As mentioned by Dennis S, Mike J's flow bench is now in Indy.
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| Slant Six Cylinder Head Porting and the Book of Secrets https://slantsix.org/forum/viewtopic.php?t=62141 |
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| Author: | DadTruck [ Tue Mar 27, 2018 9:43 am ] | ||
| Post subject: | Slant Six Cylinder Head Porting and the Book of Secrets | ||
As mentioned by Dennis S, Mike J's flow bench is now in Indy.
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| Author: | DadTruck [ Tue Mar 27, 2018 10:33 am ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
concerning the Book of Secrets, listed below is what Mike and I discussed over the bit of time while we were together at the flow bench. * Seat Angles: Mike used a 30 degree angle on the intake and a 45 on the exhaust. We talked at length on how a 30 degree valve seat 'opens' earlier but gives up flow at the the higher llifts. Mike said that with a head that is flow limited like the slant he was a believer in getting the flow started as early as possible. Mike put preference in maximizing low and mid flow volume at the expense of the max flow at full lift. He commented that the cylinder sees full lift once, but the mid and low valve opening occur twice on every cycle. * Where to work in the port cavity: do the work in the port bowl, leave the port arms alone, except to clean out casting flash, obstructions. Mike will reduce the height of the valve guide boss in the bowl. More so on race heads, less on street heads. As expected the short side radius gets attention. * Intake to exhaust flow balance: Mike agrees the standard 75 to 80 percent is a good target. Make said generally there is more time invested in the intake than the exhaust. * Valves: Mike uses Chevy 2.02 intakes cut to a 1.76 head diameter and the matching 1.60 exhausts cut to 1.46 diameter. Intake valves get a back cut. The valves have 11/32 stem diameter. the stem length is .110 longer than the stock slant valve stem. Mike said he did not make valve train geometry adjustments due to the longer stems. He said he liked the Chevy valves as they are produced in such great numbers they are relatively cheap. I found a set of 8 intakes and 8 exhausts new on Amazon from Elgin for 88.64 with free shipping. * Valve springs: beehive matched to the cam for pressures. * Valve seals: on race engines, seal on the intake stem, to prevent sucking in oil, no seal on the exhaust stems. * Guides: bronze * Rod and Main Clearances: .0015 to .002,,, Mike said he runs the thinner oil, going to 0 w 30 when he needs to go really fast, said it really frees up the motor. Also said he seldom spun the motor above 6200 RPM. He said he typically used Clevite 77 bearings, but he is sure he used other bearings with out issue. Said he used a stock high volume pump,(I believe he was speaking of a pump that was ported to increase flow) but never a high pressure spring or shimmed the spring to push up the pressure. Said that he did not use a rod bolt stretch gauge or torque and angle. He said for critical fastners he folllowed the bolt or engine spec for torque, would bring up the torque in several steps, let the tight joint sit overnight, loosen the fastner, then again over several steps again bring the bolt up to the torque spec. He said he used ARP bolt lube. Timing chain sets: Mike said his preference was the crank sets with the multi key ways. Mike felt it was just easier to deal with. Mike J was very successful for many reasons,, more than just the head porting, more than the engine building, looking at the Buzzin Half Duzzin,,, the front and rear suspension were reworked, rack and pinion steering, delaybox and other electronics, air shifter, and on and on and on, and he had an on staff mechanical guy to help out and Mike raced the car on a regular basis. Touch all he bases and you get a home run. He also said the slant six drag scene was a lot of fun, but he is totally done with that and moving on to other adventures. |
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| Author: | sandy in BC [ Tue Mar 27, 2018 10:39 am ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
Nice write up. Thanks for sharing Mike! |
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| Author: | slantzilla [ Tue Mar 27, 2018 10:49 am ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
One thing John didn't say about the car is that Mike and Blaine worked very hard on getting it light, and making it roll very easily. I was amazed how easy it is to push, even compared to my Daytona. 
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| Author: | drgonzo [ Tue Mar 27, 2018 10:58 am ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
Thanks DadTruck! |
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| Author: | Dart270 [ Tue Mar 27, 2018 11:40 am ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
Very cool points, and writeup, and discussion. Thanks to Mike, John, and all... Lou |
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| Author: | Badvert65 [ Tue Mar 27, 2018 12:49 pm ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
This is info we can use. I've added another chapter to my own "Book of Secrets" (INSERT EVIL LAUGH) |
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| Author: | Greg Ondayko [ Tue Mar 27, 2018 2:21 pm ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
This thread = sticky. Thanks. Mike, Dennis, John for your dedication in such pursuits. Greg |
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| Author: | Exner Geek [ Wed Mar 28, 2018 7:02 am ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
I think it might be misleading to say that Mike used 30 degree seats on the intakes for his race heads. When I asked him about improving the flow on the head he did for my street car, which does have 30 degree seats, the first thing he said is that we would have to go to 45 degrees on the intakes. Ask Lou, Greg, Rick or Guzzi what the intake valve angle is on their race heads, I would be surprised if it was 30 degrees but I could be wrong. |
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| Author: | slantzilla [ Wed Mar 28, 2018 9:11 am ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
Having heard the entire conversation many times, I can assure you Mike was adamant about 30. I know the first head he did for me was 45, but the second and all following freshen ups on both were 30. |
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| Author: | DadTruck [ Wed Mar 28, 2018 9:35 am ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
Quote: improving the flow
and running a 45 degree angle to get the largest flow number jives with what Mike was saying.As he said when he went to 30 degrees it was an attempt to maximize the total flow and not only focus on the highest possible high lift flow values. Mike said he used graph paper and charted out the flow at the valve lift values from closed to open, and worked the valve angle & porting process to maximize what he described as the 'number of boxes under the curve". He said he counted the boxes on the graph paper as he did not know how to calculate the actual area. If he did all of his heads that way, or if the graphing was a technique developed recently, I do not know, but Mike did not come across like he was just yanking our chains. |
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| Author: | Rick Covalt [ Wed Mar 28, 2018 3:46 pm ] |
| Post subject: | Re: Slant Six Cylinder Head Porting and the Book of Secrets |
Yes mine are 30 degrees. |
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