This is not the very best stuff to use for this but it does work and is easliy available. I was smearing some silicon on a mold and I brought one of my spare slant 6 cyl heads over and smeared the ports for some port molds. I do this because often we (and I am included in that we) have misconceptions about what a port actually looks like. This removes the mystery. The bad section of the slant six intake port is clearly visable and I indicated it. I drew on the paper behind it (blue) an approximation of what I would do to improve it. I am no artist so please forgive my not good drawing but i hope it gives the idea anyway. Will the head stand that? I dont know but I have 3 and a 4th promised so I will sacrifice it gladly to find out. I used white GE household silicone. Smear it around the guide area first thinly then the next day with a blunt instrument (popsicle stick?)loosen that chunk but dont remove it. Smear the rest of the port several times and work away all the time at making it lose. If you oil it first sometimes you cant get it to stick so I do it dry. Do not use silicon sprays like WD40 for a mold release as it reportedly does the opposite. Don
That's a lot of material to remove from the port wall. You best be sure that there is enough material to allow you to remove that much w/o hitting water. Might want to buy a junk head to cut apart before you start grinding on your good one.
I think you may have missed something. Read again. Most of the bad part is a guide ramp. Typically they are solid but tis true one could strike water. That isnt the end of the world though. That can also be repaired. I like if possible to remove the guide ramps in a head completely then reguide it as I do that with my /6s anyway dwn to .343 or .312 stems. I leave the minimum sticking up although in the slant 6 it isnt too bad anyway. Then give it (the little section of guide sticking through.) a mild clean up. The base port is actually better than i had thought. Anyway I have 4 heads total so far. (3 spares)If i kill one so be it. The one on the rail I have beat on quite a bit already. Don ( Will the head stand that? I dont know but I have 3 and a 4th promised so I will sacrifice it gladly to find out.)from first post.
Never ported a slant six head in my life, so I cant comment on the likelyhood of hitting water, but heres what I use for making port molds. http://www.smooth-on.com/Silicone-Rubber-an/c2_1113_1135/index.html If you are talking about reducing the guide boss, theres usually no water there, More likely to hit water on the short side. Slant six heads are pretty common, why dont you cut one up? Then you know just where you are likely to get into water.
I hope it s not off topic , but here s a link to use regular silicone to mold parts . It dries in less than 1 hour . All you need is water and acrilyc paint . http://www.taxidermy.net/forum/index.php/topic,39157.0.html
No. Dead "rats" would come from blown up BB Chevies. For those concerned please note that I have been porting heads since 1965. This is not my first peak inside. So this was just to show that even without super duper port mold you can get a mold that will give you an idea of what you might want to do. I have used this quick method off and on when I had such a question. It goes along with the idea that "A picture is worth 1000 words." Don't worry about the specifics of this head. I will deal with it. There are a lot of ways doing things. Some better than others but sometimes you just want to know. You dont want to order $50 worth of stuff and wait ten days for it to come. This is quick and easy. And yes I realize not particulariy pretty. I did find out exactly what i wanted to know though. Don A couple have suggested why not cut a head up to check wall thickness. . I guess I just think different. Why not just port it and see . If I ruin it (which is unlikely since I can also repair it here. )so be it. If I cut it up it is gut fuer nicht! (good for nothing) If I port it and I don't ruin it? BONUS! Actualy after many years porting I can often tell by the temp where I am grinding if it is getting thin. The temp starts to go up and you can feel it with your finger. You stop then. Not later. I might not get all I want out but should be able to make a good improvement anyway. Don
Only problem is the "port and see" method won't tell you how much wall you have left. You might not break through, but you could be left with only a few thousandths, possibly leading to bigger issues later. Cutting a head up would give a much better "feel" for how much material can be taken out.
OK lets cut to the chase. I have ported heads both for myself and professionally since 1965. I have not ever had one go kaput after it left here. So on that bases alone I find it hard to work up a sweat. Secondly I do not have the abilty (equipment ) to cut up a head. I would have to PAY (Say what!?????) someone to do it ? And who would? So that idea goes into the round file. Forget the head. It is not about this head . It is about quick cheap easy port molds. You know some of you guys can muster more worry that I have had in my lifetime. Almost everytime I try something it works or it leads me to something that works. That is how I live my lfe. I get an idea I try it . If it doesnt work I figure out why and try again and again and again if necessary. To be honest most works first or second try. While folks are sectioning heads and measuring and postulating on whether the geedee is too close to the wingdoe I will have built two or three and run them as well. Like I already stated the metal gets warmer as soon as you get in the danger zone. You can feel it. Doesnt mean it is 010" thick. More like .125 but there is a noticable warmth not present before. That is your warning and you heed it immediately. After 45 years of doing this i really must say I find it hard to follow this angst over porting. And if I did go through to water which is unlikely I have no trouble repairing it here myself by myself. Dont worry. I am not. don
I like the idea of casting the port flexible and be able to take it out for study and get the grey matter working. Doesn't matter, porting or not I like it. Thanks for posting, nice to see how others do things. Vergil
Did you ever think about ponctuation ? This help reading Most of us who read you like what you do . It seems you speak sometimes just to be hated . The way you tell things seems to need an answer , but when you ve got one , you are not so nice and always answer about what you ve done for years ... And how YOU RE right . Maybe it is . Many guys here like what you do . I m one of them . It s just that sometimes you seemsso proud of you that I don t know . I love what you do . I hate the guy who makes this . Sorry , english is really not my native ...
Wouldn't have guessed you weren't from around here... Here is a question for you Don, not to hijack your thread, if you were to attempt a new cylinder head from scratch, what would you start with?
Pour mon Ami en Montreal. Je demere au Point Claire 3 ani. Je ne parle pas bein mais I began my official career as a Mechanic at the ESSO station (it was Texaco back then) just below (north of) Fairview Shopping Centre on Rue St Jean (Dollard des Ormeaux) I only pull out that stuff when I feel I need to defend myself. Otherwise if I was not under attack for doing something I have spent a lifetime doing I would keep it shut and never bring it up. Sorry. If i was building a new head? I have thought about it but really the slant six head is more than up to the job. People often get figures of 200 to 220cfm (intake)when porting. It is generally considered that 1 cfm will support 2.2 hp. I tend to take 2 instead to allow for real life factors so if I have say 200 cfm even I should be able to produce 400 hp. I am not and niether is anyone else. (no blower or turbo) so IMHO the cylinder head is not the real obstacle. Smoley Yunick used a formula he developed which was cfm should be 5.5 times cylinder on cubic inches for full flow at 8000 rpm. So if I used that and I have as I do 246 cubes currently divided by 6 = 41 cubes per cylinder X5.5 =225.5 cfm BUT I cant nor do i want to turn my slant to 8000. I need only 6500 max and probably not even that but that would require 225.5 cfm X6500/8000 = 183.21875 or 184 cfm for max flow at that RPM. That is easily doable and one has to realize contrary to popluar opinion the cylinder head is not the big buggaboo. I personally think it is a lack of a cam designed for a engine that is so so over square. I could be wrong but I have two ways of investgating that. One is build an engine with similar cubes but a shorter stroke hence the piston casting fun I was doing and the search for a 198 crank to put in my recently aquired 170 block which will get a huge overbore as well. The other area I am exploring is cams for this engine. I have had two custom made so far and think I am on the right track but not completely sure yet. Despite my belief the cylinder head is good enuf with a decent port job I still explore stuff just out of interest. In this case I had a misconception (that means I was wrong. You can say that. You won,t die) of what the port was like just out of sight in the port end. It is actually better than I thought. I did this sort of stuff with the 440 BTW in the 90s and discovered a lot. Much of what we were told and sold by Mopar perf was **** and just someones idea of what they thought might work. I became a man on a mission to find out what did work and had better results than I ever would have perdicted using a lot less $ and some very different cams and parts. From that came some mag articles I was asked to write (Chrysler Power mag) and later the book on BB Mopars. I am on a similar mssion with the slant six although it just started out as a fun car to try the snowmobile cabs on. Somehow I got really interested last year and so I am exploring a lot of stuff. I have little gold but lots of time and curiosity. So as yet no cylinder head redsign for that motor. The STR 8 Buick? I havent done a lot on them but I recall they are small in port size or so it seemed. I would do everything I could to increase intake flow. (Back cut and shaped valves, three angle valve job. Valve bowl rework, Port (dont polish) I would then find out on a flow bench at what lift max flow occurs and would cam it to that. Duration I would pick from desired and pratical RPM because that is what duration does. Duration then decides final compression ratio so that would come next. That is how I would approach it. Don
I used to get the same guff for just doing it instead of pondering. Half the fun is trying new stuff and if I can break it, I can usually fix it or at least learn something in the process. You, however are taking it to a whole new level of fearlessness which I truly respect. Keep it up and good idea on the quickie port mapping technique.
Under attack?? How do you figure anyone "attacked" you here? Here you are complaining about how how difficult it is to get your mold out of the port, and I offered up info on a material that is stronger, gives a better mold with no shrinkage, and doesnt need a release agent, and you call that an "attack"?
"Here you are complaining about how how difficult it is to get your mold out of the port" I said what?????? Where?????? You must be on a different thread. And btw George my comment was not aimed in anyway at you or your idea. I had been there twice already to check it out just so you know. It is saved on my favourites. I was looking for a pourable mold material last week and found a "smoothon" dealer who carries it in TO. But when I just casually am working in my shop and think about something like i did in this instamce i just use what i have or can get in a few minutes. I probably wont need another port mold for a year or so. Maybe never. I did this before when doing little experiments. It worked so well I thought I would share it when I was doing it this time. Don
Ok, fair enough. I will mention for others that are reading, you can usually get smooth-on or a similar GE product in most medium to large urban centers from places that cater to contracters who build swimming pools and hot tubs. Here in Vancouver, you can get it from Fibertek. Saves the h***le of mail order. If you keep it cool, un-mixed RTV has a pretty good shelf life, and a pound will make quite a few port castings. As someone else has mentioned, you can also use it to make a mold of small plastic and bakelight parts that you need to reproduce on a limited basis, and pour two-part epoxy resin into the mold.
Don, Have you ever done any porting work on a '23 Olds 3 port head? At some point, I'd like to do some work on mine, but hesitate out of sheer ignorance in the matter Thanks, Bill
No I havent. Most of my work is limited to BB MOPARs, early Hemis. 318 poly ,Small block Dodge, Chev, Ford and Dodge 6 cylinders. And to keep food on the table even several BB Chevs and Small block Chevs. Sometimes the problems are obvious like casting flash and rough spots. I would fix them first. Most of the power is produced in the bowl under the valve. Don't get carried away. Just improve it without risking damage. For beginning I often suggest using a round mounded stone rather than a cutter. Much easier to handle and does a better job. In fact when i am tired or not feeling well I switch to that to avoid getting in trouble. Making a port mold is a real eyeopener. Use whatever you wish. The good stuff like George mentioned works better but for a quickie my stuff works if you just need a quick look. Lastly never hesitate to try something. First learn all you can. (And never forget the guys who have never done it dont know anymore than you do before you start. ) David Vizard books are well worth a look. Think it through then go for it. In engines often more is too much. Be aware of that. Dont get carried away. The first set I ever ported are below. I worked in private and never told a soul what I was up to. Sometimes that is best. Dont do anything too extreme at first. I still only do foolish stuff for myself when i am exploring possiblities and am always aware it might not be good. With something rare you cant do that. Even if you do just a gentle clean up and nothing more it will be a good improvement. Don
Some good advice there^^ especially the stuff about working the pockets with a mounded stone instead of a cutter. Also, if you are going to shape the guide boss, a 1/4 ball works really well for that. I agree 100% about the port mold, it can really help to see the inside of the port in three dimensions. Ironic, most of my porting experience is BB mopar as well, also FE's, chevies of course. Never got my mitts on early hemi stuff. Maybe someday in the future.
Mine was back in the day. No wonder I feel old. Anyway another side to this topic. For years I used an electric die grinder. Then it died and I couldnt buy that style anymore. They are getting hard to find now or the ones you see at the surplus store look su****ously cheap. I absolutely hate running my 5 hp Compressor to drive an air gobbling 1/8 hp air powered die grinder. It seems so wasteful to me and noisy. I wondered about what a Rotozip would be like with its 1/4 inch collet in place. This morning because I had a job to do I went and bought one at Lowes. $80. In 10 minutes I did more work with it than I would have in an hour plus with air. And I can still hear myself think. I was cleaning up a raw casting from a carb adapter i cast up last Fri. It goes from a old WCFB pattern to a 2 slot Modern Holley pattern. I will rework my manifold too. The casting still needs a trip to my mill so bear with me on that. It is for my 318 Poly in my new Fed project. I have the carb and intake but am still waiting for my 318 engine and trans to arrive from the wreckers. Don
Honestly, I prefer the air grinders. They DO use a LOT of air. I used an electric for years, I find less vibration with the air grinder. I was using a 3/8 collet Sears electric for years. The little 1/4 collet Rotozip you describe there DOES look interesting. Does it have a fair bit of power? Do you need a speed controller with it? My Sears was WAY too fast, the first time I got my hands on a nice long shank cutter, it helicoptered on me IMMEDIATELY. Lesson learned. Had to clean my trousers after that! I have never tried casting aluminum. Read a bit about it and have seen guys do it, really neat stuff. When I was a young guy, I did pour and fit a babbit bearing as part of my machinist training, that was fun.
Don, Thanks for the info- hopefully I can pull a casting over winter break to get some ideas of where to smooth things out!
I had a Sears for years. I let a guy use my shop once while i went to Florida and he put a wire brush in it and used it like a drill. It died. (he almost did) Was never able to replace it. I just got the roto. It has a lot of power and doesnt run too fast. I would have been two hours with the air tool. I was total about 12 minutes. SO far i like it but I have only had it a bit so I better not say too much till i have used it for awhile. Re casting. I enjoy it. I am just learning this fall but it is to the point I need something I just make a stryofoam model , pack it in sand and pour it. My wife is an expert chocolate molder. I used to wonder what the big deal was. Now I understand. It is a lot easier than I would have thought. However it is sort of like playing the violin. Easy to learn to play but a lifetime spent trying to improve. Don I should say I spent a lifetime trying things but sort of crawled into my shell for awhile Watching George Miller make that cylinder head was a big inspiration to me and I decided to get back to my bucket list as it were. I have had more fun since then then probably in the last 10 years. McTim with his Y block rail and Roseville Carl to have rekindled the compe***ive spirit in me race car wise. Thanks guys.
My Sears is getting pretty old (about 35 yrs) I think I will replace it with a Roto. There are lots of times when its still good to have an electric die grinder, even if I find I still use the air grinder for head porting. Thanks for the tip, I am gonna check it out.
The Jalopy Journal
