Engine swap


The old and reliable.

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Post Thu Jul 18, 2019 10:22 am

Engine swap

Considering an engine swap for my 1948 KB-6. So I’m looking for information/thoughts on the BD308. The truck came with the original BLD269 but was locked up and needs a rebuild. How does the BD308 compare to the BLD? Obviously more displacement... Also, what modifications will be required to the truck and driveline? Thoughts? Thanks!

Golden Jubilee
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Location: Lyman, IA

Post Thu Jul 18, 2019 12:18 pm

Re: Engine swap

The BD 308 and its little brother the BD282 will be a bolt in replacement for the 269 or 250 that you have now.
Instead of being a lined engine (the BLD uses dryliners) the bores are machined directly into the block casting. It allowed them to increase the bore slightly.
The 308 has a larger bore but same stroke as the BLD 269
They are in the same "family" of IHC engines so most externals will fit.
The ONLY slight problem is the oil filter on the BD will hit the steering gear on a K series. Since the oil pressure relief is in the filter base, you need to use the BD filter assembly but you can relocate by tapping the holes in the base and block and running oil lines, while remote mounting the filter assembly where there is room.
I often thought about making a "billet" adaptor with oil passages machined in, to raise the filter above the current location to about where the filter is on the BLD.
I would use the BLD bellhousing and flywheel (fairly sure it will bolt on, but you could also use the BD flywheel) and everything from there back can stay the same (clutch, trans and driveline).
You can't just use the BLD filter housing as it is set-up for a bypass type filter and the BD block is set up for a full flow, there are not interchangeable.

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Post Thu Jul 18, 2019 2:05 pm

Re: Engine swap

Great info! Thanks for the comprehensive review. Those dry liners are what is causing me the most indigestion with my BLD. Through help on this site I found one but the machine shop really wants me to find 5 more due to wear in the others. Just curious if the BD produced a noticeable change in power...I understand the KB’s stop very well but take awhile to get up to speed.

Golden Jubilee
Golden Jubilee

Posts: 5170

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Thu Jul 18, 2019 2:24 pm

Re: Engine swap

Never did a 308 swap myself, had a 282 that I gave away. I have 3, 269's so that is what I'll stick with. Grossing over 18K my K-7 handled it well, just not fast, 45-50 mph, slower on hills. About how my 855 Cummins felt pulling 170,000 lbs !

Golden Jubilee
Golden Jubilee

Posts: 5170

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Thu Jul 18, 2019 2:29 pm

Re: Engine swap

I wouldn't expect a big difference between the 269 and 308 in speed, these are torque-pulling engines and the 308 will pull better than a smaller bore, neither will be fast with the long stroke. The difference will be seen on a hill which engine has to downshift sooner pulling the same load.

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Post Thu Jul 18, 2019 3:00 pm

Re: Engine swap

Ok, pretty much what I was expecting but wanted to hear it from someone with more IH experience than myself. I presume parts availability is somewhat better for the 308 as well. This truck is being rebuilt for light work, parades and shows so I’d probably never notice the power difference. Maybe originality is more important then. I’ll keep looking for liners in the meantime but also now know the 308 will fit right in. Thanks a bunch!

Golden Jubilee
Golden Jubilee

Posts: 5170

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Thu Jul 18, 2019 4:02 pm

Re: Engine swap

There were likely far more BLD's made than the Medium six BD's They came out in the early 50's and the SV came out in the late 50's. Although they were kept in the line-up until the late 60's not many were put in trucks. With the "big 3" all offering V8's a 6 cyl was a hard sell to make, even though it would have been my preference.
Main and rod bearings are just as hard to find for the 308 as the BLD, piston show up from time to time and rings are not a problem. Gasket kits used to be available from Victor but no longer. So in short, not a whole lot easier to source parts for, so buy a runner not a project!

Golden Jubilee
Golden Jubilee

Posts: 5170

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Thu Jul 18, 2019 4:39 pm

Re: Engine swap

If all your going to do with it is a few thousand miles a year, you don't need perfection. Replace the real bad liner, remove and ridge at the top of the others, hone to break the glaze and re-ring. I once took an engine burning a qt/25 miles to a qt in 1500 just by re ringing. The bore were shaped like a cone, and I had to remove the ridge to prevent breaking of the top piston land, but it ran well.
Machine shops are afraid if they suggest that, you'll come back if things are 100%. You don't need an engine to work day in day out at full load, just something to get down the street.
If your careful you might even be able to save the piston in the bad liner by slitting the liner to release the piston.
A whole lot cheaper than a new engine or a set of liners/pistons.

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Post Fri Jul 19, 2019 10:23 am

Re: Engine swap

Thanks Cornbinder! Always great information. What you said is exactly what I have discussed with the shop, I think they are just afraid that I wont be totally satisfied. I’ve found 1 liner and that piston is ok.

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