Sunday, August 12, 2012

Cary's Ultimate Small Block Crate Motor

I installed what I believe to be the Ultimate Small Block Crate Motor in Nan's 56.  However, you can't buy this engine; you have to assemble it from a few GM Performance parts.

My requirements were:
  • The engine had to be fuel injected;
  • It needed to fit the stock Corvette Motor mounts
  • It had to run smoothly enough to support power brakes
  • It had to have at least 400 HP
A logical way to meet the first three requirements is to purchase the GM Performance Ram Jet 350.  This is a good engine and has the very nice Ram Jet Fuel Injection system.  The GM Part number is 12499120; the price is about $5,750.  It is rated at 350 horsepower with a hydraulic roller cam, 1.6 to 1 ratio roller rockers.  The disadvantages of this engine are that it has cast iron cylinder heads and the crankshaft has two bolt main caps.

An alternative to the Ram Jet 350 is to buy the Fastburn 385 engine (P/N 19201331) and install the Ram Jet Fuel Injection system (P/N 12498032).  The chart below shows the comparison.  So far (knock on wood) the Fastburn 385 with the Ram Jet FI unit starts easily, runs smoothly, and has lots of power.


Component / Measure Ram Jet 350 Fastburn 385
Crankshaft Main bearings 2 bolt 4 bolt
Cylinder heads Cast iron Aluminum
Intake valves 1.94 2.02
Exhaust valves 1.50 1.55
Compression ratio 9.4 9.6
Intake lift 0.431 0.474
Exhaust lift 0.451 0.510
Horse power 350 385
Torque 400 @ 5500 RPM 385 @ 3800 RPM


  1. I am looking to put this same engine in my 56 Vette. Can you tell me if you had any problems with hood clearance? Also could you tell me the changes you made to the heater box and what brand AC you added if that's what you did.

    1. Dear Anonymous, the hood barely cleared the top of the fuel injection unit! I did, however, replace the stock motor mounts with side-engine mounts (similar to 63 and later Corvettes). So far there are no clearance issues. I made a completely custom adaptation of the Vintage Air small Street Rod A/C unit. Send me you email address and phone number to and I will help you out!