Did Something Dumb When Torquing Down Rb30 Head

[dorifticon]

Yes, was distracted, missed a key step, hope I haven't junked the motor.

rb30 is an interference motor.

Was torqueing down head, had the no.1 cylinder set to TDC, forgot to clock the cam pin to the top.

Instead of the pin sitting at 12 o'clock, was sitting at roughly 3 oclock.

3 oclock puts the valve on the piston.

was able to rotate the cam backwards to 12 oclock but there didn't seem to be much movement past where it was sitting originally in the clockwise direction.

because the piston was at TDC, the valve wouldn't have pushed it down.

how likely is it that I've bent a valve?

[jiffo]

They bend easy as.

Workshop manual writers should be shot for this ridiculous TDC hang-up they all seem to have.

Keep pistons down bores should be on page one.

[Shoota_77]

Yeah they don't take much to bend. Put the belt on (timed correctly obviously) and turn the motor over. Check to see if the valve is fully seating once it comes off the cam and is closing (watch the spring to see how smoothly it closes the valve). If it either grabs then releases or just doesn't seat at all them I'mm sorry to say but get that head off again!

[dorifticon]

Yeah they don't take much to bend. Put the belt on (timed correctly obviously) and turn the motor over. Check to see if the valve is fully seating once it comes off the cam and is closing (watch the spring to see how smoothly it closes the valve). If it either grabs then releases or just doesn't seat at all them I'mm sorry to say but get that head off again!

Is it possible to see whether the valve is seating with the rocker cover off (but the head still bolted down)?

[89CAL]

If you have literally just bolted the head down, why not take it back off and look

[dorifticon]

If you have literally just bolted the head down, why not take it back off and look

Well, didn't want to throw away a set of stretch bolts if there was some way of telling if it was ok without removing the head, but it may come to that...

[niZmO_Man]

I think the bolts were like $30-40 when I got them years ago. Surely it isn't that expensive to sacrifice?

[Shoota_77]

Is it possible to see whether the valve is seating with the rocker cover off (but the head still bolted down)?

Pretty much. You'll be able to see the valves through the ports but mainly you will be able to see the difference in height of the valve tip/spring when the compared to those next to it. If it's stuck open it will be sitting lower than the other valves when they're closed. If it's hard to turn over when the lifter starts to climb the lobe (on the problem cylinder) then the valve could be bent but straight enough to close but then grabbing in the guide when it tries to open.

[Ben C34]

Depending on what you have available pressurising the cylinder through the spark plug hole will show up a bent valve easily. As would a comp test

[dorifticon]

Depending on what you have available pressurising the cylinder through the spark plug hole will show up a bent valve easily. As would a comp test

yep, going to try to get a hold of a leakdown tester this weekend.

Ordinarily would not care about $46 for a set of bolts, but they won't be delivered by this weekend and I need the car running ASAP, was hoping to get it installed back in the car over the long weekend. If I can get a leakdown test done on Sunday I'll either be able to go ahead with installation, or buy bolts and valves as required on Tuesday...

Thanks for all the responses!

[dorifticon]

UPDATE: as I suspected I bent one of the valves, it's only on 5 now.

There's a reasonably priced reco head on Ebay, but it's for a VL Commodore rb30e, not a skyline.

I heard they had different cams - will this be a problem? Also will it bolt up and run okay with the r31?

[Shoota_77]

Just swap your cams into the new head if you're worried they'll be different (I don't imagine they'll be different enough to be a problem). They're hydraulic lifters so you don't need to worry about clearances or anything, just whack them in and off you go.

[dorifticon]

What about the distributor gears etc, will the rb30E skyline distributor mate up to the VL commodore head?

[Shoota_77]

The head will be structurally identical. If you're swapping over the cam then the dizzy drive is on there so will match up perfectly.