Valve Job

[meadowbrook]

Hi folks. 

Is it possible to perform a valve job on a 230 with the  engine in place by just removing the head? 

Since the engine has never been rebuilt and runs well with good , oil pressure, an indicated 50 psi while at speed, and does not smoke but does have a somewhat rough idle, I figured the valves must be leaking and I like to boast the engine is original  

I did check compression and it is about 100 on #6 and 5 , dropping to about 75 on the middle ones and back to 90 on #1. 

So next I'll do a leak down to be sure it's the valves. 

 

[keithb7]

I am also interested in hearing more on this topic. I am in the middle of a valve job with engine still in car. I will attempt to improve valve seal sufaces by lapping. You can see my thread on this page  

I would like to know if there is a tool that can cut block valve surfaces, with engine in place. I am doubting there is room at cylinders 5 & 6. 

My compression readings are similar. No oil burning. Upon pulling the head I can see that some valves were not sealimg well. 

I begin lapping tonight. More to come from me as I progress through the job. 

[captden29]

yes, valves can be done in the car. you need a spring compressor that works in that tight spot. I am told that chevy 350 engine valves will work in the flathead 6.if 3 1,6,and5 have 90 to100 psi, they can be left alone. even 75 psi is not too bad. you can lap them, and replace any that are damaged. that should bring those cylinders back up to at least 90 psi.i had to replace 2 valves, and I got OEM valves for that. more expensive, but keeps it all original spec,s. rough idle can be many different things, but having even compression across the cylinders may help that.    capt den

[Don Coatney]

1 hour ago, meadowbrook said:

Hi folks. 

Is it possible to perform a valve job on a 230 with the  engine in place by just removing the head? 

Since the engine has never been rebuilt and runs well with good , oil pressure, an indicated 50 psi while at speed, and does not smoke but does have a somewhat rough idle, I figured the valves must be leaking and I like to boast the engine is original  

I did check compression and it is about 100 on #6 and 5 , dropping to about 75 on the middle ones and back to 90 on #1. 

So next I'll do a leak down to be sure it's the valves. 

 

FYI.

[John-T-53]

Put a vacuum gauge on the motor while running, this will tell you a lot, and determine if a valve job is even necessary.

If your gauge tells symptoms of leaky valves, you could start with lapping all valves to see which ones need their seats recut. This is after a thorough cleaning of the block surface, ports, and valves. The best way to clean valves is by bead blasting, then put them in a lathe and polish with red scotchbrite pad and wd-40, stem included.

Doing a valve job with the block in the car is a biotch. I've done it including replacing guides. A real pain (literally - it's hard on the back and elbows). If I had to again, I would just pull the GD motor.

Lapping doesn't do much other than a final polish after you cut the seats. And as a check to see the results of the seat cutting. But, if you grind the seats with the motor in place, you'd use a hand held stone cutter, and lapping isn't really needed when cutting with this method.

http://www.cylinderheadsupply.com/sisthdvasegr.html

 

 

[John-T-53]

Tips on reading a vacuum gauge:

http://www.secondchancegarage.com/public/186.cfm

[Don Coatney]

I have an old valve seat cutter that I have not used in years. It works on the soft intake valve seats BUT it will not work on the hardened exhaust valve seats as a grinding stone is required.

[55 Fargo]

First chance you get, do a Cylinder Leak Down Test, and see how much your cyls are leaking and from where.

No point in just pulling the head and doing valves if the rings are leaking bad.

My engine has similar compression numbers, but does not burn oil or smoke, oil pressure is very good too.

My cylinder leak down test pointed to rings and blowby, if I had relied strictly on a compression test, it indicated leaking valves.

You might as well know what your up against before you make the plan......

Running the engine with a "vacuum" gauge hooked up can ell you a few things too. actually you could have a reading of 17 or 18 inches, with a slight quiver, indicating a few valves not sealing 100%.

If the gauge is vacillating like crazy, of course a valve could be burnt or sticking.

The Cylinder leak down test is a very good diagnosis, other than taking the engine out and apart for a visual inspection and measurements.

 

Edited June 13, 2017 by 55 Fargo Spitfire