This build is into it's forth year and thousands of hours in mech time with only a handfull of kills DAMMIT! : )

Whats the problem and description?

Our 1g streetable 5sp to auto converted grudge race drag car, still has a bunch of JNZ parts on it, including the jmf race mani, Kelford 280s and the Kiggly beehive springs, well it got boosted to like 65 psi and tweaked the exhaust valves.

What's weird is even after that overboost that sucker would still run very well at idle and would also still rock n roll with a boost of 33 psi but not a point more, even after turning up the hallman controller, and adding add springs to the wastegate 33 psi max???? WTH?

Here's the car running in this condition...


Anyway after much online research ( including the fact that we need MUCH STRONGER SPRINGS to do 65psi), we pull the head and see that the exhaust vales are not seating 100%... 98.5%? prolly, FRACK!!!!!!.

I mean I cannot even slide a piece of paper btw the head and valve, and it was holding 33psi, with that big S369 69mm turbo spining. Also the valves DID NOT HIT THE PISTONS. NICE!

So my question is:

If you had a need for speed on Sunday, would you pop the exhaust valves from another head, make sure they seat right and bolt the head back on? Or is it a must to have a machine shop mess with it?

Much love and thank everyone in advance for the advice!!! ; )

I've bent exhaust valves that sounds similar to what you have going on. I pulled the head and found nothing was damaged besides the bent valves so I replaced them and tossed everything back together, it ran great. Put some new valves in, lap them and let her buck.

Boomdeeze said:

I've bent exhaust valves that sounds similar to what you have going on. I pulled the head and found nothing was damaged besides the bent valves so I replaced them and tossed everything back together, it ran great. Put some new valves in, lap them and let her buck.

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Thanks for the tip brotha!!

yes i would grab the valves from another head, lap them asap and slap the head back on.

OK gonna get some new valves, casue the 20 old heads I have are unknown origin and questionable??????? So should I lap the valve seats in the head with the old valves or use the new ones. I think I know the answer... but, really do I know? ; )

Always use the valve you are planning on running in that hole to lap them correctly.

You might wanna replace the valve guides (on the bent valves ) seems like your building a beast so I wouldn't rush it together even if there fine. peice of mind is worth the time and money .

Jafromobile on YouTube has DIY valve lapping on his channel and valve guide replacing. You can find the valve compound for pretty cheap as they usually sit on the shelf a long time.

I'd use the hand tool over the drill method also
My 3 cents

First off, I'd like to say that just tossing in new valves isn't what I'd recommend. (I'd recommend grinding the seat and valve faces with a new bevel and replacing the guides on at least the exhaust side) that being said, I've seen people do it with some sort of success (and some disappointment) Make sure your surfaces are immaculately clean. Put the grinding compound on the new valve's seating surface and some oil on the stem, pull it through the head and give it some spin like your starting a fire. I'd recommend using a valve lapper that has a suction cup on the end of it and a wooden handle. Clean um up real well and then assemble the valves. Pour water in the runners/bowls and let it sit over night, then inspect for leaks.

I give it a 40/60 chance that it goes back together with 100% seal. And a 50/50 chance that one of your exhaust guides is cracked.

I'd rebuild the head, or put a completely different one on, because they're cheap, but if you just want to get it back on the track to beat the hell out of it, then give her a go.

I fill the runners with lacquer thinner and look for leaks on the valve side. But either way is a good check.

AWESOME thanks for all the great advice fellas, much appreciated!!!!

1990TSIAWDTALON said:

I fill the runners with lacquer thinner and look for leaks on the valve side. But either way is a good check.

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I too enjoy a good quality buzz with my morning coffee *tips fedora*

97gsxIA said:

First off, I'd like to say that just tossing in new valves isn't what I'd recommend. (I'd recommend grinding the seat and valve faces with a new bevel and replacing the guides on at least the exhaust side) that being said, I've seen people do it with some sort of success (and some disappointment) Make sure your surfaces are immaculately clean. Put the grinding compound on the new valve's seating surface and some oil on the stem, pull it through the head and give it some spin like your starting a fire. I'd recommend using a valve lapper that has a suction cup on the end of it and a wooden handle. Clean um up real well and then assemble the valves. Pour water in the runners/bowls and let it sit over night, then inspect for leaks.

I give it a 40/60 chance that it goes back together with 100% seal. And a 50/50 chance that one of your exhaust guides is cracked.

I'd rebuild the head, or put a completely different one on, because they're cheap, but if you just want to get it back on the track to beat the hell out of it, then give her a go.

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There are ways to test the head to see if a guide is cracked/leaking rather than rebuilding it out of paranoia that it may leak. My reply above was assuming he would test or at least inspect to be sure everything was good in the head prior to installing new valves.

1990TSIAWDTALON said:

I fill the runners with lacquer thinner and look for leaks on the valve side. But either way is a good check.

Click to expand...

I did similar with putting gas in the bowls overnight to make sure it was sealed.

OK which flipping tool do i need

ShayneZ said:

OK which flipping tool do i need

Click to expand...

For valve spring compressing and removal: LINK
For valve lapping: TOOL, -PASTE

It's a suction cup attached to a wooden handle and you rotate it with your hands .

Seriously go on YouTube and type in jafromobile and find his valve lapping video . You'll be hooked he has tons of videos for differnt 4g63 stuff

BOOM Thanks guys!!!!!!!!!!!!

https://ru-clip.net/video/7GEmuQa3dPY/cylinder-head-105-valve-job-basics.html

Just in case you couldn't find it here it is

Very good sir thanks

You’re probably burning up exhaust valves from valve float.

Bare minimum I would run a neway cutter on the seats and install new valves/springs.

Agree with above, you probably need to cut the valve seats. and should go with higher pressure springs or shim the springs you have, if you plan to exceed 45-50 psi range.