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Discussion in 'Technical' started by SMCT, Jan 5, 2017.
I'm still not on the list
Soon you will it took me a year
Your talking about the oil support rails due to the bottom ring land and the piston wrist pint sharing the same location. The 496 I just built had srp pistons double spiral locks and the oil support rails. My hands and fingers felt like raw hamburger after preping and installing all 8 pistons on the h-beam rods with the rings. The spiral locks are awesome when you slip and one slides up under your fingernail. Cool to see one going together! You do very clean work bro! Head looks nice!
Thanks, appreciate it.
Spiro locks and wire locks are just something that takes getting used to. I work with them day in and day out, and over time you start to get the knack on how to install them. On many of occasions, when it comes to "ring groove spacers" you have to be very, very careful, as we have found that the piston manufactures do not necessarily have a full inventory of ring groove spacers and on many of occasions send the pistons with the incorrect ones. Some having the i.d. of that spacer too small where as it doesn't sit properly in the oil ring groove, others that the i.d.'s are too large which has them butting and actually scraping the cylinder wall as the piston travels up and down. It has to fit nice, and the parting area has to just meet without actually butting, and the o.d needs to be less then the o.d. of the pistons skirt just right under where that ring groove spacer sits. You also have to look very closely at that ring groove spacer, as it has a dimple, and that dimple goes down and needs to sit in the opening area where the pin is. I sometimes grind that dimple down so that if the ring groove spacer does move, it doesn't lock up the oil rail and expander.
Andy - respect!!!
Ok....so today in my shop I set up my Rottler SG8 cylinder head machine to handle these motorcycle heads. Today's project was focused on the intake seat. Since the engine has low miles (6800), it gives reason as to why the current valve job looked pretty good. Not being too fond of the intake seats width, I decided to reduce the thickness (.058 to .060) of that 45 degree seat width, to .039. which is common and it will enhance the flow. The cylinder head obviously is your entrance and exit of air/fuel and combustible (ignited) remains thereafter. The more air/fuel you can allow the pump (crank, rods, pistons and rings) to take in an exhale out in a given period of time, the more power the engine will make. The port volume, shape and valve job is critical in determining the amount that will go in and be expelled out. When the intake valve comes off the seat you want a nice transition of air and fuel to enter, without being disrupted. Every part that makes an engine whole should be considered, and regardless of the emphasis on one part or another, there is no one part that is magical, as they all must work in harmony together. I have lots of different carbide inserts that can go into my tool holder and I chose one that I feel would suit this engine the best, based upon port design and the current intake valve. I could have easily replaced the intake valve for one that is larger, and of better material and design, but this ain't my race engine and it's just a cruiser for me to enjoy. You come to find that many engineering faults are not necessarily faults, but of choices which determine total cost and profitability. I enjoy fixing these choices of the manufacture because the end result will be power gains from better engineering, and with better engineering you increase longevity. The power gains are actually the side affects of better engineering. many feel that power enhancements reduce reliability, and when done correctly, they don't. They increase reliability.
Looks great sir!
Thanks for sharing. I wish I had your expertise. All can be learned with time and experience, mechanic work is just a mere hobby for me so I enjoy these post from the experts.
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Ya the support rail suck to get the entire ring pack in as well I've had some pistons that the ring land wasn't wide enough to fit the rail expander and two oil rings in. I've done tons of spiral locks and hate doing them every time. Some spin right in no problem and some are a PITA for me anyway. Prob my lack of technique lol!! Looking good bro this out to be a bullet proof engine when your done! I love how your fine tuning all the little details. Your gonna have a great dependable mtr when your done. I think they are great engines but it is educational watching you take it to the next level from a machinist view.
Totally agree..wish I had the tools and knowledge to do it myself. Instead I'll have to ship the heads away and hope they come back like Andy's.
And to Andy's point earlier you betcha S&S has to make some sacrifices to be profitable or else they wouldnt offer their extra stage kits or bore jobs. Can't send an engine out perfect everytime they run out of business! And...the shortcomings of the manufacturers is what brings you your business. Everything has it place
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My business is open to the pubic, and I have no problem with doing work for anyone herein, including supporting the shops that might not have the equipment. Thank you.
Today I got into the exhaust side on the heads. When it comes to an exhaust port, you want to get that port as close to a mirror finish as possible. The smoother the finish, the less chance for carbon to adhere to it. Carbon will hinder the ports flow. Some shaping and rolling seen below. Getting there, little by little.
I know who I'll be sending my heads to..I will just wait till you've put a few thousand miles on ..grenade free miles I might add..
I appreciate the vote of confidence...lol
Into the second head over the past 2 days. Some of the pictures will show a closer view of the back angle or what is known as "1st back angle". The seat is 45 degrees and that back is the 37 degree. The grey line shows the position of where that 45 degree meets the seats 45 degree. That is the lapping compound. I usually vacuum test the port although my fixture doesn't quite fit right on the ports face and therefor I wanted to ensure that it is making a nice seal, so I lapped the intake valves. The cutter shown is to blend that last angle after the valve job was set in place. It takes that step off which the prior cutter left. I put a radius break on that carbide cutter insert so that it would blend nicely.
The "margin' is actually very thin on these intake valves, and it's not something that I would engineer at all. The back angle (not the back cut) is severe in it's degree (my guess about 28-30) for the bowl design and port height, and once again it's not something I would engineer. I only took a very very slight amount to clean that 45 degree area. I took at best .002 to .003 as it cleaned right up. The thin margin I believe is that of factory since the bike only had 6800 miles on it. I'm not to concerned because the rpm and power level won't affect that thin of a margin. Yes, the margin is needed for some strength, but it's mainly designed for flow purposes. Once again, the factory set it this way. In our race engines we have gone to thinner margins such as .040 and .045 in thickness and we do that to keep the valve light, and that might have been their thought process also, but with less of a back angle in design, it would have enhanced flow, kept a bigger margin and would have been an equal weight, if not lighter.
Thinner margins (.040 to .045) in the race engines also allow for better piston design because the valve relief or plunge in that piston doesn't have to be so deep and therefor you can carry less dome to yield the same static compression ratio. The margin seen pictured of the 117's intake valve is probably .025 to .030. The race engines see rpms of 8400 to 8800 and carry valve spring pressures that are 330 to 360 on the seat and over 1100 on the nose (full lift). Hydraulic rollers such as what's in the 117 should be around 140 and based upon let's say a 600 cam, maybe 3350-375 on the nose, with average engine rpms of 2300 to 2500 and bursts up to 6000.
P.S. If you look at the picture whereas it shows the grey indication of where it's seating, I can actually put the valve in the lathe and thicken up the margin a bit by cutting the head diameter so it is smaller. Just a little trimming makes a big difference in the margin, and I might just do that.
Envision the area after the grey area as an area that keeps the air straight once that valve comes off it's seat (low lifts). It's kinda like a muffler with and without a 6 foot tail piece on it. If you run a muffler without at least a piece of tail that is 6 inches, then you'r hurting the flow real bad.
As of today, the heads are all finished, including all the port work, chamber polishing, valve job, oil return enlargement and surface milling. I cleaned up (polished) the exterior a little bit as well. Tomorrow I will wash and assemble them. P.S. With all the holes in my bed plate, I still had to drill two additional ones to mount these heads. I also made stand offs so the head can fixture properly.
Those look awesome. Now send them out and get them diamond cut
No time fo dat. I've met my quota for this winter already.