Don, that long stroke creates so much velocity and sudden air movement, that is probably why you can run a big carb!
I agree Mike. It affects the engi in many ways that stroke. I am step by step exploring it because I want to eat a RED for lunch with my Slant 6 FED. I discovered when doing motors for my pals 6 cyk Ford altered that you have to treat a six like it was an 8 carb wise. All the dynamics are there so his 300 Ford was carbed as though it was a 400 Cu in. the iprovements were significant. (AKA beyond I think , or it feels good , more into man look at the drop in ET!) We ran a 800cfm on it. Don
Don glad to see you are at it again. Love your thinking and explanations for your work great thread as usual..............Carl
Thanks Carl. I was shocked at how much I got out of the heads. Almost afraid to finish the clean up. I am quite happy with the head now. Don
Great stuff Don, I had better check my 312 heads, hopefully I haven't butchered them too badly!! LOL! I can remember reading years ago to leave the ports slightly rough, otherwise the fuel could cling to the ports, looks like you agree with that.
Yep I tried it on my old flo bench where several heads were sacrificed in the name of research. I have reached the point where I am done porting. I have improved this head more than I thought was possible and it is still a sound piece. It is at this point I invoke the "cabbage rule" (Quit while you're ahead) Next will be making the guides up from SBI blanks . Someone asked recently how do you get all ports to flow the same. Sometimes it is remarkable how close they will be other times it doesnt work out quite so nice that way. Bottom line is all finished ports must be able to flow more than the engine's demands. So if one flows 280 and another 276 and another 281, if the engine only can use 265 all will be well. When its full its full. As long as one port is not below demand (in this case 265 for instance) all is well. How do you know how much an engine needs? I have my way of telling . An engine running to low 7000s needs roughly a factor of 5 times its volume of one cylinder in numbers to supply that cylinder at a specific RPM. For instance if I wanted to run this engine to 7000 + around say 7200 -7300RPM I would need 246 (engine total cubes now divided by 6 cylinders = 41 (cubes for one cylinder) X 5 which = 205 CFM at 28 inches of water (H2O) Now that is a quick rule of thumb deal. The actual figires are a bit more precise but the end result will be fine. You need to make formulas work for you. Round them off where you can so you can remember them and do them from memory. Dont like math? i didnt either till realized that unlike most other things in life math never lies. BTW The geek walking around with the laptop telling you "well that formula is actually not exactly right" has never built anything and he never will. Why? Critics are rarely creative people. They have more in common with donkeys. This will get you where you want to be quickly and easily. More is not better. Enuf is better. More is just more and sometimes can be a hindrence. As long as the port can fill the cylinder properly that is all that is required. More wont get you anything. Except broke maybe. Don
Don, I am in full agreement with you about the critics, never a shortage of them!! What is your take on 30 degree intake seats? Thanks for sharing. Mike.
Me? I am a 45 degree man however I concede some 30degree seats work well too especially at lower lift. Seems to me 428 CJ was 30 degree intake (I used to be the cyl head guy for a 428CJ SS car (Gentle Benn) in the late 60s) as was the 235 chevy six. Don
Here's another interesting twist; International uses 30 on the intakes and a 37.5 exhaust angle on the V8 Power Stroke type engines!! I did a pair of those several years ago, surprised me!!
Yeah, Binders leaned towards 30s too. There were lots of others too. I was however unaffected. I am a 45 man and not 44/45 either. Today I began serious work making the new intake valves. Stainless is hard to machine and I have to sharpen after each valve is made. So I did three and am resting . The fourth one is my trysee. You always must have a trysee before you embark out in the unknown. It is however not stainless. Don
I have taken care of it Mike and for Bob your PM address isnt working so here is what we were talking about. I paint it wth Aluminum spray paint and install it wet. I learned this some 40 years ago and it has never ever let me down. Don I have finished the porting and the head is being planed .090". Meanwhile I putter away on the valves.
Hi Don very interesting work. Have you ever hopped up a flathead specifically the Chrysler flathead six?
Yes Rusty. My older brother Ron used to be pres of the Ottawa, Manatick Antique and Classic Boat Club. I ocasionally did engines for him. One in particular was a Chrysler crown in a Greavate mahagony launch and he wanted " a bit more" I did a good race type build on the block which means I paid a lot of attenion to ring fit and choice, clearances (not too tight. ) and a super multy angle valve job. I took 030 from the block and 030 from the head. I sent the cam to Crane as they still had FLathead masters and an old dude who understood the engines. He gave me a grind about two steps over stock. I never rode in the boat but Jim Potter who restored the boat after my brother sold it tells me everytime I see him it is the best working Chysler Crown he had ever seen. Now maybe he says that it everyone . I dont know . Marine engines almost always have twin carbs and BIG volume oil pans. They, unlike their automotive cousins (same motors ) are indestructable. I put it down to the oiling , specifically the high volume pan. Don
We have here a local quartetly called County Magazine. This issue out today has in the centre an real good article on the Armprop deal at Picton Airport and there right in the centre with the bottom staple going right through it is a picture of the Senior Dragster with both wheels in the air. Great Photography I would say. It says "Don Dulmage leaves in the Senior Dragster with both wheels in the air. " Actually it is my pal Patrick Doornbos driving. White helmut and there is about 8 inches of room above his head in the roll bar. (I can touch the padding when I sit there. )Pat is quite a bit shorter and not as round as I. (Geat guy and good driver though. He has a BB Chev powered FED.) Anyway it is a great photo. Copywrited of course but I will ask the flash Reg Smith for at least a unstapled copy and perhaps permission to post it one time. Don
That's great, would like to see that pic!!! By the way I got your got your DVD; good job, love the part where you dusted the Camaro!! Local drag strip; Racer A; "You racin' tonight"? Racer B; "Yup". Racer A; " Whatcha racin"? Racer B; "A Camaro". Racer A; Well which one"? Racer B; "Red one". Racer A; "Well, which one"? : P
good read. I race a slant old Dart been thinking of them ports as they were original 170 cu inch design.. any idea total port time involved? be well.
Do you mean how long did it take me? I worked a couple of hours per day for about a week. This week I have been working on the head to finish it. I rough cut the seats and finished them at my friends shop with his seat grinding equpment. i didn't have any small stuff here , just 440 size stuff. I made all the valves from other suitable cores. Two of the intakes I was not happy with and will redo tomorrow. New cam was custom made and installed and broke in on the old single spring head. This one is getting 995 comp dual springs. Tis hard as you get older to see what was once a days work is now a week or so. Anyway I am suspecting good things from this combo. This head is a far cry from the original or the one on the car now. Hopefullly it will produce. Don
Still some more good reading! thanks Don, a couple questions on 'stock' motors what would you consider a good 'everyday' cmf for the /6 {mine has an OFFY 4 barrel intake} & would header be good-bad on a plain ole daily cruising? Thanks Chuck
For CFM double the cubes. On the street go to the nearest below. Ie if you double the cubes and get 630 run a 600 cfm carb. For race go the other way ie 630 becomes 650CFM. This is known as "Don's Law" and it works very very well. I spent the day finishing making the valves and grinding them. Now all I need is to set the stem heights all the same and assemble the unit and install. The porting is the easy part. It is the long road after making a head proper that takes the time. So far I am liking how this is turning out. Don PS, Yes on the header.
Don, any chance you could make templates of those ports for guys like me to do a similar port job?...I'm planning on running a modified slant 6 on the salt someday at Bonneville and I'm always willing to try new ideas...you've already taught me a lot through your posts here and changed the way I think about how to build engines, I really enjoy your posts and real world experience...
Someone just gave me this picture taken at last years Airport drags. Even 30 40 feet out of the gate it is carryng both front wheels up nicely. I am calling it Yaba Dabba Doo! That was my pal Pat Dornbos driving. I fill out the "whole" rollbar. I can try a template of say three or four of the ports since they are all the same (intakes all the same , exhaust all the same. ) Biggest single inprovement is get rid of the valve guide boss protrusion completely in both intake and exaust ports then install a new guide with the end tappered 60 degrees that just comes into the port. That is the biggest singe improvement one can make. What would be normal and not a big deal in a large port is huge and a real big deal when the same size in a small port like the slant six head. I went to 11/32 gudes and valvestems as well. Final valve sizes were int 1.750 an exaust 1.460. I felt any bigger would lead to shrouding and I releaved the chamber wall around both valves when doing the valve job although on the intake it was minor. Engine is now back together and running. Don
Cam is run in timing set , all ready to go. I also put a new whinch on the truck to whinch the car up the ramps. I will do the final check over today and will then be ready for the Armdrop drags at Historic Picton Airport this saturday. Now we will see how it works!
I ran the car today. It worked great. Pulled hard all the way and went throughthe traps fast enuf I had to work to hold my helmut level. Also stopping is now something I dont take for granted. Had it bouncing a couple of times. Ran my pals Chevy Dragster all three runs. Spanked him twice but got spanked myself on the last run. A lot of my success is due in no small part to the converter Frank Lupo made for me. I am out and gone in an instant so even cars with a lot more power have to work to catch me. New cam and head gave me what I was looking for. In fact at the far end it is down right scary. (to me) I shifted at 5800, 6200 and 5900. 5800 felt the best. I am on auto shift so I preset before launch , pop it in drive and hang on! Don
Don: I've been casually following your builds since the articles in Chrysler Power Magazine appeared. You NEED to post this thread (or at least an article) at Slant.six.org. and show the guys over there how to really make one of these engines sing. BTW, what are your thoughts about "angle milling" the head on the "Leaning Tower of Power" and long connecting rods versus stock length connecting rods? David Gibson
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