TheSamba.com :: View topic

Fri Jan 13, 2012 3:06 pm

Hey,

I was planning on doing up a small engine using my old 74mm stroker crank, 94mm pistons and barrels, stock connecting rods and push rods, and a pair of Mag44 heads with ratio rockers.

Nothing special, but a little more power for the highway essentially. Just found out that the pistons will have to have the skirts cut to spin in the case, the pistons will tend to stick at the top of the barrels, the stock connecting rods are really the wrong length, the push rods will need to be longer, and shims will have to be used to set the deck height.

Wondering if it's worth all of this extra work for the slight bump of the 74 crank or would a stock crank, while not the optimum choice, still give that little extra that I'm hoping for.

Need help, opinions, facts. Thanks !

TC

Fri Jan 13, 2012 3:22 pm

I would put it together. It sounds like you have most of the parts

Fri Jan 13, 2012 3:31 pm

stick it togeather and see what it realy needs to be done.shims are cheep, as are longer rods&aa pistons.I would not think the pistons would need much if any work on the skirts, I used a 78.8 crank with 87 pistons, some work but not that much& a few shims.

Fri Jan 13, 2012 6:37 pm

Any stroker crank, even a 74mm, is a big improvement over the stock crank. Do you have A or B 94's? If A's then the stock rods can work but you'll have to have them stroker clearanced. A set of CroMo I or H beams would help it all fit together easier, especially if you use the shorty 5.325" H beams. If you have B pistons then you'll need a set of 5.5" rods. Push rods, you'll have to assemble the motor and see what length you need. 2054cc can be a very nice street performance motor with the right cam, carbs and heads.

Fri Jan 13, 2012 6:59 pm

I just did a 74x92 with A AA pistons and 5.325 H beams. did not need any clearancing to the piston skirts. AA's have shorter skirts than Mahle. the last engine with Mahles the skirts needed clearanced.

.020 barrel shims and the deck is .038.

the AA's were within 1 gram, the Mahles were 10 grams out, so much for paying more..

Fri Jan 13, 2012 7:16 pm

It will make a better overall motor to have 74 stroke, so yes

Sat Jan 14, 2012 5:01 pm

Thank you guys ! !

If I could pester you just a smidge more . . .

Being on the usual "tight budget" I'm going to have to use the stock VW rods I figure. The 94mm pistons/barrels that I have are non-stroker. The case is already clearanced for the crank and I can do some more for the rods/pistons.

I was wondering is it OK to take material off of the piston skits to clearance them to work with the crank using a grinder/dremel/etc. and how close should the weight of one piston be to the next one? I would guess that the same weight would be best, but how far off can I be and not cause trouble?

Thanks !

TC

Sat Jan 14, 2012 5:12 pm

yes it is ok to whittel off what ever you need to.just raidi any corners,but leave the shirt sharp where it contacts the cylinder wall so I sheers off the oil,if you bevell it there it will smoke and use oil.and balance them all down to the same weight.the harberanger of freight has digitail scales cheep that do grams.it,s not hard to do it.just do 1 then make sure you mark the corect side of the other pistons & do them then re check them all. you will be gladd for the extra work.(I think,as I have never used a stock stroke crank in any vw) shoot for about .040" piston to head clearance.

Sat Jan 14, 2012 5:18 pm

^^^ What Mark said ^^^

Main thing is to just take your time and do a good job. You can get all your pistons to be damn near equal, or within a hundredth of a gram. It's worth it.

The larger your P/C's the more clearance you'll have on the rods. Before you go grinding things down mock the engine up and check for clearance. Sometimes the case will allow everything to clear, sometimes not.

Sat Jan 14, 2012 6:35 pm

Thanks again ! I think that I can do this. As long as it'll be OK to use the stock rods along with the 74 crank and non-stroker pistons/cylinders I think that I'll be able to grind wherever necessary to make things work.

I thought that I'd end up having to buy all new rods, pistons, and cylinders in order to use the 74mm crank. If that were the case, I'd just forget all of ti and try building a stock motor for now.

I'll be sure to let you know if I'm successful with this.

TC

Sat Jan 14, 2012 6:45 pm

Post pics if you can. There's always so many people that have questions about this type of build, especially if you are using stock rods.

Sun Jan 15, 2012 3:10 am

Stock rods are just fine for a 74 stroke, I have used balanced/reconditioned stock rods and regular A pistons on 74,76,78 strokes, works great

None of these engines had problems with the mahle piston hitting the case or crank...... are you using an odd brand?

It is ok to grind a bit off the piston skirts of it hits, just try to make all four close to the same and re-balance them on a gram scale afterward. within one gram is good

Sun Jan 15, 2012 11:01 am

Thanks once again for the great answer(s) I'm a bit lost here and all of this is a huge help.

I'm using stock rods and regular (non-stroker) Mahle pistons, (and, of course, the counter balanced stroker 7mm crank.)

I sort of though that the quality pistons and barrels along with the relatively small crank would all work together pretty well, hopefully with a minimum of clearancing here and there, other than the work already done to the case when it was opened up for the 94 barrels.

I was cautioned by an experienced builder who was willing to help with assembly, that there would be problems using the combination that I had and that the rods would be wrong, the pistons were wrong, the pistons would stick in the barrels and that the push rods would need to be much longer because of the shims needed.

I can understand the ,longer rods due to the shim, and the shims make sense because of the stock rod on the altered crank. I just thought that I might be able to use some of what I'd already bought (rods, crank, pistons and barrels) and just have to buy some longer rods and a shim set.

I was posting here for a little help or opinions before I abandon my project and opted out for a simple (non-stoker) stock engine.

IF I can honestly use the stock rods and standard (non-stroker) 94mm pistons and barrels, does anyone have an idea of what size shim I ought to start with and what I ought to end up with for the deck height. The motor will just be a little extra for the highway and run around town and use pump gas. Nothing much going on really. If anyone has even an idea of where to begin, it would be a nice help.

Thanks ! !

TC

Sun Jan 15, 2012 11:15 am

your combo is fine. You'll need around .070-.090" cylinder base shim. That means longer pushrods, BUT if you are tight on money you can simply use lash caps, OR put some

http://vwparts.aircooled.net/Bugpack-s-Swivel-Ball-Style-Valve-Adjusters-Set-o-p/4010.htm

or

http://vwparts.aircooled.net/Bugpack-s-Elephant-s-Feet-Valve-Adjusters-8-p/4010-10.htm

which will "use" some of the excess lash you wind up with.

Alternatively, you can simply buy some porsche length rods

http://vwparts.aircooled.net/5-325-H-Beam-Connecti...ournal.htm

which are shorter than VW rods, and you'll have stock deck and geometry pretty much everywhere. But Porsche rods only come in more expensive H-beam style, but it will be "stock" in most every respect if you buy this one part to make everything work together.

Sun Jan 15, 2012 12:39 pm

Thank yoiu very much, John ! I didn't want to have to use cut and rebuilt longer push rods, I used them in my 1835 and had a dixckens of a time building them correctly and to the right length.

My budget for this little motor doesn't include those cool Porsche rods, this time around it's just something for a little more power getting on the highway and such, but . . .

Those elephant feet and swivel feet and all look like a wonderfully clever solution. In your mind, which would I be better off buying from you? My push rods are new, stock length. My rockers are 1.25 ratio on solid shafts, but I also have a very nice, checked over set of stock VW rockers, also on solid shafts just in case.. The cam is a little 110.. My valve springs are heavy duty ones with titanium retainers in stock (un cut) pockets. If those Mag44 heads and valves and springs seem like too much, I also have some OK/Good re-built VW heads with stock exhaust, slightly bigger intakes, and stock springs that I could use

If you have a moment, could you please post your recommendation?

Thank you ! !

TC

Sun Jan 15, 2012 12:48 pm

If your budget is tight, your budget is tight. Keep the VW rods, and use the Courier or Elephant's Feet. You will also need a Bolt On Rocker Shaft Kit, OR Side play Shims, to remove the wavy washers, because you have HD Springs. Your stock pushrods are borderline, you'll have to keep an eye on them for flexing damage.

http://vwparts.aircooled.net/Rocker-Arm-Sideplay-Shims-Set-of-8-p/4018.htm

or

http://vwparts.aircooled.net/SCAT-Bolt-On-Rocker-Shaft-Kit-20129-p/20129.htm

the SCAT is nicer than the Bugpack.

http://vwparts.aircooled.net/Bugpack-Bolt-On-Rocker-Shaft-Kit-p/4049.htm

FWIW, I prefer the Elephant's Feet to the Courier Style.

Wed Feb 08, 2012 4:08 am

Good info John! I'm building a similar motor, except smaller P/C's. So, this is a big help to ME TOO! :D

Wed Feb 08, 2012 2:24 pm

I ended up using a .1 shim just to get "0" cylinder deck on my build with NOS non decked case. There was a .040 step in the stock heads for overall deck height.

I recommed the elephant foot adjusters over the swivel foot so you dont have to grind on the rocker arm.

Wed Feb 08, 2012 2:34 pm

I wish I knew about the elephant foot adjusters before I bought my swivel foot adjusters... :roll:

I'm sure they'll still be better than stock ones though, so, it's not all that bad.

Wed Feb 08, 2012 2:37 pm

FWIW we now offer this Mini Stroker Long Block, based on the 74mm crank combo, since I have had a lot of guys interested, but some were uneasy about trying it themselves.

http://vwparts.aircooled.net/Aircooled-Net-Mini-Stroker-VW-Long-Block-p/mini-stroker-long-block.htm