For some time now I have been wanting to upgrade my 350 small block in my car. In most Auto Cross events a few hundred extra RPM would handy to make it to the turn without a shift and on the road courses I just get eaten alive on the longer straights. So it was, I was on the hunt for a new motor. After looking at all options I settled on a larger ci small block as the most affordable way to go. The LS motors are really nice no doubt but require so many other part changes and big hp LS motors are not cheap. After a number of phone conversations and a face to face meeting with Bryce Mulvey at Dr Js Performance in Anaheim CA. I pulled the trigger.
After several conversations with Bryce the Engine combo we settled on is a 421 ci SBC built around a Dart SHP block. The Block was sonic tested and had enough bore thickness to accept a 4.185 bore, and was bored to 4.155. The 3.875 stroke 4340 Crank and 6 H beam rods are both Callies Compstar pieces. The oiling system is a Melling M55A pump, a Moroso 7 qt road race pan, windage tray and pick up. The pistons are CP bullet forged flat tops with a metric 1.5/1.5/3mm stainless steel ring package. The block was machined to provide a positive deck height of .005 with .041 head gasket provides a .036 quench. The heads are Air Wolf 220s, Dr. Js 23 deg. CNC ported Brodix castings with 64cc chambers that make 11.5 : 1 compression. The cam is a custom ground Isky hydraulic roller with 254 degrees duration @ 0.50 lift on both the intake and exhaust and provides .640 gross lift with 106 deg lobe separation. Comp Ultra Gold 1.6 rockers, Manley push rods, Isky link bar roller lifters and a Cloys Tru-Roller timing chain complete the valve train. The intake is a DR Js Ported Pro-Comp Hurricane single plane, the carb is a Holly Street HP 950. The distributor is a recurved MSD billet. The combo of the recurved ignition and the tight quench allows it to run on pump gas even with the 11.5:1 compression.
On Tuesday Bryce put it on the Dr Js DTS dyno where it made 676 hp @ 6600 RPM and 599 ft lbs tq @ 5000 RPM. I cant wait to get it in the car and put the hammer down! I will complete the install with 1 7/8 Lemons headers, 3 exhaust, Borla mufflers and a RAM dual disk clutch & aluminum flywheel.
That will certainly wake that car right up. Take a look at your oil pressure and how it falls off above 5700 rpm. Looks like you may have a windage issue or your oil level was to high.
That will certainly wake that car right up. Take a look at your oil pressure and how it falls off above 5700 rpm. Looks like you may have a windage issue or your oil level was to high.
Good eye! he was still trying to work out the correct oil level, got it now and marked the dipstick.
you'll love it. It's almost identical to my Dart 421. Mine's 13:1 on E85- .680/.688 260/262. I drive it everywhere. You'll love the stupid torque it'll make. Feels like a 502 down low. Congrats!
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
New motor for My 68
Take a look at your oil pressure and how it falls off above 5700 rpm. Looks like you may have a windage issue or your oil level was to high.
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