SCCA Camaro

 Upon starting my 68 Camaro successfully after the Cam swap and installation of the Holley Stealth Ram and all of the attendant plumbing, wiring, and sensors, as well as the installation of the TPI serpentine belt set-up, I was ready for a little tuning.  With the engine running I kept a very close eye on the Holley wide band air fuel ratio gauge on my dash to make sure I wasn’t running too lean.  The Holley Commander 950 base map I had chosen (WBmp3008) seemed to be close enough—a little lean but still safe at around 15:1.  One thing I had to figure out was the idle speed.  I had set it in the software at 800 once the car warmed up (it starts cold around 1100 RPM).  This was down about 50 RPM from the WBmp3008 base map since I had considerably less overlap than the cam used for the basemap and figured it would be easier to get a nice idle.  But the Camaro was actually idling about 1100.  It turned out I needed to adjust the idle air screw on the side of the throttle body as well as set the actual timing on the car to match that which the Holley.  A few turns of the set screw closed the throttle blades enough to get the idle down where I wanted it.  I had to purchase a timing light with a dial back feature in order to match the timing on the distributor with the 23 degrees the Commander 950 was giving the Camaro at idle, but it was straightforward with the correct tool.

I also noticed a water leak from around the water pump, which meant the block had to be mostly drained of coolant and the TPI serpentine accessory drive had to come mostly off the Camaro so I could pull the long style reverse rotation water pump and try again with a different set of gaskets.  The ones that came with the water pump were sort of a cork-like material and I used the Chevy specification for the bolt torque as well as a thin layer of RTV sealant so I was a little surprised by the leak but I used a FelPro composite-type gasket set re-prep’ed the block and didn’t have any more problems.

 
The Camaro was running lean in the lower RPMs due to the higher volumetric efficiency of the shorter-duration cam I was using relative to the one used for the base map so I added ten percent to the pulse widths in the first three columns of the fuel based map and tapered them off to the rest of the map where the map stopped being lean.  This meant at the higher RPMs the Air/Fuel ratio was a bit rich which I wasn’t too worried about so I left that part of the program alone.  When the dual Spal fans kicked on the idle would start to surge back and forth 50 to 100 RPMs around the set point so I played with that quite a bit.  The Commander 950 Software has two features to keep the idle steady, one involving fuel trimming and one for adjusting timing to keep the idle steady.  I enabled both and still found the idle to hunt a little.  Good enough for a test drive though.

I had just a few things left to do on the 68 Camaro before I could fire it up.  I had to wire the fuel pump, and hang the radiator support and passenger side fenders, and install an air filter and intake to the BBK/Edelbrock 58 mm throttle body.  I also needed to sort out some of the wiring and reroute a few wires that were originally routed to the passenger side via the core support but would now reside on the driver’s side because of the relocation of the alternator when I installed the TPI serpentine set-up.  I would also take this opportunity to put the Spal fan relays on the driver’s side to keep the wires to the alternator short.  Wiring the Walbro 255 external fuel pump (PN GSL-392) went pretty quickly:  I grounded it right at the rear frame rail it was mounted on; the Holley Commander 950 is pre-wired to run a fuel pump.  I merely ran the wire under the door sill and drilled a small hole in the floor under the rear seat.  I used a rubber grommet around the wire passing through the floor of course and crimped a connector on it there.  Rerouting the wires of the front wiring harness was just a matter of cutting my cable ties, unwinding some of the wires, laying them back out headed in their new direction, and putting cable ties back on. 

Hanging the core support was equally uneventful, as was putting the passenger side inner and outer fenders back together.  I measured the diagonals across the engine bay and had to push the front end around a bit to make sure it was perfectly square.  I had saved the shim pack for the fenders so it was easy to get everything lined back up properly again.  I put the hood back on by myself, which is a little less fun than with a helper by the way.  I purchased a cone-type air filter with plumbing for the throttle body on eBay and I had to do two slight modifications to make it work.  The first was that I needed to get a larger diameter, six inch worm clamp, because I was running the 58mm throttle body.  I found an inexpensive stainless steel clamp at Home Depot.  The second was the tubing didn’t line up well with my core support and radiator.  I cut about two and half inches off one of the aluminum tubes to fix this problem.

At this point I was ready to test the fuel plumbing.  I reconnected the battery and put the ignition in the accessory position so the fuel pump would develop some pressure.  Several cycles of the fuel pump revealed minor leaks at a few of the couplings, all of which were stopped by simply tightening up the connections.  It was time to load an appropriate program into the Holley Commander 950 ECU and attempt to start the Camaro!  I decided to use the Wbmp3008 base map, which was described as: 355 small block Chevy, 30 lb./hr. injectors, Stealth Ram intake, 58mm throttle body, 20 degree Holley heads,

Lunati 30142 cam (235/245 @ .050, .507/.534, 112 LC), 9.5:1 compression, 43 PSI fuel pressure, 418 HP @ 5500 RPM, 422 ft./lbs. @ 4700 RPM.  While the duration on my Comp Cam (PN 12-465-8) was a little shorter at 210/218 @ .050, I had higher lift at .560/.555”, so figured it would be pretty decent base map to start with, although volumetric efficiency for my car would probably be a little higher at lower RPM and a little lower at higher RPM.  I figured my AFR heads would perform similarly to the Holley heads.

The 355 sbc roared to life on the second cranking attempt and then it was time to start tuning!  I had exactly one week before my next SCCA Solo II autocross event.

The next order of business was to put a serpentine belt system on the small block Chevy in my 68 Camaro for Autocrossing in SCCA Solo II.  I had just completed the cam swap and the Holley Stealth Ram intake installation, including plumbing all of the fuel lines, installing the sensors, ECU, injectors, and wiring harness.  I couldn’t yet start the car because I didn’t have the accessories installed and I didn’t want to put the old water pump and alternator back on the car, I wanted to go with a modern serpentine belt set-up.  I did some research on the aftermarket pieces, which look nice, like the Front Runner from Vintage Air that Detroit Speed and Engineering distributes, and some from March Industries, Billet Specialties, and Zoops.  I also looked at the GM replacement/upgrade piece offered by GM Performance Products.  In the end a used TPI set-up made the most sense to me mostly because I am not building a show car and I’m mostly interested in low cost, high benefit options.  The best deals I found on complete TPI serpentine set-ups were on eBay, where several sellers offered all the brackets plus the idle puller for the AIR pump and all of the bolts for less than half of the GMPP serpentine set-up and about a quarter of the cost of a new aftermarket set of brackets and pulleys.

I worked with my eBay TPI serpentine seller who told me exactly what water pump or order.  I needed the long style reverse rotation pump, which I also found on eBay.  My TPI kit arrived with all of the brackets, pulleys, and bolts as advertized plus the idle pulleys for both the AIR pump and the air conditioning.  While trying the brackets on the Camaro I realized I would have to clearance the holes a bit because they didn’t align perfectly with the accessory bolt holes on the AFR heads.  The brackets also had to be clearanced a bit around the water pump.  What I didn’t figure out until I was trying the brackets on the block was that I couldn’t reuse my alternator since the alternator housing is different, so I sourced a new alternator off eBay as well.  The vendor I found rebuilds them regularly and built a 140 amp TPI alternator for me with one wire hookup with the correct housing in a matte finish.  He also had them in chrome for the bling set.  I was hoping to find a way to run my Detroit Speed and Engineering power steering pump with the TPI serpentine belt set-up but there was no way it was going to bolt right up.

Using the Detroit Speed and Engineering power steering pump with the TPI serpentine belt had two problems: the integrated pump/reservoir that I had didn’t bolt directly into the brackets, and the TPI pulley had the wrong diameter for the shaft from the power steering pump, which was 0.620” nominal.  For solutions I first figured out a pocket in the brackets in which I could mount the pump.  With some minimal cutting off of mounting tabs and clearancing I figured out a nice place for it down low on the driver’s side of the block.  Initially I thought I might have to mount it at an angle and I called Stacy at Detroit Speed to talk to her about how well it would work.  She confirmed up to 10 degrees might be OK but obviously less is better.  I decided to take the bracket that Detroit Speed had originally sold me to mount the pump to a small block Chevy with traditional belts and weld it to the TPI bracket.  Once I figured out where within the bracket it needed to be to mount the pump correctly, I machined a channel in the bracket to receive the bracket and then took it to Ted’s Machine shop here on O’ahu to weld the two together since my little mig welder was not up to the task of welding a few half inch thick pieces of aluminum together.

I sourced the serpentine belt power steering pulley with the correct outer diameter for pump RPM and the inner diameter for correct press fit from Vinatage Air.  The results looked great and bolted right up.  All of the accessories were in place although I had to re-route a lot of my wiring harness because the alternator was originally on the passenger’s side and now resided on the driver’s side of the car.  The belt (GM PN 10105246) went right in and the accessories worked great.  You can get it anywhere by referencing the application of 1992 Camaro with V8.  I did need to adjust the flexible radiator hoses to route them away from the belt on the bottom and away from the alternator fan on the top but otherwise the TPI install was nice and neat.  I took this opportunity to machine a few 1.3” spacers from stainless steel to set the radiator back from the core support to improve weight distribution in the Camaro.