injection (EFI), the Holley Sniper is a good choice.
We will be working out the details for the Sniper as we did for the 292 conversions.

The other deciding factor was the accessibility to the engine and all the components.
Everything is within easy reach making for much shorter work intervals.
I timed changing a starter with hand tools which took 12 minutes.

With HEI and EFI, the only maintenance is changing the oil along with the rare wires, plugs, cap, rotor, and air filter renewals.

We will be offering kits as soon as they are manufactured.
As of the date of this post, we are waiting on the engine adapter castings to be machined, which hopefully won't take much longer.
See less See more
Reply
Save
Like
741 - 760 of 783 Posts
C
was this a relitively simple conversion
Reply
Save
Like
rdavisinva
carcher said:
was this a relitively simple conversion
Click to expand...
Developed a conversion kit so the engine bolts right in without making any changes to the host vehicle.
Has more than enough power for a Defender.
The nice thing is the engine is basically maintenance free.
I am going on 4 years with mine and the only maintenance has been oil, oil filter, and air filter changes.
I paid $125 for the engine with about 46K miles, so started with a good runner that had all the factory alternator and power steering units and brackets.
Reply
Save
Like
  • Like
Reactions: 2
hanzo111
carcher said:
was this a relitively simple conversion
Click to expand...
As simple as installing a engine can be. Practically a direct bolt in. Funny I installed the motor thinking it would be more difficult but it really wasn't. I think it was easier than replacing my original 19j because of all of the pluming and crap that had to go back on that motor.

  1. 5 wires for ignition *I did add new sensors to communicate with factory guages and a trick rad fan setup
  2. new accelerator cable *go cart cable from Amazon
  3. clean or replace fuel tank, fuel pressure regulator to 3psi
  4. I am using a Rochester carb NO SNIPER for me
  5. have a shop fab a exhaust down pipe and link to orig exhaust.
  6. use orig motor mounts
Reply
Save
Like
  • Like
Reactions: 3
soonermatt
2
Sorry for taking 3 months off from my engine swap. Major construction project is now over.

Curious if anyone has any ideas on my idle problem.

  1. Runs and "idles" on starter fluid. (It's exciting how well it runs)
  2. Won't run on gasoline at low throttle or near idle. Must push a lot of gas.
  3. Gas is verified and flowing well. I routed the fuel line into a gas can and it did well.
  4. All vaccuum lines are sealed off.
  5. Timing is within a degree or two per timing light.
  6. Rochester Varijet has no fuel adjustment per forums and visual inspection.
  7. 12V+ verified to both idler assembly and electric choke.

    (Edit: The white line I painted on the harmonic balancer line up at zero when the engine is running. When it's dying, the timing goes behind I believe. The timing advance vaccuum is not plugged in.)
Here is a video of it attempting to run near idle:
.
And there are no adjustments on the carb. I'm stumped:

See less See more
Reply
Save
Like
R
starter fluid will compression ignite. I had a similar problem on a 3.9 and distributor was out 180, but the dieseling of the starter fluid masked it.

you should hook up the distributor vacuum advance before you drive it
Reply
Save
Like
rdavisinva
The varijet carbs were a hybrid design that included multiple functions, provide less fuel, and help pollution control.
As such they must have all the vacuum lines and sensors connected and functioning to operate.
Plugging vacuum lines will reduce the varijet to a non-functioning state, so am not surprised that it doesn't work properly the way it's installed.
This is specifically why I never use them.
There were vacuum lines hooked to temp sensors for example that ran to the carb and distributor.
Reply
Save
Like
S
rdavisinva said:
The varijet carbs were a hybrid design that included multiple functions, provide less fuel, and help pollution control.
As such they must have all the vacuum lines and sensors connected and functioning to operate.
Plugging vacuum lines will reduce the varijet to a non-functioning state, so am not surprised that it doesn't work properly the way it's installed.
This is specifically why I never use them.
There were vacuum lines hooked to temp sensors for example that ran to the carb and distributor.
Click to expand...

Sounds to me like the worst of both worlds. (n)

I look at that "carburetor" and say to the clever-clogs who came up with it: Pick a lane! Either use a traditional, old-fashioned, proven model of carburetor, or go to FI, one or the other. Do or do not; there is no try.
Reply
Save
Like
  • Like
Reactions: 1
hanzo111
Did you make sure cylinder number one was a top dead center on the compression stroke? I don’t think that you are in the faze.

pull spark, plug number one , put your finger over the hole, turn the crank by hand until it blows your finger off of the hole.

Now follow these directions at that point. Just a summary you have to put the distributor in so that the rotor points at spark plug hole number one. Also, there are v or triangles underneath the rotor. They one of them Hass to also point the same place that the rotor is pointing.

At that point put your distributor cap on and make sure that the point where the spark plug or ignition wire attaches is also pointed there.

It’s hard to explain this. I will post a picture and a video for me YouTube. Sorry for misspellings or whatever I’m using spell voice recognition.
Reply
Save
Like
  • Like
Reactions: 1
hanzo111
2

See less See more
Reply
Save
Like
  • Like
Reactions: 1
hanzo111
Reply
Save
Like
  • Like
Reactions: 1
soonermatt
Steyn said:
Either use a traditional, old-fashioned, proven model of carburetor, or go to FI, one or the other. Do or do not; there is no try.
Click to expand...
Oh I started with a Holley 4bbl to make it simple lol. I was suggested back to this carb. Will try to make it work! (I bet it does)

I'll have to read all the above and figure out how to get this to run. Coworker explained the 3 different types of idle/advance I need to learn. I'll get that aced and post a video of the timing. There's a decent chance it runs well.

I did not know that the second carb I purchased requires vacuum and has virtually no manual. I had plugged all vacuum at the advice of comments posted here. At this point crate engine (EV) or dumping this thing on the classifieds is most likely. I just don't have time to deal with this and we're coming up on 2 years.

I'll read the above stuff and get back to it guys...

Edit: If I could give someone $30K to have a running defender right now I would. Just point me in that direction. I'm tired of having an almost running truck and changing directions, etc.
Reply
Save
Like
rdavisinva
Steyn said:
Sounds to me like the worst of both worlds. (n)

I look at that "carburetor" and say to the clever-clogs who came up with it: Pick a lane! Either use a traditional, old-fashioned, proven model of carburetor, or go to FI, one or the other. Do or do not; there is no try.
Click to expand...
It really is.
The varajet helped put an end to the 1970 & 80s vehicles that were plagued by government enforced emissions standards.
There wasn't a factory EFI option available at the time as they were not main stream back then.

soonermatt said:
If I could give someone $30K to have a running defender right now I would. Just point me in that direction. I'm tired of having an almost running truck and changing directions, etc.
Click to expand...
Don't loose faith man. We're here for you. We will give you the best advice we have even if it's not what you want to hear. Hang in there!
Reply
Save
Like
  • Like
Reactions: 3
S
3
soonermatt said:
Oh I started with a Holley 4bbl to make it simple lol. I was suggested back to this carb. Will try to make it work! (I bet it does)
Click to expand...


Great. Two more barrels to go wrong.

That's the problem with us; every one of us is secretly Wile E. Coyote at heart. Every time we think about an engine swap, the first thing we want to do is strap on a big Acme Rocket Pack.




THIS is a carburetor:


The majority of these engines left the factory with something like this. It starts. It runs. It works. It moves heavier trucks than Defenders, with bigger loads, in cold weather, on rough roads, across fields, and along highways at speeds that will get you fined. It has fewer moving parts than a ball pein hammer. Start off with one of these or something like it, get your truck driving nicely so that you know the ignition and valves and everything else are sorted before getting cute with carbs. Then, if you still want an Acme Rocket Pack, at least you know the rest of your engine is not the issue.

That's the way I look at it, anyway.
See less See more
Reply
Save
Like
  • Like
Reactions: 3
hanzo111
I’m running a Chinese monojet, and it’s a dream starts right up drives down the road accelerates well no problems whatsoever.

It may be about time to pay Mechanic two hours worth of labor to set your TDC and your distributor and hook up your vacuum ports to the carburetor it literally will take a seasoned mechanic 30 minutes to do all of that.
Reply
Save
Like
  • Like
Reactions: 3
Santiago Montenegr
I misspent a lot of my youth in a varajet. My advice is... don't.
Reply
Save
Like
  • Like
Reactions: 2
S
hanzo111 said:
I’m running a Chinese monojet, and it’s a dream starts right up drives down the road accelerates well no problems whatsoever.

It may be about time to pay Mechanic two hours worth of labor to set your TDC and your distributor and hook up your vacuum ports to the carburetor it literally will take a seasoned mechanic 30 minutes to do all of that.
Click to expand...
I'm glad to hear some feedback on the Chinese knock-offs, since they're sometimes the only option for carbs that are long out of production. I'm still having a hard time getting my head around their versions of American 1-bbl carbs costing $200-300, when they put out clones of twin-choke Webers for under a hundred.
See less See more
Reply
Save
Like
  • Like
Reactions: 1
R
if you have to run a carb and originality isn't important the motorcraft 2150 is hard to beat. 78ish mustang 2 with the 2.8 would probably be jetted close enough
Reply
Save
Like
  • Like
Reactions: 1
S
robertf said:
if you have to run a carb and originality isn't important the motorcraft 2150 is hard to beat. 78ish mustang 2 with the 2.8 would probably be jetted close enough
Click to expand...
As long as you stay away from the 83-and-up version, which is electronically contaminated.
Reply
Save
Like
R
I had an 85 F150 with one of those turds. It would not pass emissions inspection. no matter what I did to it. Slapped the whole upper end from a mass air mustang on it to fix it. Engine was happy after that, AOD wasn't.

Still, the 2150 was great on AMC V8, and makes a great upgrade to the YF or BBD on the I6. Just make sure the power valve is hooked up correctly.
Reply
Save
Like
S
robertf said:
I had an 85 F150 with one of those turds. It would not pass emissions inspection. no matter what I did to it. Slapped the whole upper end from a mass air mustang on it to fix it. Engine was happy after that, AOD wasn't.

Still, the 2150 was great on AMC V8, and makes a great upgrade to the YF or BBD on the I6. Just make sure the power valve is hooked up correctly.
Click to expand...
We're fortunate where we live. Even though the gun laws are oppressive, at least we don't have emissions testing. Nor do we have restrictions on engine swaps. If you can squeeze it in, you can run it.
Reply
Save
Like
  • Like
Reactions: 1
741 - 760 of 783 Posts
Defender Source Forum
A forum community dedicated to Land Rover Defender owners and enthusiasts. Come join the discussion about performance, overland, classifieds, modifications, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
Pre - 2016 Defender Technical Discussions Truck Build-up's & Restores Vendor Deals Smaller Projects Series 1, 2, and 3 Technical Discussions
Top