dist0rtion_69

I posted here a few weeks ago about a bent pushrod and broken rocker arm. I replaced the rocker arm/pushrod with the same thing that was on the car. The car is never shifted over 6200, and I've never missed a gear. The car runs the comp cams 274 extreme energy cam with around .48x lift. I'm running protopline vortech heads. The problem is I kept bending pushrods. I've never missed a shift, so I'm not sure exactly why it is happening. I know the timing was off for a week or so while I was driving it, and I set it back pretty spot on. Anyways.. So after getting fed up with the sluggishness of the car, I pulled all the pushrods out and they were all bent a TINY bit. After putting 10 of them in, the car felt like it gained about 75hp. It literally was just breakin my street tires loose in 3rd gear hard with the mcleod twin disk. It felt like it actually had the 350-375rwhp it was supposed to.
Anyways, so I decided this has got to stop. I took a trip up to Barnetts (a local performance shop) and got hardened pushrods of the same length. I put them in and drove it around for a few. The car felt great. However, it started to develop a slight miss. I saw a mustang and beat him with the miss, but afterwords it started missing completely. I pulled it home and the pushrod was sitting in a good inch or two, and wasn't bent. I can only guess that a lifter collapsed. So for now the car sits, til I can get a new lifter kit. However, my problem is... what caused the failure? Am I having some sort of problem that bends the pushrods.. now that the pushrods are hardened, I'm passing it on to the lifters? Are they too long are they too short? The rocker arm might have needed a little more tightening, as I heard a tapping start to develop after driving it 20 minutes or so. Are my pushrods a little too long? I'm not 100% sure what caused it.

Here is my car info:

1984 camaro z28
t-56 6 speed, mcleod clutch
350 - 40 over
forged pistons/rods
protopline vortech heads - 2.02 valve 1.60 valves, double springs
comp cams 274 cam and lifter kit
crane cams 95636-16 pushrods 7.x"? I forget exact size.. possibly 7.6"?, if somebody needs to know it to answer my question I will measure..
Melling stock replacement rockerarms.. (i have 1.6's rollers in the mail)

Considering I only rev to 6200 MAX, I can't imagine that I'm killing these parts from over-revving?

Any help is greatly appreciated, as I have to get this thing back together by Sunday for the GAFBA shootout that only comes once a year.

jzajac1

Find out what the seat pressure is on those valve springs. You do not need double springs for the cam you are using. If you're open pressure is over 350 LBS, and I suspect it is, that is probably too much for you're pushrods. Sounds like you may have used the stock lifters also. Did you install new lifters with the cam? Also, were the heads milled down any? That would call for a slightly shorter pushrod depending on how much milling was done. And do not over lash the rocker arms just cause you hear some noise. If they were properly lashed, something else is causing you're noise.....

dist0rtion_69

The inside spring is actually a damper. My bad. I asked the owner about the springs, they are good to around .500 lift. I'm using a .48x lift cam. The lifters are the same one that came in the cam and lifter kit. I will test what length of pushrod I need tomorrow.. Is there anyway to tell if they are too long without having to get a comp cams tool? Thanks

jzajac1

If you are using non-roller lifters, the correct pushrod length is 7.724". If your pushrod lenght is correct, the rocker arm and valve stem will be at a 90 degree angle when the valve is at 1/3 of its maximum lift.

dist0rtion_69

*gasp* holy crap I'm running 7.8".. No wonder! The lifters are hydraulic, but not roller lifters. Vortech heads aren't shaved any.. So it is 7.724? Thats a freakin big difference.. No wonder the lifter lasted like 10 minutes. The part# is Crane Cams 95636-16. The part is on Jegs


270-95636-16 7.800'' Standard, 16/pkg $150.99

So what is this actually standard for?

jzajac1

I couldn't find that pushrod # in the Jeg's book or the Crane website. The closet I found in the small block series 636 number was 8.062" long. The pushrods I gave you is GM p/n 12495491 from the gm performance catalogue. They are hardened and will work for your application.

grygst76

you need to go with standard/stock pushrods and run guideplates as well...are those vortech heads? If I remember correctly there is no pushrod "holes" so it's possible they are just slopping around inside the chamber, Unless you are running self aligning rocker arms could be your problem right there

dist0rtion_69

I have guide plates, and 3/8" studs. Taking these pushrods back today and going to get some shorter ones.. Thanks!

dist0rtion_69

Update:

The pushrods we needed were much shorter, and the long ones I used caused some serious damage. I only drove with them 15 miles, but I collapsed a lifter. I put it back together with a new lifter. Then like 7 of em started raising hell and the car developed a serious miss. So we pulled all the lifters and they were caved in the bottom. Then we realized holy crap, we bet it trashed the cam. Sure enough 2 lobes of the cam were seriously ground from the lifters, which were caved in. So we took this opportunity to put some k-motion 750 valvesprings, a 240/246 cam, and some new xtreme energy lifters. The car runs smooth as anything now And the 240/246 has some real mad topend compared to the 230/236!

Thanks for you guys helps.