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PostPosted: Mon Jul 23, 2001 3:54 pm 
Hi. I am porting/polishing my SL6 head. I gasket matched it already with a Fel-pro gasket. I have heard that mirror finish on exhaust ports is the best, and slightly rough surface on intake ports works well. Any advice?
Also, a few of the valves have deposits and corrosion, and the springs are a little rusty. The head had been sitting awhile when I got it, so it needs TLC. The valves are stock size and appear to be new. Should I run the same springs? I believe they are stock.
I must also clean the corrosion off the head, is "hot tanking" the best way to do this?

I appreciate all your guys' help. I have gotten some valuable info off this board. Keep it up!

Thank You, Jeremy Moore

dodgedart75@hotmail.com


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PostPosted: Fri Jul 27, 2001 11:26 am 
Quote:
: Hi. I am porting/polishing my SL6 head. I
: gasket matched it already with a Fel-pro
: gasket. I have heard that mirror finish on
: exhaust ports is the best, and slightly
: rough surface on intake ports works well.
: Any advice?
: Also, a few of the valves have deposits and
: corrosion, and the springs are a little
: rusty. The head had been sitting awhile when
: I got it, so it needs TLC. The valves are
: stock size and appear to be new. Should I
: run the same springs? I believe they are
: stock.
: I must also clean the corrosion off the head,
: is "hot tanking" the best way to
: do this?
:
: I appreciate all your guys' help. I have gotten
: some valuable info off this board. Keep it
: up!
:
: Thank You, Jeremy Moore


As a one-time minor porter of cyl. heads (both street and race), I can tell you that, yes, a smooth finish on the ex. and a rough one on the intake, is the thing to do. What is happening with the intake is that the rough surface is precluding "fuel cling", which supposedly messes up fuel atomization going into the chamber.

Also, try NOT to grind too much away under the valve head in the pocket, especially on the common wall with the ex. pocket. You want to grind on the AWAY side of the pocket about half way around. This will encourage the heavier fuel to turn the corner more efficiently. The air, being much lighter, turns the corner no matter what.

Throw away those valve springs and get some new ones! Any rust means that material is gone and the last thing you need is a broken spring at 5000 rpms! Stock springs are inexpensive and even some hp springs are not very costly, either.

The best thing you can do to clean your cyl. head is take it to a machine shop which has one of those "shake and bake" cleaning machines. These things have a large rotating rack for at least 4 heads and a serious gas flame heats them very hot, turning to carbon, any grease or dirt on the head. After that operation, the rotating continues with small steel shot being air pressured onto the head to knock off the carbon. At the race shop where I worked several years ago, we had one of these and it was super!

If you can find a machinist to do a custom valve grind for you, have him narrow the seats on your valves for better flow. Easy to do and inexpensive.

One last item: if you can find some over sized intake valves, it would be to your benefit to install them. Large intakes ALWAYS help, but the exhausts only need be done in a race motor.


grandpabauer@yahoo.com


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