Carrera 2 replica engine for the Ghia - Choices

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RHough
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Fri Jul 15, 2016 10:07 am

Piledriver wrote: OTOH, the one on #3 probably "kissed" the head when the #3 rod bearing died, and knocked off the carbon there.
(The sharp "edge"/transition gives that away, usually there's a narrow but gradual transition area)
Also, you are running too rich to have that much carbon build up that soon.

One option you have at this point is to use Mahle "B" (78-82mm stroker) pistons with longer H-beam rods.
If you intend it to run over 7K, that is a very good plan.
LOL ... Remember the Weber tuning posts in this thread? The only way I was able to reduce the lean transition from the idle circuit to the main circuit was to run the idle circuit at 11.5:1 or richer. That means 95% of the time the engine was running pig rich. 12-13 MPG. That is why I seriously doubt there was any detonation problem. That rich means a cool/slow combustion cycle. The EFI conversion is aimed at curing the tuning.

Tech information is hard to come by. The case is machined to 97mm for the spigots and the Heads are machined to 101mm for the top of the cylinders (AA Thick Wall 92's) This is the same as the 94mm cylinders.

I can reuse the cylinders with other pistons to maintain and have them honed to get the right clearances if they are too small for 92mm Mahles. If they are too big, I'm hooped. From what I've found online It seems that the Mahle P&C combos are thin wall so they would be a too loose fit in the case and heads?

I have 5.394" rods now. What length would I need to use 'B" pistons?

Here are the other piston tops and the skirt of the #1 piston. #1 is the only hole that had the coating gone by the wrist pin hole.
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Piledriver
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by Piledriver » Fri Jul 15, 2016 11:56 am

The rod length you can easily use would be 5.5"-5.7", depending on what length the AA jugs actually are and what stroke you go with and how much cylinder spacer you want to run.

You are not limited by past decisions at this point, I'd lean towards 78mm and 5.5" hbeams, and buy cylinder spacers as needed. A 78-82mm crank costs the same as a 74.

DPR makes nice correctly machined welded cranks, if the case is new, 65mm t4 mains are an option, uses a BMW or Dodge main bearing.(thin steel shell, also probably available in Clevite trimetal, even coated K series)
Even just the T4 center main will help. Chevy (buick) rods, use the excellent Mahle/Clevite coated rod bearings. Lighter rods too.

They might be able to fix your Chinese crank and turn it into a 78mm, nitride it, dubious if they will due to unknown metallurgy, but worth asking.

Before you get too carried away see if your engine builder is going to work with you.$$ wise, and have your case and jugs checked out,
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RHough
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Sat Jul 16, 2016 12:37 am

I sent a copy of the RPM warning about AA cast pistons to AA for comment. Only one vendor has mentioned below 6500 RPM for the AA cast pistons. :twisted:

It will be interesting to see what AA's response is.

Any bets on AA saying the Cast Pistons are fine to 7000?

I started to massage the piston tops with a soft dish scrubber and WD40 ... the carbon build up is vanishing and the pistons are starting to look like new. I may reuse them after all.

I'm waiting to get a response from the builder. I sent this tonight:
I have been agonizing over this for days. There are a few issues.

First is pretty simple. The engine xxx delivered was not what I paid for. I asked for advice several times about parts selection and made the intended use I had planned for the engine clear from the beginning. The Long Block is advertised as having 4340 Chromoly Forged I Beam Rods. Changing the rods to something else without asking me first was not your call to make. The I-Beams list for $159.95, the rebuilt Race Prepped Rods list for $129.95. If the Race Prepped Rods are better quality *and* less money why are the 4340 Rods called out in the Long Block?

Second is a lack of communication. I specifically said that my concern was quality not cost. As an example when your project manager pointed out that the CB 1.25:1 Rockers required different pushrod tubes but the Scat rockers did not (but cost $120 more) I didn't blink and approved the change. And I thanked him for the advice. From the selection of a W-120 cam and L5 heads it seems obvious the engine needed to spin over 6500 to make best power. No one suggested any changes. The pistons and cylinders used for the engine are cast AA 92's in thick wall cylinders. After finding these in the engine I was surprised to see that ACN states not to use them in engines that turn more than 6500 RPM? When I asked you about redline, you responded that the engine should have been good to 7000 RPM. No one at suggested I upgrade the pistons, crankshaft, bearings, valve springs, or push rods during the build. The 4140 74mm Crank (EMPI) is $229.95 made in China, a DPR 74mm Type 1 Crank is $329.95 for $100 more I'd have been happy to be asked. If the bearings or valve springs were not right for a 6500-7000 RPM engine I'd have upgraded; no one asked. The engine is advertised as using the same 0.006" cold valve lash as stock. After the rocker stud failure at 2 hours when I asked about valve clearance you asked what pushrods I had and to set steel PR's at zero. No one asked if I wanted ACN designed HDAL PR's, another $20-30 change missed.

Third is the quality of the work on the engine. The cylinder studs were hacked off after the heads were installed. There is no way anyone that knows what they are doing would try to thread a head nut over those butchered threads. The case hardware looks like some hardware store generic washers and fasteners. It has been a few years but I remember the early cases uses a sealing washer and nut then VW came out with a case nut that had a sealing surface that eliminated the washer. The oil pick-up appears to be jammed into the case and the bottom of the baffle is not parallel with the bottom of the case. Balancing holes in the crank and flywheel were not de-burred. Double thrust cam bearings were installed and one is showing thrust wear. If the L5 head valve springs, 1.25:1 ratio rockers, and W-120 cam were going to eat cam thrust bearings I would hope that an experienced builder would have suggested straight cut gears. I ordered the pulley tin and crank pulley when I ordered the engine and on teardown found the back of the pulley was rubbing on the tin. Might have not been that way when it left the builder's shop but that is how I found it. At about 2 hours the right side rocker studs failed requiring a 300 mile tow home.

To recap.
1. Not the engine I paid for, parts changed from spec without my knowledge or permission.
2. Very little communication to make sure the engine would be correct for my intended usage. Missed opportunity to offer upgrades to the basic package.
3. Suspect/sloppy assembly.

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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Thu Jul 21, 2016 12:08 am

Who said bent crank?

I am happy to report the engine builder has stepped up on this. I'm 100% satisfied with the resolution! It is a shared, no fault solution.

The the crank cause the failure? Is the #1 main bearing and damage due to the crank getting bent or did the failure bend it? Don't know and don't care unless it is likely to happen again.
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I've started a new thread on the resurrection and my version of a home build. Can I get it done for the Great Canadian VW show in August?
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by Piledriver » Thu Jul 21, 2016 1:39 am

I vote gravity poisoning.

I would also bet that was your "rev limiter" as it shredded the bearing.
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Fri Jul 29, 2016 7:01 pm

Piledriver wrote:I vote gravity poisoning.

I would also bet that was your "rev limiter" as it shredded the bearing.
How about a pressure plate out of balance? It has been so long since I've looked at a clutch in a car nothing set off any alarm when I took the engine apart. I do know that the the pressure plate was not with the engine during the build. It was installed after the long block was delivered.

I never wondered what holds the pressure plate centered on the VW. The plate came off the flywheel and the new pressure plate dropped in with no issues ... either the locating lip on the flywheel is too large to locate either pressure plate, both pressure plates are (different brands) finished too small to fit the flywheel properly, or new pressure plates often out of balance (and a loose fit on the flywheel is normal) ...

The old flywheel on the new crank spins perfectly, without the pressure plate. When the new pressure plate is installed it was 6oz out of balance.

Could an out of balance flywheel/pressure plate combo be the root cause of the failure?

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Re: Carrera 2 replica engine for the Ghia - Choices

Post by Piledriver » Fri Jul 29, 2016 7:05 pm

Contributed, yes, but I don't think it could bend your crank like that unless it was made from cheese.
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