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Need help planning a vintage speed engine build
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Chris Paterson
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PostPosted: Mon Apr 19, 2021 1:06 pm    Post subject: Need help planning a vintage speed engine build Reply with quote

Firstly, I have never built an engine below the heads before; only top end. I've been learning a lot and reading books and forum threads on engine builds and I would really like to try building an engine.

I have a 58 PGSG that has a stock 36hp in it that I bought as a rebuilt long block. Recently the transmission was replaced with a tunnel trans with a 4.12, while maintaining the small nut RGBs, but with the tallest possible gears. The old split case got all jammed up and so I took the opportunity to make an optimistic update. The engine is definitely anemic, especially on hills. I live in Seattle, and there are quite a few hilly streets, but I don't do a ton of freeway driving.

I picked up a couple of core 36hp engines; one that is all together that I was going to tear down and another couple in pieces from a guy who was clearing out his garage and is "done" with busses. From the "done" guy I got a decent 58 case as a base to start from.

GOALS:


    1. Have fun
    2. Learn
    3. Build something that gets up to speed a little more quickly.
    4. Build something high-quality that will last and be reliable.


I am not in a rush to complete this and would like to take the time to learn and focus on doing things right.

Components I'm thinking:



I was thinking that I would just send the case down to Rimco (open to suggestions) to have them clean/inspect and machine the case. My questions are:


    1. Is this a good setup? Something better that I should consider?
    2. Has anyone ever done a dual carb single port engine? They say the 1600sp engine is preferred over dual port for the bus because of the torque, could this apply to the 36hp okrasa set up as well?
    3. What exhaust considerations should I have? Can I use the stock VW logo exhaust and heater boxes or will that be too restrictive? If I can't what's a good exhaust that has that vintage speed look?
    4. I've never done this, what should I expect for machining the case? I know the P/C will need to be opened up for 81mm, but what about crank clearancing or other modifications?
    5. I've been reading that the WW Okrasa carbs need jetting and rebushing out of the box. Is that still the case or have they improved the manufacturing?
    6. Should I consider any machine work on the heads? I'm assuming they'll need to be opened up to 81mm too?
    7. What can I safely use from my core engines? Pushrods? Pushrod tubes? Rockers? Cam Gears?
    8. Should I have case savers installed on a 36hp?
    9. Does it make sense to put a lightened flywheel in it?


Any thoughts welcome! Thanks in advance!

Here's my bus; it's all original paint
Image may have been reduced in size. Click image to view fullscreen.

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5500
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PostPosted: Mon Apr 19, 2021 3:17 pm    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

Sounds like a fun project!
The WW stuff makes finding parts easy, but they're not simply bolt on parts. There's a fair amount of case prep, clearancing and machine work needed to build a solid motor. The WW heads aren't consistently prepped and will benefit from disassembly, mild port matching and a good 3 angle valve job. The carbs don't work optimally out of the box. Joe Ruiz, aka Mr. Okrasa, offers rebuilding service where he replaces the venturis, rejets and bushes the throttle shafts. He has many years of experience building 36 hp motors and is an excellent source for information, machine work, engine building, etc... Engine assembly also requires measuring combustion chamber volumes to calculate cylinder barrel shim thickness for proper compression ratio. Actual assembly isn't difficult, but establishing/engineering the correct parameters for your motor are time consuming and require some expertise. There are some good videos on Youtube that give a decent idea of what goes into a vintage speed style build. I have found tons of very useful information doing searches in the vintage speed and performance engine forums here as well. Lots of expertise but you have to do a bit of searching and reading to find it.
Your bus looks awesome! Good luck!
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Braukuche
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PostPosted: Mon Apr 19, 2021 4:11 pm    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

I wouldnt use Rimco, heard too many horror stories as of late.
The WW set up is the way to go. Like the other poster said it’s not a simple bolt together. Many of the usual things apply when building a stroked engine in regards to clearancing things, and some will require machining, so finding a good preferably local machinist is key.
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1956 Ghia
1959 SO-23 Westfalia
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1960 Baja Bug
1963 stretched double cab
1962 Golde sunroof Ghia
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Alstrup
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PostPosted: Tue Apr 20, 2021 7:27 am    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

Apart from that, you are on the right track. The Okrasa style heads really wake up with the extra displacement from the 81 mm cylinders over stock 77.
Now, with the heads. they are ok as is, but you can increase especially torque tremendeusly by giving the heads a better valve and seat job than they have out of the box, like 5-7% across the board. Sadly I do not know who to recommend in your area.
The Solex PCI style carbs in the WW kit are a little crude, but with some tlc they can be made to work quite decent.
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PeteSC
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PostPosted: Tue Apr 20, 2021 8:00 am    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

Joe Ruiz built my 36 and we opted for larger valves in the WW heads (35mm intake, 33mm exhaust). I wish I had scientific data comparing the performance to a stock WW setup but I don't. I can tell you the engine pulls quite nicely in my Ghia. I live in a flat area, but we do have lots of bridges, and I can pass other cars without downshifting going uphill when needed. My biggest limitation is the current 4.39 R&P for top-end cruising....I have a rebuilt trans with a 4.12 waiting in the wings, I've just been reluctant to take everything apart to install it.

In short the larger bore/stroke recommendations are solid, but consider doing some head work to optimize performance.
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Chris Paterson
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PostPosted: Tue Apr 20, 2021 9:38 pm    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

Alstrup wrote:
Apart from that, you are on the right track. The Okrasa style heads really wake up with the extra displacement from the 81 mm cylinders over stock 77.
Now, with the heads. they are ok as is, but you can increase especially torque tremendeusly by giving the heads a better valve and seat job than they have out of the box, like 5-7% across the board. Sadly I do not know who to recommend in your area.
The Solex PCI style carbs in the WW kit are a little crude, but with some tlc they can be made to work quite decent.


I’ve been curious, would it be possible to run a single carb? I’m wondering if you can do some head work on stock heads to open them up and then use a 1600 single port manifold (cut and welded)? Part of me kind of likes the manual choke I’ve got Wink also, I like the simplicity of single carbs. I don’t love the idea that you buy WW Okrasa kit and then have to sink a bunch of money into it to make it work.

I found this while digging through the forums
https://www.cbperformance.com/product-p/3340.htm
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5500
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PostPosted: Wed Apr 21, 2021 3:18 am    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

From my research, a single carb/stock 36 hp head combo isn't going to provide significant increases, even with reworking the heads and adapting a larger carb, but it can be done. Anything is possible. The question is how skilled are you at fabricating/modifying and how much more power do you want. No matter what direction you choose to go, you'll be modifying or paying someone to modify parts to optimize performance. These are 60+ year old motors, designed nearly 100 years ago and improving them isn't easy or cheap.

There are spacers available to adapt that carb to your manifold. Later manifolds won't work without modifying the width and manifold to cylinder head mounting flanges.

Honestly, its much easier and less expensive in the long run to adapt a later engine. This doesn't sound like the direction you want to go in though.

Have you tried basic bolt on tuning mods? When I had my original 57 oval 40 + years ago, I found that by ensuring a properly operating distributor, fresh ignition wires, replacing the 28 PCI with a 28PICT, keeping the valves adjusted, and running fresh oil with frequent changes made drivability much more tolerable.

Not a bus expert but if you are running "freeway flyer" gearing, it doesn't work with 36 hp motors... they just don't have the output to produce enough torque at lower rpms to keep your bus moving at highway speeds.

Again, research is your friend. Many have done (or attempted to do) what you seek to accomplish. Lots of good information buried in the vintage speed forum, much of it older but still valid.
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Alstrup
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PostPosted: Wed Apr 21, 2021 4:32 am    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

Chris Paterson wrote:


I’ve been curious, would it be possible to run a single carb? I’m wondering if you can do some head work on stock heads to open them up and then use a 1600 single port manifold (cut and welded)? Part of me kind of likes the manual choke I’ve got Wink also, I like the simplicity of single carbs. I don’t love the idea that you buy WW Okrasa kit and then have to sink a bunch of money into it to make it work.

I found this while digging through the forums
https://www.cbperformance.com/product-p/3340.htm

It can be done, also with decent results. In fact I´m "doing" it right now, with a 1385 30 "lookalike" I heve a company not far away that can cnc bend tubing, so I am making a new 30 hp manifold, only larger. I will be using a 32 mm PCI on this engine. One of the larger issues is the cylinderheads and how to make them perform. I opted for an oval intake. This way I only need to split the lower part of the cool tin and reshape to mnake enough room for the manifold, and it will look very stealthy.
As for camshaft. I have been all over the off the shelf solutions, but nothing really suited my needs so I ask Elgin make me a cam. He/they have done that before for me, always with very nice results. They know their stuff. This engine will also be using stock style 1,1 ratio rockers to get some proper lift on the valves. My math says approx 45 hp and 108-110 Nm torque, which is in stock 1600 sgl port territory.

But i will warn you, before you get all the little things done in such a set up it will be just as cheap to build a regular dual carb OIkrasa style engine. and it will also pull more power.
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5500
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PostPosted: Wed Apr 21, 2021 6:00 am    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

Alstrup, your technical knowledge and fabrication skills are amazing!
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Braukuche
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PostPosted: Wed Apr 21, 2021 7:41 am    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

If you want the stock look you could run the big bores, stroke it and use a modified stock carb with bigger Venturi and jetting. It will make a difference.
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Go Reds! Smash state!

Retirement is here!
1956 Ghia
1959 SO-23 Westfalia
1960 double cab
1960 Baja Bug
1963 stretched double cab
1962 Golde sunroof Ghia
1963 356 B coupe
1963 Notchback
1967 21 window less rusty now
1973 Ghia convertible
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Alstrup
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PostPosted: Wed Apr 21, 2021 10:29 am    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

Braukuche wrote:
If you want the stock look you could run the big bores, stroke it and use a modified stock carb with bigger Venturi and jetting. It will make a difference.

Yes, it will make the engine more torqey, up to around 3000 rpm. From thereon up there will be very little if any gain. The intake manifold is simply too restrictive. You - can - however use a maifold from a 34 hp (40 US) which will immediately give you about 250 rpm more working area and with a 1286 cc displacement give you about 5 hp more over stock.
5500 wrote:
Alstrup, your technical knowledge and fabrication skills are amazing!

My fabrication skills are not worth writing home about. My strong sides are ideas, reserarch and then I am in the postition that I know a lot of talented craftsmen, each their area, that understand my thinking, most of the time, and can make my ideas come to life.
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Chris Paterson
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PostPosted: Wed Apr 21, 2021 1:36 pm    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

5500 wrote:
Have you tried basic bolt on tuning mods? When I had my original 57 oval 40 + years ago, I found that by ensuring a properly operating distributor, fresh ignition wires, replacing the 28 PCI with a 28PICT, keeping the valves adjusted, and running fresh oil with frequent changes made drivability much more tolerable.


Everything is in tip-top shape right now, I do have the 28 PCI in it, so that could be an improvement I could make potentially. Not sure how big of an improvement that would be?

5500 wrote:
Not a bus expert but if you are running "freeway flyer" gearing, it doesn't work with 36 hp motors... they just don't have the output to produce enough torque at lower rpms to keep your bus moving at highway speeds.


It's not a typical "freeway flier" with a 3.88 R/P, it's just gearing that would be on an early 63' bus with a 40hp; a 4.12 R/P. But yes, it is pretty anemic right now on the freeway with it's stock 36hp

Alstrup wrote:
Yes, it will make the engine more torqey, up to around 3000 rpm. From thereon up there will be very little if any gain.


That doesn't seem worthwhile, 3k rpm is pretty low.

Maybe I'll stick to plan A since this is the first time I've done this. I'll stick more closely to the path that has been traveled before.
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esde
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PostPosted: Fri Apr 23, 2021 2:53 pm    Post subject: Re: Need help planning a vintage speed engine build Reply with quote

Other carb options, that you will find if you read it all:
- weld up the stock intake and machine it for the larger diameter 1500/1600 single port ends, including tapping for the more widely spaced studs. I think Burly describes this pretty well in the 36hp challenge thread.
- Take a 40hp zenith NDIX manifold and narrow it slightly to fit the 36hp. I am going this route on one engine right now.
- If I was going to the trouble and expense of the Okrasa heads, I would get a proper valve job done and run dual Dellorto 36 DRLA. Getting nice twin port heads and topping them with single port carbs is just stupid, even if it is period correct.
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