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posted January 15, 2004 10:09 PM
Just wondering what the max stroke on a GM 400 block is WITHOUT hitting water? 4.00"? let me know what you guys have done. thx

posted January 16, 2004 02:17 AM
I will say about 3.850......that assumes you use a rod that is skinny on the big end. Also assumes these rods have cap screws instead of nuts and bolt.

Then rod length is in there a little too..the above is a crower sportsman stroker rod.

I would core fill the bottom of the block BEFORE I started grinding, then if you happend to hit water it not too big a deal.

I've got a 406 with aluminum rods, THEY ARE HUGE ON THE BIG 2 bolts on each side of the pan. Had to grind out to the center of the oil pan bolts to get the rods to swing, then Dave @ Crower had to build be a special EXTREAMLY small bse circle cam and I still needed to mill the top of the big end to swing past the cam.

Keep the cam in mind when adding stroke.

posted January 16, 2004 07:04 AM
i did a 3.875 stroke without cap screws and it is just fine

posted January 16, 2004 02:24 PM
agree with sixwillwin. 3.875 is about as big as it will go. off the top of my head, makes about 421cui but best to check that with a calculator (obviously will depend on bore size).

posted January 16, 2004 03:31 PM           
capscrew rods help clear the cam, but are worse on the block side...

why do you car if you hit a water jacket? just grind into it then fill it when your done, easy as that.

sure isnt a big deal.

you can use cast iron repair stuff that is 2 part from about anywhere that you can drill and tap its so hard.

posted January 16, 2004 10:38 PM
If you core fill the block that should be done BEFORE any other machine work. Core fill can and will make the cylinders .001-.002 out of round, hard to seal a ring on a egg shaped bore. If you just use 2 part epoxy to fill the hole in the oil pan rail that can be done any time.

On a 400 block I like to core fill the bottom of the block, from the oil pan rail to the bottom of the frost (soft) plugs. This helps from splitting a cylinder with lots of compression, also keeps the deck from cracking. Since the fire is on top the piston and the pistons stay above this area, i've NEVER had a problem with over heating.

posted January 16, 2004 10:47 PM           
Jeff, whats lots of compression for a 400 block?

Good pt about up to the freeze plug only.

[This message has been edited by dirtrace (edited January 17, 2004).]

posted January 17, 2004 08:39 PM
If your asking me at what I point I core fill....anything over 12 to 1...... I know most people don't start having problems until you get over 13 or 13.5 But to me core filling the block is cheap insurance.

I would never consider building a 400 block over 14 to 1 without core filling.

Also bore size has some thought in this...standard to .020 over core fill at 13.5 .030 over bore and .040 13 to 1 I will core fill. What all this has to do is CYLINDER WALL THICKNESS....... and this has to do with core shift ..... if the block has lots of core shift once you bore the cylinders they will become too thin some times....... to put the cylinders where they belong sometimes you take out .005 on one side and .025 from the other....... a good machine shop can and should sonic test before doing any machine work.

xx RACER 96
posted January 18, 2004 01:44 AM
The use of block filler will tighten your piston skirt clearance, you will need to add 1 to 2 thousandths depending on your application.

[This message has been edited by xx RACER 96 (edited January 18, 2004).]

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