84 85/86 87 109 Block

[rob350]

My block has a 20 bolt oil pan.

 

[Boost231]

mine has 14 bolts what are you trying to say? im guessing your saying your 85 has a 20 bolt 109 in it?

 

[Dwayne]

Mid-year 85, Buick switched from a 14 bolt pan to a 20 bolt pan. My dad's 85 had a 20 bolt pan but was not a 109.

 

[rob350]

mine has 14 bolts what are you trying to say? im guessing your saying your 85 has a 20 bolt 109 in it?

Mines a 20 bolt, but not a 109.

 

[bison]

Mid-year 85, Buick switched from a 14 bolt pan to a 20 bolt pan. My dad's 85 had a 20 bolt pan but was not a 109.

The front cam journal is grooved like a 109 on these also. I think the last three numbers is 140 but not sure. They have the taller deck and longer head bolts also. I would not have any worries running any of these earlier castings. There is no proof the 109 is stronger. They are all equally weak imo.

 

[turbofish38]

I don't have the casting numbers handy but another myth or more accuretly misnomer is that only the 109 blocks have the 20 bolt oil pan. Okay I've owned quite a few hot motors. Here's the scoop. The 84 blocks are 14 bolt and the 85 blocks have 20 bolts. The 85 block casting is not 109. I've never found any evidence to indicate other wise. Only the 109 blocks have the drains on the side which leads me to believe that they are the beefiest castings. Just look at all of the Stage castings. Those are heavy duty and every one of them has the same spot cast into them so you can install a drain plug. I'm not saying a 109 is a Stage1 block in disguise but one thing we all know about Buick blocks is that with each new casting came improvements to make them more durable. Years ago 109 NA blocks were hard to come by. I see more of them in the boneyards today than I do with the 14 bolt castings only because of attrition. If the average car in the boneyard is say, 20 years old than logic says that they should be easy to find and in a few years extinct. I stopped collecting 109 blocks years ago in other words.

 

[bison]

I don't have the casting numbers handy but another myth or more accuretly misnomer is that only the 109 blocks have the 20 bolt oil pan. Okay I've owned quite a few hot motors. Here's the scoop. The 84 blocks are 14 bolt and the 85 blocks have 20 bolts. The 85 block casting is not 109. I've never found any evidence to indicate other wise. Only the 109 blocks have the drains on the side which leads me to believe that they are the beefiest castings. Just look at all of the Stage castings. Those are heavy duty and every one of them has the same spot cast into them so you can install a drain plug. I'm not saying a 109 is a Stage1 block in disguise but one thing we all know about Buick blocks is that with each new casting came improvements to make them more durable. Years ago 109 NA blocks were hard to come by. I see more of them in the boneyards today than I do with the 14 bolt castings only because of attrition. If the average car in the boneyard is say, 20 years old than logic says that they should be easy to find and in a few years extinct. I stopped collecting 109 blocks years ago in other words.

If you look at where the blocks fail the casting is nearly identical through all the years. The blocks have been improved to oil the bottom end better but GM never thought we woudl be pushing these things as far as we have. 109 blocks are not rare and certtainly wont go extinct any time soon or ever for that matter. They produced so many that when you see mid size GM cars equipped with v-6's from 86-87 they are almost all 109's.

 

[Nick Micale]

If you look at where the blocks fail the casting is nearly identical through all the years. ..........

I agree with this, block failure due to "excessive" HP usually is in the cylinder walls and main webs. Since all Buick V-6 production blocks are rather similar, they should all fail similar.:smile:

Lots of massive failures are with cast cranks that take the block along with it. Have seen much less block failure lately with the use of forged cranks.

In my early years with big block Buicks, the main webs were are problem there too. At 500+ HP a girdle was a must for reliability.

Since stage blocks have over 50 lb's on a 109, lots of that beef is in the main webs.

 

[d0n_3d]

Wow I didn't know that was a touchy subject

That's just what I was told from a little birdy thats been building these engines since they came out

Oh well...

 

[boostingbuick]

I say run what you have. I have seen no issues with running a 84/85 block.

 

[Boost231]

i agree. use the 84/85 block you have. dont spend the money trying to get a 109

 

[conn84gn]

Use the 84/85 motor
Mine is my backup
The Flat Tappet coming out
It's getting a small 201/201 Billet roller cam(because I have it)
885 lifters
Everthing else been done 15000 miles ago
0.20" over TRW pistons
Ported heads 1.5/1.77 valves RJC braces
Ported 87 intake, plenum Throttle body
Roller timing chain
etc.