Need help finding engine vibration

[HICKL]

I recently put a new comp cam, torker II intake and roller rockers in my Z. It seems like immediately after I did this work, my car seems to have picked some vibration above say 3500 rpm. It is bad enough to make shift earlier than you want to. Before, I could wrap it out as far as I dared and never noticed this. It starts to pull really good then right before it hit's the shakes. I have been told it may be a tuning issue but not really sure where to start. Anybody got any ideas on what the cause of this may be?

 

thanks

Jeff

[grumpyvette]

first check the basics, adjust the valves, look for a bad ignition wire or plug, check for a bad cam lobe,check for a fouled plug, broken valve spring, do a compression test and check the timing, look for vacuum leaks ETC.

its NOT uncomon for a valve spring to brake or the valves to need careful adjustment with a new higher lift cam install.

 

ignition

 

http://www.2quicknovas.com/happytiming.html

 

http://www.centuryperformance.com/timing.asp

 

http://www.boyleworks.com/ta400/psp/distcurve.html

 

http://www.lotuselancentral.com/lec/timing.htm

 

carb

 

http://www.bob2000.com/carb.htm

 

cam degreeing

HERES several differant sources of instructions to read over

 

http://www.thedirtforum.com/degree.htm

 

http://www.hotrodder.com/kwkride/degree.html

 

http://www.454ss.com/whitess/Camshaft.htm

 

http://www.cranecams.com/?show=article&id=3

 

http://www.holley.com/HiOctn/TechServ/TechInfo/IECCTech8.html

 

compression

read this

 

http://www.xs11.com/tips/misc/misc3.shtml

 

http://www.goodvibesracing.com/leakdown%20Tester.htm

 

http://www.globaltoolsupply.com/cgi-local/SoftCart.exe/online-store/scstore/p-P1-275.html?E+scstore

 

http://www.tavia.com/cat8.html#3

 

 

 

http://www.motorcycleproject.com/motorcycle/text/leakdown.html

 

http://www.xs11.com/tips/misc/misc3.shtml

 

http://goodvibesracing.com/Leakdown%20Tester.htm

1) For most accurate results, engine should be up to operating temperture.

 

2) Remove all spark plugs.

 

3) Rotate crankshaft until piston being tested is at top dead center of compression stroke.

 

4) Screw the spark plug adaptor hose into spark plug hole making the sure the o-ring is seated properly.

 

5) Connect the spark plug adaptor hose to the coupler of the leakdown tester.

 

6) Connect leakdown tester to a good source of compressed air, preferably a filtered and water trapped source.

 

7) Adjust the regulator on the leakdown tester so the the LEFT HAND GAUGE indicates at least 10 pounds less than your sorce pressure. The leakdown percentage conversion table shown below is based on regulated pressures of 100, 90, or 75 psi.

 

8) Read the RIGHT HAND GAUGE (differential gauge), then look up gauge reading on the conversion table below to get actual leakdown percentage. After noting percentage of leakage, turn the regulator knob counter-clockwise to relieve the pressure. This reduces the shock to the gauges. If you ever get an unrealistically low pressure reading on the right hand gauge, there is a finite possibilty that something is blocking the small orfice located within the hex tube located between the regulator and the main body of the leakdown tester.

 

9)To remove any obstruction that may be lodged in the metering orfice, unscrew the hose coupling assembly from the aluminum body. Ultilizing a 1" wrench, remove the knob assembly from the regulator. Blow compressed air in the opposite direction (from the coupling end) to clear the orfice. Re-assemble the regulator and the coupling.

 

NOTE: DO NOT ATTEMPT TO REMOVE THE BRASS HEX NIPPLE BETWEEN THE REGULATOR AND THE ALUMINUM BODY. DAMAGE MAY RESULT.

 

http://www.needboost.com/part/summit_dual_gauge_leakdown_tester/

[HICKL]

thanks Grumpy, I know I am getting some blow by and sucking oil thru my pcv tube. I wouldn't be suprised if I had a plug or 2 fouled. I'll start working down your list.

[HICKL]

Plugs look ok, they have a little black on them from the aformentioned blowby I guess, but the electrodes looked pretty good. Maybe a little lean though, they all had an area that was fairly white.