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Member w/ Title Problems
Join Date: Aug 2003
Location: Bristol, VA
Posts: 975
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Valve sizes
Experienced fellow Pelicans,
Recommended valve sizes for a 1.9, running Web 86 cam, 0.035" deck height, 54cc combustion chambers, Weber 40's, SoCal climate? BTW, it's going in a 69' IRS Bug.
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2023 Ford F-150 Platinum 5.0 Coyote FX4 2019 Toyota Sienna XLE AWD Metal Building Erector, Recovering Porsche Guy Last edited by Jason Porter; 03-08-2004 at 11:28 AM.. |
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03-08-2004, 11:24 AM
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Banned
Join Date: Feb 2003
Posts: 1,207
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I'd say 42 x 36 just like a stock 2.0 .
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03-08-2004, 11:32 AM
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Registered
Join Date: Dec 2003
Location: Milky Way Galaxy - 3rd Stone
Posts: 871
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The "old rule of thumb" is small valves make torque and no rpm and large valves make HP and high rpm. It is a matter of increasing the volumetric effeciency of the engine.
I do know that if you only change the valves, you aren't doing the total job as you have to take into consideration the modification of the entire intake and exhaust tract to realize the full potential of a valve change - Can you say MONEY!!!!! Even the 2.0 had larger intake/exhaust tract diameter than the 1.7/1.8 to take advantage of the larger valves.
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Ron Meier Backyard Shadetree Mechanic 1974 914/6 conversion with 2.7L (The Grey Ghost) 1973 Chalon with 2.4T MFI (Schlitzalom) All my 4 cylinders are gone 
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03-08-2004, 03:45 PM
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Banned
Join Date: Nov 2000
Location: Upper Back Bay Newport Beach California
Posts: 3,287
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Stock 74 bus heads are what you want to use 021.101.371H 41 x 34 these will give you more comp. with the dished pistons you are running. With flat top and .035 you are at 9.2 to 1 even with the RX-7 oil cooler I put on Bills Bug ( this is my old Bug that I got from Bill Culver a WW-2 P-51 Pilot and a really nice guy who passed away in 1995, He bought the car new and then gave it to me when he could not drive anymore. When I had it I always called it Bills Bug As In the Surfs up let go to Malibu I will drive Bills Bug). I would use .045 which is 8.9 to 1.
Call Rick Conemac he has a set. Steve For Engine Capacity and Compression Calculator http://www.aircooled.net/gnrlsite/resource/specgeninfo/calcs.htm Last edited by SteveStromberg; 03-08-2004 at 04:27 PM.. |
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03-08-2004, 04:13 PM
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Banned
Join Date: Feb 2003
Posts: 1,207
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You might also want to buy the Engine Analyzer Plus software (or the Professional version) to help design your motor. It's fun to play with and with the Plus version you can even enter full flow curves for the head ports.
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03-08-2004, 04:40 PM
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Member w/ Title Problems
Join Date: Aug 2003
Location: Bristol, VA
Posts: 975
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I already bought brand new unused heads, flycut for 1.8/2.0, with 39x33's.
At this point I'm at the point of no return for deciding to go 1.9 or 1.8...
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2023 Ford F-150 Platinum 5.0 Coyote FX4 2019 Toyota Sienna XLE AWD Metal Building Erector, Recovering Porsche Guy |
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03-09-2004, 11:42 AM
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