Some details re Weslake 4 valve Chev 350, ex Bellis-----Originally Posted by nzboss
The short block was just the usual racing small block v8, Steel GM crank, Carillos, roller cam, roller chain cam drive, forged pistons etc but the pistons were flat tops, in fact slightly recessed, and dry sumped with Weaver 3 stage pump.
The heads were were designed to just bolt on with a minimum of modification and had beautifull porting, twin rocker shafts, 2 inlet and 2 exhaust valves per cylinder that were operated by forked cast steel rockers with an adjusting screw at the pushrod end. (Tappet adjustment was done by grinding the lash caps so you had equal clearence at both valves, then adjusting the final clearences with the screw). The valve stems were same diameter as BMC A series and quite/very long, the heads quite small and the valve lift was quite low. It also had individule intake runners with slide throttle plates and Scintiller Vertex magneto locked with no advance and Lucas timed mechanical fuel injection. (To get it to idle at acceptable rpm I fitted an electronic distributor with centrifugal advance so the timing at idle was retarded because the throttles leaked so much air it idled way too fast.
The weakness with the engine design was the angles of the pushrods especially the inlets. Even thought they were 3/8 diameter hardened chrome molly tube they still flexed excessively as evidenced by the contact markings, yet when turning the engine by hand there was plenty of clearence!
When first running it on the dyno I was impressed by the exhaust noise, it was beautiful music! And produced 605 bhp at 6000 rpm, with a flat torque curve from 2500rpm. The power fell off very quick over 6500 due to the flexing pushrods losing valve control. Then we encountered issues with inlet valve springs, (breaking), and the valve covers and valley filling up with oil due to excessive oiling to the valve gear and poor drainage, this caused oil leaks and loss of oil pressure due to low level in the dry sump tank an probably aireation. These problems explained why Bellis could only do a couple of laps at a time before blowing smoke and oil at the two meetings he raced it at (Puke and Bay Park) After modifying the oiling system and the inlet rocker geometry and springs/retainers it started to go pretty well.
Roy Grainger raced it quite successfully in his leaf sprung old technology super saloon speedway car with a Powerglyde auto with no torque converter/clutch, locked in 2nd gear, but cooling was a problem so I converted it to run on methanol, this kept it cooler and gave if more power as well. (Not that it needed more)
I spent many hours on that project and learned heaps, didn't charge enough, but I enjoyed it and have a soft spot for that engine.
PK.
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