Resucitar la carrera - Rebuilding the 1968

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RHough
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Resucitar la carrera - Rebuilding the 1968

Post by RHough » Tue Jul 19, 2016 1:05 pm

After the untimely demise of the 92 x 74 "Carrera Replica" engine a new thread about the resurrection/rebuild is in order.

The 92 x 74 dimension Type 1was selected to duplicate the Porsche Carrera2 engine in the 356's The goals were 130 HP and 120 ft/lbs. The engine pushed the Ghia to a 7.1sec 0-60 time so the performance goal was met or exceeded. A 356 Carrara2 was slower 0-60 (9.2 sec) according to the road test information I can find. The engine died before I got to the street drags for a 1/4 mile time. Based on the 0-60 of 7.1 the engine was putting out 140+ HP so the car should be under 16sec at about 90 mph at the strip.

Planning and Demise Thread here: http://www.shoptalkforums.com/viewtopic ... 3&t=145538

One of the features of the 356 Carrera that was not duplicated was a dry sump oil system. Thoughts on the Cheap Thrills Racing version are here: http://www.shoptalkforums.com/viewtopic ... 7&start=16

We don't know that the deep sump system contributed to the engine failure but we are taking no chances with the new build.

Cleaning the case after the failure is job one. Bob Hoover has some opinions on this in his blog: http://bobhooversblog.blogspot.ca/2006/ ... -plug.html

His thoughts on oil temp sender placement are interesting.
OIL_TEMP_LOCATION.JPG
I may relocate the oil temp sender there to allow use of the stock OP switch and gauge sender at the standard location. I think the oil return location should see the same temp on a dry sump system as the wet sump. It might be interesting to just add a sender there for the ability to see the temp of the oil coming out vs the temp of the oil going in from the tank. Thoughts?

I also ordered a Krankvent system based on the information in this thread: http://www.shoptalkforums.com/viewtopic ... ase+vacuum

While I'm waiting for the internals I'll toss the engine back together with and empty case to get the oil system plumbing and components laid out to save assembly time later.

After the Weber tuning saga and suffering with 13mpg I'll be going EFI on this engine. Mario from the Dub Shop has a new ECU: http://thedubshop.blogspot.ca/
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Not looking for any more HP, just improved drivability, cold start performance and fuel economy. Sequential injection and Idle Air Control should correct the carburetor faults that I could not tune out.

Can I get it done by August 19 for the drags?
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Re: Resucitar la carrera - Rebuilding the 1968

Post by RHough » Wed Jul 20, 2016 8:49 pm

Cleaning the Oil Passages

These are the 11 plugs that need to get pulled to clean cases prior to assembly.
Tools required: 1/8" drill
Slide Hammer with #8 sheet metal screw for pulling the plugs
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Re: Resucitar la carrera - Rebuilding the 1968

Post by Piledriver » Wed Jul 20, 2016 9:37 pm

If you have a case with the fuel pump pushrod*, do NOT drill/plug the left plug.
The pushrod guide already plugs it, there is no pressure there.

Just pull the pushrod and install a blockoff cover where the pump was.

*most common on 72-74? Buses, which were 1.7s or 1.8s and had carbs.
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Re: Resucitar la carrera - Rebuilding the 1968

Post by RHough » Thu Jul 21, 2016 12:12 am

Piledriver wrote:If you have a case with the fuel pump pushrod*, do NOT drill/plug the left plug.
The pushrod guide already plugs it, there is no pressure there.

Just pull the pushrod and install a blockoff cover where the pump was.

*most common on 72-74? Buses, which were 1.7s or 1.8s and had carbs.
I have a Type 1 boss. :-) The only plug I haven't pulled is the one in the 19mm hole on the oil pump inlet side.

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Re: Resucitar la carrera - Rebuilding the 1968

Post by RHough » Thu Jul 21, 2016 12:23 am

A slide hammer? WTF?

Some of us old guys remember drilling and using a little slide hammer to pull the anti-tamper plugs out of carbs so we could tamper ... er tune the idle mixture. Try to find one now ...

How about this:
DSC_0194.jpg
I had to turn the head of the sheet metal screw down to fit inside the jaws and then had to add a clamp to keep the screw from spinning ... works like a damn!

The right way is a drill press and 2000 RPM ... but if you have a steady hand and a good eye ...
1, Centre Punch
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2. Drill
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3. Screw in Puller
4. Tappetity Tap tap and the plug is out ...
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Rinse and repeat ...

Now to look inside and clean!
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Re: Resucitar la carrera - Rebuilding the 1968

Post by Piledriver » Thu Jul 21, 2016 1:35 am

RHough wrote:
Piledriver wrote:If you have a case with the fuel pump pushrod*, do NOT drill/plug the left plug.
The pushrod guide already plugs it, there is no pressure there.

Just pull the pushrod and install a blockoff cover where the pump was.

*most common on 72-74? Buses, which were 1.7s or 1.8s and had carbs.
I have a Type 1 boss. :-) The only plug I haven't pulled is the one in the 19mm hole on the oil pump inlet side.

:oops: Sorry, I get build threads mixed up.

Don't forget the little one that feeds #4, it always had trash trapped in it.
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Re: Resucitar la carrera - Rebuilding the 1968

Post by RHough » Thu Jul 21, 2016 2:21 am

Cleaning the passages ...

Tools required:
Long brass brushes or a rifle cleaning kit.
Lots of solvent/cleaner
Electric Drill (optional)
Flashlight

I found a set of long brushes at Princess Auto that had both Stainless Steel and Brass bore brushes in 1/4, 3/8, & 1/2 for less than $15

This is why we clean. This is the oil feed hole from the pump. It was tapped for a NPT plug and the plug was covered with grey sealer when it was inserted. What happened to the metal from the tapping process? Why use a liquid sealer here?
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While I was staring into my case I noticed something I don't remember from the 36HP daze. A cast in oil deflector? One of the plugs in the front of the case was for access to machine this feature:
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Brush in drill entering lifter gallery.
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Go slow as the brush goes from bore to bore. Keep rinsing with solvent as you go.
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But don't go all macho and push the tool in too far ... you can damage a lifter bore.
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Once all the passages are brushed out. Blow them dry, run more solvent through, brush again and you are ready to drill, tap and fit your NPT plugs ...

You can get a set from CIP for $19.00 CAD https://www.cip1.ca/ProductDetails.asp? ... 12-4500-50
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Re: Resucitar la carrera - Rebuilding the 1968

Post by RHough » Fri Jul 22, 2016 12:32 am

Ready, set ... WHAT?

From the Bob Hoover Blog:
Whatever pipe plug you use, steel or aluminum, you want the ones that are installed with an Allen wrench. Ask for the ‘internal wrenching' type. Earl's sells them. Cost the earth but it's a one-time thing.

TAPPING THE HOLE

Tapping the hole to accept the plug is where most mechanics come to grief. Not so much in the tapping but in starting out with the wrong diameter hole, or making it too deep. Being tapered, a pipe-thread tap is happiest working into a tapered hole, which is accomplished by drilling a starter hole that's too small then opening it up with a tapered reamer. Most mechanics, VW or otherwise, have never even seen a tapered pipe-thread reamer and their eyes pop open when they see what they cost. But there it is.

The depth of the threaded hole is fairly critical. Go too deep on some locations and you're liable to block the oil flow. Ideally, the plug should be fully seated either flush with the case or no more than one thread below. If you start with a properly tapered hole you can achieve this fit every time by putting a reference mark on your tap but if you've never done this before it would be best to keep trial-fitting the plug.
The Plugs from Bugpack (now EMPI) were only $19 ... The reamers however are holy holy mother of ...

$158 to get the three reamers for 1/8, 1/4, and 3/8 NPT ... no wonder most people don't do this!

So I'm waiting for the tools to ream my holes ...

Made up the parts list for hose and fittings for the dry sump system ... ordered from Summit.

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Re: Resucitar la carrera - Rebuilding the 1968

Post by RHough » Fri Jul 22, 2016 9:48 am

The package from CB Performance should be here today or Monday so I tossed the engine and exhaust together with no guts and tossed it back in the car for doing the oil system install.
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The tank will be on the right and above the pump inlet. The supply hose to the pump has plenty of room, The scavenge side return to the tank will run from the left facing outlet to a horizontal filter (no 90° fittings) then tuck up above the header in the valence back to the tank. All -10 AN hose.
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As part of my noise abatement program I'm changing the valve covers. The stock tin does little to reduce noise from the valve train. The valve covers also help cool the oil, more surface area inside should equal better cooling. The o-ring seal should allow heat from the head to transfer to the cover, the cork gaskets insulate the cover.
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There is more interior volume too if you have valve gear / valve cover fit issues. The marks inside the old cover are not normal ... that was damage from a broken rocker stud.
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I really like CSP stuff. The service / shipping from Germany is as fast as any supplier in the US or Canada ... sometimes faster.
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Re: Resucitar la carrera - Rebuilding the 1968

Post by RHough » Tue Jul 26, 2016 12:48 am

Parts are trickling in the pump from CB, the Krankvents for the PCV system, the drills and tapered reamers ...

I should get the new crank and rods off to the machine shop for balancing Wednesday.

I have a question about case prep.

Do I pull all the studs out of the left case and file/stone the sealing surface flat around the threaded holes? If local distortion of the case around each stud is not a problem then I'll just clean the crap out of it prior to assembly.

Looks like lots of room for the dry sump plumbing ... -10 fittings -12 won't fit.

Oh, and why doesn't CB sell a steel oil pump cover? I think OEM steel is a better choice as far as keeping the tolerances tight inside the pump. Who specs aluminum for pump covers? Am I missing something?

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Re: Resucitar la carrera - Rebuilding the 1968

Post by Piledriver » Tue Jul 26, 2016 4:07 am

You aren't missing anything.
Bling sells, soo...

Steel or cast iron is better, if you can score a melling pump cover they are thin iron or steel.
EMPI even has one that's not too bad, and Bus Boys stocks a similar one in steel..
Can be had full flow style or std.
Berg sells one with a built in pressure relief.

Jake Raby made a run of thin tool steel wear plates to go under the bling parts but I don't think enough folks got the point.

Someone was also testing a hard anodized aluminum cover.
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Your rods suck

Post by RHough » Wed Jul 27, 2016 7:41 pm

The new crank, rods etc went to the balancer today. The DPR 74mm stroker measured exactly right. .25mm mains and STD rods.

As part of my overthinkers anonymous program I've been staring at the oiling system of the crankshaft. Then reading about inside and outside oiling #2 mains ... gahhhhh!

It occurs to me that the direct drilled cranks work differently than the cross drilled cranks. I've overthought myself into thinking that the direct drilled crank is probably better.

The crankshaft oiling system is the same on both overall. The pump feeds the mains. #1 main feeds #3 Rod, #2 main feeds #1 & 4, and #3 main feeds #2.

In overthought detail the dynamics inside the crank is interesting. First off the pump doesn't need to blow oil to the rod bearings, the rods suck. Yep the rods suck. The rod bearing surface is orbiting the main journal so oil in the passage is forced from the main bearing up the passage to the rod and into the rod bearing. The rod bearing is fed by centrifugal force. The rod sucks.

I got to thinking about this after reading about bearing failures in cross drilled crankshafts. The writer claimed the pump had to overcome the centrifugal force *inside* the main bearing before it could pump oil out to the rods. I haven't seen every engine ever built but I've never seen one where the main bearing od is greater than the stroke. Anyone that has ever used a 1/2" credit card to swipe gas out of the neighbor's car should get this. Once the siphon is started the fuel flows up from the tank then down into your gas jug.

The same force is at work inside your crankshaft. Think of the oil supply at the main bearing as the fuel tank, the oil passages as the siphon hose, and the rod bearing as the gas jug. The oil passage from the centre of the crank to the rod bearing is longer than the oil passage from the main bearing to the centre of the crank. Once the crank spins centrifugal force will get the siphon and the crank will tend to suck the oil off the main bearing and pump it to the rod bearing. All the pump has to do is keep the main bearing primed, the crank will do the pumping.

So why do bearings fail in cross-drilled cranks? The simple answer is the pump is too small. The direct drilled crank from DPR that is based on a VW forging. Each main bearing has two rod bearing feed holes that are direct shots to the rod journals. Each of the feed holes is relieved into a little oil well that looks like an oil scavenger or vacuum attachment. The rod vacuums oil off the bearing as it rotates. On #3 and #2 that is 2 full sized holes that are straight between the main bearing and rod. On the crank with cross-drilled rod bearings the two oil feeds on the main meet somewhere inside the crank, a third hole from the outside of the rod journal intersects the fourth hole cross drilled in the rod. The feed for the rod at best is limited by the diameter of that one passage that Tee's into the rod journal and further limited by the accuracy of the drilling, the sharp corners, and the 90° intersection inside the rod journal. The rod depends on a single passage for oil, a passage than cannot be looked through or cleaned without pulling the threaded plugs out. It doesn't matter how hard you suck if the hole is plugged, or the holes misdrilled ... On the direct drilled crank the holes are straight, no plugs to pull, you can see through them. I like that.

That brings us to #2 main that feeds 2 rods. Either the #3 & #2 are living large with more oil than the need or #1 & #4 are starving? That brings us to the two different styles of #2 main bearings.

Does it matter if the oil channel is on the inside or outside?

I don't think so. Look at the relative size of the holes that feed the bearings. The oil supply to #1 is smaller than the feed to #2, #2 has two rads sucking it dry so it gets a bigger hole ...

Oh and the plug we pulled out of the oil passage to the #4 bearing that is a "Restrictor" ... right ... look at the feed hole in #4 ... There's your restriction.

The next overthinkers topic will be "Do I need to change the oil pickup?"

The cross-drilled rod crank is on the left showing the tortuous path the rods have to suck oil through, the VW crank in on the right showing the simple oiling passages. Hmmm?
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How to set pushrod tube length - use a hacksaw!

Post by RHough » Thu Jul 28, 2016 5:32 pm

This was my Overthinkers Anonymous task for today. Preparing the pushrod tubes for assembly.

These are "Windage Tubes", for those that have no idea what they are here is a picture. The longer spigot goes into the case and acts like a dam to reduce the amount of oil that can be forced *up* the tube by cornering loads. The normal windage in the case tends to pump oil up the tubes into the 3/4 head too. The long spigots reduce this too.
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These are stainless so they won't rust. Woo Hoo! The are also shiny so they don't radiate heat very well ... they will be flat black when I'm done.

The bellows on the tube is a spring to maintain pressure on the seals in the case and head so they don't leak. The sealing pressure is designed to be constant as the engine expands and contracts each heat cycle. The tube material sets the 'spring rate' the case to head distance is the 'installed height'.

Like most things VW there is a specification for the tube length. 190 - 191mm (7 9/16" for the colonies).

When you are blueprinting (who doesn't?) you will often find a tube that has been in service has taken a set and is no longer long enough to provide sealing pressure.
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This so I laid out a template:
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How should I make then longer? Like this? OMG :-(
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How about keeping the tube straight and the bellows spacing even? Use a hacksaw!
Not my idea ... Bob Hoover's: http://bobhooversblog.blogspot.ca/2007/ ... tubes.html

The tool is an old hacksaw blade set in wood:
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This is how it works
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And the result
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I was having so much fun that I made it too long ... but that is an easy fix compared to keeping the tube straight while you make it longer.

"Just use your thumb to open up the bellows ..." yeah right. I'll use a hacksaw thanks.

There are 12 on each end, about 10 minutes a tube, just to set the length ... say 90 minutes start to finish ... at your internal shop rate of $50/hour is $75 in labour and they aren't cleaned, prepped or painted yet ...

A set of new windage tubes is $45 ... but they would have to be blueprinted and painted too ...
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Oil Pickup ... why?

Post by RHough » Thu Jul 28, 2016 5:56 pm

After several meetings of Overthinkers Anonymous we have decided to deal with the oil pickup ...

This is the pickup as installed in the new AS41 case.
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The deep sump extension was clamped to the end of this. Granted with the deep sump getting the umbrella to fit the case and strainer is not an issue, but the OEM German oil pickup is different. The German one looks much more expensive to manufacture than a bent tube brazed into the cover. On the theory that VW didn't spend any more than they had to when the designed the engine how cheap can you be to use this?

The question at OA is how to remove the new OEM oil pickup and replace it with a German OEM part? Just whack it out with a hammer?
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Re: Resucitar la carrera - Rebuilding the 1968

Post by Piledriver » Thu Jul 28, 2016 6:47 pm

Pull the nut/stud, pull and wiggle, it just has a light press fit.
That really does look horrible.
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