jimmyblue

iTrader: (11)

I figure a Z06 cam and headers are in my future, nothing
more extreme. I can get a clean set of heads any old time
for $200 or so it appears. Grind back the valve stem bosses,
put a radius on the short side of the intake port, make the
bowls look smooth and polish the chambers all seem like
good clean fun. Though I saw somebody selling heads they
managed to bust into the water jacket so pointers would be
nice.

Who out there has had decent results (or exceptionally lame?)
from DIY porting? Anyone with a shade-tree shaving-maker's
guide to the LS1 casting?

I've got the itch to try....

LOnSLO

iTrader: (15)

Go for it. I ported a set myself, but I also had a set of MTI stage 3 heads to reference, and a flowbench at my disposal. I also had a head that had been cut in several pieces so that I knew where not to remove too much. I ended up breaking through on the short turn of one port and ruined the head. But, it was outflowing the MTI head for a little.

technical

Get a nice set of abrasives and a die grinder.

I ported the crap outta a set of L-98 heads on my last car. Intake ports, exhaust ports, bowls, chambers...the works. The throttle response with those heads, relatively small cam (208/221 .474"/.510") and ported TPI manifolds was incredible. Made great power from 1200 to about 5800rpms which isn't bad considering it was TPI.

Hysteria

Not a problem, I ported my LS1 and a friends 5.3 heads. Cut the ramp down, tulip shape the valve guides, knock the knot down from the rocker bolt in the intake runner, header match the exhaust and polish it all out and you are done. Be careful on the roof of the exhaust port, there is a water jacket that runs right under the hump behind the guide, just blend that hump into the port roof and start about 1/2 inch in on the port match.

FASTONE

Have you ever ported heads before??LS1 heads are fairly easy to work on,don"t cut too deep on the intake swirl ramp as you can go thru.Streamline the guides,blend the stud boss.Theres a ridge where the port and valve inserts meets that needs to be smoothed and blended,also you can remove the casting ridge that runs down the side walls of the intake port and knock the casting finish off as well just to make them a little bigger.On the exhaust port you will see where the exhaust manifold is bigger then the port is by the black residule from the exhaust,this is a good guide to port by, go up and out to each side but don"t go down.BTW you"ll need a flame shaped carbide cutter with a 6 inch shaft and either an air or electric grinder,if you have a compressor you can get a grinder for about 30 bucks at Lowes or Home Depot.Use WD40 or AT fluid on the cutter to keep the aluminum from galling up on the bit.You need a good light and some goggles too.Also a small table and a stool is nice.Good luck!!

buschman

I wouldn't over do it. Polish em up, take out any casting bumps, and try and smooth the edges out. You can cut through the rocker bolt path.

My best suggestion is not to try and shape with abrasive bits. They are more for smoothing and polishing. To shape you really need a carbide cutter. Talk to Mondello Technical school, they can get you started with everything you'll need including electric die grinders, carbide bits, and the right abrasives.

(805) 237-9185

Mike

jazzz007

I'll let you know about Friday. Started on mine yesterday. It took me about 10 hours to do the intake ports on one head. Blued the intake to the heads to get a match. I opened the bowl up slightly and knocked down the hump where the rocker stud sits. blended the rest of the bumps. After I roughed it out I took a piece of 1/4" brass bar 4"long and made a buffer. Took a hacksaw and split one end about an inch. This let me use 180 grit emry tape for a buffer that could reach the back. Polished everything out including the cast line. Don't have a clue if it will ever hold water again. LOL

FASTONE

Don"t polish the intake,just use the carbide cutter it"ll be plenty smooth.With a good carbide you should be about 1 hour on each intake port with no breaks. About the same on the exhaust port but spend the time to polish it really smooth.Be really careful around the valveseats!!!Or you"ll be

Richard@WCCH

iTrader: (3)

Just bolt the head into the CNC and press the "start" button............piece of cake......

Richard

jimmyblue

iTrader: (11)

I did one set of SBC 350 heads years ago, have the
tools (except I would have to go get some long shank
burrs, all of mine are short). But knowing when to
say when, and leave enough casting meat for good
reliability, is something I haven't got...

Maybe I can scare up a junker from the dealership
and section it, just for a little better idea of what
does and doesn't want cutting.

technical

That's why I don't use anything that can cut too much material away too fast. It'll take a bit longer, but tends to leave you on the safe side.

buschman

I tried at first with the 80 grit sanders and the finish comes out very lumpy in my opinion. You have to use too much force to shape with abrasive bits. It's effortless with a cutter. You just have to have a good deal of control. Shaping with a cutter, and then smoothing with an abrasive should give you a better surface than just using an abrasive.

Have you seen APE's new setup? Damn those are some clean heads! I can't imagine those are done by hand. Does anyone know if machined heads are better or worse than hand ported heads? *Assuming an expereinced professional is doing both* I'm wondering what the Winston cup, NHRA, and F1 guys use?

Mike

LOnSLO

iTrader: (15)

For a good looking finish after you polish the ports, use a flapper wheel with bees wax.

Stryker

iTrader: (5)

wheres a good place to find the cutting bits? ive attempted to use cheap abrasives to port with and they instantly been coated in metal... i guess i need to study more

how much are good cutters? im using a 1/4 air die...

LOnSLO

iTrader: (15)

Use transmission fluid on the cutting bits to keep the aluminum from "clogging" them up.

technical

I picked up a nice carbide bit from the snap(er head)-on guy. A little pricey.
I can't remember where I got the stone bits.
Summit used to sell a nice set of >"flapper"< rolls, they may still carry them.

I ported my plenum with the carbide bit, and my neighbor kept a nice constant spray of wd-40 on the bit while I cut. Worked real nice.


edit: I just realized what you guys meant by "flappers", Summit sell the rolled abrasives, cartridge rolls?

buschman

I got my carbides from Mondello(number above) and you can also get rolled standard abrasives from them. These don't clog with metal, they just tear away as they are done. Much easier to work with. I used WD40 with the carbide bits.

I was told by Mondello not to use flappers. The standard abrasives and buffer wheel should do the trick.

Mike

turbo'd stang

I ported a set and let a guy that ports take a look at them. He said they looked good except for the intake bowl. He claimed that right beneath the valve seat, where there is a sharp edge there....the heads like that edge there. Anyone confirm this? I smoothed it up, which he said hurt flow. He is supposedly doing a valve job and will be flowing them for me...this was 3 months ago..lol.

Thanks

FASTONE

You only need a 6 inch stemed flamed shaped carbide cutter and a regular stemed round ball about3\8 or 1\2 inch.You can do both the intake and the exhaust with the flame, the ball is for working around the valveguides.A good carbide cutter will be about 50.00$.Even a good cutter will gall up with aluminum,when you are cutting you can spray wd40 on the port wall itself also on the cutter if you want.If the cutter gets plugged up with the aluminum take a small screwdriver or something with a sharp point and clean the aluminum off the cutter.

FASTONE

BTW I did a set of Vortec sb heads and had them flow tested 3 times 1 time with the stock valves a 2 times with bigger valves and just because you make it bigger don"t mean it"ll flow more.Also as a side note the bigger valves helped more (10-15 cfm) in the midlift areas then on the 500 to 600 lift areas.