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Engine rebuild 101
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kiwighia68
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Location: Auckland, New Zealand
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PostPosted: Sat Jun 10, 2017 12:33 pm    Post subject: Re: Engine rebuild 101 Reply with quote

KGCoupe wrote:
John Moxon wrote:
KGCoupe wrote:
John Moxon wrote:
You can still find those Speedwell dual carb kits...some original, some repros...even in the Samba Classifieds ;)

Yes period correct "Vintage Speed" would certainly add a "cool factor" to a 1500cc engine project.

John, would you happen to know of any sources for the "very realistic spray-on imitation vinyl" and the "adhesive strips to simulate the seam" found in a real vinyl roof mentioned in the article?

Knowing kiwighia68, he won't be able to stop at just the engine performance improvements and will "need" to take his project all the way to the very last detail.
:)


I'd have to run that past the Karmann Ghia Ethics Committee before passing on that kind of information. Hopefully they would block it.

:) Yeah, fat chance of that!

Why I bet the committee wouldn't even approve something as simple as the removal of the '66 model year only special dash trim and its replacement with "adhesive 'wood' dash trim" ... let alone approving something more advanced such as the "installation" of a faux vinyl roof.


You're all wromg, gentlemen. I have no plans beyond finding an appropriate HO original block and slowly but surely unravelling the mysteries (with your help, of course) of an aircooled VW engine while I rebuild it.

And I found the right shortblock yesterday - in a shed where a man hasat least 40 engines sitting on shelves, parts galore, some rare buses and a pristine, unmolested single cab with split windscreennd semaphores.

So tell me: Do I go all original for 53HP or all out for 100HP as KGCoupe suggests?
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Zundfolge1432 Premium Member
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PostPosted: Sat Jun 10, 2017 5:03 pm    Post subject: Re: Engine rebuild 101 Reply with quote

Stay stock, stock will always be in style. In the long run you'll be glad you did.
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kiwighia68
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PostPosted: Sat Jun 10, 2017 11:00 pm    Post subject: Re: Engine rebuild 101 Reply with quote

Zundfolge1432 wrote:
Stay stock, stock will always be in style. In the long run you'll be glad you did.


When you say stock, do you mean literally everything, or only the top of the engine parts (carb, dizzy, generator, fuel pump, etc.)? The reason I ask is that I would like to keep the original appearance but improve the performance with a better cam and some balanced parts (which ones do I need to balance?) and a ligther flywheel.
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Rome
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PostPosted: Fri Jun 16, 2017 5:48 pm    Post subject: Re: Engine rebuild 101 Reply with quote

If you want to stick with a stock single-throat single carb for a stock "looking" engine, then there's not much choice for a non-stock camshaft- usually just a "cheater" cam. Since you'll need to take the engine fully apart for a cam change, I also recommend you have the engine case set up for case savers. Keep your 10mm head studs and specify case savers for that stud size. You can also get case savers which are for the later, dual-port style 8mm cylinder head studs. With those 8mm stud sets, you'll need to get a set for single-port heads. Reason is, that the two center studs in the upper row on the engine case are slightly longer than the 8mm sets for dual-port engines. The center top studs were made shorter for the dual port engines so they would not contact the inner face of the dual-port cast aluminum intake manifold ends where they bolt to the head. The 8mm studs which you'd need for single-port upper centers are the ones which are on the outer locations in the upper row.

Also have the machine shop skim the surface of the case all around each cylinder hole. This is called "decking" or "facing" the case. The machinist must use the centerline of the crankshaft bore to set the decking depth, which usually removes no more than 1mm off the case edges. This will ensure that both adjacent cylinders sit the same distance away from the crank, and that once the cylinder head is fastened down on top of the cylinders, the head would be perfectly level because the tops of the cylinders are level. If you can visualize this machining operation, this also brings the piston 1mm closer to the top of the cylinder top edge at top dead center because the piston and connecting rod extended length stays the same, but you are bringing the cylinder down closer to the engine case. This decreases your piston deck height, so that you must have your cylinder head combustion chambers measured for volume after your machining operation for the thick wall 88's (see below) and then finally determine your compression ratio. The CR needs to be compatible with the camshaft, as well as with the fuel grade you intend to use.

How about installing 88mm thick-wall cylinders to get 1679cc? That's nearly 200cc more than a stock 1500 (exactly 1493cc). You can buy cylinder kits on which the bottom end fits into the stock case hole without any machining. But you must have your cylinder heads machined for the thicker wall diameter, the same diameter as for 90.5mm cylinders. Have a 3-angle valve job done to the heads for slightly increased flow.

Add a good German supplier stock muffler painted with high-heat flat grey paint, and use taper tips to maintain your stock engine appearance but with a better sound and gas flow. These modifications would not change the stock appearance of a '67 1500 engine but would get you maybe 5-7hp increase.

I also strongly recommend trying to rebuild your German-made fuel pump and distributor, then finding a stock carburetor whcih was factory-matched to the distributor. You can perform some mild enhancements to the carb but the main factor on choosing a "good" carb would be that the throttle shaft has no sideways play when it is fully closed. I remember a tech article in HotVWs by well known domestic engine tuner David Vizard in the late '70's or early '80's to modify a stock VW carb. Among several efforts, he knife-edged the throttle plate, and slimmed down the throttle shaft between the two plate retaining screws to increase flow. Slimmed down the sides and "lip" end of the discharge tube that is cast into the top of the carb body, also for slightly better airflow. This all takes practice not to break through, so you could do that on a broken carb that you get cheaply or free. Hand files are sufficient. With the increased engine displacement you could also go up 1 size on the main jet.

With all that, you should not hesitate to drive the Ghia at 75-80mph for hours, since the original factory top and cruising speed in '67 was already 82mph.
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kiwighia68
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PostPosted: Fri Jun 16, 2017 11:31 pm    Post subject: Re: Engine rebuild 101 Reply with quote

Rome wrote:
If you want to stick with a stock single-throat single carb for a stock "looking" engine, then there's not much choice for a non-stock camshaft- usually just a "cheater" cam. Since you'll need to take the engine fully apart for a cam change, I also recommend you have the engine case set up for case savers...

How about installing 88mm thick-wall cylinders to get 1679cc? That's nearly 200cc more than a stock 1500 (exactly 1493cc). You can buy cylinder kits on which the bottom end fits into the stock case hole without any machining. But you must have your cylinder heads machined for the thicker wall diameter, the same diameter as for 90.5mm cylinders. Have a 3-angle valve job done to the heads for slightly increased flow.

With all that, you should not hesitate to drive the Ghia at 75-80mph for hours, since the original factory top and cruising speed in '67 was already 82mph.


There's too much sound advice here to answer in one post - but I'm going to save it all for the second engine I intend to build. The first is just an education project.

Thanks for taking the time to share your knowledge. Just a couple of points: (1) I already have case savers in the second short block I bought, and the seller told me the cam had been reground. (2) I recently missed out in an auction of the very special VW carb (i was in the wrong time zone when the auction closed). 3. 75-80 miles an hour here in sleepy NZ will see me "don't pass go, go straight to jail".

I'm working on the education engine at the moment, and am in the process of cleaning parts. I'll post some photos in a few days.
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c21darrel Premium Member
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PostPosted: Mon Jun 19, 2017 11:35 am    Post subject: Re: Engine rebuild 101 Reply with quote

Quote:
There's too much sound advice here


True that! Excellent advice/info!!
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kiwighia68
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PostPosted: Mon Jun 19, 2017 1:22 pm    Post subject: Re: Engine rebuild 101 Reply with quote

c21darrel wrote:
Quote:
There's too much sound advice here


True that! Excellent advice/info!!


You have to complete the sentence, Darrel, otherwise it will look as if I'm ungrateful. "... too much sound advice here to answer in one post..."

I'm stuck in my real job at the moment and will get back to the engine rebuild next week. with pics.
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PostPosted: Mon Jun 19, 2017 2:46 pm    Post subject: Re: Engine rebuild 101 Reply with quote

Embarassed
3 pages in and we are still cleaning parts...c'mon Chris. Wink
You cant write all day and night. You need some quiet time i the garage getting your hands dirty. Your wife probably wants you out of the house anyway. Smile
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kiwighia68
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PostPosted: Mon Jun 19, 2017 3:00 pm    Post subject: Re: Engine rebuild 101 Reply with quote

c21darrel wrote:
:oops:
3 pages in and we are still cleaning parts...c'mon Chris. :wink:
You cant write all day and night. You need some quiet time i the garage getting your hands dirty. Your wife probably wants you out of the house anyway. :)


My wife is at work. I'm editing the manuscript of my next book. My fence needs fixing. I need a haircut. I want to go for a long drive in my Ghia - my neglected Ghia. All to be taken in hand some time today. Then some more cleaning of parts.

Be patient.
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kiwighia68
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PostPosted: Mon Jun 19, 2017 8:23 pm    Post subject: Re: Engine rebuild 101 Reply with quote

Fixed the fence, did some editing, cleaned some parts.

Here's the "new" old engine case with an HO number for 68 Bugs, Ghias and Buses. That one will have to wait for the final attempt at building an engine. It has space savers and I've been told the cam has been reground.

Image may have been reduced in size. Click image to view fullscreen.


I'm going to use a used set of Mahle 1641 pistons and cylinders on the practice engine build. Here's before and after:

Image may have been reduced in size. Click image to view fullscreen.


Next will be the fuel pump and the distributor. Both original.
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