Chevy Camaro V6 - Project Fast Victor 6, Part 5

Cam Change, Again?

Hib Halverson Oct 26, 2006 0 Comment(s)
Sucs_0665_six_01_z Chevy_camaro_v6 Engine 2/15

In Part Four, which was about engine computer programming, we wrote "...we knew a calibration exhibiting good drivability, as well as increased performance would be challenging."

Whoa! Did that statement prove prophetic! PFV6 had problems with idle stability and knock retard. We tried for more than a month to calibrate our way out of those troubles; we couldn't do it.

Another project goal was to pass an exhaust emissions test. While our Camaro's biannual California smog check wasn't due, we went to Quality Auto Service for a mock test to see if it passed. Owner Mike Garibay is well versed in emissions testing and service, and his shop is one of our favorites for its customer relations.

Smog check's "Enhanced Program" applies in California urban areas and combines visual inspection of emissions parts with a chassis dyno exhaust gas test. We passed the visual and the tailpipe checks. However, we still flunked because the car's computer had DTC P0300 in its memory, due to misfire at idle; any fault code causes immediate failure.

Sucs_0665_six_02_z Chevy_camaro_v6 Emissions_test 3/15

Mike Garibay prepares our car for smog checking by inserting the "sniffer" in our Flowmaster exhaust.

We went back to our calibration specialist, Z-Industries, for another run at improving idle. In fact, we visited Z-I four more times-each a five-hour trip-attempting to beat misfire. Z-I's Ron Zimmer changed fuel calibration, varied idle speed, and experimented with spark advance. By adding a little more fuel and jacking idle up to 850 rpm, just 50 shy of California's 900 rpm limit, we saw incremental improvement, but code 0300 persisted.

Z-I also worked on knock retard trying several spark calibrations, even one across the board, retarded from stock. We could mitigate knock retard, but not eliminate it. The symptoms were both detonation and "false knock" due to valve noise discussed in Part 4.

Second Cam ChangeMark DeGroff, our cylinder head specialist, quipped, "Are you finally ready to throw in the towel and admit you need a different cam?"

We threw in the towel and sent COMP Cams an SOS.

Sucs_0665_six_03_z Chevy_camaro_v6 Cam_install 4/15

Installing a slightly milder COMP Cam eliminated problems with misfire at idle.

Billy Godbold, an engineer responsible for COMP's NEXTEL Cup cams, suggested a new profile with two differences from the first FV6 cam: 1) 4 degrees less intake duration, 2 degrees less exhaust duration, and 2 degrees more lobe separation, all to reduce overlap thereby improving idle. 2) About a 14-percent reduction in velocity just as the valve hits the seat. Tearing down our 3800 Series 2 V-6 was becoming a regular thing. This was our second cam change, third intake removal, and fourth pushrod change, so we acquired additional tools to make the job less tedious. Ratcheting combination wrenches are the rage, so we got a set (PN#SRW27K) from Mac Tools. Known as "Mac Edge," they make combination wrench use easier. We ordered Mac Tool's "Zero" ratchets in 3/8-drive (PN#XR8PAZ) and quarter-drive Flex Head (PN#MR7PAZF). Several toolmakers have ratchets with as little as 5-degree lash. The lower lash mechanism, however, makes a weaker tool. The Zero uses a cam and roller-bearing assembly-like a sprag in an automatic trans-so it has no lash. This makes for easier use in tight spots, but also, a strong, durable tool.

Sucs_0665_six_04_z Chevy_camaro_v6 Intake_centerline_checking 5/15

We checked the ICL on No. 1 intake the easy way, with the valve train assembled. We're wearing Goodyear's snazzy, new Performance Mechanics Gloves.

The second cam installed generally like the first in Part 2, however, while troubleshooting false knock retard, we'd temporarily gone back to stock lifters and a longer pushrod. So we reinstalled COMP Cams Pro Magnum roller hydraulic lifters (PN#875-12) and shorter, 7.000-inch COMP Hi-Tech pushrods (PN#7936). This time, we degreed the cam with the heads on, but again, used the "intake centerline" (ICL) method to check No. 1 and No. 3 intake lobes. If you do this with the valvetrain assembled, the lifter's adjuster must bottom before checking begins. We turned No. 1 intake to maximum lift, paused 5 minutes for the lifter to collapse, then, determined the ICL was 118 degrees

We checked No. 3 ICL with a more accurate but more difficult method. We removed the pushrod and rocker, attached a COMP Cams extension (PN#4912) to our dial indicator stem, put it through the pushrod hole in the head, and indexed on the lifter body. The No. 3 intake centerline was also at 118 degrees. Once we advanced the cam by 2 degrees, using the INTENSE Racing adjustable timing chain set installed in Part 2, ICL was the 116 degrees required by COMP Cams, so we buttoned up the motor. During the cam change, Z-Industries' Ron Zimmer had our engine computer reinstall a program we ran before we tried to fix idle and knock.

Sucs_0665_six_05_z Chevy_camaro_v6 Icl_lifter_body 6/15

Indexing off the lifter body, finds ICL more accurately and doesn't require a pause for lifter collapse, but it's more time consuming. When you're doing the rear cylinders, you may have to view the indicator dial with a mirror.

With a little less camshaft and that earlier cal, the engine ran pretty well. Idle stability was improved. Misfire was virtually eliminated, and valve noise was reduced. We still saw some knock retard but we also observed the air/fuel ratio was a bit lean, which can cause detonation.

We headed back to Z-Industries for more fine-tuning. First, Zimmer added fuel at wide-open throttle then went a little more aggressive with the spark cal. Also, we limited knock retard to 7 degrees, down from 15 degrees. If we didn't have to pass California's emissions test, we could have stuck with the first camshaft provided we'd used an off-road calibration where code P0300 does not require the check engine light and knock retard be disabled. A modified 3800, calibrated that way, requires at least 91-octane gasoline.

Little ExtrasA rainy spring in Southern California had us trying Super Silicone wiper blades (PN#93060) from WeatherTech Auto Accessories, made by PIAA from "activated" silicone rubber. As the blade wipes, it leaves a slight residue, which builds over time, causing water to bead and making the wiper's job easier. Silicone WeatherTechs are more durable than typical rubber units, too, so they hold a sharp edge longer.

Sucs_0665_six_06_z Chevy_camaro_v6 Hir_headlight_bulbs 7/15

A Harison-Toshiba HIR bulb (left), is reminiscent of an old-fashioned light "globe," but that's where similarities end. An optically-transparent coating on the inside of that spherical section reflects infrared radiation back at the filament, making it hotter so it produces more light than it can by current flow, alone.

FV6 needed better headlights-not cute, blue bulbs, either. We wanted lighting that worked, so we installed Harison-Toshiba, Halogen Infrared (HIR) bulbs (PNs #9011, #9012) from Daniel Stern Lighting, a performance lighting compo-nents distributor. Not "over-wattage," blue-tinted stockers, Harison-Toshiba bulbs' critical dimensions are the same as OE, but they use HIR technology, which eliminates short life, greater heat production, and higher current draw of over-wattage bulbs. Their power consumption is the same as stock, yet the low beam produces 87 percent more light, and the high beam produces 50 percent more light. Stern's HIRs enhanced our nighttime driving safety.

Thermal insulation on the engine's fuel hoses needed replacement, and we wanted to insulate other fuel system parts near the engine, too. We cut the tattered OE stuff away and replaced it with Design Engineering's Heat Sheath (PN#010419), using longer lengths to insulate more of the hoses. We used DEI Cool Tape (PN#010413) to bond the Sheaths to the hoses. We cut a 7-inch-by-10-inch square of DEI Floor and Tunnel Shield (PN#050503) to cover the ends of the hard fuel lines adjacent to the left exhaust manifold. All this was to keep the fuel cooler. More Cool Tape repaired insulation on crankshaft and camshaft position sensor wiring where it passes through a very hot area adjacent to the EGR valve. Lastly, in preparation for a future header installation, we added DEI Protect-a-Boots to our MSD Super Conductor plug wires.




Connect With Us

Get Latest News and Articles. Newsletter Sign Up

subscribe to the magazine

get digital get print