Gain extra benefits by becoming a Supporting Member Click here find out how!
Classic Performance Products Classic Parts
Ciadella InteriorsAmerican Auto Wire Classic Industries
Chevs of the 40sDanchuk Catalog
Hellwig Products IncPerformance Rod & CustomEcklers AutoMotive
Octane Lighting
Impala Bob's Bob's Chevy Trucks Bob's Chevelle Parts Bob's Classic Chevy

Username Post: Valve tap, cam and lifter question.        (Topic#342426)
Green74 
Forum Newbie
Posts: 3

Age: 26
Loc: Ga
Reg: 09-29-16
02-04-17 11:47 AM - Post#2675123    

1974 Chevrolet Chevelle 5.7 350 2bbl bone stock. Head rebuild about a couple years ago, but still stock. Noticed a slight tap a couple days ago and it turned out to be a loose rocker arm for some reason (could just be a defective valve lash nut) on #4 cylinder intake valve, I also noticed that the exhaust valve next to it was barley even opening. I then adjusted both the intake and exhaust valve lash to correct adjustment and the tap on the intake valve went away, still... barley any lift on the exhaust valve, almost no lift at all. If correct, I may have a bad lifter or cam. From my understanding, if one is bad then the other is as well? Engine runs ok but backfires through carb when I rev the engine, which also contributes to my theory.. the simple valve adjustment was enough to improve preformance but engine should be running better. If i do need a new cam, which I'm probably sure I do. What do you recomend I do if I want to increase performance while keeping the heads stock? I don't have a ton of money and I'd like to be able to put this sucker back on the road asap. I do have plans to upgrade intake, carb, and also heads but not in the near future. My understanding in valve function isn't very broad so I need a bit of help.. Where do I go from here?

Hold my beer. Watch this...


 
Shepherd 
Contributor
Posts: 714

Loc: Lake George, NY
Reg: 11-11-15
02-04-17 11:54 AM - Post#2675124    
    In response to Green74

If you lost a cam lobe, your more pressing issue the metal floating around in the oil, as the filter did no trap all of it. Before you change any parts, pull the pan and look at the bearings and crank.



 
bobb 
Super Senior Member
Posts: 5296
bobb
Loc: paradise
Reg: 09-05-03
02-04-17 07:05 PM - Post#2675207    
    In response to Green74

i would run it and tighten the adjuster on that ex valve when running to see if there is a difference. if there is no change i would be thinking the cam lobe rounded off. stick a big rare earth magnet on the oil pan to help with the oil contamination.

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 16953
grumpyvette
Age: 69
Loc: FLORIDA USA
Reg: 03-16-01
02-09-17 06:59 AM - Post#2675930    
    In response to bobb

reading the links should help


http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


 
Green74 
Forum Newbie
Posts: 3

Age: 26
Loc: Ga
Reg: 09-29-16
03-06-17 08:40 PM - Post#2680111    
    In response to grumpyvette

I overlooked the importance of making sure the engine was free of contaminate.. probably the reason the cam lobe wore off in the first place,maybe not but I do remember back when I sent the heads to get rebuilt a couple years ago, I was not very concerned about cleanliness as I should have been when putting them back on. It's making sense. I would definitely not like to get it right on anything else than my first try. My understanding now is that if I go ahead and swap the cam without really taking the engine apart and making sure it's free of contaminate I'll run into problems again sometime sooner than later. I'm rethinking the strategy.. rebuilding the engine seems like the proper way to go at this point. This is he closest thing I have to a mentor, I appreciate the feedback. It's given me more perspective, thank you. I'll be back...

Hold my beer. Watch this...


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 16953
grumpyvette
Age: 69
Loc: FLORIDA USA
Reg: 03-16-01
03-07-17 08:47 AM - Post#2680177    
    In response to Green74

if you have questions don,t hesitate to post them, here or on my home info website, and read all the links and sub-links it should help reduce any further issues

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


 
Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

878 Views