Edlelbrock says not to use 1.6 rockers with their cams. Anyone know why
your not suppose to do this?? This is the cam I would like to use.


#2209

ENGINE: CHEVY 265-350 V8 (1987-Later)
RPM RANGE: 1500-5500

Duration at 0.006" Lift: Intake: 280° Exhaust: 290° Duration at 0.050" Lift: Intake: 212° Exhaust: 222° Lift at Cam: Intake: 0.308" Exhaust: 0.319" Lift at Valve: Intake: 0.462" Exhaust: 0.479" Timing at 0.050" lift: Open Close Intake: 1° BTDC 33° ABDC Exhaust: 48° BBDC 6° BTDC Centerlines: Lobe Separation - 112° Intake Centerline - 107°

Note: Uses stock hydraulic roller lifters and pushrods.

CAUTION: Use Edelbrock Performer-Link Timing Chain and Gear Set #7801. Do not use late model timing chain and gear sets that are designed for emission- controlled engines. These timing sets are machined in a retarded position and are not recommended for this camshaft installation. Edelbrock Timing Sets feature three keyways for specified timing selection. Use “0” position for most applications.

Do not use dual valve springs. Use recommended valve springs with closed pressure of 120-130 lbs., open pressure of 320-340 lbs, and max lift of .500". Use stock ratio rockers only.

 

Comp Cams says not to use 1.6 rockers with their Xtreme Energy cams, too. Yet people do it (myself included).

It's added stress on the valvetrain and I guess they get nervous that people will break/wear out something and come back demanding a refund.

Small Block Chevys (the old ones before the LS-series, anyway) use some of the lowest ratio rockers arms in the small block world @ 1.5:1. Most other manufacturers small blocks are and always have been at 1.6 or higher, as are big block Chevy rockers at 1.7:1. That's the long way around the barn to say 1.6 ratio rockers ain't all that big a problem if you want to use them. Edelbrock is saying "this is the combo as we tested, confirmed and offer it to you- if you want to try something else, you're on your own."

 

Another reason may be because going with a 1.6 artificially increases the lift of the cam. So a .480 lift cam from Lunati will actually be .530 or something with 1.6 rockers. Maybe someone can say how to to calculate the increase in lift?

 

ok, i think i get it now. I picked up a 99 vortec tahoe motor. I was gonna use
that cam, but called crane and they hooked me up with what i need.
I will use a weiand action plus intake 750 edelbrock carb (thats all I got for now) and this cam. What anyones input on the cam??


Part Number:109821Grind Number:HR-276-2S-12 IGEngine Identification: Start Yr.End Yr.MakeCylDescription1987UpCHEVROLET8GOOD IDLE, DAILY USAGE, PERFORMANCE AND FUEL EFFICIENCY, 2600-3400 CRUISE RPM, 8.75 TO 10.75 COMPRESSION RATIO ADVISED. BASIC RPM 2000-5500Engine SizeConfiguration 305-350 C.I.V Valve Setting:Intake.000Exhaust.000HOTLift:Intake @Cam325@Valve488All Lifts are based
on zero lash and theoretical rocker arm ratios. Exhaust @ Cam339@Valve509Rocker Arm Ratio1.50 Cam Timing:TAPPET@.004Lift: OpensClosesADV Duration Intake27 BTDC69 ABDC276 ° Exhaust75 BBDC29 ATDC284 °Spring Requirements: Triple Dual Outer InnerPart Number99846LoadsClosed125LBS @1.800or1 13/16 Open334LBS @1.320 Recommended RPM range with matching componentsMinimum RPM1600Maximum RPM5800Valve Float7100Cam Timing:TAPPET@.050Lift: OpensClosesMax LiftDuration Intake0 BTDC34 ABDC107214 ° Exhaust48 BBDC(6) BTDC117222 °

 

Anyone know what the Compression ratio was for the 99 chevy tahoe !!

 

The Vortec 350 motors? I beleive they were factory rated 9.1:1 or thereabouts.

 

Cool, I thought they were in the 8's.. Thanks

 

I think you guys are thinking WAY too hard. You have ALL successfully outsmarted yourselves.

The REAL reason probably is, because Edelbrock doesn't sell them.

 

Or because they likely sell a cam that dose a better job of creating the desired performance with a 1.5 rocker than that cam and 1.6 rockers.

Theres also clearance issues. Maybe they felt that 1.6 rockers cut in to the safety margin to much since factory castings can vary a lot from one to the next.