Head rebuild

[Drfixit]

My L18 I believe has a bad valve. What should I expect to pay to have the head re-done and what do I need to be sure is included. Can I get new rockers and springs? I know they should be sure the head is flat do a valve job, knurl the valve stem seal opening(Does that sound right?) Performance isnt an issue just reliability. I think A87 is on the head should I look for a completely different head or is it an ok one?

Thanks
Doc

[athoose]

Might be cheaper to get a used one.

[zed]

You can do most of the work yourself - makes it much cheaper. All you need is a valve spring compressor, valve grinding stick and paste. If the head is not warped, maybe all you need pay for is the new valve seat. New rockers, springs are expensive - I would only replace if they are badly worn. New valves are quite cheap - I lap mine in myself. Check valve stem to guide clearance. Honsowetz says not to knurl guides.

[Drfixit]

Originally Posted by zed

You can do most of the work yourself - makes it much cheaper. All you need is a valve spring compressor, valve grinding stick and paste. If the head is not warped, maybe all you need pay for is the new valve seat. New rockers, springs are expensive - I would only replace if they are badly worn. New valves are quite cheap - I lap mine in myself. Check valve stem to guide clearance. Honsowetz says not to knurl guides.

ok assuming the head is flat I am perfectly capable of taking the valve train apart but doing a valve job yourself? Doesnt that require aspecial fixture or something to kepp the anngle one the vlaves right? Now I have hand lapped valves AFTER the machine shop did the valve job.

As for a used head, again assuming the head is not warped I would like to simply improve on what I have. If I rebuild this head I know what I have.

Keep the info coming please

Doc

[banzai510(hainz)]

a basic regrind shouldnt be to much, 150$

rockers should be put on same lobe where they came from. fi good dont worry about them. have new stem and groind the seats and maybe new guides if worn. When new guides and valve seat installed best to find a shop that knows aluminum as I have seen in Car magazines where the shop didnt heat the head correctly and install the seats and the seat will come out later due to the head shrinking and not being fully instlled correctly.(this can happen to any head rebuilder but just to let you know. All my head have been OK so far as for wear. Most older heaead maybe the seat are sunk in.

make sure that the valves stems are pretty close to the correct height so all the lash pads look even or minor adjustment. mean in on eseat is suck 20thou and the other is perfect. Hopefully the machinist make them all even!!!!

[DanielC]

There are a few issues with a L-series motor. the rockers and cam have to stay together, and you have to keep the rockers in their original position. the valve stem height has to stay very close to the stock position, or it will screw up the geometry of the valve train, and may possibly use up all the adjustment of the valve clearance. Usually, when a shop does a valve job, the valves end up sunk farther into the head. On many engines this can be compensated for, but not so much on the L motor.
Do not get the valve guides knurled They will wear out quickly, and need to be replaced again, soon.

[hang_510]

Originally Posted by athoose

Might be cheaper to get a used one.

not unless it was already done, correctly!

you may have to do the same thing to it once its on the bench...


i spent ~$400 on mine w/new seats for larger valves, guides, surfaced not shaved, 3 small crack repairs...

[HRH]

Standard head rebuild around here is $300 if you bring it to them.

[Drfixit]

Originally Posted by HRH

Standard head rebuild around here is $300 if you bring it to them.

Ok thanks for allthe geat info.I think I amgona start with pulling the head and see what we have.

Mark

[datzenmike]

Originally Posted by Drfixit

My L18 I believe has a bad valve. What should I expect to pay to have the head re-done and what do I need to be sure is included. Can I get new rockers and springs? I know they should be sure the head is flat do a valve job, knurl the valve stem seal opening(Does that sound right?) Performance isnt an issue just reliability. I think A87 is on the head should I look for a completely different head or is it an ok one?

Thanks
Doc

Pop the head. Gaskets are < $25. Pull all valves and inspect them. Keep the valve, valve spring, rocker, keepers etc from each valve position in a labeled zip loc baggy. Probably a lap will fix it up. One new valve is cheap, lap it in put back on with new oil seals... done. Cost:

Gasket.................. $25
Intake valve .......... $19
Exhaust valve......... $12
Lapping compound... $10
Valve seals............. $25? $3 each? I don't know.
Total....................<$100 even less if valve(s) not needed.

Time well spent with your Datsun....... priceless!