Rockers not fitting after cam?

[one_and_only2004]

Hi all, I've had my cam installed (comp cams stage 2 supercharged) this week and was advised by mace that my cam won't fit with my 1.8 rockers. My mechanic put them in (1.8 Yella Terra's) and everything turned over by hand fine, but i told him to put the stockers in - we just did that and the motor refuses to turn over due to the valves hitting the pistons!
Have you got any ideas?

 

[MACE]

one_and_only2004,

Are you 100% sure that the valves are hitting the pistons?

A few things that come to mind and that is that

The factory rocker haven't been installed incorrectly
The 1.8's may have bent something whilst being tested, or that the lifters weren't pumped up yet as it was being turned by hand. Once pumped up with the stock rockers "true" valve lift occurred
The standard rockers may not have been standard afterall,
It's dropped a valve.

I would be very surprised that it's bent a valve due to the lack of piston to valve clearance, unless the heads you purchased had a significant amount of material off the cylinder block mating surface machined (to increase the compression ratio). I say this because we've installed bigger ecotec cams before (like our comp cam stage 3 item) on standard headed cars without any problems before.

This is all I can think of at the moment as I'm a bit under the weather

Please keep us posted.

Kindest Regards,
Steve

 

[maldotcom2]

When you put the stock rockers back on did you use the stock pedestals as well?

 

[one_and_only2004]

one_and_only2004,

The factory rocker haven't been installed incorrectly
The 1.8's may have bent something whilst being tested, or that the lifters weren't pumped up yet as it was being turned by hand. Once pumped up with the stock rockers "true" valve lift occurred
The standard rockers may not have been standard afterall,
It's dropped a valve.

The motor was just turned over by hand ie breaker bar on the crankshaft. The mechanic noticed something was wrong when he was putting the standard rockers (the ones that came with the car) back in and he noticed that he couldn't get them fully screwed down. He turned the motor over and it wouldn't turn because it was hitting the valves.
Stock pedistals have been used, the only thing that wasn't swapped over was the Pushrods because one of my old ones was bent. Is there a difference in length between stock and higher ratio pushrods?

 

[chevy_big_block_bro]

Shouldn't be

I put stock length hardened push rods in with my 1.95's in the old VT

Do you know the history of the heads/motor? Are they stock rockers as Steve said?

Look for little weld pools around the pushrod seat

The cam is made to go with stock valve train so if its all stock then there's a problem. Can you measure the pushrods?
They should be 7.050" and also stamped on them if they're after market

 

[one_and_only2004]

Motor was stock when i bought it, 40,000kms on it. We measured the seat to the other one, looked at everything to see what the difference was between everything and the only difference is the valves are bigger and the ports are massive.
The rockers are definately stock - i swapped them out myself.
The mechanic was going to compare the length of the pushrods to the standard ones tonight to try and work out what's going on.

 

[MACE]

The motor was just turned over by hand ie breaker bar on the crankshaft. The mechanic noticed something was wrong when he was putting the standard rockers (the ones that came with the car) back in and he noticed that he couldn't get them fully screwed down. He turned the motor over and it wouldn't turn because it was hitting the valves.
Stock pedistals have been used, the only thing that wasn't swapped over was the Pushrods because one of my old ones was bent. Is there a difference in length between stock and higher ratio pushrods?

It would most likely be the longer pushrods pushing the valves further open. I don't know the exact different in length but there is a definitely a difference, as also indicated by how your mechanic set the rockers up. When he cranked the motor did it turn over a little and then stop, or just not turn over? Either way I think that there is a good chance the all will be fine once you revert back to the original length rods. This can be verified by doing a compression check once you get the car running again.

I've had valve kiss a piston before when the timing belt gave way when the car was idling. The second time it happened the engine was doing around 4500RPM and bent 5 of the 6 valves (yes it was a 3 cylinder screamer )

 

[chevy_big_block_bro]

Why would you put longer pushrods in? Is there a benefit. I would have thought that a longer pushrod to the extent of not letting the rocker bolt down on a bigger cam wouldn't let the valve fully close on a standard cam. Maybe i'm missing something like the action of the hydraulic lifters.

 

[one_and_only2004]

Yeah it turned over a little bit both backwards and forwards, so it's not locked up completely. I guess i'll find out how he went tomorrow. I hope it's all done, i have to head off to the gold coast tomorrow arvo!

 

[one_and_only2004]

Why would you put longer pushrods in? Is there a benefit. I would have thought that a longer pushrod to the extent of not letting the rocker bolt down on a bigger cam wouldn't let the valve fully close on a standard cam. Maybe i'm missing something like the action of the hydraulic lifters.

These pushrods came with the Yella Terra rockers in the kit, so i just put them in.