1791 85.5x78 "Stock Stroker" Build

[jason]

Hey Marbleknight, I hate to be off topic here but I see that you used a bolt stretch gauge. Did you stretch with a wrench or use the torque wrench? I have always just used a torque wrench. I am going to use a stretch gauge on my next build and think that it would be hard to get an accurate reading taking it on and off and wondered how you did it.

[marbleknight]

[marbleknight]

Worked on the main bearings again today - switched out #3 with a new bearing and torqued the case up again. This time I oiled up the case threads and went up to 30ft-lb instead of 25. All bearings look good with about 0.003" oil clearance so I'm moving on. Finished the crank assembly now that the bearings are squared away.

Took the cam out of the bag, installed the bearings in the case and checked the cam endplay. I checked it three different ways to be sure about the endplay. Feeler gauges, dial indicator, and depth gauge. Lightly tapped on the cam with a soft mallet in both directions to seat the cam thrust bearing.

Cam endplay was initially about zero or 0.001". I removed material from the thrust bearing to increase it to 0.003" which is where I left it. I chose to file it with a very fine, flat file instead of the usual sanding method with sandpaper on glass. The filing seems to make more sense since there is no chance of abrasive grit breaking loose from the sandpaper and getting stuck in the bearing.

When I first wrote this post I questioned why the thrust bearing has to be installed at all in the case to check cam endplay, why not just hold the thrust bearing up to the cam and check with feeler gauges? It's pretty clear now that the thrust bearing must be seated on its saddle in order to get a true picture of the endplay. That was the reason for lightly tapping the cam back and forth. So as in other posts scattered about the Samba, I agree you should not remove material from the thrust surface of the bearing until you have seated it. Just don't bang the hell out of it when you do.
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1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm)

[jason]

I usually do the sanding when setting the endplay. I always wondered about setting it with the case split though. Lets say I get both sides at .003, when case is bolted it could be .000 depending on which side of the bearing the clearance is. I came across a thread the other day and can't find it again but there was a few of the big builders saying that they just seat the bearings until the endplay is correct. I'm going to assume it is bolted together when seated.

[marbleknight]

Started on the first trial assembly and found that the lifters are too fat. Not too surprising, I've heard this is an issue on many performance builds with aftermarket lifters.

Needed to find out how much oversize the lifters are, so I removed them and used gauge pins under the cam lobes to gauge the distance from the tops of the lifter bores to the nose of the cam lobe.

This distance ranged from 0.233 - 0.241" across all 8 lifter bores. Next I measured how far the lifter stands up above the tops of the lifter bores when they're dropped all the way down in the bore. Almost all were 0.245" which means they miss clearing the cam by 0.004 - 0.012". For those of you who are wondering, you can't just measure the thickness of the lifter's head to find this out because the side opposite the ground face is tapered, and plus the lifter bore is chamfered and you don't know how much of the taper fits in the chamfer... ugh. Put the lifter in the bore and measure from the face down to a point, then take it out and measure from the top of the lifter bore down to the same point.

I can have some material removed from the underside of the lifter (machine work) or perhaps the lifter bore chamfers can be increased. We're talking max 0.012" here so it's miniscule.
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1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm)

[Quokka42]

Usually you would take the material from the lifter bore - in fact increasing the chamfer is sufficient for most builds.
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There has only ever been one man who was perfect, and they nailed Him to a cross.

[modok]

Some lifters are thicker than others.
Scat or CB lightweights would probably have enough clearance with no work.

Check the thrust surfaces on the cam, many are parkerized and should be polished.

[[email protected]]

http://vwparts.aircooled.net/Heavy-Duty-Lifter-Bor...l-rent.htm

in many cases it's not the height, it's the radius in the case which is holding the lifter up.
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[marbleknight]

[bugguy1967]

Lol! As soon as I read you had a cam to lifter clearance issue, I automatically guessed you were using Engle lifters. You'll avoid that issue with almost any other brand you go with.
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[marbleknight]

So today I got to the part of this build I have been waiting on for awhile... finding out how much the case has to be clearanced for the 78mm crank. I got the Chevy journals to minimize the necessary clearance, and I can truly say it paid off. Barely any clearance work was needed at all, and I truly think I could have done zero to the case if I were willing to notch the rod bolts, but I'm not a fan of doing that. I know lots of folks do, even very seasoned builders so I'm not saying it's a bad thing, just not my thing. Seems wrong from an engineering standpoint.

Ran through the usual procedure of attaching a piston with no rings to each rod (one at a time) and letting it run through a revolution in a barrel to identify the collisions. The rod bolts hit the spigot undersides as you would expect them to:

Even here it was just a small interference. The rod bolts are 5/16" diameter which means just a small amount of clearance work had to be done. I marked the spots with a marker and took the crank out. Hooked up the vacuum and positioned the hose right over the area to be clearanced. Strapped on the headlamp and buzzed out some divots with a carbide bit in a die grinder. Barely a chip made it past the suction of the vacuum hose.

The bolts clear nicely now. I will re-check when I set crank endplay but it's not going to change that much.
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1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm)

[marbleknight]

[marbleknight]

Today I finished up the case clearancing and a few other misc items but by far the most interesting work was on a tool I made to cut the lifter bores so that the fat Engle lifters will sit down like they're supposed to. John pointed out in a previous post that the lead-in chamfer to the lifter bores can contribute to the lifters standing up higher than they're supposed to, so I decided since this is not the last engine I'm going to build I would make a tool to do the cutting quickly (and free) in my shop. I decided to make the tool out of the best thing possible; and old lifter.

I don't have a big machine shop like some folks, no mill or lathe, and certainly no tool grinder (the kind that holds tool blanks in a collet and has multiple axes for grinding all the surfaces necessary for cutting tools) so I improvised. As you'll see, anyone with basic tools can do the same. I was a machinist out of college and ground end mills and other fluted cutters for a living so this was a walk down memory lane.

The concept was to make a single cutting lip on a lifter that would change the chamfer at the lifter bore to match my lifters better. I started out by cutting the back side of the lifter on a lathe (at work) to about a 20 degree angle with a 0.5mm radius in the corner.

Next I cut a slot which is the beginning of the cutting lip. Here is the improvisation I was talking about with a flat surface, vee blocks, and a dremel tool but it worked perfectly. This first cut was perpendicular to the face of the lifter. I chose to plunge in from the face of the lifter rather than take the chance of hitting the lifter's shaft with the cutting tool, plus it's easier this way.

Now a cutting surface is formed, right on the centerline of the lifter I might add, but it's a 90 degree angle and needs relief. I used some shims to change the angle of the vee blocks with relation to one another and thereby sharpen the cutting lip.

Now that the cutting surface is fully established, the rest of the surface on the backside of the lifter must be relieved so the cutting lip is the highest point. Since this doesn't really have to be pretty, I just ground it down with a thick grinding wheel, taking care not to contact the cutting lip but minimize its width.

I also widened the gap near the cutting lip so the chips can exit more easily.

Used the file to clean up a little, then let it slip into a lifter bore to check proof of concept. I checked the contact of the cutting lip with the chamfer and it looked good, so I rotated by hand once. It cut as designed. Note the shiny surface from the new cut.

All that remains now is a way to drive the cutting tool. I originally intended to press a drive shaft into the pushrod end of the lifter and drive it from the outside of the case, but I found that pressing anything into the lifter changed its diameter to the point where it wouldn't fit into the bore anymore smoothly, so I decided to weld another old lifter to the tool, face-to-face, and drive it using the welded-on lifter.

I'll post up the results tomorrow.
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1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm)

[mark tucker]

be sure there is no burr to eat at your bores and use lube. also have a lookm at your bores real good&mesure them, the one in the pic dont look so good.

[marbleknight]

Finished the lifter bore cutter and cut the bore chamfers so the lifters will have about 0.040" clearance under the cam at full lift.

The welded cutter.

Channel cut through for chip exit.

Cut vs. uncut bore.

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1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm)

[andy198712]

Cool! Thanks for sharing
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[marbleknight]

Now that the lifter bore chamfers are complete, I moved on to the deck height measurements. According to my theoretical deck height projection sheet, the deck heights should be 0.092". I posted this sheet up a while ago, you can find it here:

http://www.thesamba.com/vw/forum/viewtopic.php?p=7447149&highlight=#7447149

I cleaned everything again and dropped in the bearings, crank, lifters, cam, and closed the case up. I put the top two rings on a piston, oiled up a barrel and inserted the piston into it. I used this barrel and piston combo to measure all the deck heights one by one. I found TDC with an indicator and measured deck height with a depth gauge.

All deck heights were between 0.091 and 0.094, so the chart was right. I'm shooting for a compression ratio of 8.4:1 so my deck heights need to be 0.065. That's just enough material to take off to clean up the deck surfaces and get them nice and flat for a good seal. There will be no shims in this engine. Here's the case after decking:

Before moving too much further into the final assembly I wanted to make sure all the work on the oil galleys and their plugs was complete. The first test was to take the new oil relief and control plungers and slide them into their bores to make sure they are not impeded by burrs from the drilling and tapping I did after I removed the oil galley plugs.

As it turns out, there were burrs holding the plungers up. This picture shows a burr that was pushed into the plunger bore from the tapping (left side).

The oil relief plunger had a similar issue, seen here before and after deburring.

I deburred all trouble spots carefully until the plungers would fall in and out of the bores by gravity alone. Next I checked out the fitment of the plugs to make sure they weren't going too deep so as to obstruct a galley. Some of them did. I either shortened them accordingly or ground a semicircular groove into them to match the galley (requires knowing the final orientation of the plug - just put it in tight and mark its orientation and grind accordingly).

I also wanted to be sure no plugs would interfere with the plungers moving up and down inside their bores so I used a screwdriver to push the plungers all the way into the bore, marked the position on the screwdriver, then removed the plungers, installed the plugs and repeated. The line on the screwdriver showed that the plunger returned to its original position so the plug wasn't obstructing it.

The plug for the old oil inlet from the pump stood a little tall so it was marked and ground as well. All the other plugs were installed with thread sealer.

Lastly I started thinking about the engine break-in a little and decided I wanted a forced oil pre-lube setup. I know the necessity of pre-lubing before break-in is debated, but it seems logical to me. The main reason is because I don't want all my cam break-in lube getting wiped off turning the engine over trying to build oil pressure. Plus it gives peace of mind knowing the oil is there before it fires. I plan to use an old oil pump driven by a drill to do the pre-lubing.

Next I will build the final mock-up to verify deck heights and start rocker geo checks.
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1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm)

[marbleknight]

First task today was setting the distributor drive shaft endplay. I started by putting the distributor clamp on the case to see how far it stood off the case when tightened down. It was a mile. I had to bend the clamp to get it fairly flush to the case.

I inserted the distributor drive shaft into its bore and put two shims at its base to start with.

Next I inserted the distributor, engaged it in the drive shaft, and held it flush to the clamp while I moved the drive shaft back and forth to check play with feeler gauges. The gap measured 0.030" so I left it at that.

I rotated the distributor drive shaft so the groove where the distributor plugs in was perpendicular to the block (the groove is offset and goes towards the rear, away from the flywheel). I held the shaft in that position as the distributor was put back in and re-engaged with the shaft. Turned the body of the distributor so the rotor pointed to the #1 mark and tightened the clamp around the distributor.

By this time the thread sealant on the oil galley plugs was good and set up so I decided to do the final flow test on the block with all the plugs in. I flow tested by pumping in the liquid into the oil cooler return and successively blocking off orifices after I confirmed flow to them.

Flow was good to all points. #4 main is still a little wimpy but it's there. I blew out all the galleys and the rest of the block and set it aside to dry.

While the block was drying I decided to do the piston ring gap checks. I pushed each of the rings into a cylinder with a piston (squarely) and used the feeler gauges to check the gap. They were not good.

The gaps were tiny - about 0.010 to 0.013". Every single one of the top and middle rings had to have material removed to open up the gaps. I made another setup with a dremel tool similar to what I did with the lifter bore tool I documented earlier. The setup ensured the ring was ground squarely and as precisely as possible. I opened all gaps to 0.025".

Interestingly, the ring manufacturer said that a gap of 0.003" per inch of bore would be acceptable. That comes to 0.010" gap for these 3.366" pistons (85.5mm), which means they would have been in tolerance. But I've seen it all over the place here on the Samba that that's too small. Maybe that spec is for water-cooled engines...
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1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm)

[Boolean]

That ring gap is huge. 0.016/0.018 top/second would have been better.
You should get new rings and do it again.
You should aim for a bit more gap on the second ring to reduce ring flutter.
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I strive for perfection. Excellence will not be tolerated!
Build thread here:
http://www.thesamba.com/vw/forum/viewtopic.php?t=529379

[Boolean]

It will work anyway of course, but with the attention to detail you have shown so far it would be a pity to have those extra horses in the sump.
_________________
I strive for perfection. Excellence will not be tolerated!
Build thread here:
http://www.thesamba.com/vw/forum/viewtopic.php?t=529379