engine assembly problem

[badsix]

I'm assembling my engine to figure my dome volume and to check for valve clearance. during assembly I put the crank in the case it spins free with very little drag. then I installed the cam with the timing marks correct. now the crank is tight, It turns but has quite a drag on it. the problem is with the crank up against the thrust at the flywheel bearing it turns hard. if it move the crank to the pulley end it turns free and the gears line up perfect. when its back on the thrust the gears are off about 1.12mm. cam and crank gears are new, cam is new and has no end play. crank is std. case is std. crank bearings are std. what's wrong ?
Jay D.

[S.J.Szabo]

How much end play are we talking about?

[badsix]

I have about 1.45 total end play now I just have the crank and cam in one half of the case no flywheel
Jay D.

[badsix]

how do I get this in the 356 forum that's were I was trying for
Jay D.

[Impi]

Hi
Due to manufacturing tolerances the crank and cam centerlines may be off a few hundreths from design. the factory compensated for this by slightly varying the cam gears pitch and supplied cam gears in order to correct for these minute variances. camsgears were marked + or - the std gear not receiving any markings or a 0 if you move the crank you also alter the mesh with the crank gear and when that happens you will have less drag. I would suggest installing your old gear and checking again.
BTW used cams worn against the crank gear looses this minute pitch difference so that all used gears are probably closer to the 0 gear than when new. also fit the oil pump as well because if the tang goes too deep into the cam it also causes problems.
Hope this helps
Armand

[356JAGER]

Your crank end play should be .005 to .008 inches. The cam gear clearance should be .0006 to .0016 inches, measured with plastigage at three points
around the gears diameter. Sounds like your cam gear may be large causing a
bind.
Cheers,
Joel

[badsix]

yes i'm going to try the old gear tonight. the problem is with the crank back next to the thrust bearing the cam and crank gears do not line up. the crank gear is about 1.2mm towards the thrust bearing. this line up problem causes the gears to bind up, it almost as if the cam gear needs to fit further onto the cam by the 1.2mm. then the gears would line up and every thing would spin freely. we'll see tonight what happens with the old gear, both are o gears. maybe an improperly machined gear
thanks Armand for the tip on the oil pump dr. I will check it.
thanks Jay D.

[badsix]

well I installed the old cam gear an o gear also and its really binding up. it lines up better than the new gear but its not meshing right. my next plan is to maybe take 1mm from the mating surface of the new cam gear. any other ideas out there.
Jay D.

[Jack Staggs]

Ok, here's how we do it. Assemble the crankcase halves together with the crank and #1,2,3 mains in place. You only need to install the 6 large nuts, not the perimeter ones. No glue, flywheel or shim installation. Check for free rotation of the crank. Good so far? OK. Now test end play of the crank. It should be very loose, 2+ mm in any position. No? Force the crank to the flywheel end, and try to rotate. Binding? That's a good thing. It means that the crank grinder left a strong radius on the center (#2) main bearing. Oh, you are using a new scat crank? Notorious for narrow #2. You will need to clearance both halves of the #2 bearing shells with a bearing scraper on the side that is closest to the pulley end, AND ONLY THIS AREA. Oh, you don't have a bearing scraper? Shame. A sharp Boy Scout knife, or a Dremmel will due. Put it together again. Enough end play now with no binding in any location? Ok. Now take it all apart and fit the cam to check for binding in every location. Great, but not yet. Look closely at the cam bore in the cases, particularly on the end near the cam plug. 616 cams run in the cases, without bearings, so if any greater than insignificant wear is seen, the cases will have to be narrowed to retrieve the cam bore to spec. You see, if the cam is allowed to slop form side to side, valve clearances are varying, since on these engines, one lobe operates 2 valves, one on either side, with valve springs forcing it one way and than the other, depending on spring load. It's a simple engine. Fun stuff for us, even more so for DIY guys!

[356JAGER]

Or after removing the oil gallery plugs, drilling, tapping and fitting new allen plugs to the holes, then cleaning the galleries and the rest of the case, bolt it together and check all the crank and cam bores at a minimum of two points in each for proper dimension and concentricity. If any is out of round or oversized, the case will need a line bore. As with all things, it's mostly all in the preparation.
We used to make our bearing scrapers from broken triangular files, ground to a point with all 3 corners ground and honed, but then I'm old school and frugal..

[badsix]

NO real fun yet Jack! but I did locate the problem. it was the front main bearing, it wasn't seated all the way down on the dowel pin. I think all's well now everything spins free. I'm going to run plasti gauge tomorrow night then check valve clearance. one other question is my oil pickup tube is lose. its flared on the end so I don't think it can come out. but what does one do with a lose one.
thanks Jay D.

[Jack Staggs]

Jay, I do not understand what you are talking about. The front bearing, aka #1 bearing, aka thrust bearing, aka flywheel bearing, can only fit in one way. Period. If it were out of position,and the case halves were to be bolted together, it would be damaged beyond use and require replacement. You mention plastigauge. Good stuff. I use it on occasion, but I do not know how to use it on full circle bearings, only on half shells. Please explain how to do that.
Joel, good point on measuring crankshaft and camshaft bore sizes. Some folks use "pop" gauges for measuring bores. In my experience, these gauges are only accurate to .001" at best. For critical crankshaft bore, where tenths of a thousandths of an inch can make a difference on bearing crush, I prefer 3 pin inside micrometers. Since they are hugely expensive, and I don't have one, I send every case out for measurement. You suggested "line bore" (sic) for correction of oversize bore of crank or cam bore. I'm not really a fan of align bore main journals, as odd sizes have been difficult (and costly) to find over the years. Perhaps things are different with newer (Chinese?) suppliers. I am baffled by your suggestion that cam journals can be bored to correct " out of round or oversized". I try to keep up with the latest machine processes, but I may be out of touch on this. Do you know of a source of cam bearing inserts that can be fitted to 616 engines, with appropriate machine work? My only alternative all these decades to correct worn cam bore (and retrieve crank bore to std, not to mention oil pressure issues) is to have the cases narrowed and rebored to standard spec, at significant expense, usually a few every year. Any help will be appreciated.

[badsix]

Jack, I just have one half of the case open with the crank and cam laying in that half. it was the bearing next to the third part of the case, it just wasn't seated all the way down on the dowel. and i'm just going to plastigauge the open bearings on crank and cam I couldn't get the plastigaude in the full bearings i'll haft to figure out how to do that i'm surprised that you can't put insert bearings in these cases like they use to do vw 36 and 40 hp cases maybe bearings are the problem.
thanks Jay D.

[Jack Staggs]

Wait a minute... you haven't even bolted the case halves together yet??? Never mind. I don't understand your methods.

PS: 36 and early 40hp VW don't have cam bearings either.

[356JAGER]

Jack,
We're talking about the same thing. Obviously the case halves would have to be cut to resize the bores
, both crank and cam, to standard. Main bearings, German and others, are readily available in .025 and .050 mm case oversize with stock and smaller bores for ground cranks. Run about $ 550 up on E bay. Not having used them I cannot attest to their efficacy but someone's buying and using them. I have heard that since they are made of a different alloy than the originals there may be issues with the amount of 'crush' provided when installed in the case.
The following is from Duane Spencer's 912 guide:

" If the camshaft bearing bores are oversized it is possible to save the crankcase by boring it out to fit Volkswagen cam bearings, and is a sound solution to the problem ".

Here's a link:
http://vwparts.aircooled.net/VW-Engine-Bearings-s/98.htm

Cheers,
Joel