I have logged 600 miles on my 383 (388) in my 67 El Camino. Here are the specs:
- GM 4-bolt main block, .060 overbore
- Eagle crank and cap screw rods
- Keith Black 12cc small dish hyper pistons (CR is 9.6-1)
- Speed Pro moly rings
- Clevite bearings on main and rods
- Dura bond cam bearings
- Super Flow heads, 192cc and port/polish work, 2.02/1.6 stainless valves
- Comp XE 264 hyd roller cam and Pro Mag rockers @ 1.52 ratio
- Comp Magnum push rods
- Edelbrock RPM Air-Gap intake and 600 cfm carb (tried 750 for a while)
- HEI ignition and Taylor wires
- Hedman Elite headers 1 5/8" X 3"
- Flowmaster American Thunder system with 40 series 2-chambers
- Phoenix Transmissions 700R4, 2400-2600 RPM converter
- 10-bolt rearend with the stock 3.36-1 ratio
- Rear tire size is 275/60-15
The reason why I am posting this is because this combo is amazing. I had an old school 355 in it's place prior to the install that made 365 HP/410 TQ but required super unleaded fuel and it got 10/12 MPG (yuk). I have been able to run cheapo 87 octane fuel and my first tank of fuel I pulled down 16 MPG and this was with the engine still in break-in. I am going to fill up again today after work but I am suspecting this tankful will be closer to 20 MPG due to my switching to the 600 cfm carb. I can't really feel alot of differance between the two carbs.
This is the cool part. When I hammer the gas, the right rear tire gets roasted and the truck hauls the mail. Lots of throttle response and the front end lifts hard. 100 MPH comes very quickly. I can't wait till spring to test this combo at the track. This is NOT a race combo. I built this engine to showcase my talents (for my business) and to be my daily driver. It has exceeded all my expectations at this point.
I had a couple people tell me the cam choice was wrong and that it was too small. This is by design. I believe "great heads/mild cam" is the way to go for daily drivers and to get mileage to boot.
Just thought I would share!