a rough estimate of your VW engine stroke.

[grandpanystrom61]

Good day to all, I just watched a racing engine mechanic show how to find a estimate value of your engine stroke.

With a thin straight rod of metal, slide it down the spark plug hole until it stops. Note what you are aligning with to make the mark on the rod. Remember this area as the next mark has to be at the same point of reference. IF lined with the tin shrouds, you can use this edge, just make sure same spot when marking the rod for the second time.

Now I rotated CCW to BTDC mark, that put's #2 at TDC, and #1 down at the end of its travel, slide the rod down #1 cylinder and mark it. Now you can take the rod and measure the distance between marks, this gives you a rough estimate of what the stoke is. My 74 1600 DP, which I know was rebuilt at least once, measured 76.14 mm, checked the process twice and 2nd time was 76.46mm, so straight rod and same angle and reference mark is the key to accurate measurement.

Now I will look up and see if one can have such a thing as a 76mm stroke, I read about 69mm and 84mm so far in other articles. Getting interesting.

 

[FuzzyWuzHe]

Interesting ... but wouldn't a VW book tell you the stroke?

Does the stroke vary much from 74 1600 DP to other 74 1600 DP's?

I might be missing something.

 

[DeathBySnuSnu]

Told ya so....

Did not think it was going to be totally stock inside there.

Stock stroke for 1300 (1966 year) until the last type 1 made was 69mm.

There are some odd stroke cranks like 74.3 and such. Not very popular now a days.

You can do 74 to 76 stroke crank with no real heavy machine work inside the case.

Mine is 86mm and is far as you are going to be able to go without buying a billet drop cam race case.

I thought I had all the stroke charts over in tech?

 

[DeathBySnuSnu]

Get an eyeball on it and see if there are shims under the cylinders where they meet the case.

 

[grandpanystrom61]

I did it because it was a simple proven way to get an idea about things with out cracking it open. Rex your video link actually allowed me to view it. There are six different ones to watch, all had educational value to them for me.

I am glad it is the only engine I have to play with, trying to keep the info separated from American to VW would really lead to major errors for me, at least I think.

Humm, so lay down under the engine so that I can see the cylinder heads, follow down from the valve covers to were the heads meat the case, a seam line should be present, correct.

Now how does one see shim's, oh not round shims around the bolts, but a large shim that would cover the entire surface that the cylinder head and case have, were they mate together. Correct

I will give it a look a see, all is up for IRS bushings replacement, among other things.

Also learned that I did not perform the compression test accurately, a general idea, but still could be 10 to 20 or more off on true PSI reading. Just the same I learned about the leak down test, the proper way, and how to make sense of the data you get, so than one can get an idea about valve leakage and/or cylinder ring leakage. Very interesting, why am I doing this, because I had my timing off, some how, and the engine has run hot for a bit, enough to change the coloring of the chrome exhaust pipes. Yep, a real newbie screw up.

 

[grandpanystrom61]

a pic is worth a thousand words

I took a picture of what I thought might be the shim you mentioned.



that wheelie bar is in the way a bit, another try.



The the top are of the pic is of the cylinder head, as the push rod tube goes down to the case, at the bottom area of the photo you see that other tin I mentioned, just up a little that the shim ?

 

[grandpanystrom61]

I got to draw an arrow pointing to what I think is the shim.

 

[DeathBySnuSnu]

It looks like you are at the head end of the cyl.

I can not quite place where you are.

But if it is shimmer at the head to cylinder joint you will not be able to see it.

Under the cylinder to the case joint where the head studs screw into the block.

I am at the shop working on an leaking oil hose on mine right now. Lemme see if I can get a pic. Mine has huge shims.

 

[DeathBySnuSnu]

At the base of black cylinder.

Hard to see as all painted black together.





NOT the head end. Even though mine is shimmer. 050 there also.

 

[grandpanystrom61]

wow, a very clean engine, but did not expect less from you. I am sure at first this engine looked that clean, but now it has the layer of crude, oil and fine dirt, road grime. I will get it cleaned up so I can see better, and yes I was the wrong end again. So this does prove what another said, really get to know and understand the engine before rebuilding it, it will make all the difference in the end. I totally agree with this, off to the garage I go

 

[DeathBySnuSnu]

Well mine only has around 200 miles on it yet.

I try to clean it. But the bottom will get nasty because I don't lay on the ground to clean it.

I just got the oil line back on and about to crank it up.

 

[grandpanystrom61]

So there is the tin that in the way mostly, right side (1,2) is got the grime, but I looked at the left side (3,4) and 4 was cleaner than 3, plus hard to get back and get the angle I need to see that area.

So I did not snap a pic, probably should, but at that section of head enters the case, are they flat surfaces (case & head) or is there a lip on the cylinder that mates with the case ?

I ask because I can not really see a shim, but it does not look like the cylinder mates flat against the case, a fine edge of the cylinder can be seen and I slide a .025 gauge along the case and into that space, .030 would not fit.

I will take the pic, hard for me to see a difference when I do not know what I am really looking for, maybe others will see it.

back in a flash, Let it roar Rex.

 

[DeathBySnuSnu]

Ok well.....that does narrow things down a bit.

No huge shims. Most non stocks do require shims and/or custom machine work.

It does not look cut for 94mm bore. There is additional machine work involved in that.

It does look like the step the cylinder sits on is very small.

Possibly 90.5 to 92 bore cut.

So assuming it is 76 stroke then....

For a no to minimal shim it would have to be extra short rod (not common) or B pin height pistons and a long rod.

 

[grandpanystrom61]

This does give me some idea of what it maybe, if one ever had to pull a head off than they could measure the cylinder bore. Eventually with all the data collected one might get real close to figuring it out with out cracking open the case, but still one should wait on buying parts for the rebuild until they know what they have inside the case.

A bit chilly still, but afternoons are nicer, so the sun is pushing me to ride, so not much longer I hope before I can do it.

 

[grandpanystrom61]

I was told that if I pulled the oil pump out that I than could see the bolt pattern of the cam. 3 rivet or 4 , something like this, which I believe the 110 cam is the 3 rivet, or bolt style. I will get the terminology more correct soon.

I guess one should check for wear in the oil pump occasionally, and a few other things can be noted to help identify the volume output of the pump, well is stock or more ?

I want to ride, not play mechanic all summer.

 

[DeathBySnuSnu]

Ok.....yes if you pull the oil pump out of the case you can identify a few things about the cam.

Most cams are stamped on that end.

And you can see if it is flat and 3 bolt or dished and 4 bolt.

Almost all the hot rod stuff is flat 3 bolt.

The oil pump body does not have to come out of the case to identify the pump.

The sizing terminology is the width of the gears. Diameter is the same the width is what changes. You can just take off the cover and pull out a gear. Nothing holds it there, it is trapped by the cover.

The pump could wear on the outside diameter and or score up around the outside. But that is more rare unless some metal has been pumped through.

The main wear is end play. We are only talking a couple thousand extra end play and hot idle pressure will be low.

I see pumps put on with a thick gasket or gobs of silicone. That just kills the pressure.

You want the pump gear smooth flush to the body and a super thin paper gasket on the cover to make the end play.

 

[grandpanystrom61]

I asked because I wanted to see if this was some correct info, and is the info I get worth the effort.

I think it would be worth the effort to see what condition the oil pump is in, plus you said "gooped up orange sealer" well that is what was done to this one. Looks like most was used between the case and pump, not much if any between pump and cover plate.

A nice clean up job is in order in this area, for sure, so no real wasted time doing it. At least I can put it back together correctly and gain a little bit more knowledge about this engine.

Thanks for the reply.