What pistons needed for stroker motor

[49-blues]

What is the proper pin height or comp height needed for the new stroker kits with 3.625" crank and 6.00" K1 rods(or are they actually 5.960"-5.970")?im building a 4.1 production block stroker motor and need the correct pistons to use. Or would i need a different length rod? thanks for any input.

 

[Mike Licht]

what bore size are you after?
Mike

 

[49-blues]

4.00"

 

[Mike Licht]

That is .035 over. We are deciding right now on doing a 4.1 stroker piston to offer as an option but the oversizes are all over the place and I can only do two sizes I was thinking 3.985 and 3.995 but I wil check the to see if there is a difference in price for the 4" since is is so common the ring may be a bit less. I just have not bored enough production block to see how they stand up at .035
Mike

 

[49-blues]

Wouldnt a 3.995" piston in a 4.00" bore have .005" wall clearance- shouldnt that be about right for a forged piston expansion ? I for one would definently be interested in say a Diamond piston in that size. What would the required pin or comp height be? Mike- did you ever get that stage2 headed production block finished? if so how did it work out?

 

[TurboCrazy]

Bore size

Back 11-12 years ago, when I built my first production 4.1. I got the pistons from Duttwieler. 4.00" was what he recommended boring it too, and only sold pistons for that bore size.

 

[49-blues]

Whats your opion on the 4.1 production block-is it worth building?

 

[Mike Licht]

I have only built a few but they all ran very well a couple cracked from the head bolt hole to the water jacket and this is a weak point of that block. I know a 274 with some iron heads, a smaller cam a 67 turbo and 3000 stall would be a ton of fun on the street.
Mike

 

[49-blues]

Mike- thats very similar to what i was planning-274 cu in,218/218 roller cam, champ irons and forged internals with caps.

 

[TurboCrazy]

YES, it is worth it. One thing I think is absolutely necessary, and the reason mine has taken so much abuse for so long is Hard Blok. I half filled the water jackets. Yes, I drive it on the street with no heating problems. I feel that Hard Blok should always be used when building a 4.1. If interested, let me know and I'll tell how I did it.

Brandon

 

[49-blues]

Thanks Brandon- yes i would like to know how you did it-do you put it in before machining?

 

[skylarkstage1]

Brandon- would like to hear more about your 4.1 build. Thanks

 

[TurboCrazy]

Block needs to be as clean as possible. Oven baked and shot blasted is the best. The shop I used for this closed up about 4 years ago.:frown: Anyway, I'm sure a few went when I mentioned half fill the water jackets! And some may also realize that a half fill is above the water pump port in the block. This is the difficult part. Originally, I used modeling clay to form and maintain a waterpump port. The problem is removing the clay once the Hard Blok has set up. It's a real PITA to get it all out. I've got a new idea to use a hose, but haven't tried it yet. I got to looking at some of my old notes and pictures and I built my first prod. 4.1 14 years ago. I put steel mains on it back then too. I cut down 4-bolt main caps to fit the 2-bolt registers. This was several years before they were available from the venders. The rest was just good madhining practices. IMO the Hard Blok makes a huge difference. I wouldn't build another one without it. Oh, I almost forgot. You need to drill the little steam holes between the cylinders, like the stageII 4.1. This is outlined in the Buick Power Source book. You will have heating issues without the steam holes. If you have more questions let me know.

HTH some, Brandon

 

[gnxtc2]

IMHO, I would deck the block first then bore the block within .005" of the bore size. Then I would order the pistons. There are too many variables in pre-ordering piston sizes. Prior to ordering pistons, you are going to need deck height, rod length, cc of the heads, compression ratio you want, etc, etc, etc. There are too many variable in pre-ordering pistons, all motors are not the same.

Billy T.
gnxtc2@aol.com

 

[49-blues]

Thanks Billy. Did you get your car all together yet and hows it running?

 

[Jeff Strube]

What is the proper pin height or comp height needed for the new stroker kits with 3.625" crank and 6.00" K1 rods(or are they actually 5.960"-5.970")?im building a 4.1 production block stroker motor and need the correct pistons to use. Or would i need a different length rod? thanks for any input.

I wanted to no the Same think what Pistons and Comp Ht are you running
3.625 Stroke 6 inch Rod with .927 Pin. What is your set up how much Compression are you running? What Brand of Piston do you have How much did they Cost?

 

[Jeff Strube]

What is the proper pin height or comp height needed for the new stroker kits with 3.625" crank and 6.00" K1 rods(or are they actually 5.960"-5.970")?im building a 4.1 production block stroker motor and need the correct pistons to use. Or would i need a different length rod? thanks for any input.

I wanted to no the Same thing what Pistons and Comp Ht are you running
3.625 Stroke 6 inch Rod with .927 Pin. What is your set up how much Compression are you running? What Brand of Piston do you have How much did they Cost?

 

[TexasT]

Hate to bring this back from there dead but I've aquirred a 4.1 that is already .040 over. It was sitting as an overstock so I think I did alright on it if I can use the bores like they are and hope they are straight. With the Advent of custom Pistons in just about any pin ht and, size I think I can do well. I haven't pulled it apart yet to even see if it has a rolled fillet crank or the two dot rods but I was thinking a chinessuum forged crank, a pair of billet center main caps, and some hard blok in the bottom to stiffen it up. This is a street car. And I do experience triple digit temps for much of the yr. I have some used radiators with what appear to be good end tanks and was thinking I'd have one recored with a four core setup so I can continue to use the trans and engine oil coolers as well as the aux trans coolers I am already using. Will run a slic and will have ac. Or might go to a 1 or 1.25" tube two core aluminum radiator. This would probably force me out of the oil cooler in the rad but maybe not if I pony up the coin for an expensive one.
Any suggestions are welcome. Let's have some more discussion on the subject.

 

[TexasT]

I didn't even get to the quarter or half fill of hard blok or maybe a slanted fill on each side to stiffen up the outer sides of the bores. I've never done anything with the hard blok but I do know the production block is pretty flimsy.