Does the vortec heads use a different length push rod than the stock 78 corvette head? I installed the heads with the original 78 push rods. The car cranked ran at idle for about 3 seconds and knocked. I shut it down immediately. It sounded bad. I pulled the valve cover off and every push rod was bent badly. I know I won't sleep at all tonight. I hope the valves didn't hit the top of the pistons.
Please Help.

Thanks

 

If your pushrods are bent, in all probability the valves DID hit the pistons! Pulling the heads would be wise.

 

Are you using the self aligning rockers? I think this is a must with Vortec heads.


[Modified by ORVette, 6:49 PM 4/27/2002]

 

I went through the same thing with mine when i put them on. I went through two cams and three sets of pushrods/hardened. I had the self-align rockers screw in studds and guide plates also. I swapped in new z28 springs and i thought maybe they were coil binding, i checked they werent. Turns out the dampner in the valvesprings were, pizzed me off. Took them out and no problems since.

 

John,
It's good to hear from someone who had the same problem. I was running the same cam with the original heads. The cam has 495 lift. I had installed the z-28 springs on the old heads when I installed the cam. The vortec heads I bought used. I sent to the machine shop to have them reworked. I told them that I had a cam with 495 lift. He said the springs he installed were good to .500 lift. But, with my old heads and Z-28 springs I didn't have dampners and no problems. With the new heads he installed dampners. I woundered if this would be a problem but I trusted his judgement. He said they could be used to .500 lift.

When this happened to you did you pull the heads again? I'm woundering if I should pull the heads or just pressurize the cylinders and remove the dampners. Your help is greatly appreciated.

Thanks,

 

John,
Did your Z-28 springs come with dampners? I don't remember mine coming with dampners.

Thanks again,
Kerry

 

corvette4life- Sorry to hear what happened. The Vortec are awesome heads at a great price. What intake manifold are you using? I know the Vortec heads require a different manifold due to the angle the manifold bolt go into the head.
Dan

 

Kerry,
I rebuilt the motor and put these heads on from the start.
First setup was factory vortecs with new z28 style springs,they did come with a dampner. I also used the self-align rockers. I went to break the cam in and after i got done it wouldnt idle anymore. Pulled the covers to check the rockers,maybe needed to reset the lifters. About four of them were off the pushrods and the rest were loose. I pulled the heads off to make sure the pistons were ok. Got them off pistone were fine. Heads werent. Pulled a few studds out of the head. Took the heads in screw in studds. Put a knew cam in again. Put the heads back on added hardened pushrods and guide plates had roller rockers i wanted to put on but the heads werent milled enough for them to work. Put everything back to gether. Start it again. Same god damn thing. This time i double checked the coil bind and there was enough clearence. Ripped everything apart again. This time i noticed the dampners in the springs were a little shiny. Turns out the dampner was coil binding therefore bending crap. I took the valvesprings in and had them checked if they would work without the dampner and it checked out ok. Put a new cam in again, new pushrods, and i had to do a little work on the valve stems. They got a little buggered up. I have since then had no problems, thank god. I am using the XE268 and the springs are for up to a 490 lift.

 

don't forget to use rocker arms with a long slot.

 

John,
Thanks. You were right on the money. My pushrods were not hardened so they bent fairly easily I guess. All were bent after only about four seconds of running. Some cracked, one busted in four pieces. This is the bad part. I pulled the intake and only two of the four pieces were in the lifter valley. So, I pulled the oil pan. I found another piece but the length still didn't add up to the lenght of the others. We looked forever. I was ready to give up when my friend spotted it. The remaining piece had gotten jammed in the bottom of the piston. On the side skirt right below the wristpin. It was hanging down and had not even touched the cylinder wall. i touched it was a screw driver and it fell out. It left a tiny circular mark on the side skirt base just below the wrist pin.

Fortunately I shut it down as soon as I heard the knock and it was only idling at 700 R.P.M.s . I'm livid at the machine shop for doing this to me. I specified three times that I had .495 lift. They assured me that the springs were right.

After finding all the pieces and cleaning everything i reinstalled the oil pump, and oil pan. Changed the oil and filter. Then I went up top. I didn't remove the heads. I pressurized the cylinders and swapped the valve springs with the valve springs I was running on the original heads. They only had about 3,000 miles on them. They are the orange Z-28 springs. They do have dampners also. keep in mind I didn't change the cam. I had been running this cam with the old heads that is when I installed the Z-28 springs that were on the old heads. I put these springs on the new heads. reassembled everything and it runs great.

I noticed that the dampners that the machine shop had installed were binding like the ones you described. These dampners did not sit down on the spring seat. They sat up on the boss. The Z-28 dampners that were with my Z-28 springs that I installed sat all the way down on the spring seat just like the spring. With the spring removed you can see some of the dampner coils are still overlaping.

I'm going to take them to the machine shop tomorrow with the bent and broken push rods. I drove the car about 100 miles the afternoon and no problems.


Thanks for all your help.
Kerry

 

It looks you had it worse or as bad i i did. My rods didnt break though. A couple or them cracked where they bent. But yah all of mine bent like crazy. I had to bend a couple of them to get them out.
Keep a close eye on your cam. I would almost take it out and take a very close look at it. Excpecailly if it is warrantied. No sense in taking chances. Hope everything works out.