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| New cam new head https://slantsix.org/forum/viewtopic.php?t=48866 |
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| Author: | Dolmetsch [ Mon May 21, 2012 9:29 pm ] |
| Post subject: | New cam new head |
At the close of the last season I began work on a new head for the Sr dragster. I also ordered a custom made cam to my specs. Sat I tried it out at Picton Airfield Armdrop Drags. I have no idea about the et other than a good guess but I ran against my pals Hilborn injected 454 FED all three passes. I beat him twice. He got me once. I am somewhat content to be able to run such a car heads up and be in the hunt. I took a lot of liberties porting the new head. Made my valves from Stainles chevy cores. Made up my .343 guides from SBI relacements. Installed dual springs as well. Final sizes were 1.460 ex and 1.750 intake. Cam lift is .565" and it is a hydraulic . This was the first outing with the new stuff and I am pleased so far. A friend took video of all three runs. He said he would give me a USB drive copy. He lives 70 miles away but I will get it sooner or later. Don |
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| Author: | Dart270 [ Tue May 22, 2012 5:47 am ] |
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Sounds great, Don! Glad you have had some success there. Keep us up on your innovations... Lou |
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| Author: | Dolmetsch [ Thu May 24, 2012 4:45 am ] |
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The second picture at the bottom is me on the final pull to the traps. You will notice I have my head forward and tucked down. At that speed my visor was thereatening to blow up as the wind is very strong once you get over a certain speed. http://countylive.ca/blog/?p=26397 The car above was the car I raced all day. We run heads up. Don |
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| Author: | Dart270 [ Thu May 24, 2012 6:14 am ] |
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Very cool! Looks like you have put a lot of work into that car. Lou |
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| Author: | Dolmetsch [ Thu May 24, 2012 10:22 pm ] |
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It is a labour of love though. I spent the morning checking over for the next race in July. Did some minor correction on carb jetting. Probably not enuf to make a huge difference but just to get better, more even, plug colour if nothing else. Also dropped the heat range of the plugs slightly. I have been running the stock RN14YC plugs but dropped to a RN12YC just to make sure I dont invite trouble. Rechecked everything on the carb including float levels . I pulled the valve cover and went over the head bolts torque after making sure the rockers and pushrods were all good and the rocker shaft bolts were not lossening. I run a hydraulic set up and the cam is my specs. It is quite a bit off the beaten path but I have suspected for a long time that what we were usually offered was not what these long stoke small bore motors really want. I am about as far as I can go with hydraulic and this cam has faster ramps then most solids anyway. I am thankful I found a company who would make it without second guessing the idea. Powerband is strong and flat. From even a moderate launch on the converter I am GONE! I would rather have the competition trying to run me down than try to chase them. Any time and distance made up at the start and mid range is a huge advantage down track. Tomorrow I will begin checking fluid levels and smell . I would like smaller front tires but I have now P155X80R13 on it. I am not sure where to go from here. Next race date is at a timed track. I know what my competitor runs there but I dont believe I will run those kind of numbers. I suspect my rail is just very well suited to the Picton Airfield conditions. Don |
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| Author: | Dart270 [ Fri May 25, 2012 6:24 am ] |
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Don, I think that's great you are trying a different cam profile and type. There is not enough development on the 225 to really know what is best for different conditions, IMHO. I am very interested in your cam specs, when you are ready to share them. For what it's worth, Cameron Tilley in Oz found that some slower rate of lift (and lower lift) cams were better than fast rate, high lift cams, even with really high flow heads (225 cfm intake, 190 cfm exh at 0.500-0.600"). Also, more intake duration was definitely better. Best, Lou |
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| Author: | Dolmetsch [ Fri May 25, 2012 12:27 pm ] |
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It is my opinion that because of the long stroke and the speed at which the piston goes from tdc to max speed (when rod and crank form a right angle) we dont have time in a 225 to fool around. That valve MUST be open and open quickly. otherwise the valve becomes an obstacle standing in the way of natural airflow that would take place say if for instance the valve was not there. In the case of the 198 or the 170 this would not be a problem but with the 225 it appears to be. So even though I dont run a lot of duration per say I am wanting "right now" valve opening. I have run 4 cams in this particular engine now and this one is producing rather remarkable performance. The previous one which was in the same vein although not as "active" produced also posiive results. The other two were cams ground under conventional wisdom and while they worked they were a far far cry from these last two and especially this last one. Maybe I can explain it another way. If the piston moving down the cylinder reaches max velocity BEFORE the valve reaches max lift then power is lost. I think that is understandable to almost anybody if they sit down and think about it unhindered by conventional engine thought (which is often Small block chev technology in reality and often doesnt apply to long stroke engines like the 225 slant and other similar motors (428 Ford is in the same boat to some extent) There is a lot more thought and fooling around that goes into it but this is the gist of it. In fact I am still pinching myself after last Sat race. Got more then I expected . That doesnt happen very often. Don |
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| Author: | Dolmetsch [ Sat May 26, 2012 11:14 am ] |
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BTw It says TBI slant six under my name. ???????????? Never not once ever had Fuel injection of any kind on a slant six. Always carbs. Today a single four barrel before snowmobile carbs. Don |
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| Author: | Dart270 [ Sat May 26, 2012 12:39 pm ] |
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Don, That "TBI" just refers to your "level" of posts on this site. At a certain number of posts, it changes. Nothing implied about your car(s). I agree the 225 is a different animal, and I can see your argument on the valve opening vs. piston speed. Valve diams (limited by bore) relative to stroke are at least as important, IMHO. Are you willing to share cam specs? If not, why? Lou |
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| Author: | Dolmetsch [ Sat May 26, 2012 4:34 pm ] |
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Cam is hydraulic . Lobes are the fastest lifter velocity I could find. Intake is 251, exhaust 257 Duration is measured at .050" . This set of lobes is faster (or as fast as ) then all mopar specific I could find both solid and hydraulic. I used duration at .200" to compare. Ist cam of this fast ramp style I speced at 110 and it was slightly milder as I was wading in carefully so as not to lose my way. (This one is 108.) When I discovered it liked it I moved to the more agressive one. Cam is in a 106 intake cntrline . Lift is .564" both lobes. As I raise duration I alway raise compression ratio to keep cylinder pressure where it should be. Why am I hesitant? Well first I have been called a fool more or less already even here before and wasnt really anxious to get burnt again but that is kind of a side issue. I am deeply involved in sorting through this combo much like I did with the BB Mopar before publishing the book. Not everything you try works. Sometimes it doesnt work because you did something else that messed it up or something broke or malfunctioned you werent aware of. You have to keep plugging away. Checking correcting trying and FAILING . Eventually you find your way then you are still not sure if you are where you think you are. I have not yet seen the video from the weekend. I would be a lot more comfy if I had. I am not sure if all the performance is cam related. If there is more to be had etc. I did go nuts on the head too but the other head had the same intakes and actually slightly bigger exhaust. I also planed .020" more from it than the previous one to adjust for the extra duration on intake. A couple of other things. No one makes this cam or anything like it so just using the same specs will get you probably nothing. Also the vast magority of racers or hot rodders do not understand the advantages of a hyd cam over a solid under 7000. (and any 225 slant six should never see 7000 rpm) A slant six is not an easy motor to run at perf speeds with a hyd cam. I am exploring this motor in my retirement and a trying to ignore what is popular thinking unless it fits the program because I firmly believe in my heart that there is a lot more in these motors then any of us has ever got out. Sort of like a half baked cake right now. Smells good but it isnt done yet. HOWEVER I must say running an injected 454 FED heads up with a 246 slant six and winning 2 out of three was beyond my wildest imagination. Both cars are FEDs and with drivers weight difference is minimal to say the least. Less than 100 lbs I think. Until I get to study the video, making sure he was running decent and started well I wont be satisfied that I actually pulled it off despite what onlookers have been saying ever since. I have been going over the car inch by inch since making sure it is all good for next pass. And correcting this and making small changes when I see something I think could be improved. I tend to be private not because I want to be mean but because I am starting with a clean sheet of paper. The 440 project was not much different. It began with putting the mopar engine book in the trash can more or less and starting over. Folks who know the OR 440 story will understand. I dont know what else to say. That is the best I can explain it I think. Re the cam The cam card states clearly from the company who made it and I quote "Customer Supplied All Specifications." Other then mine it does not exist so specs are pointless except for interest. There is a lot more to cams then duration and lift and lobe centres. Let me run it and rub on it a bit more. If it turns out as good as it appears to be I will share all. Maybe do another book. Even then though with cold hard facts in front of them there will be those who will still refuse to accept it. I have in the past taken abuse from the famous and obscure. Not a whole lot of fun when you are sharing with the sole objective to help your mopar pals eat more camaros. And when you are sharing actual tested, proven, repeatable results and not some untested opinions it is hard to understad why. But I guess that is life. It does make you gun shy though. Also this engine is so inexpensive that alone would be a deterent to most folks who believe more is always better and $$$$ cures all ills. Don |
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| Author: | Rick Covalt [ Sat May 26, 2012 5:48 pm ] |
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Quote: Also the vast magority of racers or hot rodders do not understand the advantages of a hyd cam over a solid under 7000.
Can you share more on this. I'm interested in the whole hydralic cam thing. Keep on testing and let us know how she does!!Rick |
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| Author: | Dolmetsch [ Sun May 27, 2012 6:00 am ] |
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I will try. first the practical limit for RPM with a hydraukic is 7000 RPM. Lots of engines dont require that much RPM even in full race trim. When you look at cam specs you will see cam lift for cams is given at zero cam lift in most cases. That is fine for a hydraulic but a solid must have valve lash. So suppose you have a mopar 509 cam. Hyrd you will get almost all the .509 lift . In a solid you will get .509- .025 valve lash intake = .484 " lift (now you know where the mopar .484 lift hyd come from ;>) On the exhaust .509 - .032 =.477" Then there is the fact that a solid must take up the lash and lower the lifter back down. This takes approx 7 degrees at the beginning and at the end for about 14 degrees of no power producing duration. When i runmy 440 motors I use a 253 @ .050 hydraulic or a 267 @ 050 solid to run the same RPM range. The solid lifter is not bothered by RPM as long as the springs can handle it while the hydraulic is limited to 7000 RPM. REcently some companies have been exploring the ability to speed up the valve action or lifter action in the Mopar cams because of the huge .904 lifter. It just so happens that the hyd version of these cams appear to have the fastest ramp speeds at the RPM range i was looking for. That is why they got the nod. A Roller would be best but we dont have that optionfor these engines. So from a practical standpoint the custom made hyd cam gave me the fastest valve opening I could have at the Duration (RPM range I wanted to run. And it gave me all of my valve lift , not just a portion of it. (gross lift - lash) I hope that helps a bit . Don |
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| Author: | Team Green [ Sun May 27, 2012 10:21 am ] |
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Great information. Thanks for sharing. |
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| Author: | Dart270 [ Sun May 27, 2012 10:24 am ] |
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Thanks for explaining your thoughts and your setup. We are all looking forward to your conitnued experiments and successes. I am right with you in that failure is the only way to really make progress. When/if you are comfortable, more specs on your car, motor, cam, etc will be much appreciated. I would be quite interested to try a hydro cam at some point. Lou |
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| Author: | Dan-o [ Sun May 27, 2012 10:43 am ] |
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Keep up the good work. I look forward to reading about your exploits. What is this "other book" referenced for Big Block building? Did you write one? |
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