Pontiac - Street No question too basic here!

          
Reply
 
Thread Tools Display Modes
  #1  
Old 11-01-2005, 03:35 PM
68blkbrd's Avatar
68blkbrd 68blkbrd is offline
Junior Member
 
Join Date: Aug 2004
Posts: 14
Smile Wiped Cam-picking a new one

Seems like I wiped a cam lobe on my Comp 292 Magnum cam.
1800 miles on rebuild before it went.
First, what should be done to the motor now? Does it hace to be completely diassembled? Can frequent oil changes work?

Looking for for a new cam preferably hydraulic.
Specs are as follows:
1968 Firebird Coupe
400 .030 over
750 Holley Vac secondary 50cc pump
Edelbrock Performer RPM Manifold
Headers with 2 1/2 exhaust Flowmasters
Nodular Crank .010 under
HEI with MSD 6AL
Factory reconditioned/resized rods
#13 heads milled .010 - 2.11/1.77 Stainless Valves
Dual Valvesprings
Speed Pro Forged Pistons .030 over
Muncie M-20 4 speed
3:23 BOP rear with Powertrax Locking Differential
255/60/15 rear tires

My goals are hot street driven. Weekend driver with gobs of power and torque
Idle quality/ vacuum is not an issue for me with non-power brakes, 4 speed
Thanks in advance.

__________________
1968 400 4-speed Triple Black
  #2  
Old 11-01-2005, 06:40 PM
DPlum DPlum is offline
Senior Chief
 
Join Date: Jun 2005
Location: va gainesville
Posts: 275
Default Help is on the way

Call John Partridge at Bullet cams he is the owner ask him for help John knows pontiac's

  #3  
Old 11-01-2005, 09:20 PM
Speargun's Avatar
Speargun Speargun is offline
Chief Ponti-yacker
 
Join Date: Sep 2005
Location: Silver Springs, FL
Posts: 942
Default

The Comp 292 Magnum is a good cam for that combo. I ran a setup real close to yours years ago and am building a new 400 pretty close to the same.

It's a pain in the @$$, but remove the inner valve springs during the cam break in. This way you will run less risk of wiping out the cam.

The easiest way to replace the springs with the heads on the engine is to feed nylon rope through the spark plug hole until it covers the top of the piston. This assumes that you have the piston near TDC.
This way, if the valve drops, it will only hit the rope and not cause any damage to the piston or valve.
================================================== ======
Here's what I'm building:

400 - .030
stock crank .010 .010
Scat H beam rods
Keith Black flat tops .003 in the hole

Comp Cams grind P8 292H-10 cam
Gross Lift .501 .501 (.551 with 1.65 rocker)
Duration @ .006 292 292
Duration @ .050 244 244
Centerline 106
Lobe separation 110

Heads are stock #16
.042 copper head gaskets
Hooker Super Comp headers
Holley Street Dominator intake
Edelbrock 750 carb.

Desktop Dyno puts this comba at 488hp to 531hp depending on the head flow and around 490 ft lbs.

  #4  
Old 11-01-2005, 10:13 PM
Superduty65's Avatar
Superduty65 Superduty65 is offline
Senior Member
 
Join Date: Mar 2005
Location: Southern California
Posts: 175
Default

I just went through this, in fact my motor is still at the machinist. I got into my motor and because of the cam going so quickly (about 150 miles) it ate the heck out of all the bearings. It was only one lobe even. I couldn't imagine if more than one lobe went bad what it would have looked like. I even had to have my crank turned. I was using a comp XE268H. I went to the XE284H this time and the machinist told me to run it for a whole hour at 2000-2500 rpm. This is the first time I have heard a whole hour for the break in. Thats gonna be fun. I will be using old weak springs to break it in. He told me to use compressed air through the spark plug hole at 120psi to hold the valves in while I change back to the good springs. Good luck with the change and I hope your's comes out with less damage than mine did.

__________________
Semper Fidelis
  #5  
Old 11-02-2005, 02:18 AM
6T5 Cat's Avatar
6T5 Cat 6T5 Cat is offline
Chief Ponti-yacker
 
Join Date: May 2005
Location: Bear, Delaware
Posts: 560
Default

Your machinist is correct. I always do a 1 hour break-in run on flat tappet cams. I vary the RPM to diffrent speeds every 5 minutes between 2500 and 1800. And I put fans in front of the radiator to keep plenty of fresh air flowing. I've never wiped a cam lobe in 45 years. But, just to be safe in my older age, I've switched to using all roller cams.

__________________
[SIGPIC][/SIGPIC
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 05:20 AM.

 

About Us

The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.

 




Copyright © 2017