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Separate the Twins? - Twins #2, Comments
https://www.slantsix.org/forum/viewtopic.php?f=19&t=27397		 Page 2 of 7
Author:  Doctor Dodge [ Mon Feb 25, 2008 9:24 pm ]
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Yes, I feel that the "BH" blocks are the best US made blocks and i have inspected a bunch of SL6 blocks over the years.

I recently sold the other BH block I inspected for this job, to a local SL6 racer that cracked his 3 freeze plug engine block. At first he did not like the idea of changing away from "original"... I showed him the two block types side-by-side and he quickly changed his mind.
Heck... the engine he is building is for a "raced-out" 65 Dart with cam, headers and a Hyper-pak intake... what is original about that? :roll:
DD
Author:  Evilsizer [ Mon Feb 25, 2008 11:13 pm ]
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is the BH block the 2 gen or 3 gen block?
Author:  66aCUDA [ Tue Feb 26, 2008 7:54 am ]
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Doug
A picture of where the BH stamp is found might be approproiate.
Frank
Author:  Doc [ Tue Feb 26, 2008 8:41 am ]
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Not counting the aluminum or 170 blocks, I would say the 5 freeze plug "BH" is a "3rd generation" 225 block.
I know of 2 different early 225 blocks (3 freeze plug) but I'm not sure if the casting p/n changed during that run.

As with the early blocks, the 5 freeze plug type has many different version, most likely based on the foundry or the pattern builder.
In simple terms, there are 3 main groups of RG (225 / 198) blocks, the 3 freeze plug, the 5 freeze plug and the cast crank blocks.

The "BH" is easy to spot on the driver's side (freeze plug side) of the engine.
DD

Image
Author:  Evilsizer [ Tue Feb 26, 2008 8:55 am ]
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good to know, thanks doc!
Author:  runvs_826 [ Wed Feb 27, 2008 12:10 pm ]
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In regards to boring and piston selection what are the options? I know you can use the 2.2L piston if you can make up the difference of pin location. For Eileen you opened the bore up big time! Is the following all done with custom pistons from let's say Arias or is there other pistons like the 2.2L than would fall under this catagory?
Second question is with the block filler where do you insert it as approximatley. I saw the layer at the bottom of the water jackets through the freeze plugs. I will review Twiggy one more time to double check, but I think the engine obviously could benefit from this but a little shaky on the whole process. Do you plan to coat the pistons again? I was going to look at that for the turbo build and a cryo treatment for the rods and crank after balancing. The next "challenge" build is going to hopefully push the limits so all the easy tricks is what I need!
Author:  Doc [ Wed Feb 27, 2008 1:27 pm ]
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Yes, piston selection for the SL6 is limited these days. That is why the 'long" 198 connecting rod is helpful, that opens up the selection range to the 2.2 / 2.5 Mopar engine family as well as some other pistons.
Using piston manufacturer's diametric listings can be helpful in selecting a piston or another make's year and application so you can do additional homework.
See This List for an example of a dimetric list.
DD
Author:  sandy in BC [ Wed Feb 27, 2008 3:53 pm ]
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<Sandy Immediately runs downstairs and tosses block onto newly milled head with oversize valves>.....turns out "Some adjusting of the pins is in my future"......and the pins dont let the block seat fully on the head.

It looks just like in the photo #2.

so....watnow?
Author:  Doc [ Wed Feb 27, 2008 4:19 pm ]
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Take some measurements and then shift the head's location on the block.
4 ways to do this:
-Make some off-set dowel pins. (a "dab" of braze and a lathe)
-Grind "oval" the the holes in the head, drawing arrow on parts helps.
-Grind / file flats on the side of the pins to allow the needed shift.
-Drill out the location holes in the head and install some off-set cam bushings.

Image

I find that you can only get the chambers "pretty close" and then you have to scribe and grind-off the remaining exposed edges.
So it is a two step process. First center the valves over the chambers and then grind-out sharp edges and shrouding that remains.
Pay closer attention to the valve placements, rather then the overlapping / exposed edges you see.

Once you get the position set, punch, grind or engrave some 'witness marks' so you can return the head to that placement once the pistons are installed.
DD

Image
Author:  Evilsizer [ Thu Feb 28, 2008 12:43 pm ]
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what years would you say they made the "BH" blocks? i went looking on mine the other night, not letter stamping. just a little oval plate with numbers, from what i recall it was "31030" on the tag.
Author:  Doc [ Thu Feb 28, 2008 12:51 pm ]
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I find most of the BH blocks in 70-75 vehicles.
Yours sounds like a later block, it may even be a cast crank engine.
DD
Author:  Evilsizer [ Thu Feb 28, 2008 6:09 pm ]
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yea thats what i figured Doc based on this article here
http://www.slantsix.org/articles/stroking/stroking.htm
and that i didnt see a BH stamped on it. would it be possible though to change out the crank? is it that bad to have a cast crank and try to net something in the 200-230hp range out to it?
Author:  Joshie225 [ Thu Feb 28, 2008 6:46 pm ]
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The BH is actually cast into the drivers side of the block in big raised letters. It's not stamped. It's shown in the block article.

The cast crank is still plenty strong. There was a 300hp build (Romeo Furio's) based on a cast crank engine. You can't put a forged crank in a cast crank block.
Author:  Doctor Dodge [ Thu Feb 28, 2008 9:28 pm ]
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Here is another photo of the "BH" cast into the side of the block.
DD

Image
Author:  rosspulliam [ Thu Feb 28, 2008 10:46 pm ]
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Doc wrote:
We did basic deburring, oil hole reaming and "banana grooves" before sending the crank off to a different shop for shot peen, grinding and rebalancing.


Is it possible for you to expound on this a little bit? What is Banana Grooving? Maybe some more close ups of the specifics what you did to the crank?
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