My friends 327 just had some major problems. First his cam had a lobe ground off and the lifter was messed up. Now there are a few valve springs that have broken. The internal spring part. How can this happen? Too much lift or what? It's a 69 camaro but I can't find any other message board that I trust more with technical advice.

------------------
, Jon (91 RS too many mods to list)

[This message has been edited by JPrevost (edited November 30, 2000).]

 

What cam? What kind of springs did he use. The best thing to do now is to get a complete Comp Cam kit. It will have the cam,lifter,springs,locks and retainers. That way he will have a good "matched" setup next time.
Can you get more specs on the motor?

------------------
350 4 bolt main, Speed-O-Motive 383 stroker kit, re-sized rods ground for clearance,Hypereutectic pistons,9.8:1 compression,HPC Coated RPM intake, Speed Demon 750 cfm carb,World Products Sportsman II heads,2.02/1.60 valves, K-Motion springs, Comp Cam 1.6 roller rockers, Lunati adv.292/230@.050 with .512 lift,Crane pushrods,Proform HEI and MSD6A box,HPC coated 1 5/8 headers, 2.5" exhaust with 40 series mufflers,TH350 with B&M 3000 stall, Powertrax NoSlip Locker, 4.11 gears.

 

This sounds to me like stock springs with a total valve lift over .500"...

What cam? what rockers? and what springs?

This is a textbook descritption of what happens when somebody tries to economize too much on a cam swap while going overboard on the cam.

------------------
"So many Mustangs, so little time..."

 

He didn't go overboard with the cam, the lift is like .510 and I don't have the exact specs on the cam but let's just say it put the car into a 13.1 ET. So I bet it was just the valve springs being over rated. They're dart iron eagle heads. I don't know but anyways, you guys just think that the cam was too big for the springs? I was thinking it might have been something else like the fact that it's not roller or maybe the spring to rocker gap being too big or too tight.

------------------
, Jon (91 RS too many mods to list)

 

What springs?

Any 1.25" (stock diameter) valve springs WILL NOT survive for long with that much lift. If that's what they are, then he needs to upgrade. I would suggest Comp 986s and the retainers to match. Unfortunately this requires machine work: the spring pockets in the heads won't accomodate the larger diameter springs. They will have to be machined.

Basically, .510 lift with stock springs is in fact a major overboard experience. It may not seem like it but it really is. Also, consider that for a 327 to run 13.1 in a 3200 lb 1st gen, he's probably shifting at 6600-6800 RPM, which further aggravates the problems. The RPM contribution comes from teh fact that every time you bend a piece of wire, heat is generated; at those RPMs, those "pulses" of heat can't escape from the spring, so it heats up and fatigues. I've seen valve springs come out of engines before (usually after some have failed) that had literally turned blue from the heat.

Bottom line: the cam is too big for the springs.

------------------
"So many Mustangs, so little time..."

 

Actually the springs where rated for that lift. We found out that it was the rollers that are the problem. They're crane roller tips but float at higher rpm. So the roller tips were floating off the valve stem and just hitting the edge of the locks. So now he's going to use some stock rockers for a while and not race. He's going to be getting some true roller rockers and we'll be doing that in a couple weeks.

------------------
, Jon (91 RS too many mods to list)