September 2011 Archives

It's a Home, on Wheels

84 MidasIn my opinion by far the best tow vehicle to go to the track in is a motorhome. They are built on truck chassis, come with big block engines and can be bought dirt cheap. The best ones have a built in generator and roof A/C. Our 1984 Midas is a 24 foot class A sitting on a Chevrolet "P" chassis and has a 454 big block, Turbo 475 transmission, twin cylinder generator and roof air. It even has a toilet and a shower and a double bed. We picked it up this year for $2500 and were impressed by its clean interior and brand new tires ($1200 worth!). I was less impressed with the mechanicals but it made it the 20 miles from PawPaw to home, but as you'll see later it's amazing it did.

It was obvious from the start that the exhaust was leaking badly, a common problem due to the heat generated "under floor". I did some research and found that these models use cast iron manifolds with air injection. An engine driven air pump injects air into the exhaust ports to reduce emissions. It also overheats and cracks the manifolds, not to mention causing a huge restriction in exhaust breathing. You can see in the pictures below the huge crack in the manifold. Also shown are 3 of the spark plug boots that were melted beyond recognition. It's amazing this motor ran at all.

Exhaust CloseupExhaust Crack

As Michigan is a no-inspection state, that system is coming off and is being replaced with headers, a 2.5" dual system with crossover and some Flowmasters that I kept from the RX7. Not only will it flow and scavange better, it will run cooler and sound better too.  Also coming off is the non-functioning engine driven A/C compressor, condenser and evaporator. They don't work so why have them cluttering up the engine, it's hard enough to work on without all that extra crap. This is where I'm at today, everything thats coming off is off and it's time to start putting it back together again.

EngineValleyExtra Crap

The top end is getting an Edelbrock Performer aluminum intake, Edelbrock 750 cfm carb and MSD HEI distributor.  All fluids are getting replaced, anti-freeze, oil and trans fluid, possibly rear end oil too. I'm going to engineer some kind of cold air induction system for a little extra power for the 131 D Avenue hill. It doesn't look like much of a hill when you're in a car but our old motorhome (basically the same as the new one, just a little older and 3 ft longer) pulling the open trailer couldn't get up it any faster than 45 mph. This time we'll be pulling a 26 ft enclosed.

I will also replace the radiator, waterpump, starter all belts and hoses. It no fun being miles from home and having a waterpump fail. It may seem like overkill but these vehicles are often neglected and trusting 27 year old components or the questionable maintenance of some previous owner is not an option for me. More pictures as the work progresses.

A Tale of Two Big Blocks

BB452BBC452BBCHeadInjection

I decided to kick start the Monaro project by building the motor. Nothing like hearing the motor running to get you excited about hitting the track. Several years ago I bought an alcohol injected big block from a mate and I ran it in the Monaro for a while, best time 10.31 skating all the way. Its been in pieces for a while and it was time to put it back together. The block is a special "bowtie" casting that has 4 bolt main and can be bored to 4.6". It is currently at 4.375" which combined with a 3.76" stroke crank makes 452 cubes. Not a big motor but a high winding one. Unfortunately the bowtie block has badly scored lifter and piston bores and I'm on a budget so boring, sleeving, new rotating assembly etc is out of the question at this time. That block will make a nice 540 in the future. As it happens I bought a two bolt block some time ago with the same bore. I cleaned up the block, honed the bores and assembled the bottom end with a 427 steel crank 10/10, I beam rods and domed forged pistons with gapless rings.

Previously I've paid to have the heads set up but this time I invested in the tools to do it myself. The heads are a 1971 026 casting, rectangular ports, ported by a local guy called Dave Crane. Valves are 2.30 intake, 1.88 exhaust. I bought the matching spring set (springs, locks and retainers) and roller lifters for the Lunati roller cam I had, which was a 1.55" diameter, requiring the spring pockets to be opened up. CompCams sells a tool that machines both the inside and outside spring pocket, which registers on the valve guide and makes the job easy. Using a valve spring mic I set up all the valves at the specified 1.95" install height with CompCams spring shims. Valve seals are Viton. I did have a machine shop surface the heads and cut the valve seats as they had been sitting for a while and had some pitting. CompCams guides, HiTech 3/8" pusrods, ARP rocker studs, Crane steel roller rockers and stud girdle top off the top end.

Other odds and ends required to complete the motor:

  • Cloyes Hex-a-just double row roller timing chain
  • Cloyes aluminum timing cover with cam button
  • ARP head bolts
  • ARP main studs
  • Gaskets
  • Federal Mogul main and rod bearings
  • Moroso high volume/standard pressure oil pump
  • Moroso 7 quart oil pan and pickup
  • ARP oil pump drive and oil pump stud
  • Fluidamper harmonic balancer
  • ARP balancer bolt
  • Victor Jr Intake
  • 1050 Dominator carb (Pictures show an injected setup on the intake at the moment)