SCCA Camaro

I had my camshaft in the 68 Camaro and it was time to start putting the Holley Stealth Ram intake in place so I was ready for the next SCCA Solo II competition.  I laid a bead of silicone sealant on the ends of the lifter valley and some intake gaskets (Fel-Pro PN 1205) on the heads before laying the Holley Stealth Ram intake on the block/heads.  After that I bolted on the upper plenum using the Holley Gaskets (PN 108-119) and then the fuel rails.  Then I simply plugged the sensors into the wiring harness: throttle position sensor (TPS), intake air temperature (IAT), manifold absolute pressure (MAP), and coolant temperature.  Then I plugged in the idle air control (IAC) and the fuel injectors themselves.  I had previously installed the Bosch wide-band oxygen sensor (Holley PN 534-197) as well as the Commander 950 ECU.  All of the sensors where easy plug-ins with the wiring harness since they all use the OEM-type plugs.  The instructions with the wiring harness claim you need a two inch hole in your firewall but I found I was able to get everything through one and three quarters inch hole with a little filing to square the hole up a bit.  I needed a vacuum cap on the throttle body and needed to run two vacuum lines from the upper plenum, one to the fuel regulator and one to the MAP sensor.  For a throttle linkage, I got a quarter inch diameter brass rod and threaded the ends with ¼-28 threads to fit on two shackles that I inherited with the Camaro when it had a carb.  A simple e clip to the throttle body and a clevis pin on the other shackle to the throttle lever linked it together.

For spark, I was using the GM small body computer-controlled distributor with an MSD external coil (PN 8226).  Dear old dad did a junk yard crawl for me to get the wires that connect the small cap computer-controlled distributor to the MSD coil, since they were hacked off the wiring harness I had sourced off of eBay.  I was a little unsure about the distributor install because it was computer controlled, but it turns out it was a piece of cake.  All you need to do is install it like a traditional distributor.  That is, pick a point on the cap to be cylinder number one, and have the rotor pointed right at it with the number one cylinder at top dead center on the firing stroke.  Remember that your camshaft turns once for every two times your crank turns over, and that your distributor, which is driven by the camshaft at a one-to-one ratio, also turns at one half the speed of the crank.  That means that for a given crank position, there are two possible distributor positions.  One will be the correct with the distributor pointing at the number one plug on the cap as the cylinder is entering the firing stroke, the other will be out of phase one hundred and eighty degrees.  Both will have the number one piston at top dead center, but in one case it’ll be on the firing stroke and the other will be on the exhaust stroke.  David Vizard’s book How to Rebuild Your Small-Block Chevy has the best description of how to drop a distributor in that I’ve seen anywhere.  Using his method the oil pump tang needed just a little nudge of the crank to drop in place.  The last step is to synchronize the timing once the car is running so that the Commander 950 knows where the distributor is when it needs to adjust timing. 

I had the top end of the engine block of my ’68 Camaro completely stripped down.  The block still had the crank, connecting rods and pistons, but a loosely-attached oil pan and the scattershield were about the only other things bolted to the short block.  It was time to start the re-assembly.  But first there were measurements to be taken.  It turns out the block had some replacement pistons, and that these were 0.045” from the deck height at top dead center rather than the usual 0.025”.  Using a Fel-Pro 1003 head gasket with a compressed height of 0.041” would yield an abysmal 9.4:1 compression ratio with my 64 cc combustion chambers in the AFR heads and the stock 350 stroke of 3.48” with the thirty thousandths overbore 4.030” pistons.  Craig at Ted’s Machine Shop hooked me up with some Fel-Pro steel shim gaskets (PN 1094) that had a compressed height of only 0.015”, lifting the compression ratio to a more respectable 10:1.  I had been using the CamQuest software to determine which camshaft to select and how much power I was likely to make.  At 9.5:1 CR, torque was estimated at 435 lb/ft at 4000 RPM, and HP 393 at 5000 RPM while at 10.0:1 CR, torque was 442 lb/ft at 4000 RPM and  HP was 401at 5500 RPM.  More importantly, average horsepower went from 99 HP to 117 HP.

I put some oil on the new hydraulic roller cam and put it in the block, aligned the true roller timing gear set (Comp Cams PN 3100) straight up, and put the heads on the block without gaskets but with some play-dough on the tops of the pistons.  I then put the pushrods in the block and adjusted the rockers (Comp Cams PN 1305-16) for zero lash plus one quarter turn (as the Comp literatures suggests).  After turning the engine over two full revolutions, I removed the heads and checked the thickness of the play-dough to ensure the valves had enough clearance from the pistons with the new cam.  Then I cleaned all of the gasket surfaces and the head bolt holes, after which I placed the ARP head studs in the block with some PTFE sealant on the threads.  Then I placed the Fel-Pro 1094 gaskets on the block and threw the AFR heads on the studs.  After that it was a simple but tedious matter of torquing down the nuts on the head studs according to ARP instructions in three passes.  For a timing chain cover, I used a Cloyes Quick Button two piece timing cover (PN 9-221) with an integrated roller bearing to control camshaft end-play.  After installing the cover I checked end-play on the cam and the installation of the cam was complete—time to move on to the intake and EFI installation.

I decided to get the ’68 Camaro’s engine block down to a state in which I could complete the camshaft swap and build it back up using all of the EFI parts I had accumulated.  These included the Holley Stealth Ram intake and plenum, fuel rails, fuel injectors, fuel regulator, BBK 58 mm throttle body, GM small body computer-controlled distributor, and MAP, IAT, TPS, and temperature sensors.  The camshaft I chose was a retrofit hydraulic roller from Comp Cams with retro roller lifters, new pushrods, and full roller rockers in 1.6:1 ratio.  I started with removal of the air cleaner and carburetor linkage, followed by the distributor.  I regrettably removed the alternator and attendant brackets (I had just gotten them aligned correctly after many weeks of loosing belts during SCCA Solo II events).  I removed the Edelbrock 1406 carb and Chevy cast iron intake as a unit, and was able to start working on getting the heads off.  Of course this requires removal of the headers, and in fact on the driver’s side the headers need to be completely removed from the engine bay from underneath the car in order to remove the head, because of how close the steering gear box is to the engine.  Once the heads were off the car I inspected them and the pistons to make sure I had only the one bent valvestem.  I confirmed I had only one bent valvestem and took the head to Ted’s Machine Shop here in Honolulu.  Craig had them fixed up in a few days; it would be awhile before they were re-united with the block.

The radiator had to come out of the Camaro in order to pull off the cam swap, and I had substantial corrosion of the sheet metal of both the core support and the passenger’s side inner fender, particularly around where the battery tray used to be, probably as a result of leaky battery at some point in the forty year history of the ‘68 Camaro.  I had purchased replacements for both from Classic Industries and I decided to take them out in order to create some room to work, figuring I would replace these while I had the front end of the car apart.  This necessitated not only removal of the radiator, but the hood, front wiring harness, passenger side headlight bucket, and horns.  Separating the inner fender from the outer fender yielded a big surprize:  my Camaro’s build sheet!  Alas, it was too far gone to recover or even to read anything off of.  Nonetheless, I saved what I could of it…

With the disassembly nearly complete, I turned my attention again to the engine.  It was time to remove the water pump, which was an Chevrolet cast iron pump that I wouldn’t be re-using, because I was also going to install a serpentine belt front accessory drive from a TPI Camaro on the engine block after the cam swap.  I borrowed a harmonic damper pulley from Craig at Ted’s Machine Shop when I picked up my repaired AFR head, and used it to remove the damper so I could take the old stamped-steel timing chain cover off the block.  I had to loosen the bolts on the oil pan and tilt the front end of the pan down to remove the timing cover.  This revealed the timing gears, which were the OEM style.  Removal of the timing gear from the cam allowed the chain to come off; I put the gear back on the cam to aid in removal of the camshaft.  The cam started out rather smoothly, but about a third of the way out it hung up and I couldn’t seem to get it moving again.  Not wanting to force the issue, I took a break and leaned back.  Then it dawned on me—I hadn’t removed the fuel pump, and the fuel pump plunger was catching the cam.  A few bolts later and I had the fuel pump off and quickly thereafter the camshaft was out.