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78 Lesabre sport engine swap question

4523 Views 36 Replies 9 Participants Last post by  damar121979
Have recently purchased a minty 78 lesabre turbo coupe with a seized engine. After inspection found the crank and piston are shot and have decided to scrap that dog of an engine and replace it with a olds, buick or poncho V-8. I have a nicely done up '69 Pontiac 350 in my shop already to go. Looking at the motor mounts am questioning whether they will work since they're different from the later 70's type mounts. Can anyone offer some help on making such a swap work? What should I use for mounts? What other things should I consider? As well, I will have all the parts to the old 3.8 including a turbo in great condition with only 70,000 miles. Your help is greatly appreciated.
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Thanks Richard for the offer on the heads.......found a 4.1 crank in good shape in vancouver........don't know the year......does it matter? Are there any other considerations using the 4.1 crank on my '78 3.8 turbo?
.....found a 4.1 crank in good shape in vancouver........don't know the year......does it matter?
You found yourself an excellant rare piece. As I recall the 4.1 engine is the only other Buick engine that carried the 'rolled fillet' crank that was used on the turbo engines. (Basically it's a heavy duty service crank).

Consider yourself very lucky! I believe you should have no problems using that crank on your engine.. :headbang:
I was also lucky the guy at the wrecker was a Buick guy! He was well aware of the fact it was a rolled fillet crank and as he put it, "All the Grand National guys inquire about the 4.1 crank" I don't really know what to look for in a used crank other than it being in visibly good shape. I can get it for $300.00....sounds fair to me.........hopefully it works out as I'm dying to get this Lesabre on the road! Engine bay powerwashed and painted, all brackets and accessories sandblasted and painted....looks like new!
.... I can get it for $300.00....sounds fair to me!
$300.00 :eek!: ....is that in American dollars?
I hope you're aware that you may partially be paying for his knowledge of Buicks, his awareness of the crank's rarity and the fact that the GN guy's drool over it .

Remember, the regular crank is usable too and I'm sure you can get one for so much cheaper and pretty much anywhere.

It's nice to have the 'rolled fillet' crank but it's been proven that the basic crank will hold up just as well. In my opinion the 4.1/turbo crank is over-rated.

I'd save some of that money for the other stuff the engine may need.
How bad is the crank you already have? It may very well be a rolled fillet crank....they can take much torture and can be cut at any machine shop...:sw:
That sounds a bit pricey to me too. I think an Eagle crank is only about $500 CDN.
Well, Its all irrelevent now, the wrecker that had the 4.1 crank now says he doesn't have one. The hell with it, I'm going to a 3.8 NA crank....tired of dealing with ******* Bubba's at the wrecker yards. (I apoligize if any of you guys out there are named Bubba). Apparently my engine spun a bearing and the previous owner drove it quite a while like that......I trust my engine builder's knowledge and he says the crank is hooped but he does say the block is in good shape cannot offer any warrantee on running a NA 3.8 crank.
Fair enough, its not a race car anyway.........
.....cannot offer any warrantee on running a NA 3.8 crank..........
I would'nt trust him if he could'nt warrentee the 3.8 crank. If he machines it, then he should guarantee it. If he was good he'd know it's the same differance. Any GM person can state that.

Will he warrentee the pistons if they are after-market and not OEM? Any good machinist would warrentee their work and know this to be true.

Maybe he's the only guy out by your way? I'd get a second and third opinion.
Heck, when I had my engine done they respected my knowledge and worked with me. They machined and warrenteed everything I asked them to modify.

A good machinist takes pride in their work and back it up.
I guess I shouldn't say he won't warranty it, he's just saying that the factory installed the heavy duty crank for a reason and if a NA crank breaks, he can't guarantee it......simply, its not a factory part. He's just covering his ass and knows a NA 3.8 will probably be fine. He's a reputable builder and I've had two engines built by him before with great success. Who out there REALLY knows what a NA crank will take compared to a Rolled fillet crank. Has anyone actually taken two identical 3.8 cars, side by side, with the two different cranks and run them both equally hard to breaking point to see how much of a load each will sustain? I doubt it......... I'd love to see the test results. I'll bet my last Canadian dollar (or .82 cents U.S) that GM never tested the 3.8 in that fashion....THEY were just covering THEIR ass by installing a hard crank. GM must have had some question as to whether a NA crank would hold up because auto manufacturers do not waste money by installing expensive H.D parts unnecessarily. And thats what its all about isn't it? Covering thy ass.........
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..... And thats what its all about isn't it? Covering thy ass.........
Yep....but I bet your broken crank was a 'rolled fillet'...:yup:
I beat my 3.8 crank with a smashed piston, (tip of a spark plug imbeded into it), a worn bearing and a blown head gasket for 12 miles! :eek!:

I had the crank cut to a .020 and it's now still pumping. :yup:

Gotta love these Buicks! :headbang:
Ok guys.........Went to the big city and found a beautiful running NA 3.8 for sale in an 81' Regal....fired it up and it runs like a charm! Low miler too. Apparently the owner wants to put a Buick 455 in this Regal. So, picked the complete running engine up for $325.00 with all the bolt ons which i think is a steal. Obviously I will clean and reseal it, change head gaskets and paint it up nicely and bolt on my turbo stuff. Anything else I should consider before dropping it in......maybe get the heads done? You guys all are all saying that theres not much difference between an NA and turbo block, other than the crank of course. I always thought that turbo motors, like my Trans am 4.9 Turbo, had lower compression but not the 3.8? Any thoughts or suggestions on the swap over to the new(er) NA motor?
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Hey Rolly...I'm not sure about the hot air carbed engines but the base CR is only 8:1 on my car.
'78 Lesabre 3.8 Engine swap

Ok....now i'm confused. Earlier in the forum I put the question out there looking for suggestions on what to do with my seized '78 3.8 Turbo. I believe someone suggested finding an early '80's 3.8 and transfer all my turbo parts over. Now, i'm reading, from a section in this forum, that after '78 the heads and intake changed and is not interchangable and the exhaust manifolds as well?????? Does this mean I can now NOT transfer my turbo parts over from a '78 Turbo block to a '81 NA block? I now have a great running '81 3.8 NA motor and a siezed '78 Turbo motor. Whats the straight goods and what are my options. I don't want to rebuild the turbo block because it's way to expensive. I'm counting on you guys for your expert advise. Thanks!!
The '78 had low port heads. In '79, they went to high ports. My understanding is they will bolt up and all will be OK. If you could get 1979 intake and exhaust manifolds, you can take advantge of the better heads.

You should get a book called V-6 performance. It covers the pre 1983 motors very well.
eBay: V 6 Performance by Pat Ganahl (1986) (item 200105135656 end time May-29-07 12:11:42 PDT)

I think it is still in print, so you should be able to find it cheaper.
Thanks for the clarification......so, to recap, Unless I can find '79-up Turbo intake and exhaust manifolds, the '78 heads will bolt up to the '81 block. Simple enough....Thanks!
That's my understanding, altough I've never done it myslef (I have 82/83's). That books covers this well. Worst case you would need to use you 78 heads on the 81 block.

You could even use 1980 manifolds. The '80 intake is aluminum, but has no knock sensor hole, which is OK becuase your '81 block has one. (They moved the sensor from the intake to the block in 1980.)
i have those engine parts, i am parting at this time an 80' lesabre turbo.
p.m. me if interested, as all good parts will go on e-bay :cheers:
I have a 78 lesabre sport and it seems I have to idle it higher than normal to keep it running any ideas on what could cause this to happen it only has 68,000 miles on it and wanted to get it running for the summer please help
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