But for a budget build, it should still run pretty well. You're pretty limited on lift with the Vortec heads unless you do some machining, and you'd be better off with a 2.02/1.60 head anyway. Upgrade the heads, and use a good cam in the 2500-6500 rpm range, and you'll get there. Personally, I think expecting north of 400hp from that combo is pushing it. It's been a really great motor for the street, and has decent manners in traffic.ĭo what you will with that info. Compression is just a hair under 11:1, and it runs just fine on 93 octane. It's a little lazy down low, but pulls like a freight train from 3500 to 6000 rpm. Since you mentioned that you are a noobie I recommend removing the heads.I'm making just about 425hp, on a Vortec 350 block and bottom end (motor had 10,000 miles on it, so it didn't need any cylinder work or bearings, but I re-assembled with ARP fasteners, since it sees 6500rpm occasionally), Keith Black 10.8:1 pistons, cleaned up 70cc Performer RPM heads, upgraded springs, solid pushrods, scorpion 1.5 full rollers, Comp XR294HR cam, Performer RPM Air Gap intake, tweaked Holley 670 carb, full MSD ignition (box, coil, distributor), Hooker Super Comps, and a few other goodies. Obvoiusly drilling the heads while attatched has it's drawbacks.
The pockets may need to be widened to accept replacements.įor the pushrod hole, a 1/2" drill bit usually opens the hole enough. Another problem you may run into depending on spring selection will be the spring pocket. On higher lift cams you'll have to get the heads cut. I have done this to several engines I've built without a problem. With lower lift cams like the LT4 Hot Cam there is usually enough meat on the bottom of the retainer to safely reduce it's height. Recommended retainer to seal clearance is. 2.grind the bottom of the spring retainer to get the proper clearance needed. 1.remove the heads and have the guides cut to accept a higher lift. And yes, even with 1.5 rockers you'll be exceeding the lift capability of Vortec heads which leaves you basically 2 choices. DAmnons specs are correct, but also remember that when you change rocker ratio you also end up changing duration by 2-3 degrees.
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