Well the time has come, I have been waiting to do this for a long time now and I finnaly get to... port and polish a set of heads on my 350! I have been reading up as much as I can on here, books, and other online resources, I have all the tools and bits. The only problem is while I was reading, it only told me how to. Has anyone out there done this at home and took off something they shouldn't have? Or done something that made a world of difference? In other words, I want to learn :Smarty: from past mistakes... thanks! :TU:
All I can say is that bigger is not necessarily better. For both intake & exhaust ports, it's better to raise the roof than to drop the floor. Smooth out the short side radius but don't hog out the long side. If you plan to teardrop the valve guide bosses in the bowls, be prepared to have new bronze guides installed. Protect the seats with old valves while you work the chambers. Guides and valve job is to be done when all else is finished. Do put a smooth finish on exhaust ports and combustion chambers, do not put a smooth finish on intake ports. Devon
I never would have thought about putting the valves back in for the chambers, I was just going to try and be very careful, that will make things much easier. I saw some pictures of teardrop valve guide, can i really take out that much material on those? Just from what I have seen it seemed like an awful lot. I do plan on having everything replaced new when I take it to the machine shop, my train-of-thought was to get all porting done now so I wouldn't have to take apart my newly rebuilt heads when I get them back. Thanks Devon!
If you're working from the valve side, having a valve in it will make it much more challenging:bla: .. I opend up the casting as close to the seat as I could. http://www.turbobuick.com/forums/engine-tech/327627-best-cylinder-head-mods-stock-heads.html This is a good thred.. There are plenty of them out there.
FYI, don't put your valves in during the chamber work unless you're planning to have them replaced. If you're going to keep using them, find a junk set to use instead so that a few hits from the carbide burr won't ruin your day. Devon
Well I tried it last night for the 1st time and I had alot of fun doing it. I know it sounds elemantary but wear saftey glasses! Nothing like having the head of the bit get caught in a corner and snap of and fly towards your head, luckily I was. Im going to start keeping my tissues, I had enough metal bits in my nose that I could probly get a few bucks from the scrap yard.. next time ill wear a mask. Nicked the valve seat a bit too, hope the machine shop can fix. Jay- Thanks for the thread that was a good source I haven't seen yet. So remove the exhaust guide entirely? will that still hold up ok? If you look in the pictures I didn't do much with the intake guide yet, I just rounded it off a bit. I feel comfortable in grinding the guide down I just want to make sure it will still be strong. Devon-I was thinking about getting new stainless steel valves for the head, ill post a pic later but my valves looked like something you would see on a 'before' picture on a Z-Max commercial. Thanks for the help everyone!
Thanks ill remember not to, I like that picture its a nice close up. Ill be grinding carefully away again tonight.
Ive heard this too...is 90% the general rule? Ive read somewhere that if opened all the way, as much as possible, you get maximum flow, but give away some bottom end. Of course I read/heard this after opening mine all the way up....... Is there a way to quantify the difference? tenths? torque numbers? I guess one would have to dyno compare.
Lemme guess, I no longer owe you for a FULL set of bits..... No biggie if you broke one of mine. Are you using any cutting oil on the bits??
I almost used the bits I got you but held off, ill try the cutting oil aftet I order a all new bit set :TU:
Go ahead and use my bits and we'll replace them later.:TU: I dont need them at this exact moment anyways and you do. Besides, once your done figuring it out on your heads, you can do mine!!!:bla:
So I have been reading about both, but when polishing the bowls does anyone reccomend stones over sandpaper bits? or the other way around?
Go from coarse for shaping, then finer for finish work. The abrasive rolls will 'give' a little to produce a surface without gouges. Carbide....stones....then abrasive rolls for finishing. No need to overdo it your first time, just smooth out the original cuts and blend everything. For consistency, do one step on all 8 ports. That is, shape one area on all 8 ports, then go back and shape another area on those 8, etc. When all 8 are shaped, start finishing steps, once again, one step on 8 ports before moving to the next step. I put a piece of rubber hose over the nut on the grinder to prevent it from hitting valve seats and damaging them. Your work looks pretty good so far.:TU:
Do not use cutting oil on cast iron. Use cutting oil on steel and aluminum, but cut cast iron dry. Always use "double cut" carbide bits on cast iron. They will last longer and they will not have the grab and rebound of single cut bits. Get high quality carbide bits and have them sharpened after they start to get dull. You will know they are dull when they start to cut slowly. Using cheap bits will waste a bunch of time and money. Using dull bits will just build up heat and cause them to chip and force the sharpening facility to have to reduce their diameter, thus reducing their life. I am fortunate enough to have a high quality manufacturer near me: http://www.huffcarbide.com Good bits and several sized and shapes will make your life much easier. For cast iron cylinder head porting, the most effective carbide bur is a double cut cylindrical round head with an extra long shank. Here is a link to a catalog where you can see the different types: http://www.sgstool.com/catalogs/PDFs/BurCtlg.pdf Check out page 6. For bowl work, use the largest diameter double cut cylindrical round head you can get. This will be the easiest to control and give smoother results without creating "divots". On the larger diameters, keep the speed down. Overheating the bits will dull them quickly. For shaping the guide bosses, I usually use a ball shape and the flame shape. For enlarging ports, I use an extra long double cut cylindrical round head for flat surfaces. I use a flame for the long side radius and the same cylindrical round head for the short side radius. Finish and blend with sand paper rolls. I see you nicked your valve seats a few times. DO NOT let this happen. If you nick up your seat to badly, the machine shop will have to "sink" your valves to create a new seat surface. This will hurt flow and can cause inconsistent valve tip heights that can have a negative impact on valve train geometry and lifter preload on engines with non adjustable valve train.
Keep your cell phone out of your pocket and in the house. Cast Iron powder loves the magnet in the ear-piece. Don't ask me how I know that. I taught myself how to do the heads. I'm no Greg Gessler or Walt Weslake, but they turned out nice. Take your time!! I've done 3-4 set's of heads and have never broken a "Rotary File".( Said So right on the Buick Factory box ). There's no big rush. I had mine tilted up just right so I could slide a small flourscent Light fixture under the ports. Sure, tripped the GFI a few times. No harm done. I sealed it off the best I could and put the end of the shop vac in the small space created. Taped up a few of the ports that I wasn't working on for more suction. Wear Ear Plugs. Probably don't need to tell you that. But have fun and concentrate. I used my die grinders with different tip's but also a battery drill. It goes a lot slower but you can concentrate better. Have a Dual charger available. Have fun! PONCH
Great tips here. Light up the ports and use the shop vac to keep the port clean while you work. On a safety note, I always use ski goggles when porting. Those cast iron chip are uncanny at finding a path to your eyes, even with safety glasses. I went the extra mile with the goggles after my 2nd trip to the optometrist to have shavings removed.
Thanks for all the advise everyone, it really is helping. The bits I am using righ now are a 1/4 inch ball, a 3/8 ball, a flame and a double cut cylinder burr. By far my favorite one to use as of now is the cylinder burr for its consistency without making a bunch of gouges (as speedtigger had mentioned, it took me a bit to figure that out, :spank: ) I really am not trying to overdo anything, my favorite move is to gently go back and fourth with the cylinder burr untill it smooths out, and use a flame on my rounded parts. For the guides, I am not trying to make them any smaller, just put a slope on them. On the sides of the guides I am trying to make the path just a bit smoother and a bit more concave.(the 1st pic has a before and after guide smoothing) I took the advise and did not totally open up the valve ports to the max ( I was to afraid to hit the seats, luckily I only 1 valve seat.) I applied the same basic principals to the exhaust side, just trying to smooth everything out, its a bit smaller area to work in though. I fear I am trying to be to "exact" with the burrs, I am trying to make everything smooth the 1st go round. I am hoping that the polishing process will give me the finish I set out for. Ear protection is a must! The 1st day I did not wear anyting thinking that I would be fine and I was rewarded with a dull humm for the rest of the night. I never heard of the cell phone thing but I must say it makes sence! I am guilty of taking the phone in there before..ill be more carefull next time.. The next time I go into the garage I am throwing a tube on the nut, that thing seems to catch everything. Its quite a suprise to when you are so into grinding then bam! Oh and I threw in a pic of my valves just for the fun of it
