40hp questions

[crowlejo]

hello,

What type of machining (if any) needs to be done to get a counterweighted 69mm crank into a 40hp case? Also, can the crank be used with everything else stock? I know I will have to machine the rods. I also know I can just put a 1600 in it but I dont want to. I just wanted to see if this would work. I read all of the posts about big bore and everything, I just don't remember coming across anything talking about the machine work needed on the case or heads to accomodate the 69mm crank. Any info would be greatly appreciated.

thanks,
Josh

[Howard 111]

It won't work. The 40 horse case is too short for a 69mm crank, It's not the stroke, but the actual length of the crank.


.

[ALB]

In the book "How To Hotrod Volkswagen Engines" author Bill Fisher talks about putting a 69 mm crank (part # 311 105 101F) with 40 hp rods in a 1200. You have to narrow the big ends of the rods about 0.020" on each side so that they measure 0.900" wide.

He also talks about using 36 hp rods and offset grinding the crank rod journals 5mm off-center to the 1.9685" diameter of the 36hp rod journal and ending up with a 74mm crank. With 83mm big bore 40hp pistons and cylinders you end up with a 1602cc 40 horse motor.

All the details are in the book; pages 83 and 84 in the chapter on crankshafts. Sorry, I don't have a scanner. Hope this helps. Al

If you're interested in the rest of the details I'll see about using a neighbour's scanner to get you the rest of the info if you can't find it.
It's not that much but i don't type fast enough to do the whole thing here...
_________________
On a lifelong mission to prove (much to my wife's dismay) that Immaturity is Forever!!

[Matthew]

[Howard 111]

You're right. It's been 38 years since I had a 40 horse.

[62 in progress]

I'm starting the same process of big boring my 40hp. I'm going for the 69 crank/83 big bore idea. Just got my 40hp case back from the hot tank and set the 69 crank in case. It fit perfectly, No machining! Off to a great start!
I'm getting alot of great info from The Samba members here and "How To Hotrod Volkswagen Engines".

[ALB]

Josh- check you pm's. Al

If someone is interested in what's in the "How to Hotrod VW Engines" book say so and I'll post it. Al
_________________
On a lifelong mission to prove (much to my wife's dismay) that Immaturity is Forever!!

[gerg]

It is a great book, along with the VW parts interchange guide.
_________________
Gerg

. . . I got 99 problems and my bus ain't one . . .

'65 Sunroof Beetle
'65 Vert
'60 Singlecab

[andk5591]

Wait for Gutamodo to respond - he seems to know more about 40 horse than anyone I know of........
_________________
D-Dubya Manx clone - 63 Short pan,1914.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Cindy's daily driver.
Max - 73 standard Beetle hearse project - For sale
66 bug project - Real patina & Suby conversion
There's more, but not keeping them...

[ALB]

For anyone interested; from "How to Hotrod Volkswagen Engines"
note to some- remember that this was written about 1970 and the 69mm
stroke motors were still pretty new.
"If the cam bearings are not worn out; or if you have one of the replacement 40 hp cases that was supplied with the changeable insert cam bearings, you may be intrigued by the prospects of having up to 1602 cc.

Some machinists who specialize in vw case work install the insert cam bearings and bore the case for oversize o.d. main bearings.

First of all, remember that the 40 hp engine is narrower than the later engines by about 3/4 inch. Thus, the sheet metal, connecting rods, pushrods and tubes, studs, intake manifold and exhaust header are all shorter than the later stuff. So, to avoid the expense of changing these things for later parts, let's investigate what can be done to make your 40 horse come alive. The 1300/1500/1600 crank drops right into the case without any machining. The rods are wider on the 40 hp so you'll have to turn approx 0.020" from each side of the big end of each rod so that the big end measures 0.900" wide. Don't get lazy and try to take 0.040" from one side because that won't work. Rod side clearance should be 0.008-0.012" with the rod held against one side of the journal.

When this is done you'll need cylinder spacers approx 0.100" thick to go under each cylinder.

77mm pistons and cylinders= 1285 cc's; the same size as the vw 1300.
82 or 83 mm =1457 or 1493 respectively. There's even a 69 mm roller crank (made by SPG) for the 40 hp engine. It's the same as the other 69 mm roller cranks except for 40 hp length rods designed for use with the 20 mm piston pins. The 0.100" spacers are needed under each cylinder and the heads can be flycut or the rocker stands shimmed an equal amount to get the valve-train geometry nearly correct.

To go bigger, dig up a set of 36 hp connecting rods in good condition. A
crankshaft specialty company can grind a 69 mm crank's journals 5mm (0.19685") off center to the 1.9685" diameter of the 36hp rod journal. The
journals are ground to a narrower width to give 0.015" side clearance on the 36hp rods. The journals should be Tuftride hardened after grinding. You end up with a crank stroked to 74 mm. Youll have to use spacers approx 1/4" thick under each cylinder and then work out deck height and valve-train geometry. You'll have to cc your heads and check closely to keep the compression at a reasonable figure.
There's even more displacement available through even larger bores and longer strokes for those who want to go all out, but I'd have to recommend the 83x74 as a practical limit because the internal bracing of the 40 hp engines is just not as good as the later cases." Author Bill Fisher

That's pretty much it for what's in the book. I've condensed and paraphrased some of it, but haven't left out or changed anything. Al
_________________
On a lifelong mission to prove (much to my wife's dismay) that Immaturity is Forever!!

[AlteWagen]

what is the best way to clearance the 40hp rods at home? I was thinking belt sander but not sure it would keep the rod "square"
thanks

[ALB]

derluftwagen- I think it would be pretty hard to keep the sides square with
a belt sander. Someone please correct me if I'm wrong, but trimming the
big ends down is a job for a machinist. Al
_________________
On a lifelong mission to prove (much to my wife's dismay) that Immaturity is Forever!!

[gerg]

I agree.
_________________
Gerg

. . . I got 99 problems and my bus ain't one . . .

'65 Sunroof Beetle
'65 Vert
'60 Singlecab

[Howard Sanson]

Bob at demellos ? CA Lake elsinore he can do this ?

[[email protected]]

I was told i can't use 356/912 616 rods on a vw 1600cc 69mm crank but was never given a reason to why not ..anyone ???

[modok]

Too much side clearance.
It would work with enough welding, but there isn't anything particular good about a Porsche rod verses, any other kind.

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