4.1 block #25505553

[orangecar]

Picked up a standard bore 4.1 block, number is 25505553, block looks good, is this a desirable block or should I look for a 291. thanks.

 

[SHADOWII]

Should be...

a good block, from what I remember, it is a caddy block and supposedly has a thicker deck than the others. I had one but ended up selling it to a friend because he wanted it for an n/a? Just check for any cracks in the deck bolt holes etc. there is plenty of help on the boards for building.

 

[UncleDave]

Castings

Supposedly, the 25514291 is the more desirable casting, as it has a thicker deck and is beefier around the water jacket than the other castings. But they all need help on the bottom end.

 

[forzfed]

a good block, from what I remember, it is a caddy block and supposedly has a thicker deck than the others. I had one but ended up selling it to a friend because he wanted it for an n/a? Just check for any cracks in the deck bolt holes etc. there is plenty of help on the boards for building.

Here is a pic of my 291 block. Look at the thickness of the block around the water jackets, pretty beefy.

 

[orangecar]

Thanks for the picture, block I have is identical to yours, looks heavy around water jackets, has the reenforcement bars on the outside and the backs of the cylinders in the lifter valley.

 

[forzfed]

Your block looks good. Make sure to test the block first. My first one was cracked. Good luck with the build!

 

[Lvnspeeed]

Where do you find these blocks, I mean what did they come in so i look in juck yards for one....

 

[orangecar]

These blocks came in 80-84 caddy, never seen one in anything else.

 

[novaderrik]

which Caddy?

 

[forzfed]

Here is a list...

*

Buick
80 STD-Electra, OPT-LeSabre
81 STD-Electra, Riviera, OPT-LeSabre, Riviera T Type
82 STD-Electra, Riviera, OPT-LeSabre, Regal Note: Included in Grand National Package
83 STD-Electra, Riviera, OPT-LeSabre, Regal
84 STD-Electra, Riviera, OPT-LeSabre, Regal
*

Cadillac
81 OPT-All except Limo
82 OPT-Seville, Eldorado, DeVille, Fleetwood
(NOTE: badges will say 4.1 for V6, 4100 for Cad V8)
*

Oldsmobile
81 STD-98,Toronado
82 STD-98,Toronado
83 STD-98,Toronado
84 STD-Toronado
*

Pontiac
82 OPT-Bonneville, Grand Prix

 

[UncleDave]

Do you mean, where to find any 4.1, or just the beefy ones like a "291" casting? Because I think those were produced only one or two years, circa 1984-5?

 

[71 Trans Am]

Any problems using a 4.1 block for a turbo project?

 

[Turbo-Archie]

Thats what we are talking about: Turbo application.


They all seem to crack here, thats why guys remove the top threads in those holes..


..

 

[Jordan_J]

Thats what we are talking about: Turbo application.


They all seem to crack here, thats why guys remove the top threads in those holes..


..

What problems will those cracks cause? Blown head gaskets? I've searched and searched but never found an answer.

 

[asloan5]

What problems will those cracks cause? Blown head gaskets? I've searched and searched but never found an answer.

Crack kills

 

[Jordan_J]

Crack kills

But how is what I'm not seeing. The water jacket cracks to the head stud/bolt holes that are already down in the water jacket. I can see it loosing strength to hold a head down and making it more prone to lifting the head and blowing a gasket. But other than that I really don't see what it could do.

 

[Lvnspeeed]

So it is not worth going the 4.1 route and just stay 3.1? I wana build a new motor for my car while the one in my car is still together so I can just do a swap and have less down time on the car.

 

[just plain john]

No personal experience here, but I have read (on the Internet so it must be true!) that the threads are cut all the way to the deck surface and that by removing the first couple the deck surface is not distorted in the same way. Plenty of 4.1's out there, it's been done before.

 

[jdpolzin]

I personally wont ever build another 109 becuase the torque of the 4.1's are noticeable. So far we have 5 different cars running 4.1's. 2 of which should be in the 9's this spring! 291 is the cast number to have, I'll be pushing a 484 block with stock main caps this spring to see what it's limit is.

Biggest thing, as posted earlier, is to remove the first two threads, no biggie!