Ok, I've been reading up on head porting, and I picked up a pair of 416s for 40 bucks to go on my 350 build. First off, I want them checked by a machinist. Should I hand them over, have him check and clean them, then port them? I also want 1.90 or 1.94/1.60 valves in them, do I do that part myself or get him to do it? In Sitting Bull's great post about this, his seem totally clean in the first place, so I would think I get them worked over first by the machine shop. Should I just have him prep them for the bigger valves? Hope that made sense...
Thanks folks! Also, feel free to check out my post on this board about the 350 I'm planning on building and please give me your ideas/suggestions/criticism. Cheers!

 

I find it a great deal easier to work on clean parts. Just a personal preference of mine.

I would suggest taking them to the machine shop; having the guides replaced or bushed, valves cut in, screw-in studs, sping pockets enlarged, and any other machine work of that sort done; then port them when you get them back, and take them back to the shop for a final clean-up (and seat touch-up if necessary) before painting and installation. You don't need the valves themselves for any of that, so you can wait on buying them until the castings are ready. You can lap the valves yourself if you want. DO NOT use the Permatex lapping compound that comes in a tube, it's like gravel. Use a product called "Clover" instead, you should be able to get it at a machine shop or a real parts store (not AZ, CSK, etc.). If you have or can obtain a spring height micrometer and a spring compressor and a pile of shims, you can also assemble them yourself; if you lack the micrometer, then pay somebody to do it for you. The installed height of the springs is critical.

 

For someone who knows what they are doing, or has done it before, these instructions are great.

For a first timer though, I would have the heads cleaned up, and then do all of your portwork before you pay for machine work. There is a real chance that you could screw up the head. Then you are out the money you paid the machine shop. Also, you could seriosly mess up thier work on accident.

 

When I brought my heads in for clean up prior to porting, I asked if they had a junk SBC head laying around that I could practice on. They gave me an old 882 casting and I practiced on that.

 

I got the heads from Apeiron and he had them cleaned at a machine shop first. Good luck and don't be reticent to ask questions. We all love helping out if we can

 

Great, don't worry, there will be alot of questions asked. So I think I'm gonna take 'em to be checked and cleaned, then I'll work on porting them. I will definately acquire some junk heads to practice on first. My plan for these heads is to port them (duh) and have the machinist install 1.94/1.60 valves (trickflows) and to install all new springs, pushrods, rockers and locks from crane. Sound like a good plan? Should I have the old studs removed and new ones installed? Which type? Thanks

 

I would add having the guides machined down for positive stem seals.

Either have the press-in rocker studs pinned, or pulled out and machined for screw-in shoulder-type studs.

 

I would bring the heads to the machiest to check them out to see if they are good but i would not have him do any machine work on them untill you have Ported and polished. I know working on a set of clean heads is nice but... They wont be clean when you are done porting and second and most inportant... If when you are porting and polishing the heads and you slip with a stone or heaven forbid and carbid cutter and hit one of the valve seats you will have to bring it back to the shop and have him start all over. Minnor slips are not uncommon. The job of porting and polishing is not hard but it takes a lot of time. Its great that you want to do it yourself others should do the same. I did mine a few months ago. I had made a few small mistakes (slips) with the porting tools that if I had the valve work done I would have waisted money. I had the bigger valves but in and the head unshouded. U will see how easy it is to slip when working in the chamber area. The carbon that collect there is bad. I would wait untill you are done p & p and when the heads come back you have a nice clean head that all it needs is some soap and water and then some w-d40

 

Ok, I see where you're coming from. Did you mean to wash the carbon off with soap and water, then hit it with wd-40? Thanks!

 

1) Disassemble heads.

2) Take heads to machine shop. (Skip #1 if you can't/don't want to disassemble them.)

3) Have shop tank the heads & valves, and check the heads for cracks. If you want and/or they want, have the seats opened up for the larger valves.

4) Take the heads home and do your porting magic.

5) Return the heads to the shop for whatever else is left - guide replacement (if required), whatever you're going to do the rocker studs, cut guides for positive seals, the "valve job", and assembly.

 

Some good advice here. I always like to port on stuff prior to cutting the valve seats in case you walk the tool bit across the seat, or ding it with the mandrel. IMO.

 

I was a newbe to porting and polishing when I did my heads last fall. I made a few mistakes with walking bits. I was putting in bigger valves. The machinist said it was good that I was putting in bigger ones. It was not a serious mistake but enought to make a differace. NOTE: I was being as careful as I possibly could and made the mistake. save your money untill you port then let the shop work its stuff. You can also ask them how you did on them and they might, might tell you where you can improve. They prolly wont tell you hidden tricks but should tell you if you did it right or not.
getur done!

 

I have been porting some of my heads over these cold months, but I am always scared about how much to grind off. Is there a way to measure, I really do not want to get into the water jacket.

 

Ok, I see where you're coming from. Did you mean to wash the carbon off with soap and water, then hit it with wd-40? Thanks!


The chambers on the heads are rough and hold alot of carbon. They need to be smothed out as much a possible i say that like its easy..its not the area is easy to mess up with stone and mistakes are costly. The smooth surface of the chambers prevents or at least controls the amount of carbon in them. The WD-40 is to sprayon the engine and heads to prevent them from rusting. Its the only use i have found for WD-40 thats useful anyway.

As far as taking to much metal out, it is possible and the slot for the push rods are the thinnest area. Remember you are not making the ports bigger except the port entries when you match the gasget the rest is just smoothing out the rough (exhaust) and fixing the sharp or pertruding areas of the intake ports and valve seat area. when air flows thur the heads you want it to flow as smoothly as possible if there is sharp or pertuding edges then the air starts to bounce around the ports and slows the flow down. I dont know if you can measure them but if you are grinding a lot of metal than its to much

 

How to clean heads:

Deep sink

Brass bristle brush

Easy Off Oven cleaner


Your heads will come out so clean they will look like they were hot tanked.

 

Not surprising, considering whats in the tank and what's in oven cleaner.

 

Suggested alternate:

How to clean heads:

Deep sink

Brass bristle brush

Nitrile or latex gloves w/cuffs

Well ventilated area

Easy Off Oven cleaner


I wasn't that impressed with the Easy Off, myself. The $'s for the tanking was well worth it.

 

Sissy

 

No, wisened...

 

Rubber gloves are more convenient than skin grafts.