AirSpeed VW Community Forums
Technical => Engine Tech Forum => Topic started by: Skidd on May 05, 2007, 12:16:30 PM
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Hi I'm building my first vw motor it's a 1914 with 120 engle cam, 40x35.5 heads, 1:1 rockers and duel 36 dells. My current deck hieght is .97mm and the heads are 54, that would make my C/R 8.9:1 right? In your opinion is the deck height to high? with that C/R will it still run off 87 octane?
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I think c/r ratio will be fine .. but only .038 \" deck height is pretty tight. I'd add a .010\" shim under the barrels.(then double check all 4 deck hieghts)
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I would agree with Hans! .038\" is bare minimum for the street and measurements must be correct on all 4. Better to put the .010\" in and be sure you are not going to hit at any time. The change in deck hieght will only drop your comp ratio by .2 to 8.7 still enough to run an engle 120 around town.
It would work better though with a smaller chamber and at least 9.5:1 but then you would have to use premium fuel. It is a trade off really depending on what you want from the engine really. Street driven daily and rock solid reliability good on long trips or weekend racer limited miles just out to piss off mustang owners and rebuild every 2 years. The cam you have chosen is the latter and really should run at least 9.5:1 to realize it's potential. Just my 2 cents worth.
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2 years! :blink:
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2 years! :blink:
You are getting very good advice from very competent people above.
You may want to be very clear as what you are building the engine for? Once you do so, they can better guide you to build the engine you want.
My 2 cents.
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You are getting very good advice from very competent people above.
You may want to be very clear as what you are building the engine for? Once you do so, they can better guide you to build the engine you want.
My 2 cents.
Yes Emillio, I have known these two characters for a long time. I was just kidding around. [_[
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My beetle is not a daily driver but I like reliability. I also like the sound of pissing off mustang owners. I'm leaning towards the 8.7:1 but also concerned about wasting power. It's hard making up my mind. Thanks for everyones advice it's greatly appresiated.
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Ok I triple checked the deck height and the head cc without shims and I was a little off :blush: . the heads are 52cc and DH is #1-0.091, #2-0.099, #3-0.099, #4-0.086 inch. To get my DH to 0.050 inch, what are my options? Thanks
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did you have the case faced for the cylinder seats?
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The case is an old AE case. I had it cut for 94's. I don't know if that answers your question, I dropped it off at airspeed for them to send it out. This is my first engine build and I'm trying to learn as I go.
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if you didnt request that it be done then it may not have been, you may need to have it or the cylinders machined to allow you to reduce your deck height.
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the case has to be decked for 94s, typically not needed to be requested. I'd shoot for around 8.5 and around .050-.060 deck
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Which is better the case or the cylinders?
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I did my case, that way I dont have to have my cylinders machined if I have to have them replaced.
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add .020\" shims (.058ish deck) and I'd call it pretty dang good at 8.7. Double check the deck, cylinder length, etc. maybe shuffle some parts around to try and even up the numbers.
If the case hadn't been decked you would be seeing aboot 2mm deck.