1993 Bluebird MiniBird Engine thread

[craigify]

I'm starting this thread to track the progress of my engine rebuild on my bus. If you look at my profile, I have my bus registry available for you to check out.


Some background:
I bought my bus to be a Mardi Gras vehicle. I live in New Orleans. The goal was to store some scaffolding and barricades in it, and set this up every year for Mardi Gras on the parade route. We would set up a reviewing stand for friends and family, so I thought this would be a great way to store the stuff and keep the bus on the parade route. SO I did this for a few years until I realized how cool this bus was. Then I learned that other people think the same thing, and they've converted their business into things, and call them Skoolies! So here we are..

Engine background:
Anyway, so originally this bus came from a fleet in Alabama. It had a 350 cid chevy small block, 4L80E automatic transmission and 1990s area throttle body injection. The previos owner swapped a big block 454 in it, and did a shitty job. I decided to replace this with another 454, which I built. I figured out how to read the ALDL (ODB1) data stream and had the fuel system programmed.

Unfortunetly, I realized that my 454 build is not ideal for my application and my fuel system. I am now rebuilding the top end of the engine.

Overall plan:
- Keep the bottom end. I have stock flat top pistons. Bore and stroke, are I'm guessing, stock 454. That's 4.250" bore and 4" stroke.

- I've ordered a set of rebuilt 1996-2000 series L-29 Vortec heads off of the last generation of 454s. These have a newer, heart shaped combustion chamber that is supposed to be better at total fuel burn. It's also 100cc in size, which will, along with all other components, raise my static compression ratio to around 9.0:1.

- I've ordered a stump puller camshaft from Bullet Cams in Olive Branch, MS. Effective power range is around 1,400 rpm to somewhere around 4,500 rpm. Maybe 4,800rpm.

- I've got 5.13:1 gear ratio, and 19.5 truck rims, which is about 33" tires. In overdrive (0.75:1 transmission ratio), this puts my 60MPH speed at 2,400 rpm. I plan on reducing this to a 4.30:1 gear ratio, which will put my 60mph speed at just around 2,000 rpm and 65mph at 2,100rpm.

- Given my powerband, I'll have plenty of power to downshift to third gear, which at 60 is 2,600 rpm and 65, 2800 rpm, to muscle up a hill and come back down into 4th. The goal is to be much more efficient with higher compression and head design and burn less fuel. See below. I'm already running very rich due to a problem with the camshaft selection.

- The camshaft that's in there now does not produce enough vacuum for the fuel injection style that I have, and I constantly foul out spark plugs because the MAP sensor, which is the major factor for fuel delivery in this style of electronic fuel control, cannot handle such a low vacuum.

- I've already put Hurley Tri-Y headers on it, and I've installed a O2 sensor with a heating element to make sure it is hot enough to work properly.

- Based on what I've read on the internet (lol), my peak HP will hopefully be in the mid 300s and peak torque will hopefully be 500-600 foot lbs. I don't know at what rpms these will be in, but probably between 3,000 and 4,000. This leaves me with room to downshift, raise rpms to climb, then go back to cruise at low rpm.