Thought I would finally get around to posting these here for anyone interested. Enjoy, there is both intake and exhaust along with a chamber side head shot. Let the power innovations begin




The above picture is looking at the valve boss of the intake through the intake runner.


Intake port above, and intake bowl view below.




Exhaust port view above and exhaust bowl view below.

 

hello experts and I hope some of you are reading.. I purchased a 1991 7.3 idi over the internet unseen and told it had 68000 miles and run good. when replacing oil leaking intake gasket I noticed coolant in the intake port or boss whatever it is called in the head, sitting on top of the intake valve on no.1 cyl. I removed the valve cover and the top of the head on no. 1 cyl. end of the head was full of gunk and creamy sludge and carbon like material, it was not metal as I tested with magnet. It also had a cracked exhaust manifold on the end bolt ear on no. 1cyl. I removed it and all looked normal like the other cylinders. My question is do I have head problem and if it were burning a little water did it hurt this engine. the oil I drained from this engine looked normal.

 

Well there is no coolant in the Intake manifold so if you can see coolant on the back of the valve it could only get there from 1 You spilled it down there when pulling the rad hose off...(If you pulled it).. or 2 the cylinderhead is cracked in the intake port area. Bummer....The goop in the head is from steem pushing past the valve seals (all seals leak some exhaust gasses past the guide, thats what hardens them) and condensates in the valve cover as goop. It looks like the you found a problem while fixing another one....If your cooling system is still intact you could do a coolant system pressure test and see if you can see coolant pool on the intake valve. This would confirm the bad news...

 

I am going to be doing up a head here at some point after im done with my current upgrades on my truck.

I am going to try a few different port shapes on the 4 different cylinders to see where the improvements show on the bench.

Our heads flow great (for a diesel, more than 7.3psd, 6.0, and 6.4) with good lift, but its the low lift (start of velocity) that needs the attention, and you pick up low lift flow by working the seat angles and bowl shape.... These heads will gain more from a simple valve job than they will from a full port.

 

racer30
I did not pull this engine, I thought that maybe they could have spilled some coolant down air cleaner hole of the intake but I see not sign of coolant in the intake and it is only no. 1 cyl. that had coolant in it. the gunk on top of head under valve cover is so bad that you can not even recognize the head bolts and seems almost granular like, but has nothing sticking to a magnet and it is all in that area of no. 1 cyl. The other side of the engine under that valve cover is much cleaner and normal looking, nothing like this.

 

I am going to do my heads this weekend, what would you do diferent to the seat angles to improve flow. I was planning to do a standard valve job but am wondering what improvements could be made?

 

Jeff, I have to honestly say at this point that I do not know... Thats what I am going to try and achieve with the flow testing...

Right now the best advice I can give, is ask your machinist what seat angles generally lead to low lift flow improvements... and roll with it.... It wont be 100% accurate, but its better than shooting blind...

 

Don't forgot, when looking at valve job angles, visualize the convergent side (above valve) and divergent side (chamber side of valve. Don't leave out modifications to the valve head either. You are creating a venturi to promote efficient flow which you need proper pressure recovery to efficiently finish the flow path into the cylinder. Being a 2-valve head we naturally have swirl plus with the aggressive turn of the port helps to a point in addition to the swirl chamber itself.

I haven't been able to measure the throat diameter, however I don't remember if I measured it beore I moved to Ohio (the heads are 800 miles away). Make sure you don't go too large in the throat area too.

 

The endless debate on valve angles.....I do agree that a good valve job will increase power. however,,,,most valve angle research you will find on the web is on gassers and they have throttle plates that change the speed and velocity of the air along with many other things like RPM, valve weight,spring pressure ect ect... IMO the most improvement will be in using a multi angle valve job along with some work blending the area just under the valve seat in the port throat above the port floor. This will help flow when under boost. The IDI ports are big for the RPM range of this engine so making them bigger is not needed, making them more efficient is what is needed. I personally didn't do a multi angle valve job on my engine build only because I am on a budget and my heads and valves were in good shape. I did however work on the port throat under the seat, the inside of the turn in the port Intake and exhaust and on the guide boss in the exhaust side only. This was only because I had the heads all apart to change the valve springs and couldn't stop myself from messin with them... LOL.

 

Let me know what works and then we can compare notes, I got the best results from the backcuts and polishing.

 

Have the ports mapped out and when you find you primary flow path make adjustments when and where you need along. When flowing the heads spray some dye and the dye will show you where there is going to be boundary problems and may impede of flow quality. DI or IDI engines we don't have to worry on suspension of fuel, so a matter of understanding fluid flow is a principle interest. So once you can test and find if there may be any flow problems, you can begin your fixes and all we need is a good surface texture to keep the boundary layer adhering to the runner wall, floor or ceiling. When I can I will be having my IDI heads flow-tested, right now I am burried into some 6.0L PS heads I am trying an idea on.