Thanks. Got them ordered. Both front and back. Got a small setback. After getting the EFI dialed in and the trans/xfer case working well, I found the head is cracked at the water jacket between cylinders 2 and 3. Now to undo ALOT of crap, pull the heavy beast and see if a local shop can fix. Either TIG or nickel brazing.
Another Chevy 250 Conversion
- Thread starter bboretsky
- Start date
I have an integrated head that I don’t plan to use
So the guy I got the engine from gave me two more heads. You would think I could make one of em work for me. Had the first one magna-fluxed to make sure it was not cracked. Ordered a new gasket set with the valve stem seals. Tomorrow I will tear it down, lap the valves, new seals and install. Just out me a couple weeks behind. The good is that I out new seals on the LT230 and all good to go there. Also fixed a pinhole in the washer bottle. Both front and rear pumps working. The good is, even with the cracked water jacket, the engine and EFI system are working really nice.
So I am almost ready to put the new head assembly in. Head is cleaned up. Valves lapped. New seals. Then I took it to another level with the carb intake. As we all know there is not much that can be done with the intergrated head, especially with the 2 barrel rochester 2SE design. I used a cutoff wheel and cut the intake plenum OUT. Now it is the same dimension as the 2300 Holley. I then increased the side towards the three intake ports (center, forward, and rear). My original 2300 adapter I built will have no restrictions to the intake ports now. Tomorrow I will bolt everything up and fine tune the EFI. Pics are before and after. I still needed to clean it up for the final fit, but this is the idea.
Attachments
Today was a watershed moment. Was having issues with the EFI cutting out at about 2500 RPM. Then the Holley fuel pump quit. I jumpered it to confirm. Picked up a Spectre one for 100 bucks. Installed and purged the line. Went for a test fire and started. Checked static timing and was spot on. Checked for leaks and dropped her off the lift.
Went for a short 2 mile shakedown. Letter her cool off and I will recheck everything.
Video tomorrow and exhaust on Monday.
Went for a short 2 mile shakedown. Letter her cool off and I will recheck everything.
Video tomorrow and exhaust on Monday.
So I now have about 250 miles on the setup. 235/70/16 tires. 3.75 hearing with a 1.211 center diff. Rpm at 110kmh is about 2500 and almost 3k at 120. As 110 I am at 16 percent throttle and 23 at 120. Upsizing tires to reduce some of the RPMs.
Tomorrow is have a set of relocation pins for the parabolic leaf springs. I will be moving the front axel back about an inch or so to get enough space for some 285/75/16 tires. Test fit they were rubbing the fender extensions in the front. Plus is am fitting longer shackle arms on the front and rear. From the original 3 inch to about 5 inches. Just a little lift for good measure. Also ordered some new fender flares that are 2 inches wider.
Second impressions of having the GM 250 vs the 12j. I could easily do 140 or more, but no need. Quiet is the TRUTH. Now is hear the trans whine and all the rattles and whistles. Amazing to think that I had to drive at 75/100 percent throttle to get to 110 and that was on a long flat. Now I barely touch the throttle through 4th gear. Typically maybe 25 % if I am hard acceleration. No need for more!
Radiator temps are perfect. Oil pressure is wired for both dummy light and bar based gauge. Last thing to sort from the original install is the fuel sending unit. Reads full so I am not sure what actual is.
Tomorrow is have a set of relocation pins for the parabolic leaf springs. I will be moving the front axel back about an inch or so to get enough space for some 285/75/16 tires. Test fit they were rubbing the fender extensions in the front. Plus is am fitting longer shackle arms on the front and rear. From the original 3 inch to about 5 inches. Just a little lift for good measure. Also ordered some new fender flares that are 2 inches wider.
Second impressions of having the GM 250 vs the 12j. I could easily do 140 or more, but no need. Quiet is the TRUTH. Now is hear the trans whine and all the rattles and whistles. Amazing to think that I had to drive at 75/100 percent throttle to get to 110 and that was on a long flat. Now I barely touch the throttle through 4th gear. Typically maybe 25 % if I am hard acceleration. No need for more!
Radiator temps are perfect. Oil pressure is wired for both dummy light and bar based gauge. Last thing to sort from the original install is the fuel sending unit. Reads full so I am not sure what actual is.
So I did a few more things:
1. new shoes. 285/75/16 Essentially a 33x10 tire.
2. Fitted 50MM (1/15/16 in wheel spacers.
3. New Terrafirma Wide Wheel Arch Kit. This is a 2 inch wider than the original. Subtle difference in the Santana fender well sheet metal. There was no need to keep the existing ones as there is no gap between the wing and the wells.
4. 1 inch relocation plated fitted to the leaf spring perches. It's small but makes a nice visual improvement and helps with clearance on the front wing. No rubbing.
5. Taller leaf spring shackles. Again just a small change. Originals were 3.5 inches center to center. New ones are 5.25. Helps add to the visual and a bit more flex and travel.
Took her for the longest test drive, about 40 miles on a 70MPH Highway. Can talk in the cab now. RPM at 75 was right at 2950, which is what I expected. I stuck to 70 and she purred along at 2800.
The bad:
1. Door seals are crap. Very stiff so I will be replacing with Original LR soft ones. Same with the window track felts.
2. More sound proofing around the trans tunnel needed. hear the whine of the trans more than the engine.
3. Axle shaft teeth are worn (Rear axle). Gear backlash is fine, bit I have slop in the axle ends. Upon inspection the shaft teeth on the ends are worn and VERY loose, accounting for the clunk when I let out the clutch. Axles shafts and outer seals, as well as outer ends are ordered.
4. Have not sorted the Fuel gauge yet.
Oh, and the snorkel will be removed it is just there for decoration and not connected. Still have to refit the Grill, but need the buttons...
Here is a before and after pics.
1. new shoes. 285/75/16 Essentially a 33x10 tire.
2. Fitted 50MM (1/15/16 in wheel spacers.
3. New Terrafirma Wide Wheel Arch Kit. This is a 2 inch wider than the original. Subtle difference in the Santana fender well sheet metal. There was no need to keep the existing ones as there is no gap between the wing and the wells.
4. 1 inch relocation plated fitted to the leaf spring perches. It's small but makes a nice visual improvement and helps with clearance on the front wing. No rubbing.
5. Taller leaf spring shackles. Again just a small change. Originals were 3.5 inches center to center. New ones are 5.25. Helps add to the visual and a bit more flex and travel.
Took her for the longest test drive, about 40 miles on a 70MPH Highway. Can talk in the cab now. RPM at 75 was right at 2950, which is what I expected. I stuck to 70 and she purred along at 2800.
The bad:
1. Door seals are crap. Very stiff so I will be replacing with Original LR soft ones. Same with the window track felts.
2. More sound proofing around the trans tunnel needed. hear the whine of the trans more than the engine.
3. Axle shaft teeth are worn (Rear axle). Gear backlash is fine, bit I have slop in the axle ends. Upon inspection the shaft teeth on the ends are worn and VERY loose, accounting for the clunk when I let out the clutch. Axles shafts and outer seals, as well as outer ends are ordered.
4. Have not sorted the Fuel gauge yet.
Oh, and the snorkel will be removed it is just there for decoration and not connected. Still have to refit the Grill, but need the buttons...
Here is a before and after pics.
Attachments
SoonerMatt
New member
I'm doing a very similar build over on DefenderSource. Spoke with Robert yesterday and ordered a kit from him. Should have the engine on Saturday. I'm certainly paying attention to this.
I need paintable fender flares and don't know if the stock ones will work. Now I'm curious about these TerraFirma.
Anyways -- wanted you to know that another American is swapping over a 250 and following this build!
I need paintable fender flares and don't know if the stock ones will work. Now I'm curious about these TerraFirma.
Anyways -- wanted you to know that another American is swapping over a 250 and following this build!
So here i am after a summer with the new engine package. Runs great. Fuel injection was the right way to go. Engine is smooth and quiet compared to any diesel (and I own several trucks with Cummin and CAT). Cruise at 75 all day long. Pass Subaru Tards instead of the other way around. roughly 10k miles since the conversion and never left on the side of the road and not afraid to take it on a trip. Could I have done a LS, sure, but what do you gain? Not much in my opinion. The beauty is that I can convert it back to the 12J diesel if I wanted to with 1 wire terminal. But Why would I. I now have something that is highway drivable, does not have the death wobble, quieter, and reliable. Had one person hear ask if I was going to put a Chevy logo on the front. Any NAS or ROW rig with the V8 is a Buick block, so should you have a Buick badge on it?
End of rant. In the end I was one the road in less than 80 hours of my shop time. Worth the time/effort/budget.
End of rant. In the end I was one the road in less than 80 hours of my shop time. Worth the time/effort/budget.