SCCA Camaro

I had installed the Holley Stealth Ram in my 68 Camaro SS for SCCA Solo II autocross competition in the CP class, but I still had fuel plumbing to do.  I started with a Walbro 255 external pump (PN GSL-392) rated at 255 liters per hour, some OEM-style fuel filters (WIX 33481), some 3/8ths steel brake lines from NAPA, some 3/8ths tube nuts, 3/8ths barb fittings, 6 feet of 3/8ths SAE J30 rubber fuel hose rated for fuel injection, and some couplings.  I also had a tubing bending tool, and a double flare tool but did a lot of the tubing bending by hand.  The basic drill was the 68 Camaro is an original SS, so had a 3/8^ths fuel line from the tank to the engine bay already.  I decided to use this as my supply line.  From the factory it was a single tube from the sending unit all the way to the fuel pump on the block.  This was unwieldy for taking on and off the car so I cut it in the middle and made a coupling there with a couple of double-flares so it would be easier to manage.  The front half I left alone for now, and the rear half I bent and cut to put the Walbro pump in line.  I initially put a fuel filter in line upstream from the pump as you can see in the picture, but later changed this by putting the filter downstream in the engine bay.  I had already welded a return line into my sending unit and put a flare on the end to act as a barb.  The original sending unit pick-up line had a flare on it with a rubber coupling to the fuel supply line, so all I had to do was use some of the SAE J30 hose here.  Then I cut the back half of the original supply line, put two flare nuts on the ends and flared the tube.  The local NAPA had a coupling to go from the tubing flare nut to the in and out ports on the Walbro pump so I was in business.  I also purchased some tubing clamps from NAPA to secure the tubing. 

In the engine bay I merely bent the fuel supply line up away from the headers, cut it, and flared it for a connection via rubber hose to the supply side of the fuel rails on the Holley Stealth Ram.  Mine was missing the fitting, so I purchased an AN-6 to 3/8ths barb 90 degree fitting to connect the supply line to the supply rail using the fuel injection-rated hose.  Next in the plumbing was the connection from the passenger side rail to the driver side fuel rail, and again I was missing this connection.  Two more AN-6 to 3/8ths bard 90 degree fittings and a length of the SAE J30 hose got the job done here.  At the pressure regulator on the driver side fuel rail the unspent fuel starts its return path to the tank.  Here my eBay-sourced Holley Stealth Ram was also missing the fitting I needed for the return line.  It turns out it was a Saginaw fitting, a metric fitting GM uses for power steering and fuel lines with an odd shoulder flare and an O-ring.  This was very difficult to find locally here in Honolulu, but I did finally find a fuel line repair fitting at Red-Line Auto.  This I screwed directly into the fuel regulator; I flared the other end so I could use some more of the rubber SAE J30 fuel hose to my fuel return line.  For the fuel return line, I used two pre-fabbed 5 feet long sections of 3/8^th steel brake lines from NAPA.  I bent them both by hand to more or less follow the fuel supply line on the passenger side of the car along the subframe and back to the fuel tank.  When the bends were tighter I switched over to the tubing bender so as not to kink the tubing and secured both of the lines to the car with the tubing clamps from NAPA.  Another short section of the SAE J30 rubber hose isolated the fuel return line from the 3/8ths fuel line of the sending unit.  I wasn’t sure yet what I’d do regarding a fuel pressure gauge but thought the rubber hose in the engine bay would give me some flexibility to do that later…

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.