Ok, i ususally shift at 5000 plus/minus 100rpm. I was installing my LT1 intake the other day and realized I had 3 bent pushrods. Not really bent like an "s" but definately bent. I have comp cams hardened pushrods. The ones that are 38 bucks a set. My springs are not in bind b/c the cam lift is well below their ratings. Could nitrous cause more pressure on the valve and cause this? I am kind of lost b/c IMO 5000 rpm isn't excessive. Thanks

 

$38 for comp? or do you mean crane?

I know crane has a cheap set, and they're just that, *CHEAP*

 

Pushrods just dont bend themselves. Something somewhere is hitting something else. Either a valve is contacting the piston (highly unlikely) or the retainer is hitting the guide (likely) or you have a bunch of loose rockers and the pushrods are getting the crap beat out of them. Ive heard of them getting bent from valvetrain misalignment, but thats not very likely IMO.

 

What springs are you running...

If you're running a set that came with your AFR heads like other manufactures do (WP) that are supposed to be "generic" or a kind of "Guess" at what cam you're running you probably have low lift seat pressure. If that happened to be the case there would be your answer...

What are your spring ratings?

Do you have self aligning rockers or non self aligning rockers, and do you have guide plates or no guide plates

 

I have the genero AFR springs. They are rated to .560 lift. I will look the ratings up. I have max of .486 and with hyd. lifters probably less. I have AFR heads,I believe all AFR heads for a SBC use guideplates, as do mine. I have harland sharp 1.5 rollers which are not self aligning.

 

Whos guide plates does AFR use? their own or comp or someone else? I've seen comp (in my opinion one of the best cam manufactures) make guide plates that ate a set of crane pushrods within the first few minutes of running. You're losing ALOT of lift seat pressure if thats what they're rated at and you're running .070 less approximately. With an LT1 intake and AFR's the engine is going to want to spin RPMS, you're looking at valve float. I'd begin with putting in some springs specific to your cam/lift/lifter type.

Then from there look at your guide plates (make sure they're smooth enough) and for any performance application you want to make sure you get hardened pushrods made by a reputable manufacture, and that are the correct length to fit your valve train geometry. Comp has an adjustable pushrod tool for $20, when you make your next purchas on pushrods that tool will help you get the EXACT length pushrods you need. 5 minutes spent on geometery can be worth 10s of thousands of miles in engine life.

 

I bought comp cams part number 7808-16. These are heat treated and cost 38 bucks. I see what you are saying about too much valvespring. Also, I looked at my valvetrain geometry and it looked correct. Thanks for the help

 

OK, my springs are. 1.437 OD 120# @1.800 310# @1.250 rate 345 max lift .550 I really don't know what this means. Do these springs seem terrible for my cam?

 

We need to know your assembled height to figure it out, also the "Pound per inch" of the spring.

If your assembled height is 1.800 (probably somewhere in the 1.700-1.800 range?) then you can do the following math:

1.800 - .480(your lift) = 1.320 (compressed spring height)

If your springs progressivly put more seat pressure on the head, and you have 310# @ 1.250, obviously you have less than that at 1.320, less pressure means more prone to valve float. My springs were super progressive, they were super light on the seat and very heavy at lift, so we need to know your spring "rate".

But at least this should help you see why it may seem that your extra lift spring (max .550) would be "to much" but is actually weaker at your lower lift cam than what it should be "over the nose" of the cam lobe.


On a side note, I hope you're finally satisfied with "technical content"

 

He gave you the spring rate. That can be determined with open and closed pressures along with heights anyway.

Doesnt sound like springs are the problem to me. That doesnt mean though that the retainers arent contacting something. If you have a micrometer, you can take a spring off, put the retainer and locks on, measure the distance from a point to the top or bottom of the retainer with the valve closed and with the valve as far open as it'll go with the seal and retainer in place. That'll be the max lift the valvetrain can handle aside of the spring. Ideally you want another .060 for clearance from the seal, but thats not gonna bend a pushrod, its gonna destroy the seal... which makes me think of an idea. Hows the valve seals doing?

I dunno why there would be a problem with AFR heads and that little lift, doesnt make sense. Used these pushrods on anything else besides these heads and cam setup?

 

I'm not trying to push anything here...

but that still seems increadibly cheap for a set of "hardened" pushrods?

Did you try to scrape them with a knife or something sharp? If they scrape or mark at all they're not hardened.

 

He didn't give it to me "Per inch"

I'm lazy