Dropped valve head repair

[BogusSVO]

4G63 Dropped Valve Head Repair


The Subject head is a 1G 6 bolt head.
This head had extensive work done to it and would cost way more to replace than repair.

The head was loaded with SuperTech +1mm valves, and duel valve springs and Ti retainers.

How the head looked when I received it.

A closer look at #4 cylinder, the one that dropped the valve.

Yes it looks pretty beat. But it is fixable.

First thing to do is disassemble the head and get a parts list going.
At first look, I thought the 4 valves in the #4 cylinder would be the only ones needing replaced.
It turned out only 4 valves of the 16 could be used.

The SuperTech duel springs and Ti retainers tested fine and will be used. About half of the Ti retainers had be rubbed on.

At this time it was decided to install bronze guides, to replace the stock appearing cast iron guides.

The bronze guides installed.

Once the head was cleaned, a couple small cracks were found in #1 cylinder.

The seats were cut out

Then the head was pressure tested, using 35psi in the water jacket.
The head did not leak.
So work progressed by removing the 4 seats in #4 cylinder.

New counter bores were cut, and oversized inserts were installed.

Some grinding, polishing and blending was done to smooth out some of the damaged area in the combustion chamber.

Next was to mark the spots to be welded.

What it looked like once back from the welder.

Also to note is the spark plug inserts were installed in cylinders #1 and #4 before welding.

From this point a bit more blending was done to smooth out the welds and a full valve job was performed.

As the seats were cut,

Valve tip height was checked and set to the proper specs.

Spring installed height was measured and set to 1.550 @ 85lbs

New 3g HLAs were installed, along with the followers and cams.

Bottom of the head.

Close up of #4 cylinder after repair.

Head thickness after repair and rebuild. 5.159
Head build # BBB 744

 

[prove_it]

You didn't mention bowl volume measurements. I take it you didn't bother? I would still not run that head in anything making over 300whp.

Also what would the final bill be, you say it's cheaper than replacement? I can find used heads for less than $100.

 

[toybreaker]

Gentlemen,

Dale is making an effort to show how things get done at the machine shop.

Not every customer has unlimited funds, nor do they always have nice cores to work with.


When I was behind the counter, I got all kinds of "experts" telling me how to do my job

... it's one of the main reasons why I left the business


Unless you have run the machines, try and refrain from posting a critique of his work.

... sh*t's a lot harder to do in real life than it is from behind a keyboard /ubbthreads/images/graemlins/wink.gif

 

[BogusSVO]

Quoting prove_it:
You didn't mention bowl volume measurements. I take it you didn't bother? I would still not run that head in anything making over 300whp.

Also what would the final bill be, you say it's cheaper than replacement? I can find used heads for less than $100.





Last time I heard about this head, it had been dyno'd a tad over 625hp, and no head issues.

Sometimes I get an email/pm from a customer once the build is done and how things are going.

IIRC, after parts and labor, the bill was about $1100.

Oh I buy heads in the $100 price range all the time.

But due to the work that was done to this casting, and who built it before me, it was cheaper than starting with a new casting.

Did you want CC numbers on the bowl/runner or the combustion chamber?

I can dig through my notes and try find that info.

But if all you are looking for is how head thickness changes combustion chamber size, you can find that over here.
click

Sorry mods/admins for linking to another fourm.

 

[prove_it]

No, I do see what he's doing. It's nice to see how everything comes together in the machine shop. I'm not trying to insult or attack his threads.

 

[donniekak]

That looks similar to a failure I had with super tech duels. I missed second hit the 8500rpm limiter, and the car died. Upon tear down, one of the exhaust valves had the head pulled off it, the valve stem was still in the retainer, with the locks holding it in place.

 

[BogusSVO]

What brand valves were in the head?

 

[donniekak]

Stock 2 piece.

 

[misterfixit]

I have to ask so apologies it's Silly question time. Toybreaker I don't run machines. But if you've been fying on any civil airliners recently what I do keeps you in the air.

Question to the OP. Why weld the aluminium after pressing the seat in? Surely better to do the welding before cutting the the c'bore. Once the seat is in (Press fittied in) the hoop stress around it should be even. The stiffness of the wall also is what it is so will be even. Welding the aluminium when the slug is press fitted in will cause the local portion of the c/bore to yield and lead to other less flexible parts of the cbore with a residual higher stress.

Just curious. We have used welding to restore manifolds and transmission castings in titanium and aluminium and you sure as hell don't want residual stresses is odd places or doing thin in odd ways.

Rich

 

[BogusSVO]

Since the damage did not extend deep into the counter bore, less than .030 on most points. I installed the seats then had the pits welded after so it be another way to lock the seat in place.

Most of the time the counter bore will be fully welded then new counter bores cut. but this was more welded for cosmetic than a structural repair.