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posted on December 30th, 2013 at 04:10 PM
F.VEE Valve Spring Pressure
Gday all.
I was looking around the web a while back searching for info on valve spring pressure, in particular seat pressure, for basically stock VW T1s.
I found somebody's reply on here saying they use 68lbs seat pressure on their Formula Vee 1200 engines, and they run to 5500 no worries without
float, and 6000 at a pinch.
Just to confirm the parts on a F.VEE 1200 though please?
31,5mm intake valve with stock OEM cam, lifters, retainers, collets and valve springs?
And the seat pressure is around the 65 - 70 lbs mark?
This is all before I start pulling the pin and ordering parts that I want for my heads. Yes, I could go all standard so everything fits together
beautifully without a care in the world, or even order heads off the shelf that are WAY better than what I could do, but where's the fun in that?
No seriously though, I'm just trying to severely minimise valve train weight (without using half the world's Titanium) as a bit of a science
experiment just for stamps. It's all good fun in the end.
modnrod
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posted on January 5th, 2014 at 10:22 PM
"Huh!" he said.
No, not "Hhhaaaaarrrrggghhhhhhh..........." like someone in pain, but rather "Oooooohhhh!!!!" in surprise and very mild astonishment.
No one building Formula Vees anymore, or did the animators all go on holidays for the week?
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posted on January 5th, 2014 at 11:30 PM
Ring jerry k in Morley,he might have some good info for you...
modnrod
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posted on January 6th, 2014 at 12:46 AM
Jerry K?
Thanks Chris, but I am not knowing this gentleman. Could you please advise with a company name or phone number?
Ta mate.
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posted on January 6th, 2014 at 06:06 AM
I very much doubt if any F Vee engine builders would give out their 'secret' valve spring specs.
Are you using a stock cam, carby, compression, etc? If so, I cannot see any point in revving over 5000. The heavier the valve springs, the more HP
they use up.
I'd rather wear a Beetle out by racing it than by polishing it!
cb john
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posted on January 6th, 2014 at 07:24 AM
Stock springs are in 90% of Vee engines...
modnrod
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posted on January 7th, 2014 at 11:45 AM
Quote:
Originally
posted by HappyDaze
I very much doubt if any F Vee engine builders would give out their 'secret' valve spring specs.
Why not? I used to have a clearance, and anyway, I can buy them a chocky frog if they want!
Are you using a stock cam, carby, compression, etc? If so, I cannot see any point in revving over 5000.
None of the above at all, but all close enough so I can use the stock specs as a good baseline.
The heavier the valve springs, the more HP they use up.
TADA! I'll buy you a chocky frog too Greg!
I have always wondered why other OHV motors that have similar valve sizes and weights, similar valve spring sizes, similar rocker ratios (to our 1.4s
anyway), and in addition have MUCH smaller lifter diameters (which means they "yank" the valves more) can seem to get away with seat pressures of
about 80-90lbs to rev to 5500 safely, but we are told VWs can't.
Hence the question.
80-90lbs is what I have always used in this style of "stocker-plus" or "Super-stocker" motors, but I didn't want to share and then face
excommunication from the VW world for being a heretic!
PS: And my reason for asking also is the specs I'm using.Valve weight is 52g (thin-stem 35mm) instead of 70g stock
35.5mm.
Retainers weigh 7g (Titanium) instead of 15g stock.
Springs weigh 2/3 of stock, and are "beehives" so reduce the required pressure by a further 10% due to not having to control as many oscillation
forces.
The lifters are lightweight CBs, and pushrods will be still light HD aluminium.
The cam lift rates on the down ramps are designed to be smooth to reduce spring pressure to follow them, and both ramps are as close as possible to
stock lift rates given the extra lift.
I'm going to use 70lbs seat pressure, which will go to 170lbs over the nose roughly. I would use even less pressure on both if I could, but I'm
happy with the spring package overall, so it will be OK even if a little overkill I think.All comments are welcome!Lynch mobs will be shot at while
I'm running away.
HappyDaze
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posted on January 7th, 2014 at 04:01 PM
This should give you something to think about .
52 years ago I fitted the balsa from inside 36hp push-rods to the inside of my 40hp push-rods.
Why? Because balsa is lighter than oil. Try it, and see how much
weight you save.
I'd rather wear a Beetle out by racing it than by polishing it!
cnfabo
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posted on January 7th, 2014 at 05:20 PM
Quote:
Originally
posted by modnrod
Quote:
Originally
posted by HappyDaze
I very much doubt if any F Vee engine builders would give out their 'secret' valve spring specs.
Why not? I used to have a clearance, and anyway, I can buy them a chocky frog if they want!
Are you using a stock cam, carby, compression, etc? If so, I cannot see any point in revving over 5000.
None of the above at all, but all close enough so I can use the stock specs as a good baseline.
The heavier the valve springs, the more HP they use up.
TADA! I'll buy you a chocky frog too Greg!
I have always wondered why other OHV motors that have similar valve sizes and weights, similar valve spring sizes, similar rocker ratios (to our 1.4s
anyway), and in addition have MUCH smaller lifter diameters (which means they "yank" the valves more) can seem to get away with seat pressures of
about 80-90lbs to rev to 5500 safely, but we are told VWs can't.
Hence the question.
80-90lbs is what I have always used in this style of "stocker-plus" or "Super-stocker" motors, but I didn't want to share and then face
excommunication from the VW world for being a heretic!
PS: And my reason for asking also is the specs I'm using.Valve weight is 52g (thin-stem 35mm) instead of 70g stock
35.5mm.
Retainers weigh 7g (Titanium) instead of 15g stock.
Springs weigh 2/3 of stock, and are "beehives" so reduce the required pressure by a further 10% due to not having to control as many oscillation
forces.
The lifters are lightweight CBs, and pushrods will be still light HD aluminium.
The cam lift rates on the down ramps are designed to be smooth to reduce spring pressure to follow them, and both ramps are as close as possible to
stock lift rates given the extra lift.
I'm going to use 70lbs seat pressure, which will go to 170lbs over the nose roughly. I would use even less pressure on both if I could, but I'm
happy with the spring package overall, so it will be OK even if a little overkill I think.All comments are welcome!Lynch mobs will be shot at while
I'm running away.
I think your onto a good thing,do it..id love to try behive springs one day..
modnrod
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posted on January 7th, 2014 at 09:43 PM
I'll give it a crack Chris, just don't expect to see it any time soon!
At least for your stuff, that is stuff that runs up around 7000 or more, have you seen this build-up below?
Gives you part numbers and everything you need. It can be done differently if you wish (it's not rocket science after all), but here is a proven
set-up more suited than my parts list........
This thread is like automotive art, the pics and detail ought to be listed as a thesis on vintage engine building, bloody good stuff from this bloke.
modnrod
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posted on January 7th, 2014 at 09:59 PM
Quote:
Originally
posted by HappyDaze
Why? Because balsa is lighter than oil. Try it, and see how much
weight you save.
I'd like to meet you Greg, we would sit down on a porch somewhere and talk crap for hours I rekn!
Here are the new engine mounts for my "current-in-progress" future drag/street bike. I fitted a GSXR oiler engine into a GSX frame using these
little bits of alloy shown below.
Old one with weight, made from 3mm steel with a captive nut.......
The new one weighs 32g, and is made from an alloy I found at work (work by the way was set up by NASA in the 70s). This alloy is 6mm thick, you can
bend it in a vice and it doesn't crack, really tough surface hardness, and weighs 75% of normal 6061.
I'd love to know what the stuff is made from, but until then I'll keep finding selective special projects for the stuff! We still have a few small off cuts to keep me amused.
(Ahem! Sorry for the OT ramble........).
HappyDaze
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posted on January 8th, 2014 at 05:39 AM
Quote:
Originally
posted by modnrod
Quote:
Originally
posted by HappyDaze
Why? Because balsa is lighter than oil. Try it, and see how much
weight you save.
I'd like to meet you Greg, we would sit down on a porch somewhere and talk crap for hours I rekn!
Fair enough, but we would probably keep sliding off......a Country Buggy would be better.
I'd rather wear a Beetle out by racing it than by polishing it!
