The sending unit has 1/8th NPT threads and you can buy a pressure gauge adapter with either barbs or AN -6 fittings on either end but I decided to machine my own from brass with barbs to go inline in the 3/8ths rubber fuel-injection rated hose (SAE J30).  I put a ½ diameter brass rod in the lathe and bored the center out to 0.330” before turning down the ends to 0.375” on either end.  I left the center at 0.500” and also left the barbs at 0.440” with sixty degrees backcut and forty five degrees on the end going into the hose.  I radiused all of the cuts and put the tube in the milling machine to drill and tap the hole for the 1/8th NPT threads.  I also picked up a couple of stainless steel worm clamps to put the adapter in-line in the fuel hose.  I installed the gauge on the passenger side firewall with a plumbing clamp I found at the local hardware store and re-bent to fit securely over the unit with a single screw.  This is essential for proper gauge performance because the sending unit needs to be grounded, which the rubber fuel hose obviously doesn’t accomplish.  For the gauge mounting I simply drilled an additional hole in the 20 gauge sheet metal panel I had made to mount my Holley Digital Wideband Air Fuel gauge in the dash.  I also made an equally-space dimple in the center of the panel so the addition of a third gauge in the future will be easy.

Wiring the gauge was straightforward: I tapped into the twelve volt supply for the Air/Fuel Gauge as well as the ground while routing the sending unit wire through the firewall grommet with the wiring harness from the Holley Commander 950.  The gauge worked well and confirmed fuel pressure at about 41-42 PSI upon putting the key in the ignition position.  The fuel pressure regulator is vacuum referenced and with the car running at idle fuel pressure was around 35 PSI.  The gauge fit well into my red LED scheme and allowed me to monitor the fuel delivery system for problems which is critical when retrofitting the 68 Camaro with EFI so I was happy.

Upon pulling out of the carport I realized the Camaro was not going to be as docile as I hoped when I spec’ed out that mild 112/118 duration cam!  It was very torquey and surged when attempting to accelerate and torque braked hard as soon as you let off the gas.  This was noticeable even in third and fourth gear.  This made it almost impossible to log useful data in traffic as the only way to drive it without the car violently bucking around was “flat out”.  My first test drive also involved topping off the gas tank and I found out that I had a leak somewhere high up on my tank (it was not leaking when not full but leaked when full).  This wouldn’t be that big of a deal except I still didn’t have a reliable reading from my 68 Camaro’s 40-year-old gas gauge sending unit so I was guessing about how much fuel it had at any moment—making it difficult to fill it up three quarters of the way.

I put the following on the www.pro-touring.com forum board hoping for some help:

When taking off in first, i find it very difficult to not spin the tires. If you are going balls out on a track it might be OK until you have to come off the gas–but in street traffic when taking off at a stop light and then trying to feather back off the gas so as not to rear end the vehicle in front of you, the car surges forward, then if you let off the gas it jerks or bucks very hard due to the torque braking. I have the Commander 950 software running and am looking at my throttle position sensor when i am doing this, and i have a relatively light foot (TPS is 1 closed and 172 for WOT, i am applying values of ~10 when this is happenning). I have found for the street the only way to drive it is to let traffic leave me to create a gap, then take off aggressively in first, then go to second almost immediately, then go to third and essentially allow the car to idle along in traffic (idle is 850 RPM). In third, the ammount of torque on tap is diminished enough relative to the load that i can come on and off the gas (again, i’m talking 3-5% of WOT) with controllable surges rather than violent bucking. Traffic around me still think i’m an idiot because the car bucks with even the slightest progressive addition of gas (i looked at my datalogs and i’m talking TPS values of around 5–roughly 2-3% of WOT).

There were a lot of thoughtful responses, and three things I could implement pretty quickly: double checking throttle linkage and spring tension, moving the idle up higher in the RPM band, and setting the shocks softer.  I disconnected the spring from the throttle linage but didn’t see any other way to make it more progressive in the short term.  I also set the DSE-sourced Koni adjustable shocks at one click out from full soft in the front (they had been set on one click from full hard) and to ½ turn from full soft in the rear.  Then I raised the idle RPM to 950 in the Holley Commander 950 software and adjusted the throttle return set screw to get the idle correct so the idle air control solenoid was in control of the idle.  I figured I would deal with the gas tank leak later since it only leaked with a full tank of gas.  Upon taking it for a test ride, it was still very rough but seemed somewhat improved mainly by the throttle spring and idle speed changes.  Unfortunately upon adjusting the front suspension I was now bottoming out on bumps at speed.  Although I had the 2001 Trans Am as a back-up, I decided to race the Camaro on Sunday and see from there what to do next.  Unfortunately I was travelling on the mainland for work and United Airlines stranded me there on July 12^th, the night before the race I had been waiting 3 months for!  The only good news was that there was another SCCA Solo II race two weeks later, so I wouldn’t have to wait too long to test out my modifications.

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.

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.

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.

I had the GM small cap computer-controlled distributor with an MSD external coil (MSD Blaster GM coil PN 8226) and MSD Street Fire spark plug wires (MSD PN 5570).  The MAP, IAT, and coolant temp sensors can be sourced from your local auto parts store since they are OEM for ’92 Camaro (and many other applications).  I had already installed the Commander 950 along with the Bosch wide band oxygen sensor (Holley PN 534-197) and the Holley in dash Air/Fuel ratio meter (Holley PN 534-200).  I had installed the wiring harness at that time and since the MAP sensor was a simple plug-in, that was installed as well by plugging it into the wiring harness and running a vacuum line off the carb to the sensor.  It was not secured anywhere in the engine bay yet, just handing off wiring harness.  For fuel plumbing, I had purchased a Walbro external in-line pump rated at 255 LPH (PN GSL-392), an OEM-style fuel filter (PN GF481), five feet of 3/8” rubber hose for fuel injection (rated SAE J30), and two five foot long 3/8” steel brake lines, pre-flared with tube nuts on them already.