working your head.

[TurboMirage]

i need to get my 1.5 head into the shop.

how can i determine if valves are bent? i "see" 6 bent ones. what about the rest, if they are thousandths off can the machine shop tell?

what kinda machining has to be done exactly to have new valves seat correctly? do the valves have to be machined themselves, or just the valve seats?

changes of turbo'ing my 4g are very good if i dont move outta my parents house, but that may happen soon.


all i've got so far is a new headgasket, and valve seals. there is 155k on the head. ive got until monday to come up with a gameplan, because that is when i want it out.

parts-
each new valve from the dealer is 18/each.

 

[Loco Honkey]

I check the valves ghetto style. I have very good eyes and can spot a hundredth runout on something... I simply roll the valve slowly across a known flat surface and watch VERY carefully.

Most valves come with precut faces. The seats, if new, will need to be cut, as well. If you have a good valve cutter, and a decent set of stones for the seats, no lapping is nessicary. I don't like lapping anyway, because even if you clean it out good, microscopic particles of the lapping compound are still there, and will continue to "lap" the valve as the engine runs. Remember to use Japanese Ink when checking the valve margin.

 

[TurboMirage]

ok, english Ji....

 

[phunky.buddha]

Made complete sense to me...

 

[TurboMirage]

ok, this is my first ever head job. ive never opened up a motor before by myself, let alone with anyone.

to me this sounds like i can just pull off the valve seats and install new ones. you think i have a valve cutter?

lapping compound? what?

see my point?

 

[Airjockie]

Just replace all the valves...give the head to the machine shop and give them their fee for the work....

if one is bent, then the others are too...since you say you can see that 6 are bent...just better plan on all new valves. when the shop does the work...they may find that the valve guides got a little magled...so they may have to replace the valve guide as well...and thats more money. If you have not done any porting or polishing on that head...then just go to a junk yard and pull a head for $50 and run that in the car...only do the machine shop work if that head is super important to you or already worked...new valves and guides, and seals is a good thing...but always remember...if you tighten up the top...then do the bottom at the same time...IE...rings, pistons, bearings....I lost $700 on an engine because I did the same thing...I had to do something with the head on my old 280ZX, and I got the timing off...and mashed all the valves. That $700 went to a machine shop to do the same work...then after it was put back together...the bottom end blew from the new pressures the valves gave the engine.....it wont happen all the time like that...but it also happened on my old 82 chevy van...I did the heads...and the rings blew about 3 months later.....

 

[TurboMirage]

oh yes the bottom end will definately be rebuilt. i've gone full out on the rest of the car no need to skimp on half the motor.

the head has already been ported to the size of the intake and exhaust manifold gasket, which i must say was a decent amount of material.

we'll see, monday i will get some prices. i can assemble the head way easy myself. i dont really see a need for the shop to do that.

 

[Loco Honkey]

Originally posted by TurboMirage@Nov 6 2004, 03:21 PM
ok, this is my first ever head job. ive never opened up a motor before by myself, let alone with anyone.

to me this sounds like i can just pull off the valve seats and install new ones. you think i have a valve cutter?

lapping compound? what?

see my point?

[post=413101]Quoted post[/post]​

You ask me how to do it. I tell you. If you don't understand the terms, go buy some ASE text books available through B&N, Amazon, or your local community college/ vocational center. If you want to half ass this like everything else on the car, just put new valves in and call it a day.

 

[TurboMirage]

if i put new valves in, i would still probably have no compression.

i just want to really know what to tell the shop to do, and i can reassemble it myself.

and of course Ji, thanks for your advice/critisism as always.

 

[Loco Honkey]

Tell the shop what's wrong, and let them decide what to do. Are you a machinist? Let the machinists do the machining.

 

[TurboMirage]

thats a good idea, exactly what i was going to do...

12 new valves + 12 new valve seals + 1 head.

so what exactly do i want done?