Don its excellent to see all of this progress on your slant dragster. After building so many outstanding big blocks, its great to see that expertise and ingenuity focused on this slant. See, retirement ain't so bad right?
MJ
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| Author: | NewLancerMan [ Fri Mar 27, 2009 9:40 pm ] |
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Don its excellent to see all of this progress on your slant dragster. After building so many outstanding big blocks, its great to see that expertise and ingenuity focused on this slant. See, retirement ain't so bad right? MJ |
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| Author: | Dart270 [ Sat Mar 28, 2009 12:07 am ] |
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We'll be interested in your results too. Believe it or not, it's tough to get a Slant to make peak power above 6500 even with really big cams - small bore, long stroke. Lou |
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| Author: | slantzilla [ Sat Mar 28, 2009 10:29 am ] |
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Don, even with the spray on my motor is about done at 6400. I have a .558" Clifford solid. Like Lou said, trying to turn a lot of RPM with a Slant is defeating the purpose of having long stroke motor. 
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| Author: | Dolmetsch [ Sat Mar 28, 2009 6:25 pm ] |
| Post subject: | Rpm |
Thanks all, I have no intention of running even 6000. I choose the cam profiles using a formula I developed over the years. It is my belief that peak power will occur at 5700. I believe that is safe for a big stroke motor like the slant six and the head flow I have available. Power will be somewhere in the mid 200s and certainly not above 300. In a 1400 pound car plus my wieght i believe it will be sufficient to give this old boy one more thrill before he is too old and too stiff to climb in the dragster. I am happy with the car in everyway but I did think it deserved a race cam, not just forced to run with this mild street grind. I plan to install it next week. i also need to improve the leverage on the master cylinder and install an idle bypass in the fuel system to stablize the fuel pressure at idle. Nice Lancer BTW. I origianlly built this motor for a 62 Valiant V200 but the project never materialized. I was most fortunate t get the motor back untouched. Time will tell if my planning is correct. Don |
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| Author: | sandy in BC [ Sat Mar 28, 2009 7:19 pm ] |
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Is it a hydraulic motor now? Why a hydro cam? |
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| Author: | Dolmetsch [ Sun Mar 29, 2009 2:39 am ] |
| Post subject: | hydro cam |
Why a hydro cam? I almost hesitate to answer since cams are not well understood but here goes. Early hydraulic cams (1950s ) were not good for racing or high RPM mostly because the lifters pumped up at higher rpm and rendered them useless. By the early 70s hi rev hydraulics became available and the factories eventually quite offering solid cams but the performance didn't suffer. Now it is no problem to get even replacement hyd lifters to operate well up to 7000 rpm. That is about the practical limit. Hyd, cams have some huge advantages. One is you get what you pay for in lift Suppose just for example you buy a solid cam with an advertised lift of .550. If you pay attention to the cam card you will notice it says "valve lift at zero lash" so a typical .550 lift solid would give in real life .550 lift MINUS .028 valve lash = .522 actual valve lift. A hydraulic cam of the same specs wold give .550 lift minus approx .006 (lifter absorbs about that on the lift) or a net lift of .544 in real life, Also a solid has to use some of its advertised duration to take up the valve lash gently and begin lifting the valve. It also has to fiddle around setting it down so I find typically about 14 degrees advertised duration is spent doing this which has nothing to do with power since the valve isnt even open yet or at least not significantly. The hydraulic cam uses the shock absorbing nature of the lifter to suck up some of the bad things valves dont like so it spends its duration making power, not fiddling with valve lash . Since both camsliftrate is only limited by lifter diameter there is no way the solid cancatch up if the hydraulic is a serious grind. Since we are talking about a slant 6 and under 6500 RPm for sure there is no problem finding a lifter that will operate in its entire RPm range. The same holds true for most 440s as well, in fact the 400 engine I did for the lemans project in France carrys one of my own private hydraulic cam grinds. I see that car is now for sale and is listed as a solid but it is not and i did not build it that way. They just cant get their head around the idea that an hydraulic makes that much power and will pull easily to 7000 rpm but it is, complete with the MP performance Hd stamped non adjustable rocker arms. Whan I was busy testing the 440 stuff before i wrote my book on it I found that it took on average about 14 degrees more duration in a solid than a hydraulic would need to equal that same rpm peak power. I also had to adjust lift figures for the loss in valve lift due to lash. Biggest problem with a hydrauic is finding a grinder wth a good set of hydraulic profiles. Racer Brown was and still is ahead of the curve on this with their ST H 42 grind for instance which a is a BRUTAL Powerful cam. A lot came out of the Junior stocker days in hydraulic am development with companies like Cam dynamics and Lunati making super powerful(cheater ) hydrauic cams that would rev 7000 with ease even with stock springs and at stock lifts. Just now in the last few years some companies are getting serious about hydraulic grinds and finally, as well, Chrysler hydraulic grinds which are also far more powerful because of our .904 lifter diameter.(allows much faster rate of lifter rise without worry of lifter cutting cam flank) BTW I know about the roller hydraulic test in the engine masters issue a few months back but do not subscibe to the theory or botched conclusions that came from that article although I know they meant well and anyway we are talking about flat tappet hydraulics. You should know however that the new Hemis are now making upwards of 600 hp in some race situations and to date there are no solid cams or adjustable rockers avaialble for them. To conclude let me give a real life example from my cruise night car, my 63 Dodge 426 Max Wedge. That engine should have adjustable rockers solids and a.520 lift cam. That would have given it a net valve lift of .520 - .028 valve lash -.492 lift. Instead I had a cam made with 310 adv duration and 525 lift in a hydraulic. it now has a net ift of .525 - .006 fudge factor for the lifter absorbsion = .549 net lift. The adjustable rockers and pushrods are under my bench and it now sports a set of stock 440 rockers and pushrods.It is quieter, faster, revs as high and makes power higher than the stock MAX wedge cam ever could have and since it never sees above 6500 rpm it is fine in that application. If it was required to run over 7000 i would have no choice but to go solid but it isnt the case here and nor is it so with the slant 6. I know this flys in the face of conventional wisdom and even more so tradtion but it is never the less so especially now as more agressive cams become available in the profile libraries of todays modern cam grinders. So bear with me while once againi put my money where my mouth is and we will see what happens. I had this new cam custom made to my specs so it doesnt exist anywhere otherwise. i am curious to see how it works out in real life. don |
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| Author: | slantzilla [ Sun Mar 29, 2009 4:57 am ] |
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I suspected that was what you were after using a hydraulic cam. The main reason many of us don't use hydraulic cams is that a Slant is a PITA to make work with one. The Slant oils the lifters through the pushrods from the top and that requires a different rocker set, and pretty much locks you in to custom pushrods to make up for any milling/decking. Valve stem height must be equal after the valve job too. There is also speculation/doubt as to whether an early head will flow enough oil through the passage in the head to support hydraulic lifters at higher than stock RPM. Make sure your cam has a groove in the rear journal instead of a hole like a solid cam or you'll never pump the lifters up either. I have a sneaking suspicion that since you made a set of snowmobile carbs work this will be child's play for you.
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| Author: | Dolmetsch [ Sun Mar 29, 2009 6:35 am ] |
| Post subject: | cam |
I did have some issues at first with the oiling but solved it in about a day. Mostly it had to do with the one funny bolt the late model head uses when hyd liftered. Stem height as a machinist I always set as a matter of course on Mopar heads. I used pushords and rockers from an 80 truck. You are right though , it was an agravation that would not have otherwise been there but I was comitted to the project so there was no turning back, (Das ist die deutsche weg!) Luckily for me the carbs are blind and dont know they are not on a snowmobile! They actually work quite well with only one little minor problem when the holley regulator starts to creep. I hope the idle by pass trick will solve that. They just cant stand above 3 psi expecially at idle or they drip. Webers would be no dfferent if memory serves me but it has been 30 years since i played with them. Luckily being sidedraft and slighly downhill since i set the engine up about 2 degrees straighter in the chassis they drip on the ground, not into the motor. Most of the time they are fine but the regulators I have had so far are not steady enough for my liking and will vary between 3 and 4.5 psi during a days running. I probably shoud just run an MG electric pump which is low pressure for SUs and such but I decided to use the stock slant six pump so i give it one more try. Actually only I am bothered by this. no one else seems to know it is going on but I want it working right. When i embark on a project like this including my latest cam I am fully prepared for it to be a wash as well but find often it is worth the effort to try your ideas. Even when they dont work it usually leads you somewhere that does. It keeps retirement interesting for me anyway. Thanks all, for the encouragement and interest. I appreciate it. I will keep you updated (even if it turns out crappy.) Don |
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| Author: | stonethk [ Sun Mar 29, 2009 6:52 am ] |
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Dolmetsch, cam specs/valve train dynamics are somewhat of a grey, mysterious area for me at the moment, but I am reading alot and learning. Maybe I missed something but reading your posts i am curios, are you using adjustable rocker arms with hydraulic lifters, for preload adjustments? If not, whats your take on this- if it is even possible. sorry if these questions are dumb.
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| Author: | Exner Geek [ Sun Mar 29, 2009 8:37 am ] |
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On my race car with Webers I use two Holley Regulators, the first one set at 5-6PSI and the second at 3-4PSI. That seems to provide consistent flow at low pressure that this type of carb likes. |
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| Author: | sandy in BC [ Sun Mar 29, 2009 9:10 am ] |
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Thanks for the detailed answer. |
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| Author: | Dart270 [ Sun Mar 29, 2009 10:16 am ] |
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This makes some sense, although I'm not sure I agree with everything there. Hydros also have some lash and lash ramp, but what you're saying is that they just require less of those than a solid. So the obvious question is why not just run bigger numbers (lift, duration, overlap) on a solid cam since it will just act like a smaller cam than a hydraulic? As you say, the solid cam will act like it has less duration and lift than a hydro with the same specs. Maybe this is why I freak people out when I tell them how big my solid cam is and it still runs fine on the street with 10.5:1 and 92 octane. I'll be interested to see how your cam works out. Thanks, Lou |
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| Author: | Aggressive Ted [ Sun Mar 29, 2009 10:28 am ] |
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Lou, What are your cam specs? and how much is it advanced? |
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| Author: | slantzilla [ Sun Mar 29, 2009 10:32 am ] |
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Quote: So the obvious question is why not just run bigger numbers (lift, duration, overlap) on a solid cam since it will just act like a smaller cam than a hydraulic?  
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| Author: | sandy in BC [ Sun Mar 29, 2009 10:48 am ] |
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Quote: Because he doesn't want to be involved in the "How do I adjust my valves" argument
please....I like to say "set the lash"Actually I think adjustment will be a big issue. If all you have is pushrod length for adjustment it could mean a lot of pushrods . My experience with Smith Bros was positive but it stll cost a hundred dollars. I would not relish repeating that each time the head was off. I suspect you would want the hydro lifter preload to be in a pretty specific range. If you said adjustable pushrod ...........(with oil pressure?) |
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