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[email protected]
Samba Member
Joined: June 24, 2015
Posts: 905
Location: Rialto. CA
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 Posted: Wed Jul 16, 2025 1:42 pm Post subject: Re: What about an emphasis on the 1200cc/40 hp motor. |
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| dames wrote: |
| Can I use any 3 rivet type camshaft in my 40hp? Looking to buy a nos one but none i have seen have the same part number as the one I have removed. |
If it's a stock 1500/ 1600cc 3rivet flat camshaft yes you can use it on the 40hp but match it with the 1500cc/1600cc rocker arms and compression it will help give little bit of power .... but if you have a 1600cc and want to use a 40hp camshaft no not a good choice 40hp cam has a lower profile your engine will be lower in power ...40hp had 7 .0:1 compression to 7.3.1 ...the 1600cc flat cam had 7.5.1 the 1600cc deep dish camshaft was for a 7.2.1 or even lower compression ...just make sure you put/ have the correct compression when you build it make sure you know what cam you have ...40hp and 1600cc the gears are interchangeable it's the same gears you can use new 1600cc aluminum bolt on gear ..just grind off the rivets on the camshaft drill/ tap the rivet camshaft so you can bolt the new gear to the cam and if you do plan on a new camshaft if your case doesn't have cam bearings get your case machined for camshaft bearings . |
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dames
Samba Member
Joined: May 09, 2012
Posts: 98
Location: uk
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| Posted: Thu Jul 17, 2025 3:30 am Post subject: Re: What about an emphasis on the 1200cc/40 hp motor. |
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| [email protected] wrote: |
| dames wrote: |
| Can I use any 3 rivet type camshaft in my 40hp? Looking to buy a nos one but none i have seen have the same part number as the one I have removed. |
If it's a stock 1500/ 1600cc 3rivet flat camshaft yes you can use it on the 40hp but match it with the 1500cc/1600cc rocker arms and compression it will help give little bit of power .... but if you have a 1600cc and want to use a 40hp camshaft no not a good choice 40hp cam has a lower profile your engine will be lower in power ...40hp had 7 .0:1 compression to 7.3.1 ...the 1600cc flat cam had 7.5.1 the 1600cc deep dish camshaft was for a 7.2.1 or even lower compression ...just make sure you put/ have the correct compression when you build it make sure you know what cam you have ...40hp and 1600cc the gears are interchangeable it's the same gears you can use new 1600cc aluminum bolt on gear ..just grind off the rivets on the camshaft drill/ tap the rivet camshaft so you can bolt the new gear to the cam and if you do plan on a new camshaft if your case doesn't have cam bearings get your case machined for camshaft bearings . |
Thanks for the reply Jerry. The case does have cam bearings. I'm not doing the build but have been collecting the parts for the chap that is. My confusion comes from new camshafts listed say they are suitable for all but as I would like to use nos parts where I can I'm seeing lots of part numbers and really want to get this right first time. I need barrels and pistons too and am still undecided on 1200 or the big bore kit. Rather than looking for new rockers I think I will bide my time and try to find the correct 1200 camshaft. Again thanks for the advice. |
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SilverThing 
Samba Member
Joined: July 19, 2004
Posts: 850
Location: Everett
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| Posted: Thu Jul 17, 2025 5:36 pm Post subject: Re: What about an emphasis on the 1200cc/40 hp motor. |
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The early 40hp engines (34PS by the German system) have a camshaft with the following specs (measured at 1mm lift at the valve):
Intake Opens: 4 degrees BTDC (Before Top Dead Center)
Intake Closes: 32 degrees ABDC (After Bottom Dead Center)
Exhaust Opens: 41 degrees BBDC (Before Bottom Dead Center)
Exhaust Closes: 1 degree ATDC (After Top Dead Center)
The later 40hp engines have the following specs:
Intake Opens: 6 degrees BTDC (Before Top Dead Center)
Intake Closes: 35 degrees 30 minutes ABDC (After Bottom Dead Center)
Exhaust Opens: 42 degrees 30 minutes BBDC (Before Bottom Dead Center)
Exhaust Closes: 3 degree ATDC (After Top Dead Center)
1300-1600 engines have the following specs (likely only due to the slightly higher rocker ratio):
Intake Opens: 7 degrees 30 minutes BTDC (Before Top Dead Center)
Intake Closes: 37 degrees ABDC (After Bottom Dead Center)
Exhaust Opens: 44 degrees 30 minutes BBDC (Before Bottom Dead Center)
Exhaust Closes: 4 degree ATDC (After Top Dead Center)
I have seen some slightly different specs online that appear to be due to the events being taken at 0.050" valve lift instead of 1mm.
I don't know when the early camshaft was phased out for the later one. I do know that the compression ratio increased from 7.0:1 to 7.3:1 in August of 1972 (by using domed pistons) at the same time that the 1600cc engine decreased compression from 7.5:1 to 7.3:1 (via slightly dished pistons). Camshafts changed from 3-bolt/rivet "flat" style to 4-rivet "dished" in August of 1971.
_________________
"I like how everyone likes talking about Zeke's Thing yet he's the only one that's ever seen it." - Katie
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[email protected]
Samba Member
Joined: June 24, 2015
Posts: 905
Location: Rialto. CA
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| Posted: Thu Jul 17, 2025 7:03 pm Post subject: Re: What about an emphasis on the 1200cc/40 hp motor. |
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| SilverThing wrote: |
The early 40hp engines (34PS by the German system) have a camshaft with the following specs (measured at 1mm lift at the valve):
Intake Opens: 4 degrees BTDC (Before Top Dead Center)
Intake Closes: 32 degrees ABDC (After Bottom Dead Center)
Exhaust Opens: 41 degrees BBDC (Before Bottom Dead Center)
Exhaust Closes: 1 degree ATDC (After Top Dead Center)
The later 40hp engines have the following specs:
Intake Opens: 6 degrees BTDC (Before Top Dead Center)
Intake Closes: 35 degrees 30 minutes ABDC (After Bottom Dead Center)
Exhaust Opens: 42 degrees 30 minutes BBDC (Before Bottom Dead Center)
Exhaust Closes: 3 degree ATDC (After Top Dead Center)
1300-1600 engines have the following specs (likely only due to the slightly higher rocker ratio):
Intake Opens: 7 degrees 30 minutes BTDC (Before Top Dead Center)
Intake Closes: 37 degrees ABDC (After Bottom Dead Center)
Exhaust Opens: 44 degrees 30 minutes BBDC (Before Bottom Dead Center)
Exhaust Closes: 4 degree ATDC (After Top Dead Center)
I have seen some slightly different specs online that appear to be due to the events being taken at 0.050" valve lift instead of 1mm.
I don't know when the early camshaft was phased out for the later one. I do know that the compression ratio increased from 7.0:1 to 7.3:1 in August of 1972 (by using domed pistons) at the same time that the 1600cc engine decreased compression from 7.5:1 to 7.3:1 (via slightly dished pistons). Camshafts changed from 3-bolt/rivet "flat" style to 4-rivet "dished" in August of 1971. |
The 1600cc decreased 4 rivet camshafts from 7.5:1 to 7.3:1 do to emissions it had to pass at that time ..... |
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dames
Samba Member
Joined: May 09, 2012
Posts: 98
Location: uk
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| Posted: Sat Sep 13, 2025 2:44 pm Post subject: Re: What about an emphasis on the 1200cc/40 hp motor. |
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| Engine build has finally started! I have got the best parts I could afford/find. At the last minute I decided to go with the big bore kit. I am aware of the clearance that will need doing to either the case or pistons. My final questions are, I have new cam followers and camshaft, is it good practice to replace the push rods too? Also have a beautifully reconditioned 28pict carb and plan to use this, can anyone advise on a good starting point for jetting? Have yet to buy tailpipes would prefer to use stock baffled ones are they going to be too restrictive with the small increase in CCs? I'm sure all of these questions have been answered before but I have spent way more than I expected on parts and am trying to get things right first time where possible on this basically stock engine with a big bore kit. |
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Dusty1
Samba Member
Joined: April 16, 2004
Posts: 2241
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| Posted: Mon Oct 20, 2025 11:54 am Post subject: |
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| williamdenson wrote: |
On the piston/barrel issue,, I remember several years ago talking to some formula V guys,,, they were using new aluminum cases and using an o-ring around the barrel to center and seal the larger opening in the case. They mentioned it casually as a standard process.
I don't know what o-ring they used, or if it was legal in their formula V rules,, but I've always remembered this as I thought about trying it. |
What we do:
We're using "new" magnesium universal cases. We cut a slice out of a cast iron sleeve intended as a cylinder sleeve. That way it's compatible metal to compatible metal. We precisely machine our chunks o' sleeve to fit our 40hp cylinder bases. We heat the resulting bushings and fit them to our cylinder bases hot.
Our 40 horse motors only contain parts that would be found in a pre- '65 Bug. No aftermarket parts aside from the exhaust.
A good Vee motor makes 65hp @ 6500rpm with some competitors claiming their motors make a little more and rev a little higher. That's from a stock 64mm x 77mm.
It's all about cumulative gains from a myriad of seemingly minor tweaks.
If you don't like competition don't build a 40 horse. You're competing with us for parts. It only took 60 years but here we are.
If you're thinkin' about a big bore 40 horse... don't be silly. 1500cc and 1600cc single ports are in every junk pile and behind every dumpster. If you like the idea of a 65hp "40 horse"... a 75hp 1600 is easier and cheaper. Your hands aren't tied by the pesky SCCA rule book.
| dames wrote: |
| Engine build has finally started! I have got the best parts I could afford/find. |
| dames wrote: |
| Have yet to buy tailpipes would prefer to use stock baffled ones are they going to be too restrictive with the small increase in CCs? |
The one obvious non- OEM part the SCCA rule book allows is a custom exhaust. We're running an exhaust designed by one of the NASCAR teams, in their spare time of course.
A good old merged exhaust system is the cheapest added power you can buy.
If you want your 40 horse to make 40hp and not much more... cork it up with the stock exhaust.
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"May you live an interesting life." |
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dames
Samba Member
Joined: May 09, 2012
Posts: 98
Location: uk
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| Posted: Wed Oct 22, 2025 4:59 am Post subject: |
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| dames wrote: |
| Engine build has finally started! I have got the best parts I could afford/find. |
| dames wrote: |
| Have yet to buy tailpipes would prefer to use stock baffled ones are they going to be too restrictive with the small increase in CCs? |
The one obvious non- OEM part the SCCA rule book allows is a custom exhaust. We're running an exhaust designed by one of the NASCAR teams, in their spare time of course.
A good old merged exhaust system is the cheapest added power you can buy.
If you want your 40 horse to make 40hp and not much more... cork it up with the stock exhaust.
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.[/quote]
Thanks for replying Dusty, not sure if im missing something with the roll eyes? I have really listened to the engine builder with the parts I have collected trying find German and nos. Sparx werks supplied the distributor and fuel pump rage in the Netherlands the reconditioned carburettor. I sent the con rods off for full reconditioning and balancing. The case has had its first line bore and lifter bores sleeved. The car has matching numbers and I would really like an engine that will last.
Im after a stock looking beetle and the merged system wont really fit in with the look, I have found a couple of ERNST exhausts made in I think 85 and will fit one of these, I guess I will have to live with the limitations of it. |
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Dusty1
Samba Member
Joined: April 16, 2004
Posts: 2241
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| Posted: Thu Oct 23, 2025 6:36 am Post subject: |
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| dames wrote: |
Thanks for replying Dusty, not sure if im missing something with the roll eyes? I have really listened to the engine builder with the parts I have collected trying find German and nos. Sparx werks supplied the distributor and fuel pump rage in the Netherlands the reconditioned carburettor. I sent the con rods off for full reconditioning and balancing. The case has had its first line bore and lifter bores sleeved. The car has matching numbers and I would really like an engine that will last.
Im after a stock looking beetle and the merged system wont really fit in with the look, I have found a couple of ERNST exhausts made in I think 85 and will fit one of these, I guess I will have to live with the limitations of it. |
Maybe Europe is different but it's easier to find 25 horse parts here than it is to find good 40 horse stuff.
We use a particular set of heads that were original to 1965 U.S. Bugs. Not '66! They look just like '66 at a glance but we defer to a higher authority. We need to pass SCCA tech and more to the point, nothing can be out of spec during a protest and tear- down.
"Numbers match" for a restoration? Yeah, I get that.
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_________________
"May you live an interesting life." |
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mrinnovation1
Samba Member
Joined: June 11, 2025
Posts: 275
Location: IL
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| Posted: Thu Oct 23, 2025 7:15 am Post subject: Re: What about an emphasis on the 1200cc/40 hp motor. |
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| Over the years I've had the 40, 50, 53, and 60hp engines and I have to say that I was most satisfied with the 40hp 1200 motor. It started out being a replacement in my '63 samba 23-window until it seized. I then rebuilt it stock and put it in a '65 Beetle where it consistently got 34 mpg. I never got close to that figure with any of the others and the 1500 auto stick shift was the worst at around 20-22 mpg. |
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