84 85/86 87 109 Block

tta1240

CAMEL TOE
Joined
May 5, 2003
im sure this ? has been asked alot,but what are the difference between the 84/85 109 to the 86/87 109 block.
 
If I remember correctly, the earlier blocks aren't tapped for the oil return in the upper part of the block, Aside from that, the blocks are the same.
 
something with the deck height as well. also something with the depth of the head bolts. Webing is different in the valley as well.
 
First off there is NO 84-85 109 block. The hot air blocks (84-85) are weaker in the lifter valley, different deck height, not drilled for oil return ect.
 
thanks for the the help.the reason i am asking is that i have a 84/85 block with a oil return hole in it, but if the block is weaker i do not want use it
 
i have a hard time remembering everthing about these cars. atleast i was right. also if i do remeber right there are some 85 GN's with 109 blocks.
 
thanks for the the help.the reason i am asking is that i have a 84/85 block with a oil return hole in it, but if the block is weaker i do not want use it

The block isnt weaker in my opinion. I would like someone to prove me wrong or show me proff. just because the lifter area isnt as beefy as the 86/87 blocks doesnt it make it weaker in the case of making power.
 
The block isnt weaker in my opinion. I would like someone to prove me wrong or show me proff. just because the lifter area isnt as beefy as the 86/87 blocks doesnt it make it weaker in the case of making power.

:biggrin:

I agree, at least down to low 10's where I have personal experience. Should go into the 9's with proper prep.

The 4.1 block, that is very much the same as the '84-5 3.8 block, has been shown to hold up at 700+ HP.
 
i am wanting my car to run low tens.should i use the 84/85 block and make it a stroker or should i but a 86/87 block.also will all of my parts from my 86/87 block bolt on.
thanks
 
The 84/85 blocks are not any weaker than a 109. The lifter galley is machined differently on a 109...ie....more webbing, but that is not the weak spot on a 3.8 block. Ever see anyone have lifter galley problems with a 3.8 ?......and you'll see more of the NA blocks showing up in TRs because believe it or not, they (109s) are getting harder to find...........'bout HIGH time to have a big-ass sale on those TA alum. blocks ain't it Nick ? :biggrin:
 
Other differences
1. block not drill for turbo oil return
2. Cam bearing on front and rear are smaller OD
If you use 86/86 cam bearings the cam will not fit (found out):tongue:
3. Has a 14 bolt oil pan
 
One other diff is the position of the lifter oil gallery. The 109's moved the oil main feed to the right slightly to help on oil issues to the mains.
 
I'm not sure if this was already posted but the 86-87 blocks have a higher nickel content than the N/A blocks which makes them a little stronger.
 
I'm not sure if this was already posted but the 86-87 blocks have a higher nickel content than the N/A blocks which makes them a little stronger.

Prove it Please!! There is an article on maybe??? GNTTYPE but I know I read it that states thats BS!! I'm gonna start looking for it but it was a metalurlagist SP?? that wrote it & I personally call BS on the Nickel statement.
Where did you read that?? Thanks!

PS: NOT trying to be a dick but I have heard that so many times & I call BS!!
 
Prove it Please!! There is an article on maybe??? GNTTYPE but I know I read it that states thats BS!! I'm gonna start looking for it but it was a metalurlagist SP?? that wrote it & I personally call BS on the Nickel statement.
Where did you read that?? Thanks!

PS: NOT trying to be a dick but I have heard that so many times & I call BS!!

Save your effort, you are correct.:cool:

This was debated many times on GNTTYPE, and one of the members had access to a lab and did testing on 109 and earlier blocks.

The analysis proved it was the same metaluragy and nickel content in ALL Buick V-6 blocks.

Amazing how long and widespread internet BS and rumors are sustained and perputated until someone says PROVE IT!:biggrin:

My other favorite is that the lifter bores on turbo blocks were machined wrong.:eek:
 
Save your effort, you are correct.:cool:

This was debated many times on GNTTYPE, and one of the members had access to a lab and did testing on 109 and earlier blocks.

The analysis proved it was the same metaluragy and nickel content in ALL Buick V-6 blocks.

Amazing how long and widespread internet BS and rumors are sustained and perputated until someone says PROVE IT!:biggrin:

My other favorite is that the lifter bores on turbo blocks were machined wrong.:eek:

so if you were building a engine would you use the 84/85 block or find and buy a 86/87 109 block?
 
so if you were building a engine would you use the 84/85 block or find and buy a 86/87 109 block?

If you are asking me, the big difference now is cost, as the 109 blocks are getting hard to find and the old blocks are still plentiful. Have not seen any difference reliability when into the 10's. Any stock block in the 9's is a ticking time bomb.

Since I like big bore V-6's, I would build a 4.1. [Oh, I just did that!:D]

The 4.1's rule, especially for a QUICK street build.:cool:
 
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