17 replies to this topic

[SMITHY2]

I've just brought a stage 3head and a set of 1.5 roller tip rockers,
also a spacer kit to fit instead of the old springs.However once all
fitted the engine wont turn over,the spacers were moving when all tightened down,
i've even tried using springs off my old rockers still locked solid.But when i use my old rockers
all fine ,has anyone any ideas thanks.

[Ethel]

springs binding? nuts on rocker posts? valve hitting pistons?

[Rosslin Racing]

when you say a spacer kit what do you mean?
if you have had the block or head skimmed you should use spacers of the same thickness to lift the rockergear up to its original height.
you should also do a dry run, put some putty on the pistons and try turning the engine over by hand, to see how much clearance you have between valve and piston. it sounds as if the piston and valves are in contact. you have also checked the valve clearance I hope.

[SMITHY2]

springs binding? nuts on rocker posts? valve hitting pistons?

The instructions that came with the spacers said they should spin freely
which they did,what would cause valves to hit piston,no probs with old rockers
turn over as normal.

[SMITHY2]

when you say a spacer kit what do you mean?
if you have had the block or head skimmed you should use spacers of the same thickness to lift the rockergear up to its original height.
you should also do a dry run, put some putty on the pistons and try turning the engine over by hand, to see how much clearance you have between valve and piston. it sounds as if the piston and valves are in contact. you have also checked the valve clearance I hope.

What i've done is bought a stage 3 head for my 1275 with roller tip rockers but the spacers are for the rocker shaft between rockers,
as they have to be made up yourself.Cant set valve clearance with these on as it wont turn over but all is fine with old rocker shaft on.

[Ethel]

Because 1.5 gives you more lift than standard rockers

[Shifty]

What R racing means is, have you slackend off the adjusters on your new rockers? If the adjusters are wound out then this can/will give problems

[SMITHY2]

Because 1.5 gives you more lift than standard rockers

So what should i be doing any help would be gratefull.

[SMITHY2]

What R racing means is, have you slackend off the adjusters on your new rockers? If the adjusters are wound out then this can/will give problems

Will give that a try thanks.

[Rosslin Racing]

the spacers I was taking about go under the rockershaft or pedastal.

Edited by Rosslin Racing, 23 March 2008 - 05:01 PM.

[Ethel]

It shouldn't need spacers under the pedestals unless it's been skimmed lots. You should be able to see if it's anything other than valve 'n piston contact by just looking and if it was hitting a piston the engine would be near TDC or BDC so look at your timing marks. Could just need the adjusters winding back - you should have a least one valve showing a tappet gap if they aren't too close.

[dklawson]

Spacers and pedestal height shims... two different issues.

Do not try turning the motor over again on the starter until you've adjusted the valves.

It doesn't matter that the old rockers worked fine. Because the 1.5 arms give the valves more travel, the valves will now move down further into/through the combustion chamber. As suggested by others above, back the valve adjusters out... almost all the way out to the point that the pushrods are barely held. Use a gentle method (pull the spark plugs and jack up one wheel and turn it while the car is in gear, put the car in neutral and pull on the fan belt, etc.) to turn the engine over by hand as you set the clearance on the valves. Remember that with roller rockers it's very easy to set the valves too tight by sliding the feeler gauge in from the front. Slide the feeler gauges in from the side instead.

Once you've adjusted the valves you can try and start the engine. Hopefully you have not done any damage to the valves at this point.

As for the pedestal shims, I have acquaintances that feel the stock rocker shaft height doesn't give good geometry even before the head is shaved. I think they routinely fit 1mm shims to put the geometry where they like it. Again, this is a separate topic... it has nothing to do with the problem presented in this thread.

[Rosslin Racing]

as we dont know what he has done with his head or the block it is more than likely the valve clearance

[SMITHY2]

as we dont know what he has done with his head or the block it is more than likely the valve clearance

Valve clearance was the problem thanks for all your advice.

[dklawson]

Nothing bent I hope. Is the engine running OK ?