The season just ended. The new cam has been made and delivered for next year. I am working on a new cylinder head as well. As age begins to overtake me I realize I am close to the "now or never" zone and choose "now." I have a spare head . I made some port molds last year of the stock ports. I am doing on port per day and am working on the intakes. I made a port mold of the stock (white dirty gray) and the brownish one is the new port roughed in. I use plain silcon RTV and smear it in and let it set then resmear and let it set. Removal takes patience but it is what I have here on hand. To those who use Megakluck Portasius Muldofus from Gogeheim's Supply House, "Thatsa nice", I use what I've got. The port mold gives me a 3 dimensional visual of where I need to make improvements. I am taking this one to the max. I know I could break through at any minute. After 43 years of doing this I am willing to sacrifice this spare head in the search. The bowl area is the most important. That is where the ponies hide in a cylinder head. The area behind it needs to be able to support its new flow. I am happy with how it is coming so far. Don
You go Don! Ports look much better than I had thought - nice smooth turn from the valve. Keep on it young man!
I took the guide boss out completely and its ramp. I am installing new guides anyway and will make them with a nonobtrusive entry into the flow area on my lathe before installing them. There is a bit of a bump in the port floor causing a restriction. (about 3/4 to 1 inch in from the flange. Normally in most heads it isnt so but this engine has it so out it comes. There is also a depression in the ports on one side of the wall. These two deals are minor massaging and not huge grinding like the bowls were so I am hoping that is no problem. I should be doing the last intake port in the morning. Don
Now that you have a mold of the port, make a plaster cast block around the mold so you can experiment with changes. The plaster is easier to work with and if the block is big enough, it can be used on a flow bench to test your progress. I have used a rubber material to make a mold of a cylinder head (chamber and ports as one piece). Then cast as above for testing my ideas on port shapes.
I've had great luck with high-tensile industrial Jello... Also it's great fun when somebody comes in and sees you munching away on a port mold...
You know I dont think it would hurt a street machine. Because of the huge stroke which means high piston speed I (myself anyway) limit the slant to 6000 RPM. I have had several custom ground cams made, in fact got a fresh one made last week and hope to start installation tomorrow. The /6 has different needs and requirments than some of the more popular engines. The more I play with it the better I understand it. I dont think the book has been wrote on it yet despite the fact others may think so. It is a different animal. I will know better in the spring. I am surprised at how much carb it can handle. I have had a 750 on mine . Currently it has a 600 but I have to say the 750 felt better and it wouldn't be what I would have thought. Interesting about the plaster idea. I have got handy making these from silicon. I guess because I always have some in the shop. If I need more it is a simple drive to get it. If I have to order there is border stuff, shipping, hassle hassle etc. I am going to stick with this for now. Stormy, If you felt like I do you would be old too. By the time I get in my dragster I have to rest for 5 minutes or so before I feel good enuf to run it. I am going to train all winter.( Mall walking) Still thanks for the encouragement. Don
Finished the roughing of the intake ports. Will start on exhaust tomorrow. i do one port per day . That way I dont get in a hurry to get done. Discipline, the key to success, often. I made up a sample intake valve from another valve today. 1.75" intakes is where I am going. .343"stems. 4.95" length it looks like at this point. Don
John at Canadian Chrome Crankshaft has ground many cams for me includuing the cam for that famous six cylinder vintage stock car four CT now called Four America. I have a working relationship with John going back to the late sixties early 70s and often use him. He also made me the cam for the Olympia Charger driver test car engine (which I built here in Canada )which is still running around Europe smoking 911s on road courses. John understands me and I trust him. He does what I want without backtalk or second guessing me. I have also used Racer Brown. For Mopar cams he is hard to beat. The fact he had them 30 years ago means diddly. I am seeing what looks like a good 50 to 70 hp plus(mph on time ticket) over the more poplular cams. Currently I am getting Comp cams to make me some. The last two. They have a new lobe out that is mopar specific. I had one made two years back and it really liked it. I need more Rpm but not a lot, just another 300 so I needed more duration. I ordered it a week ago wednesday. It arrived monday morning. That is one thing I really like. I give a lobe number or set of lobe numbers from their library, specify the split and if advance is ground in or it is straight up. 3 to 4 days later it is here. No one else has been that good with me getting stuff done and I tend to use them when I am in a flog like this. Specs? All i am gonna say is hydraulic, mid .500s for lift and 250 something for duration at .050. I have tried both 110 and 108 lobe centres. This new one is 108, I may live to regret that but we shall see. That is how you develop stuff. You take a risk on your own $ and work till you get the result you want. The Old Reliable build (440 Mopar)I wrote the book about was one such build. 23 cams, several different pistons over many years and we wound up with a reliable 560 HP engine running on 94 octane making way over 500 HP costing so little many wont even build it. (under $4000. ) I am approachng this now the same way. If I could have a cam that would chase the piston down the bore with the intake valve about .100" behind it, stay open 250 to 260 degrees at 050 and have a net valve lift of above 550 and under 600. I would be happy. No roller available makes this difficult. So I am aiming to get there another way. Because of the long stroke the piston moves away from the bore much faster than say in a 198 or 170 slant and so you can open the valve much quicker without smacking the piston since it is "gone!" When port flow is limited then having the valves open full soon and keeping them open long is your other option. I would like a real honest actual 300 HP. I may never get it. It would put me in the 9s and I doubt for this car that is realistic. What somebody got on a dyno doesnt interest me. I want to see it on the time slip under MPH. Our local track is filled with engines that "dynoed" 600 or even 600 rear wheel that run 12s and high 11s. at 105 to 118. MPH. If they were really 600 hp they would be running all in the tens and 9s. My rule of thumb "It takes 600 HP in an average open wheeled car or altered to run 8.60 160mph in the real world. Don
Ah HA! There is a dead section in the exhaust port roof. It is very bad. I am roughing the rest of them in. I have 2 ex done now. It will require raising the port opening or changing the shape of the long first half of the ex port roof to make it flow. The first third of the port roof is completley inactive. This is probably the achilles heel of this engine. I am going to think about a plan of attack while I finsh the roughing in of the rest of the exhaust ports. I might not have enuf material for the major reshape. I do have enuf for the port raising if it proves sufficient to cure it. Don
Don Are you using the string test to find the dead/bad flow areas in the port? A valve with a hole thru the seat area to attach the string will show smooth vs turbulent flow on the exhaust. Intake flow is checked by feeding the string in from the intake side. Let me know what you find.
I took a few minutes today and reworked on exhaust port to kill the dead spot. It was successful. How did I know it was a dead spot? After many any years of porting heads I am in the habit of giving the port a soft blow to cleanout the dust IN THE DIRECTION OF OPERATION> I noticed when I blew out the exhast ports from the valve side there was a large amount of dust that did not move. I blew harder. nothing. i blew hard enuf I was dizzy. Still nothing. Today I took one port and recontuored the roof from the guide out till it blended. I raised the port roof slightly at the head openng too until I could just "poof" and all would blow clean. I think it is a safe mod. I check by touching constantly where I am grinding. If it gets warm that is a warning.. You usually dont get a second one. It stayed cool the whole time. I had a flow bench for many years and learned a lot about flow some of which I didn't like at first. However flowing an exhaust port backwards while it may give some indication of cross-sectional restriction is like measuring your 60 foot times in reverse. Almost pointless. Anyway that is what I did, how I got there and how I think about such things. Don
I often used a string with my flow bench. Your right it works well. Right now after the finish mod I can empty the ex port completely just from the fan from my grinder. before i could not nomatter what blow the dust out. I still have my stringthing around somewhere. I also useda small blocker sometimes to see where a port was active and where it wasnt. on the bench you could block some aereas and have no change whatever in flow. Floor of a iron BB Mopar intake would be a good example. I have two more to do. I also started making the intake valves from Ferrra 1.94 Ch@#$%^&*valves. Turbulence is death to a port. i remeber once getting a set of heads professionally ported by a famous comapnay who will remain nameless. this was just when Flow benches were coming into use. I testedthem and found depite their beauty and cost they had only 68% of the flow of a set of untouched stockers of the same casting. Knowing what NOT to do is often as important as knowing what to do. Pretty and flow are not always on the same page however it is nice when they are! Don I also use steam sometimes to watch what goes on. I have this rgged up steam kettle.
I've found that cutting or drilling a junk casting or two is very educational as far as finding thin spots in the ports, as well as places that can be worked on a bit more seriously. I learned that the hard way too. Good Luck!
Tis True Dave but "Junk" castings now are few and far between. The slant six with the huge demand of scrap iron has all but vanished from around here. I have ported a lot of them (slant sixes)over the last 37 years though as well as the Ford six so have a good feel for the no no areas. Still I brace mself. And there is also the other side of that coin. If I ruin a head to crossection it, why dont I just port it. If I dont break through I am "in like Flynn" and if I do I am no further behind and then feel free to chop it to pieces although I would probably repair it here. If I cross section one I have ruined it for sure. And then around here it would cost my probably $100 plus to get it cut if I could find someone who would do it. There are some cutaways on line I have seen and I did look at them once or twice before but I am out here in never never never land with this port job as I have never pushed a /6 head this much before. I am done though and have just the clean up to do . Hopefully I will survive that with no disasters. String Thing. I did the string thing again just for fun. Here is my reworked exhaust port flowing with just the cooling air from my electric grinder . Don
Nice work, it will be interesting to see how this head works - I am guessing this isn't the only change being made so it would be difficult to asses how much power your "dead spot cure" for the slant exhaust port is worth. I went through the intake port into one of the pushrod holes in a pair of J heads for my 360 and I successfully brazed it up - it held fine for a few years of pounding and hopefully a few more (the motor is under my work bench right now).
I used to sleeve the X and J heads using a IDL valve guide insert and then tool them oblong by hand (use a rat tail file but grind all but the one side flat. ) The resulting slot was not unlike the old Chev V8 heads. Then I could completely chew out the bump. Dumb thing is once I got the flow bench I discovered and trick as that was it dont help flow (didnt hurt it either. ) On the /6 I am doing this and a cam change. I will have to make another manifold and headers since I have radically changed the port shape even at the manifold flange. I have the new cam already. I am hoping to raise engine Power peak by about 300 RPM. I wanna blow the spoilers off some of my buddys mega $$$$$$$$$$REDs Don
I have to admit I was surprised myself at how it just sailed out there in the centre of the port hardly moving. Valve sizes, in case anyone was wondering, are 1.75/ 1.50. 11/32 stems . Exhaust valve has an undercut stem because it needs it. Chamber wil have to be relieved right by the valve head a bit more than stock. The loss of ccs will have to be recovered with a head shave. I am doing this head because my other works so if I mess up I am still mobile. It as the same size valves but is only mildly ported. Next week I will finsh the ports with a mild clean up of any goofy areas. I will then start working on the valve sprng seat. (cut for double springs )and will start making my new valve guides. I now cut my guides to lenth before installation and taper the port end where it is exposed. My friend and the guy who trained me back in the 60s is still in business and said I could use his IDL machne for the guide installation. Back in the day(1968-1972) I used to be his cylinder head guy. Don
Wow, this is truly an educational thread. Thanks for posting Don. I have a few new ideas for a couple of engines currently lounging under the bench. I am looking forward to seeing your results in action.
I should like to take a monent to thank CRKINSP for reminding me about the string thing. I must confess I had never used it without my flow bench before but can see that it could be a real aid to home porters. It is certainly a big jump over grind and shine porting. Don "If you want to port you must think like an air"
Thanks Dave, I have now just to do some clean up. I am still hunting for my long grinding stones. Been awhile since I had them out! Intakes are pretty well there . just some minor crap needs to go. Exhaust needs a smooth under the bowl. I would prefer to use a stone for that. I always leave the surface a bit irregular otherwise air sticks to the wall and slows down the port. We are a long way from stock though. Port mouth is now changed so i have to fab my intake but been there before several times. I maybe able to alter my tunnel ram project slightly and make it do the job. As long as there are not any sudden changes in shape or size it will work fine. Don
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