Lots of snow so starting porting some heads

[LGAFF]

Started porting a spare head I have not as big as some, but valve guide bosses taken all the way down and 35mm goes most of the way down

http://i134.photobucket.com/albums/q115/lgaff/DSCN5452.jpg (http://s134.photobucket.com/user/lgaff/media/DSCN5452.jpg.html)

[LGAFF]

http://i134.photobucket.com/albums/q115/lgaff/DSCN5457.jpg (http://s134.photobucket.com/user/lgaff/media/DSCN5457.jpg.html)

[LGAFF]

http://i134.photobucket.com/albums/q115/lgaff/DSCN5454.jpg (http://s134.photobucket.com/user/lgaff/media/DSCN5454.jpg.html)

[Blue Flame Restorations]

A new way of taking out UPS frustrations??????

Sorry, couldn't resist, Lee. Looks really great!!!

[Paul Workman]

Started porting a spare head I have not as big as some, but valve guide bosses taken all the way down and 35mm goes most of the way down

http://i134.photobucket.com/albums/q115/lgaff/DSCN5452.jpg (http://s134.photobucket.com/user/lgaff/media/DSCN5452.jpg.html)

Must be tapered some... They're bigger at the top than 35mm; that's plain to see. I did my heads in stages, and the first stage was similar to what you've done there as part of my top end P&P. It gave me the biggest single "seat of the pants" boost of anything else I've done since.

[XfireZ51]

My heads were done by GVD and they start out at 36-37mm tapering down to
~ 34mm at the bottom. The guides are not done as far down as shown here.
Lee,

Will you be unshrouding the intake valves? Bowl port?

[LGAFF]

Yes, will do some research and unshroud the valves on these...

[efnfast]

Alright, I'll fess up to not knowing something. What is "unshrouding the intake valves?"

[Paul Workman]

Alright, I'll fess up to not knowing something. What is "unshrouding the intake valves?"

The shape of the stock combustion chamber presents tangential ridges to one side of both intake valves. This effectively impedes flow along that edge of the intake valves.

By cutting a radius into that tangential portion, next to the intake valves, there is better flow and is part of the "500" package.

One of my heads getting the relief treatment.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Lingenfeltercut.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/Lingenfeltercut.jpg.html)

P.

[LGAFF]

Alright, I'll fess up to not knowing something. What is "unshrouding the intake valves?"

Basically the the edges of the combustion chamber(clover leaf) sit too close to the valve edges, this impedes flow, removing material from the edges allows more flow, although it also reduces compression somewhat.

The question is, is the clover leaf design the most efficient or is a hemi design better. Not sure if the clover leaf was more about meeting CAFE and running 87 octane or performance

[efnfast]

Do we know this helps, or do we (like the way I say we?) figure it can't hurt?
Thanks for the education. -Steve

[LGAFF]

Probably 10hp maybe alittle more

[efnfast]

Probably 10hp maybe alittle more
Just from unshrouding?

[LGAFF]

yes

[Paul Workman]

Basically the the edges of the combustion chamber(clover leaf) sit too close to the valve edges, this impedes flow, removing material from the edges allows more flow, although it also reduces compression somewhat.

The question is, is the clover leaf design the most efficient or is a hemi design better. Not sure if the clover leaf was more about meeting CAFE and running 87 octane or performance

Hemi's don't lend themselves to more than 2 valves, for one thing. 4-valve chambers use the "pentroof" design: small = less heat loss, higher compression, faster flame front...

http://www.howstuffworks.com/hemi2.htm



P.

[LGAFF]

Intake ports are pretty much done, need to smooth out a few things; exhaust should be done tomorrow:

http://i134.photobucket.com/albums/q115/lgaff/Picture4380.jpg (http://s134.photobucket.com/user/lgaff/media/Picture4380.jpg.html)

[LGAFF]

http://i134.photobucket.com/albums/q115/lgaff/Picture4381.jpg (http://s134.photobucket.com/user/lgaff/media/Picture4381.jpg.html)

[LGAFF]

http://i134.photobucket.com/albums/q115/lgaff/Picture4383.jpg (http://s134.photobucket.com/user/lgaff/media/Picture4383.jpg.html)

[LGAFF]

http://i134.photobucket.com/albums/q115/lgaff/Picture4382.jpg (http://s134.photobucket.com/user/lgaff/media/Picture4382.jpg.html)

[LGAFF]

As stated, this is a head I picked up for about $200 a few years ago, so I thought I would learn the ins and outs with this one. Porting these is like tiptoeing through a minefield, at least for a beginner(me). Traditionally, the neck behind the valve bowl is an area to work..in the LT-5 I found out the material is thin. In my first port I hit a water jacket that in the normal head would not have been an issue....this will be easy to fix with welding. After that the porting was uneventful until the 2nd to last runner.

I marked this area on the photo below as "thin"....this is the transition from the thick Aluminum flange were the IH bolts, into the area the opens ups for the valve train. As I was porting, I hit this area...what was odd is that the material around it was very thick still, almost as if I hit a small defect or void. I can access the runner from the backside and it opens to oil vapor, should be an easy fix. This area was well before and off to the side of the area were the lifter sits.

I had no issues avoiding the lifter area....




http://i134.photobucket.com/albums/q115/lgaff/LT5lsn.png (http://s134.photobucket.com/user/lgaff/media/LT5lsn.png.html)

[LGAFF]

http://i134.photobucket.com/albums/q115/lgaff/Picture4381.jpg (http://s134.photobucket.com/user/lgaff/media/Picture4381.jpg.html)

The picture above is the primary...you can see it doglegs and acts as a port swirl generator.....the safest area is really to the outside of the port, although you still risk hitting the head bolt.

[Locobob]

Looking good Lee, do you remember the thread I did a few years ago... might be some helpful info in there for you www.zr1.net/forum/showthread.php?t=13497

[LGAFF]

Flat Edge Exhaust Divider, supposedly GM Engineers said it was worth 6hp

http://i134.photobucket.com/albums/q115/lgaff/DSCN5513.jpg (http://s134.photobucket.com/user/lgaff/media/DSCN5513.jpg.html)

http://i134.photobucket.com/albums/q115/lgaff/DSCN5514.jpg (http://s134.photobucket.com/user/lgaff/media/DSCN5514.jpg.html)

[XfireZ51]

That's part of what GVD did to the heads I have. GVD commented on that a few years ago at BG.