Valve questions?

[Derek Goodreau]

Just bought and installed these valves, told they would fit. My concern is that the intake valves petrude from the combustion chamber by a **** hair. (As you have the head face down and look straight across the head at eye level) I am far from knowledgeable when it comes to head work like this...its my first head job, but it don't seem right to me and im worried i bought either too big of intake valves or my seats are not good. please someone get back to me asap! Ive been doing this job for a few weeks taking my time and doing alittle work here and there, and i would love to wrap it up, but at the same time not destroy my engine. these are the valve specs.

Intake:
Head diameter--35mm
Stem diameter--6.55mm
Total length--109.5

Exhaust:
Head diameter--30.8mm
Stem diameter--6.52mm
Total length--109.7mm

Heres a couple pics of the old and new, i know its hard to see what i mean in these pics, i couldnt get the camera to focus when i tried to get a shot at eye level straight across the head.

 

[Chumpaumpalumpa]

Did you lap them all properly?

 

[Derek Goodreau]

Did you lap them all properly?

yes i did, ive also checked them for a good seal and they are good.

 

[Derek Goodreau]

i let water sit in each combustion chamber overnight and they didnt leak at all

 

[1990TSIAWDTALON]

Did you install oversize valves in that head??? Stock size Intake is 34mm and Exhaust is 30.5mm. That may be your problem.

 

[BogusSVO]

It is not uncommon for the valve margin to poke above the HG deck.

I commonly have to pull the intake valves when surfacing the 4g head to keep from cutting the edge.

head has most likely been cut once or twice.

 

[Derek Goodreau]

It is not uncommon for the valve margin to poke above the HG deck.

I commonly have to pull the intake valves when surfacing the 4g head to keep from cutting the edge.

head has most likely been cut once or twice.

Do you think it's ok to run?

 

[Derek Goodreau]

Did you install oversize valves in that head??? Stock size Intake is 34mm and Exhaust is 30.5mm. That may be your problem.

They are 1mm OS stem but I've read up that you can fit 1mm without any mods done

 

[BogusSVO]

The stem size is the same on the std and +1mm valves.

It is the head dia that is the difference.

I bet with you lapping the +1mm OS valves on the std seats, the lap line was running off the bottom of the valve face, on the stem side.

Now with the +1mm os valves and std seats, your valve tip height is too short and you spring installed height is too tight.

Do NOT run the head.

You have to have the seats cut for the +1mm OS valves, and to set the valve tip height.

 

[Derek Goodreau]

How much is it to have seats cut

 

[BogusSVO]

That depends on the shop and equipment they use.

 

[Derek Goodreau]

ok, what if i get a new set of std valves. could i lap them in without any issues and just go with those, my exhaust ones i have no issue with.

 

[Derek Goodreau]

just new intake

 

[BogusSVO]

You guess you have no issue on the exhaust side.

Have you check your valve tip height?
Have you checked your spring installed height?

You are just missing the whole concept of valvetrain geometry.

When you change one thing, it changes everything after it.

You have 2 choices,
1) have a valve job done so the seats fit the +1mm OS valves and specs are checked and set.

2) Get a Full set of std valves, and have the specs checked and set.

Even if new std valves are set in on the old seats, the specs need checked. Ef the head has had the seats cut in the past, the valve tip height can be too tall, so the valve will crack off the seat, giving you a miss or a 0 compression issue.

 

[Derek Goodreau]

Ok i will have the specs checked. I'm going to get the STD set and have those put in. I don't wanna go crazy i'm just trying to replace the bent stock ones due to timing, and the head has not been messed with its all stock, only thing that isn't is the cams, BC 272.

 

[Derek Goodreau]

I do understand the basic concept, im just new and still learning the whole concept

 

[BogusSVO]

Correction, you think, you assume it is stock. That it has not been messed with.

Have you owned the head since it left the dealership back in the day?

What is the head thickness?

How do you know it did not have a valve job 15 years ago?

 

[Derek Goodreau]

5.199