Z11 crank

[Barry Taylor]

Thanks, thats what i was thinking.

 

[Greg Reimer]

Yes you can offset grind a crank .015. that will get your 3.65 stroke. NHRA stock class guys do it all the time.

No, that would need to be a .150" stroke. Stock E cranks allow for a .015" stroke increase, but most of us that do that specify a .013" stroke increase. That's because we like to be good by .002" on everything from cam lift to bore size to stroke limits.
The addition of .013" to the stroke of a 327 plus .065" only adds about an inch to the overall displacement. It's hardly worth the effort.
The reason for the .002" is to leave a little on the good side in case the NHRA teardown tech guy doesn't read micrometers and dial indicators quite the same as the rest of us. A little leeway given up is better than failing a teardown inspection. We got torn down at Winternationals one time, they found nothing wrong, but they sometimes inspect parts based on a visual inspection, and sometimes OEM replacement parts have been known to
not pass because some tech guy said," it just doesn't look right",despite the fact that it went in right out of the box. That dispute occurred at Pomona some years back regarding valves on the SBC from TRW. If he would have narrowed the valve faces and thinned it down the way everybody else does them, the inspector might not have noticed whatever it was he didn't like. Also, it might have been an issue as to who the racer was.

 

[region rat]

When I worked for L A County Mechanical Department in the mid '80's, we had a supervisor in the paint shop that was a 409 guy, and he set out to build the ultimate 409. He had a buddy who was an absolute genius wizard who could build anything his mind could imagine. That was a lot. He had a flow bench, so he flowed a 690 head and came up with several conclusions pertinate to W motors. One fact was that the intake port entry was way too low. The bottom of the port didn't flow at all. He built up the port floor with clay and found out that it didn't affect the flow numbers. He kept adding clay until it began to restrict flow, and by then, the port was about a third full.He then turned his attention to raising the roof of the port and rechecking his numbers, that is when improvement started showing. With approval of my friend, he started experimenting on the head, and he built the roof of the port up until it was flush with the valve cover flange, then he removed the clay and welded in the floor to raise it to the point that the clay took him. There's no water passage over the top of the intake port, so that gave him some more leeway. He then did all four ports the same way, and had a 409 head that would outflow a lot of other performance motors. Next thing he did was to turn his attention to the exhausts. he found a lot of power by building up, raising, and straightening the center pair of exhaust ports, then straightening and raising the port roof on the outer exhausts. About this time, one of our other Club members had a cracked Z-11 head that was fairly original, so Ron, the wizard, borrowed it just to flow it in its OEM configuration.He said that whoever designed that head really knew what he was doing, and that it was a beautiful job redesigning that head. Of course, it was Zora Arkus Duntov behind it. He cleaned up and repaired the head for the other member in return for letting him use it for a baseline comparison. There was probably well over 100 horsepower difference between the Z head and the 690. They built a set of headers for the engine with the new port configuration, all four ports were on the same centerline since the inner pair had been raised so much. They also made a sheet metal intake starting with a nasty old 409 intake that had a broken plenum.Off that all came, the bottom third was filled in, the side flanges were left on with the top of the port removed, then the rectangular cross section aluminum tubing started getting fitted. He made an air box that had the carbs spaced further apart front to rear so that something other than an AFB could be used, and it resembled a current for that era Pro Stock intake. They also had to come up with intake gaskets, but Ron the wizard knew someone, he came over, made a pattern, then came back later with some intake side gaskets. These two guys actually assembled the engine, ran it in, and ran it on a dyno up at a facility in Lancaster,Ca. where they lived. I don't remember the actual bore and stroke or what cam they used, but it was over 600 horsepower back around 1990 or so. Certainly, better and more powerful 409's have been built since then, aftermarket heads and intakes have come along, as well as blocks and stuff, so it would have been easier to duplicate these efforts, but none of that stuff was available then. I still wonder what ever became of the Z-11 head they used as a comparison sample. I'm sure it went someplace nice.

Greg, That is about the same way we made my raised port heads. There is nothing going on nrar the floor. In the latest castings we added material over the ex ports almost to the valve cover rail.
Also added material under the valve cover above the ports on all the heads, in case someone wants to do mods lke that.
The raised port is a seperate casting so ne need to fill in the floor.
When we use a Jesel, I can move the intake pushrod .250 away from the intake port to open up the pinch. Jesel makes offset rockers that work fine. Also, Isky and Crower make tall seat lifters that can be made with offset puhrod seats as well.
Bob

 

[region rat]

No, that would need to be a .150" stroke. Stock E cranks allow for a .015" stroke increase, but most of us that do that specify a .013" stroke increase. That's because we like to be good by .002" on everything from cam lift to bore size to stroke limits.
The addition of .013" to the stroke of a 327 plus .065" only adds about an inch to the overall displacement. It's hardly worth the effort.
The reason for the .002" is to leave a little on the good side in case the NHRA teardown tech guy doesn't read micrometers and dial indicators quite the same as the rest of us. A little leeway given up is better than failing a teardown inspection. We got torn down at Winternationals one time, they found nothing wrong, but they sometimes inspect parts based on a visual inspection, and sometimes OEM replacement parts have been known to
not pass because some tech guy said," it just doesn't look right",despite the fact that it went in right out of the box. That dispute occurred at Pomona some years back regarding valves on the SBC from TRW. If he would have narrowed the valve faces and thinned it down the way everybody else does them, the inspector might not have noticed whatever it was he didn't like. Also, it might have been an issue as to who the racer was.

I had a chance to buy a Z-ll crank when I bought my top end. The guy the whole moor except for the block.
I passed on the rotating assembly. Material then was not as good as it is now. I had Scat make a crank from an American forging that still hasn't made it into a motor.
Bob

 

[region rat]

3.65 seems to be a magic number in big block motors.
Z-11, MM and the 430" Can Am motor.
Still need a long rod and super light piston

 

[oil4kids]

WOW thats a special crankshaft, an 0 - crank was pre production, so that could have been used in a mystery motor or Z11. I would guess that was a crankshaft used in early Z11 drag cars or a Nascar events or even at the Daytona 500. . Remember when Daytona lifted the displacement rules in 1963 Richard Keinath , Chevys chief engineer immediately set out to stroke the crank to 3.65 Inch. Remember the original BBC mystery motor was designed at 409 cubic inch's and not 427.

 

[oil4kids]

Here's a picture of what Mr. Keinath started. Rows and rows of big block Chevy engines from Tonawanda.

 

[Phil Reed]

Hey!!!!! How are you!!!!! Nice to see your back!!!!
PM me your phone number please!!!!!!! ! I need some more Amsoil for my air compressor.
Phil

 

[Iowa 409 Guy]

It used to be feet, now it's backs.....

 

[oldskydog]

My 66 Corvette was an original early 450(425)hp 427 car with sidepipes, tele column, teak wheel, F-41 suspension, 4:11 rear and M-21 that still had the part number tag and VIN number stamp. The only thing missing when I got it was the orignal engine. When I was cleaning out the engine compartment, on the right inner skirt was stencil that appeared to be on the bare fiberglass before the blackout paint was sprayed. That stencil was "DATONA 4.31x 3.65". I recognized that as the bore and stroke of both the Z-11 and the mystery motor. I tried everything to find all the history on the car to determine why that stencil was on there but all I found was that it sold new by Manning-McComb Chevrolet in Peoria, Ill just up the road from Fred Gibb Chevrolet noted for COPO 427 Camaros.
I found nothing of the history from then to when it appeared in Palos Cedros Ca. where it was just before I acquired it in 85. The last registration tag on the plates was 72. Apparently it had been raced before that as I found evidence of racing stripes and gold outlining of the fenders under the paint. It must have been drag raced since there was no indication of any suspension modifications for road racing.. Traco engineering was big around that time and I wonder if may have gotten an engine from them but I guess I will never know. Anyway, I sold the car a few years back so it's just another musclecar mystery of the 60's.