Piston clearance problem. need help!

[WingZr0]

I just droped Ruby, my 1977 280Z, off at a mechanic who specialize in Z cars here in town for a dianostic.

Well the problem is Ruby has been running kind of truck'ish lately and the Mechanic (mech) has found 5 things wrong.

1)

The engine Block is a N42 and the Head is a N47.

He said the pistions have built up carbon the tops and are now hitting the

bottom of the N47 Head.

My main and most important question is What kind of head gasket thinkness do I need to buy to get the proper clearance and were can I buy one at.

A place like Nappa Auto Supply maybe?

So to I can either get a thicker head Gasket to fix the clearance issue or buy the correct Head which I believe is a N42 or pay about $600.00 to have head work done on the N47 to make it compatible with the N42 Block.

Any help on this issue first would be appreaciated.

Well Just FYI the other 3 problems are

2

Crack in the Air Cleaner boot letting in "Unmetterd Air" ($80.00)

3

After market Fuel Pump running at 6lbs below preasure at it's maximum setting causing it to run lean on gas.

So that has to be changed ($400.00)

4

Modified Throttle Switch "turned all the way to one side and bent to cover up the othe problems".

I suppose to max out the fuel output (unqouted price)

5

Clogged #6 Fuel injector.

Mech said if the fuel pump is replaced the raise in preasure might be enough to ungled the injector.

Thyanx for any help at all as I don't won't to leave it at the Mech jus yet

~Z~

[jmortensen]

If you're going to pull the head off, why not just clean the pistons rather than switching the headgasket out? You might also consider WHY they're so covered in crap. Is it bad rings, Bad valve stem seals, something else?

[WingZr0]

If you're going to pull the head off, why not just clean the pistons rather than switching the headgasket out? You might also consider WHY they're so covered in crap. Is it bad rings, Bad valve stem seals, something else?

I'm not sure,

This is jus what the guy told me over the phone jus now.

I figure I can Save a butt load of money if I did the work

myself and bought the parts off Ebay and MSA.

When I pull the head off taday If there is a clearence issue to start with

I'll add a thicker gasket seal after cleaning off the Pistons and see

whats going on with those Rings and Valve Seals.

Mech said that 1976 1977 280Z's N42 Block came with Flat top Pistons and that

the N47 has what I believe he said are "Dished Combustrion Chambers" from 1979

and up Z's. I may be misqouting him on that though.

That and the Fuel pump and Crack in Air cleaner boot ain't helping.

I do seem to smell Burning oil once in awhile but theres no smoke

coming out the Tailpipe when driving. But there is a little white puff of smoke

on start up which I assume is normal is it not?

[WingZr0]

Goinng to pick up car now. Be Right Back :ninja:

[jmortensen]

Why do you have two threads going on the same subject? I thought my first response never made it in here, then I find this other post and here it is. You should post once in one forum only.

[WingZr0]

What? I made 2 thread post?

If you mean the SHORT THROW thread I thought we all abbandoned that one

for Hijacking the subjact.

If you mean something else Bro please let me know

~Z~

[Darrel]

definitely get it away from that mechanic. I believe the n47 block all had dished pistons. It was the f54 block from non turbo 280zx '81-83 that had flat top pistons. Obviously he is not the datsun mechanic he led you to believe.

www.carfiche.com and download the factory service manual for your '77.

Fix/replace/adjust your throttle valve switch

Get some seafoam, read the directions.

What is the fuel pressure? You can find what is stock in the factory service manual you just downloaded.

[bigoak]

What? I made 2 thread post?

If you mean the SHORT THROW thread I thought we all abbandoned that one

for Hijacking the subjact.

If you mean something else Bro please let me know

~Z~

Yes...sometimes posting is ssslllooowww....but don't hit refresh or back and then re-click the post button...it causes a double post.

[sblake01]

I concur with Darrel. Get that car away from that mechanic! If an engine had carbon build-up so bad it was hitting the bottom of the head it would run worse than 'truckish' if at all. Don't pull that head just yet. Replace the air cleaner boot, properly adjust your throttle valve switch and as far as the fuel pump goes, though I don't like aftermarket fuel pumps, the pressure is regualted by the pressure regulator not the fuel pump itself. If it was 6 psi below where it should be I'm not sure it would run at all. Check the fuel pressure with a guage inserted between the fuel filter and the fuel rail. It should read between 36-37 psi. As Darrel said, run some Seafoam through the brake booster hose which will clean the combustion chambers as well as the tops of the pistons (instructions are on the can) and see where you are then.

[KDMatt]

Mech said that 1976 1977 280Z's N42 Block came with Flat top Pistons and that

the N47 has what I believe he said are "Dished Combustrion Chambers" from 1979

and up Z's. I may be misqouting him on that though.

Please correct me if I'm mistaken, but I was under the impression that all of the 2.8L engines in the S30 where pretty much the same, but it was the heads that changed... so I guess I'm lost as to why the N47 head would be causing problems? Maybe the valves are 'sticking' open a bit and that's what the pistons are hitting?

Darrel is right too, dished pistons until F54 block, which came with flattops... except for the turbo, which went back to dished.

Also describe what you mean by "truck-ish" in terms of what initially brought you and Ruby to the shop, maybe that's a better place to start...?

[sblake01]

I don't know about the other years but a 77-78 comes stock with a N47 head and a N42 block and dished pistons.

[WingZr0]

Thyanx all for the replies

In the mean time I did get my Rally Calender Clock working

and installed :rambo:

I'll Snap some photos in the morning once I put the center

consel plate back in and lined up right, It jus got plain to HOT outside today

I"ll go Shade Tree Mechanic this weekend and hopefully I'll get

Ruby back in Tip Shape by Lady Hunting... I mean, ahhhhhh, Cruise Night

~Z~