Easy stroker

Gib · Post by **Gib** » Sat Jun 08, 2002 7:18 pm

I have a 2007 (or 2017, not sure) using an old Bernie Bergman crank. My heads stared off on the same damn BB motor I parted out and are now many times worked semi-hemi's with chambers at around 65cc's. With .107 shims under my barrels I calculate my compression to be in the neighborhood of 8.2-1 on a .060 spot faced, stroker clearanced, Berg case. This effectively gives me a .047 shim if I was using a case that was not spot faced (is it really necessary?).

I guess my question is: with all the math that is involved with this, in addition to semi-hemiing the chambers to get about 65cc out of them, could I have just used a 74 or a 76mm crank on a set of stroker 90.5's and assembled it virtually straight up to achieved a reasonable CR around 7.0 to 7.5-1. Size doesn't matter here, just the math and the machining (money!) required to achieve it.

Anyone out there do this? I'm looking for the sweet stroker build up that kind of falls together after a company does their "standard stroker clearancing" prep work on an otherwise stock case. A "no brainer" stroker motor.

I would probably use a 286 duration cam, like an Engle 110, in this motor with a set of un-P/P 40x35.5 heads like 044's. Good power and good torque for a good price.

Post by **sparkmaster1** » Sat Jun 08, 2002 7:37 pm

A large deck height robs power. You want the combustion in the head chamber not the top of the cylinder. If you have some heads that haven't been semi-hemi cut, don't do it. Go to Aircooled.net for the compression and cc program. It works great and saves a lot of hand held calculator time. Are you trying to use a 78 stroke crank and "b" pistons? Good luck, Tim

rajay · Post by **rajay** » Sat Jun 08, 2002 8:13 pm

Bergmann's crank's were hit and miss as far as quality was concerned, they (78mm) usually produced a 2010cc displacement with the 90.5s, your original engine had around a 7.92:1 compression ratio. I'd avoid the 74/76mm cranks as they cost the same as a 78mm which will drop into a "standard clearanced" case say from Rimco which holds some 84mm cranks, a Demello 78mm crank drops right in.

[This message has been edited by rajay (edited 06-08-2002).]

Gib · Post by **Gib** » Sun Jun 09, 2002 1:11 am

The motor I described in the first paragraph above is in my car right now. I made the mistake of buying my first motor from a local, at the time, engine builder with a big ad in one of the magazines. It was one of his hydraulic lifter 2017's. The information gained in this discussion will be used to make fewer mistakes in my next motor. A motor where I will know exactly what I have in it and why.

Short Long story - the first problem I discovered with some help from a porsche buddy of mine was it was running 10.2 CR. Had the heads semi-hemi'd and chambers blended by FAT in Orange, CA. Still a novice on motors, I endured the constant knocking at start up for another 6mo's before I ended up parting out the motor case in favor of a Berg clearanced, full flow, solid lifter case. While cleaning up the hydraulic case prior to sale, I pulled the dual relief covers and found the one that appears to control cam bearing pressure to be missing all it's bits. Oh well, I had already sold it. A learning point.

Back to the question at hand. If I understand correctly from reading the other posts. If I use a reputable 78 crank and semi-hemi heads that definately haven't been flycut or rebuilt (to maximize chamber volume) then the motor should assemble straight up to about 7.5-1 with zero deck height. This keeping the burn all in the chambers and not partially in the bore. If I had to shim under the barrels, I'd like to only go as far as the VW recommended .040 deck height.

Lets say for arguement sake it doesn't make it. Should I shim it under the barrels past .040 like I've already done or should I use copper head gasket/shims instead?

I have used semi-hemi cutting to get extra chamber volume. Is there a problem with this beyond "he said, she said".

Thanks

[This message has been edited by Gib (edited 06-09-2002).]

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Sun Jun 09, 2002 9:02 am

Shoot for 8:1 or more with a combo like that.......Toss the blue book ideas.

Bent · Post by **Bent** » Mon Jun 24, 2002 4:56 am

may-be an Engle 130 cam + 9:1 comp ratio

Bent · Post by **Bent** » Mon Jun 24, 2002 4:59 am

Use wedge chamber with 1.2mm deck.
Don't use hemi-cut with E 130