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Mon Feb 17, 2025 11:44 am

hello everyone, I would like to open my 1200 mexico, install a 1385cc kit, and I was thinking of putting 1.25, I don't know how to say it in English? I'm Italian if I translate the word it would be "castles". in any case those components that serve to press the valves more. alternative to change camshaft. has anyone ever tried with 1385cc to use these 1.25 "castels"? leaving the original camshaft. I would like to give more power to the 1385cc also leaving the carburetor original, I don't want to put double carburetor kits.

Tue Feb 18, 2025 9:09 pm

The word you're looking for is rockers, as in 1.25:1 ratio rocker arms. I don't see a reason why you couldn't try them on a 1385, but I imagine they likely won't make much difference due to the airflow restriction of the stock 40hp intake manifold and cylinder heads.

Wed Feb 19, 2025 6:17 am

You can use later rockers also, 1300-1600, they are 1.1-1 so slightly better than 1200 rockers.

Wed Feb 19, 2025 6:57 am

thanks guys, you are always super helpful and quick to respond. regarding the head I wanted to try to improve a bit the intake and exhaust ducts. then I thought of enriching a bit the mixture of my 30 pic-t 3 carburetor and setting it like the pict-2. but my beetle which is a 1200cc Mexico year 1982, what rockers will it have? only 1:1? is it possible that so modern it doesn't have at least 1.1:1?

Wed Feb 19, 2025 10:46 am

It's easy to determine what rockers your car has by just removing the valve covers and having a look. Stock VW 1:1 rockers are smooth on the side opposite of the stamped markings, while the stock VW 1.1:1 rockers have a pair of raised ridges on the side opposite the stamped markings.

In both of the pictures from the gallery below, 1:1 rockers are on the left and 1.1:1 rockers are on the right. Note the pair of raised ridges on the "smooth" side.

Wed Feb 19, 2025 12:32 pm

perfect, I didn't know they recognized each other that way. Thanks! Another question, what if instead of putting 1.25 rockers I put a 90 camshaft?

Wed Feb 19, 2025 1:32 pm

You'd need to increase the engine's static compression ratio to around 8:1 to 8.25:1 with the W90 camshaft due to its longer duration versus stock. I'd expect to see a bit more low and mid range power, but the 40hp intake and heads will still limit you up top.

Wed Feb 19, 2025 2:00 pm

If I increase the displacement to 1385cc, according to my calculations, I would arrive at a compression ratio of approximately 8.3:1.

Thu Feb 27, 2025 7:28 pm

If you join Vintage VW club of america, Jake Raby built a 1200cc and wrote a series of articles on his changes.

https://vvwca.com

Mon Mar 17, 2025 6:27 pm

Pick your 1385 cc 83 mm piston/cylinder kit carefully for your Mexican "late" 1200 case- this is the one you need- https://aapistons.com/collections/vw-piston-liner-...-european. There is a different 1385 cc kit for the original 1200 engine from the 1960's which has a different piston pin height.

Tue Mar 18, 2025 8:07 am

Fraboni Mirko wrote: If I increase the displacement to 1385cc, according to my calculations, I would arrive at a compression ratio of approximately 8.3:1.

Remember that compression ratio is mainly tied to deck height and combustion chamber volume. So to effectively calculate your compression ratio you'll have to have the engine built, figure out your deck height (increase or decrease deck height with shims or machining work between block/cylinders), and then measure your combustion chamber (head) volume. You can then plug the cc volume, bore, stroke, and deck height into online calculators to figure out your compression ratio.

https://cbperformance.com/v/enginecalc.html?srslti...e6Gd67vIXh

For reference, I just built my 1387cc engine with an 8.6 CR considering a 0.5mm deck height, 69mm stroke, 80mm pistons, and 43cc chamber volume. I used Speedwell 1.4:1 ratio rockers and had to actually get my valve guides cut down about 3mm because the valve retainer was coming down to hit the valve guide. I have around 0.410" (10.4mm) effective valve lift with the old Scat C26 profile cam that had around a 0.300" max lift. I used 2-piece lifters with Manton chromoly pushrods, and they fit along the full swing with CSP spring-loaded pushrod tubes!

So many options to go down and plenty of cool parts to throw at your engine! Good luck!

Tue Mar 18, 2025 6:04 pm

1958ghia wrote: Fraboni Mirko wrote: If I increase the displacement to 1385cc, according to my calculations, I would arrive at a compression ratio of approximately 8.3:1.

Remember that compression ratio is mainly tied to deck height and combustion chamber volume. So to effectively calculate your compression ratio you'll have to have the engine built, figure out your deck height (increase or decrease deck height with shims or machining work between block/cylinders), and then measure your combustion chamber (head) volume. You can then plug the cc volume, bore, stroke, and deck height into online calculators to figure out your compression ratio.

https://cbperformance.com/v/enginecalc.html?srslti...e6Gd67vIXh

For reference, I just built my 1387cc engine with an 8.6 CR considering a 0.5mm deck height, 69mm stroke, 80mm pistons, and 43cc chamber volume. I used Speedwell 1.4:1 ratio rockers and had to actually get my valve guides cut down about 3mm because the valve retainer was coming down to hit the valve guide. I have around 0.410" (10.4mm) effective valve lift with the old Scat C26 profile cam that had around a 0.300" max lift. I used 2-piece lifters with Manton chromoly pushrods, and they fit along the full swing with CSP spring-loaded pushrod tubes!

So many options to go down and plenty of cool parts to throw at your engine! Good luck!

What a beautiful engine you build ..keep up the great work ....

Wed Mar 19, 2025 5:43 am

1958ghia wrote:

Not to divert from the original poster's thread topic, but well done on that build. Lots of familiar touches added to it. I believe I've seen it recently on FB...if you have a build thread here please share.

Wed Mar 19, 2025 12:25 pm

Thanks for the kind words! Unfortunately I didn't do a build thread here, but "borrowed" a LOT of wisdom from many builds. :)