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Valve Train

Valve Train:  The valve train in SlowGT is set up for high rpm (9,000 RPM +) strength and reliability.  We found out early on that if you can't use an auxiliary spring set that pushes directly on the lifter, (as is available for some Chevy setups) 6,500 RPM is about the reliability limit with factory-type hydraulic roller lifters.  Although we did push the factory hydraulic roller lifters in SlowGT to 7,200 rpm before retiring them, it required a fine balance of spring pressure to avoid valve float while not collapsing the lifter.  SlowGT now runs Competition Cams solid-roller-lifters, part number 838, which have proven to be reliable and light.  The camshaft that was used for the 1999 racing season is a Cam Motion part number 51099 and has the following measurements:  

The lift was limited to 0.600 in. to stay within the 1999 Fun Ford Weekend class rules.  Since the lift rule has been lifted (pun intended), SlowGT began the 2000 racing season with a similar camshaft; the main difference being an increase in intake and exhaust lift to 0.700 in.  This camshaft has very aggressive ramps which maximize air flow through the heads with the relatively small duration numbers.  Current engine software simulations are suggesting some promising new profiles to try and we may have a new one installed during the 2000 racing season.

The valve springs are K-Motion part number K-950.  At the installed height of 1.9 inches, the spring pressure is 300 lbs on the seat and 700 lbs with the valve open.  The titanium valve retainers and the valve locks are both made by Competition Cams: part numbers 732-16 and 613-16 respectively.  The valve spring seats are Manley part number 42119.

Rocker Arms:  The rocker arms are shaft-mounted Jesel units with a 1.6:1 ratio.  These rocker units are good for 10,000 RPM + operation and we feel they are probably the best units you can buy for a small block Ford.  We intend to push the rev-limit "way up there" so these are good long term insurance for valve train stability.  Another nice feature is that they offer a wide variety of rocker ratios for fine tuning. 

Valves:  The intake valves used in SlowGT are 2.08" diameter Manley part number 11844.  These are light-weight Severe Duty racing valves - perfect for the intended rpm range.  Charles at Heads Up Performance set up the valves with a 5 angle valve job to match the heads.  For information on the exhaust valves (as well as the specific modifications to the intake valves), please contact Charles directly.  He's put a lot of time and effort into making this head combination work and we'd prefer you get those details from him.  For more information on building high performance engines, check out the books available at the SlowGT store.

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For more detailed engine-building information, check out the analyses and books available at the SlowGT store.

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Last Updated: May 22, 2001

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