What Defines a 4.1 Production Block

[Daniel Jost]

So i just went and picked up another turbo buick engine from a friend in upper michigan, when i picked up the engine he said he thought it was from a 84GN, it has a hole that looks like an oil return to the lifter valley in the back of the block, and is cast with 3.8-4.1 in the back of the block, so would this be a production 4.1 block? I guess im not clear on it all, also i brain farted and forgot to check the pan bolt count before i put it away when i got home.

Thanks,Dan

 

[TURBOELKY]

never heard of such a thing. A 4.1 production block is a 4.1, only. maybe those are just casting numbers? any pictures?

 

[Nasty Wendy]

If its from an 84 GN then it is a 3.8. I believe the only GNs to get a 4.1 was the 82 model.

 

[melrob94]

I have one also that says 3.8 and 4.1 on it. It is a casting number of 4140. I has a 20 bolt pan. I thought it was from an 85 model, since I think they started using 20 bolt pans in 85. It is a 3.8 block.

I did some research and I found that the 140 cast was a NA engine in 85. Not sure about the 3.8,4.1 stamp on it.

 

[Daniel Jost]

its a 3.8L displacement right now but it is stamped with 3.8-4.1? So this is a NA engine that doesnt make since to me seeing it had all the hotair stuff on it still?

 

[melrob94]

I'm not saying that your block is a NA motor. I just did some research a while back on the casting number of the block I have and that was the result. The 140 block wasnt listed as being offered in the turbo cars. What is the casting number of the block you have?

 

[dr_frankenstein]

you dont happen to want to sell that block do you?

A.j.

 

[Daniel Jost]

im not sure on the casting numbers of the block, i would have to check. Sorry im not interested in selling the block if that ? was towards me, im looking to start a strong build just trying to get my stuff in order...

 

[dr_frankenstein]

im not sure on the casting numbers of the block, i would have to check. Sorry im not interested in selling the block if that ? was towards me, im looking to start a strong build just trying to get my stuff in order...

Kool, I was just curious.

A.j.

 

[Nasty Wendy]

I have one also that says 3.8 and 4.1 on it. It is a casting number of 4140. I has a 20 bolt pan. I thought it was from an 85 model, since I think they started using 20 bolt pans in 85. It is a 3.8 block.

I did some research and I found that the 140 cast was a NA engine in 85. Not sure about the 3.8,4.1 stamp on it.

its a 3.8L displacement right now but it is stamped with 3.8-4.1? So this is a NA engine that doesnt make since to me seeing it had all the hotair stuff on it still?

Hmmmm do either of you guys know if your blocks have siamesed cylinders? If so they could bore out to the 4.1's 3.965" size.

 

[Anthony P]

I had 2 NOS '85 LM9 crate engines. Sold one. Both are 25524140 blocks.

Cylinders have water jackets between them as the blocks use the same "8445" heads that were used on the '86 and '87 engines.

-Anthony

 

[melrob94]

Hmmmm do either of you guys know if your blocks have siamesed cylinders? If so they could bore out to the 4.1's 3.965" size.

Not sure what you mean by siamesed. I just rebuilt the motor bored .030. It's in the car now. I thought I would beat this block up. I have a std. bore 109 also.

 

[Nick Micale]

............ it has a hole that looks like an oil return to the lifter valley in the back of the block.................

Thanks,Dan

An oil return in the back of the block would be on a stage block, not a production block?

 

[Daniel Jost]

Stage block? will they still have all the GM casting numbers like im finding? it had 8445 heads on it, i thought stage blocks used different heads than the 109s?

 

[turbofish38]

it has a hole that looks like an oil return to the lifter valley in the back of the block, and is cast with 3.8-4.1 in the back of the block

That block might be from a Riviera. The oil return line was plumbed into the back of the block like you described. I've never seen both 3.8/4.1 cast into a block though. Any pics or casting numbers?

 

[getchasum]

That block might be from a Riviera. The oil return line was plumbed into the back of the block like you described. I've never seen both 3.8/4.1 cast into a block though. Any pics or casting numbers?

have one also that says 3.8 and 4.1 on it. It is a casting number of 4140. I has a 20 bolt pan. I thought it was from an 85 model, since I think they started using 20 bolt pans in 85.

Just to throw it out there, I've seen blocks with both 3.8 & 4.1 stamping. It was an early version 4.1, 14 bolt oil pan block...Never seen a 20 bolt oil pan 4.1, Got Pics?

 

[Daniel Jost]

I will try to get pics as soon as possible, my parts are kept at my brothers house becuase i am at my apartment at collage so i have no room... The engine is stamped 3.8GM, but what i am talking about is on the back of the block it says 3.8-4.1

 

[GNeric]

My numbers matching 85 GN had this same block in it. It is a block that was to be used for either casting but from what I understand, it was used for the 3.8 only with the 20 bolt pan. Non siamesed cylinders. Have another block from an 85 T here that is the exact same...but with a spun center main so block would need to be align bored and honed.

 

[Anthony P]

Hi Dan,

I am posting a pic of what I believe you have been talking about. On the rear of the block, between the cam plug and the crank at about 10 o'clock, "85", "3.8" and "4.1" are cast into the block.

This pic is from the NOS LM9 hot air crate engine I noted in an earlier thread in this post. This LM9 engine was made 10 March 1985. Hope this helps.

 

[melrob94]

That's the same as mine.