Motor60
Samba Member
Joined: July 13, 2014
Posts: 625
Location: SoCal
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 Posted: Sun Dec 21, 2014 3:55 am Post subject: |
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| Ok cool. Would you mind typing a "recommendation" build spec for a powerful 1904? Actually, if I'm using my same gear, I'm sure my W100 cam should be upgraded. And maybe rockers? Maybe some straight cut gears? |
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GTV
Samba Member
Joined: March 27, 2004
Posts: 2084
Location: Si'ahl
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| Posted: Sun Dec 21, 2014 8:24 am Post subject: |
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Straight cut gears are not needed. Use them if you like the sound. As for the cam, something around the Engle 120/Scat C45 or equivalent. I personally wouldn't go any larger (duration-wise) as low end torque will begin to be sacrificed (and your carbs aren't up to the high rpm capability of a larger cam). Ratio rockers aren't neccessary, but a cam designed for ratio rockers will be easier on the lifter bores. More lift is of course possible, but there is no need to go over .500" at the valve for your application. For example, the Engle 120 is designed for stock 1.1:1 rockers, and lifts .435" at the valve. 1.25:1 rockers can also be used, increasing the lift to about .494". Same goes for cams designed for 1.4:1 rockers. Heads are important, this is where the power is made so no skimping there. Properly ported 40x35.5 valve heads, dual springs, HD aluminium or steel pushrods. Keep the deck height tight, Between .040"- .060", the tighter the better. Around 9-9.5:1 compression. Your Weber's will of course work, maybe upgrade to slightly larger vents (34mm) when you start tuning. 1 1/2" exhaust primaries. As for a crank, for the price there is nothing better than a DPR welded stroker. The 5.325" VW journal rods from aircooled.net will make the 74 nearly drop in without extra machining (but check everything!), and keep the engine from getting too wide.
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EMPI Power Rules! |
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