Stock 69mm crank as stroker in 40hp ?

[tristanblue]

I have a couple 40hp engines I am doing for vehicles. I want to retain that 100% stock 40hp look but would like to add some extra power if possible as one of these will be in a bus.

In particular, the one is a stock stale air 61 block. I have rebuilt stock heads with short stud kit, case line bored. I have a couple sets of MAHLE big bore 83s from early 2000s as well as a couple sets of stock 77mm p/cs. I have some nice NOS 64mm and NOS 69mm stock cranks on hand. I had planned on just doing the big bore 83s with stock engine but speaking with someone online he mentioned doing a stroker utilizing a stock 69mm crank from 1600 and then adding 5mm spacers under the cylinders. He also said to use the stock 40hp rods and have the narrowed to fit the 69mm crank. I was curious about intake and exhaust width with this or any other issues.

The above info was in brief passing and not many details told. I was wondering if anyone on here has done this mod and if it worked well or not. If there was any issues, tips, tricks etc to watch out for.

Thank you

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[tristanblue]

A 1600 looks NOTHING like a stale air 40hp (unless you drive a FORD).

This is a high dollar show vehicle, if the engine is not going to be 100% correct on the outside, it is definitely a no-go! We are just trying to give her a little more internal (hidden) power since this is a bus. Dual carbs, 1600s are NOT and option.

[[email protected]]

[jsturtlebuggy]

You only need a .100" (2.5mm) spacer under the cylinders to use a 1500/1600cc crankshaft in a 40hp engine.
Bill Fisher covered this in his book "How to Hot Rod Volkswagen Engines"
It starts on page 83 in the book.
I have done it many years ago.
Yes you have to tweak the intake manifold some as engine with gains 5mm.
It can be done and will look stock from the outside.
_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960

[anthracitedub]

I built a stroker 40 for my ghia. I cut my own spacers @.100 out of aluminum and narrowed my stock rods. The stock intake fits if you spread it just a tiny bit../ they bend easier than one might think. A stock exhaust might be harder... I’m not sure... I used an aftermarket exhaust, I had to do a slice on 2/4 pipes and reweld... also running j pipes. All the stock tins still fit ok.

[tristanblue]

[anthracitedub]

I think any decent machine shop can do the rods... I believe you just have to cut .020 off each side on the big end. I’m not a machinist by trade, but I borrowed the tool room at a place I used to work and would work on the rods a little at a time. I used a surface grinder to do them.... but in hind sight it would be better to use a lathe.
Also, I forgot to mention that you may also have to do just a small amount of clearancing on the piston skirts...depending on piston brand. On mine I had to radius the corners off the skirts.... very small amount... I also used a counterweight crank. The skirt would contact the inside of the case spigot/register on BDC of number 3. Check clearance on all of them just to make sure. Usually you have to make the changes to all the pistons to keep the weight identical.

[PEPPE]

i've used for long a such engine, 69mm crank, rods narrowed and modified for 22mm pins, 86mm vw pistons with shaved top. due to shaved pistons and flycut heads the lenght was stock. very drivable and a very good torquey engine for my 69 bay. later i changed it for a nice 1600 SP with torque cam but it is not really better. less grunt in low rpm

[tristanblue]

Thanks, yup i have dealt with the Mahle big bore skirt thing many times..got that.

RIMCO/FAT Performance is or was one of the best machine shops for VW out there and said they won't do the rods...weird?! If anybody knows of a shop they have had do this and trust please let me know. I would rather ship my rods to a machine shop who has done this then a generic local machine shop. I have had HORRIBLE luck with the later and VW parts. They either ruin them or lose the parts...LOL

Peppe some good interesting info there! If I did not have several sets of NOS 83 Mahle big bore kits here sounds like something I might try!

[PEPPE]

pretty common here, i do sometimes also 90.5mm cylinders. i have special fixtures for shortening the barrels with no distortion.

some times ago I had done some rods for 40hp, with offset and 22m pins because some friends worried about the rod weakening, also if i had no problems.

[tristanblue]

I just noticed pretty much all sorts of good info on this topic in the old "How to Hot Rod Volkswagens" book. I have read that book several times but guess I glossed over that section. Great info there as well.

I am still looking for a reliably, trust able machine shop to narrow the big ends on some 40HP rods though if anybody knows any.

Pepe do you make or would you be able to machine a set for me? stock 40 rods with narrowed big ends for 69 crank?

Thanks!
Tristan

[vwfreek61]

[PEPPE]

i believe it is unpractical ti send parts from italy to usa, expedition costs between usa and italy is increasing. years ago i spent for a set of vw rims about the same i spent recently for a filter pump.

[spencerfvee]

hi guys. I am new to 40hp motors builds . didn't vw make a 1500cc motor in the early 1960s .for the old buses. with the old 40hp heads on it ? I could be wrong spencerfvee

[PEPPE]

was it probably the very early 1500 for type3?

[spencerfvee]

[Alstrup]

It´s always fun to think outside the envelope, but in this case the only reasonable thing to do is to buy a 83 mm big bore kit and use with the stock 64 stroke and stock rods. Then everything fits and you get a little more oommph for the hills.

(I am in the middle of a 25 hp hot rod build for a ´51 split, where everything has to look and for the most extend be period correct. It is a massive job, and is only interesting because the owner has patience, so I can do it in between other stuff.)

[slalombuggy]

Talk to Brothers Machine about shortening the rods.

You could also deck the tops of the pistons if you didn't want to take so much material off the big end of the rods.

brad

[tristanblue]