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robotrophic Samba Member
Joined: March 08, 2009 Posts: 88 Location: San Francisco
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Posted: Sun Mar 20, 2016 10:57 am Post subject: An engine I'd like to build... |
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For your consideration and comment...
About to embark on a performance upgrade on my '57 beetle. What I'm after is a mix of hp, period correctness, and general neat things, so while I may be able to swap one thing or another our for a more hp, (like an okrasa kit over the jusdon), most of the stuff on this list is here because there's something I like about it. I'm basically looking to see if there is anything here I absolutely can't or just shouldn't do. It's a daily driver, so reliability is a factor. Also, I've never built a performance motor before, only a stock top end rebuild on a squareback. I'll probably start piecing the bits together over the year (just about to start a remodel here at the house, so thats going to suck up some time...)
Ok, here goes:
36hp case, original displacement
counterbalanced crank shaft - this will get me higher revs, may over heat the judson - anyone have experience here?
Judson appropriate camshaft Suggestions? Mr. Okrasa?
Ported and polished original heads would I need stiffer springs for higher revs? Rocker replacement? Steve Tims?
Judson Supercharger - does anyone use the see-dee ignition booster? is it worth it?
Solex 28 PCI w/ larger venturi are these available? Is this realistic? Is there another carburetor option I should consider?
Stock fuel pump Have had fuel consumption issues running the Judson (even having bought the replacement spring). Ill talk to Ed Fall at Vintage Werks for recommendations
010 Distributor
Fram by-pass oil filter w/ Okrasa style cooler
Vintage Speed exhaust
Transmission re-geared for higher freeway speeds
Thanks for your help.
Robo. |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Mon Mar 21, 2016 7:54 pm Post subject: Re: An engine I'd like to build... |
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A few comments, hopefully others with more experience will chime in as well
1) a counterweighted(CW) crank will not increase your rpms...it will allow the engine to rev higher safer
2) with a CW crank your rotation assembly will weigh more, meaning a fully balanced rotation assembly is critical and I would recommend lightening your flywheel to 13 or 14 lbs. I recommend DPR for this work
3) RPM's are related to your cam/valve train which is limited on a 36hp engine(~4500rpms)
4) cams, look at Aircooledresearch.com, Wolfsburg West, or Mr. Okrasa
5) not much intake port work needed or can be accomplished with a Judson. Valve sizes can increased, Okrasa valves for instance, 3-angle valve job will help and you can port/polish the exhaust side.
6) I'd leave the stock transaxle alone... |
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robotrophic Samba Member
Joined: March 08, 2009 Posts: 88 Location: San Francisco
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Posted: Tue Mar 22, 2016 5:12 pm Post subject: Re: An engine I'd like to build... |
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What is the limiting factor on the valve train? Would stiffer springs increase my limit (just curious, not looking for 8000 rpms)
Transaxle is no longer stock, its a tunnel type. And with the judson, it tops out at around 70 (speedo is unreliable, don't know top speed), though the fuel pump struggles to keep up with demand. I don't need to push 100, but cruising at 70 would be ideal. |
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John Moxon Samba Moderator
Joined: March 07, 2004 Posts: 13943 Location: Southampton U.K.
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Wed Mar 23, 2016 11:22 am Post subject: Re: An engine I'd like to build... |
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The 4:12 R/P gearing in your late model transaxle could be killing your top speed...takes more power to get above 70 than the stock split-case transaxle
You should be able to cruise at 70 at around 3400rpms...depends on tire size
Valve train: lifter options are limited, they are heavy, springs available, cam selections, etc.
While there are options for 36hp engines, they are extremely limited compared to the late model engines
The Judson and carb are also going to limit how much the engine can breathe... only so much air can go thru the single carb. It also take HP to make more with a supercharger. |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7181 Location: Videbaek Denmark
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Posted: Wed Mar 23, 2016 4:52 pm Post subject: Re: An engine I'd like to build... |
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Hello.
Unless you already have the Judson, I would advice against going that route if you intend to drive it some serius miles. ALL the Judson equipped 30 hp (36 US) that I have ever met and dealt with had overheating problems when they were used on the Autobahn, or haulin΄ small campers, even 600 lbs push up ones. I have modified (modernised) the ignition on a couple of these to work with boost retard. It has helped some, but not cured the problem.
Especially since you consider buying a new crankshaft anyway, I would suggest that you buy a WW 69 mm Okrasa style crank or a similar from DRD and of course get the rotating assembly fully balanced.
Spend the money saved from the Judson on the heads and a decent set of dual carbs for it. If you build it right you will be so much happier at the end of the day and you will have just about the same usable power, if not a tad more.
If you are determined on using a stock center mount carburettor, you can source an intake manifold from a type 1 1200 34 hp. It is a little bit larger and will release 4,5 hp over the stock 30 hp. Once it is installed, even a trained eye will have problems spotting it.
If you still want to go the supercharged way, might I recommend using a MAG charger or an AMR instead. These are much better quality and can support more power, - and do not have the overheat issues when built right.
Also, a stock 4,125 transmission has just about the same final ratio as the stock split transmission. So not much difference there. But yes it is correct that the split transmission sucks up less power than the tunnel version. But the split trans will not hold up any significant power increase in the long run, unless its built" for it. And that ai΄nt cheap.
My 02c.
T |
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robotrophic Samba Member
Joined: March 08, 2009 Posts: 88 Location: San Francisco
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Posted: Wed Mar 23, 2016 9:03 pm Post subject: Re: An engine I'd like to build... |
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John, On the doghouse cooler, yes, thanks for the suggestion. This is the type of modification I'm interested in. general conformance to original, but for a tangible gain.
Txoval, yeah, the guy who built my transaxle said the pinion gears could be replaced to give me a higher top speed. Tire size normal 165 R15.
I have a set of nos lifters should I look for something else? I like the 3angle valve job and okrasa valves idea. will probably go down that route.
Alstrup, I do have the jusdon, and i've been running it for about 5k miles with no trouble except for managing the fuel consumption at an open throttle. I would love to get a pepco sometime, but I'm not obsessed, and I'm never the guy that finds that "deal of the century". the judson has treated me well, and I like it a lot.
Can you elaborate on "getting the rotating assembly fully balanced"? that is a hair more technical that I can say I understand. Crank + flywheel + rods + pistons?
Thanks for all the input! |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Thu Mar 24, 2016 9:01 am Post subject: Re: An engine I'd like to build... |
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Rotating assembly:
This is one reason I recommended Jose at DPR Machine. DPR can add the counterweights to crank, turn your journals to desired cut (depends on bearings you can find), stroke the crank if you choose, lighten your flywheel, and provide you with a clutch pressure plate.
He will assemble these items and balance them. He will "pin" your pressure plate so that it can only be installed one way to ensure the balance is correct. You could also send him your crank pulley as well, but not necessary.
Your pistons and rods can be balanced to all weigh the same.
Balancing the rotation assembly is key to smooth running engine and prolongs the life...key step.
Other machine shops can do this, I just prefer DPR...one stop shop
Use your NOS lifters...you could go to Porsche two piece lifters/rods or there is another guy on the samba offering a similar setup |
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robotrophic Samba Member
Joined: March 08, 2009 Posts: 88 Location: San Francisco
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Posted: Fri Mar 25, 2016 7:12 am Post subject: Re: An engine I'd like to build... |
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Got it. Thanks. Have been talking to DPR about the crankshaft, will discuss rotating assembly as well now. |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Fri Mar 25, 2016 9:04 am Post subject: Re: An engine I'd like to build... |
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I had DPR buy the clutch assembly...no mark up. I prefer the diaphragm type of pressure plate
You could have them 8 dowel your crank/flywheel |
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robotrophic Samba Member
Joined: March 08, 2009 Posts: 88 Location: San Francisco
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Posted: Sat Mar 26, 2016 9:46 am Post subject: Re: An engine I'd like to build... |
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What's the benefit of an 8-dowel fly? |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Tue Mar 29, 2016 4:01 pm Post subject: Re: An engine I'd like to build... |
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The benefit and probably not necessary for your engine is a more stout connection to the flywheel. More dowels = more protection from flywheel breaking free (shearing dowels) from torque/rpms
A bit of overkill for the power you will likely see, but it sure doesn't hurt. |
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robotrophic Samba Member
Joined: March 08, 2009 Posts: 88 Location: San Francisco
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Posted: Tue Mar 29, 2016 4:52 pm Post subject: Re: An engine I'd like to build... |
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Ok, thanks, that's what I figured.
Anyone recommend for or against a 1-1/2" qt oil sump? Being that the doghouse cooler came up earlier... I'd have to accept some loss of ground clearance, but I don't have a lowered car. |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Tue Mar 29, 2016 6:25 pm Post subject: Re: An engine I'd like to build... |
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I run one, but it's hard to provide a recommendation. I used the adapter made by Aircooled Research which allows you to use late model sumps. It's a great product, but also creates another sealing surface.
From my experience, 36hp engines are cold blooded and my engine stays cool. It's hard, even in Texas to get my oil above 190 degrees.
The Judson changes this, but I have no experience with it.
My case is also full-flowed and I run a modern oil filter...so I really have over 2 qts of extra oil |
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robotrophic Samba Member
Joined: March 08, 2009 Posts: 88 Location: San Francisco
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Posted: Wed Mar 06, 2024 2:57 pm Post subject: Re: An engine I'd like to build... |
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txoval wrote: |
The 4:12 R/P gearing in your late model transaxle could be killing your top speed...takes more power to get above 70 than the stock split-case transaxle
You should be able to cruise at 70 at around 3400rpms...depends on tire size
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Hey txoval,
thanks for this note... engine is finally coming together.
my tunnel type transmission is having 4th gear pop out, and I've been wanting to go back to a split case anyways. I know nothing about transmissions, so I was wondering if I could ask you a few questions/get some guidance for when I talk to the guy who will build me a new one.
effectively, what are some improvements on stock (and if i should even make them)?
As originally indicated, It'll be a mated to a mostly stock 36hp with a good cam and a judson supercharger. Any feedback you have to offer would be greatly appreciated. |
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EVfun Samba Member
Joined: April 01, 2012 Posts: 5446 Location: Seattle
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Posted: Thu Mar 07, 2024 4:22 pm Post subject: Re: An engine I'd like to build... |
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robotrophic wrote: |
txoval wrote: |
The 4:12 R/P gearing in your late model transaxle could be killing your top speed...takes more power to get above 70 than the stock split-case transaxle
You should be able to cruise at 70 at around 3400rpms...depends on tire size
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Hey txoval,
thanks for this note... engine is finally coming together.
my tunnel type transmission is having 4th gear pop out, and I've been wanting to go back to a split case anyways. I know nothing about transmissions, so I was wondering if I could ask you a few questions/get some guidance for when I talk to the guy who will build me a new one.
effectively, what are some improvements on stock (and if i should even make them)?
As originally indicated, It'll be a mated to a mostly stock 36hp with a good cam and a judson supercharger. Any feedback you have to offer would be greatly appreciated. |
If you are comparing your 4.12 tunnel transaxle to the stock transaxle this isnt true. Here is a comparison of 4th, r&p, and final drive ratio:
Tunnel box 0.88 * 4.13 = 3.67
Split case box 0.82 * 4.43 = 3.64
The old 36 horse is a lower rpm engine by design and was geared to turn slightly slower at freeway speeds than the later 1500 engines.
A 40 horse gearbox in front of a 36 horse engine is a performance improvement, but is so because you rev the engine about 7% more.
0.89 * 4.37 = 3.89 _________________
Wildthings wrote: |
As a general rule, cheap parts are the most expensive parts you can buy. |
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robotrophic Samba Member
Joined: March 08, 2009 Posts: 88 Location: San Francisco
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Posted: Fri Mar 08, 2024 11:26 am Post subject: Re: An engine I'd like to build... |
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Thanks, but I will not be using the tunnel type transmission, sorry for the confusion.
to be clear I really have no understanding of how the gear ratios work at all. it's a complete mystery to me.
I will be purchasing a stock split case transaxle locally for a rebuild. I was wondering if there are any modifications or gearing changes I can make to the 4th gear (or anything else) to eek out a couple more miles per hour on the freeway. |
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