Bummer, dude. You need at least 0.611" lift to make a slant-6 put out as much power as a stock 440.
| Slant Six Forum https://www.slantsix.org/forum/ |
|
| Eileen - Camshaft selecting https://www.slantsix.org/forum/viewtopic.php?t=24148 |
Page 4 of 9 |
| Author: | Bren67Cuda904 [ Wed Jul 25, 2007 12:16 pm ] |
| Post subject: | |
The guy that built the head and setup the springs said from memory that my head has got a .550 lift before coil bind. I just took some measurements. I know it not the correct way to measure but it should be able to indicate a go or no go. With my .518 lift cam installed and .19 lash, I rolled the motor over to depress a valve all the way and used a feeler gauge to measure the space between a set of coils. (the inner spring has more space than the outer) I am measuring .040 between coils. There are at least 3 full coils and 2 hafe coils. Thats .160 clearance fully depressed. Add .050 for safety and in theroy I should beable to run a .610 lift cam. |
|
| Author: | SlantSixDan [ Wed Jul 25, 2007 1:24 pm ] |
| Post subject: | |
Bummer, dude. You need at least 0.611" lift to make a slant-6 put out as much power as a stock 440.
|
|
| Author: | Bren67Cuda904 [ Wed Jul 25, 2007 1:53 pm ] |
| Post subject: | |
I guess I could steal .001 from my safety cushion. 
|
|
| Author: | Doctor Dodge [ Thu Jul 26, 2007 9:02 pm ] |
| Post subject: | |
How well do you like your current cam? Does it have a good idle, good off-idle response, where is the red-line? If you had no pinging, could you "live" with the current cam profile? DD |
|
| Author: | Bren67Cuda904 [ Fri Jul 27, 2007 6:07 am ] |
| Post subject: | |
Idle is good. I was hoping for a bit more lop but it easy to drive. Off idle is good. For the 240 cam advanced 5.5* it falls flat at 4700rpm. |
|
| Author: | BigBlockBanjo [ Fri Jul 27, 2007 12:48 pm ] |
| Post subject: | |
I still say you need more overlap, ect. the Schneider grind. 106-108 *. The Crane guy is right to a degree, but like mentioned earlier, if you have too much pressure to use down low, your really losing horse power. An engine is a precision "pump", and if you motor was built to swallow a huge cam, you can only influnce the low end so much... hmmm...I mean even if it has more top end than what you want, your timeslip would improve greatly with a larger cam, since a larger cam would be closer to the "perfect grind" that meets the requirements for your motor. My .02...... |
|
| Author: | Bren67Cuda904 [ Fri Jul 27, 2007 1:00 pm ] |
| Post subject: | |
It is my understanding that going down to the 108 from the 110 I have, my problems will get worse. I've been told I could keep all my cam specs the same but increase the lobe center line from 110 to 114 and my compression problems would go away. Instead were going with more duration and keeping the 110 lobe seperation and sould do the same for bleeding off some compression. I talked to 4 different cam companies and they seem to agree for the most part. I hope that I explained my problems clear enough to these guys. I hope I don't have a worse situation coming in the mail. 250/250@50 110LobeSep.562lift. |
|
| Author: | Doctor Dodge [ Fri Jul 27, 2007 9:09 pm ] |
| Post subject: | |
Quote: ...I've been told I could keep all my cam specs the same but increase the lobe center line from 110 to 114 and my compression problems would go away...
This is not true, you need to decrease the lobe centers to increase the overlap event.Based on you low redline RPM, a more aggressive lobe on the same centerline should help. ( if the low redline is really cam related) I would think 60 to 65 degrees of overlap should work pretty good based on your cylinder pressures. Ask the cam grinder to figure-out the amount of overlap at 106, 108 & 110 lobe centers when using the lobe profile you have selected. DD |
|
| Author: | BigBlockBanjo [ Fri Jul 27, 2007 11:02 pm ] |
| Post subject: | |
Quote: I talked to 4 different cam companies and they seem to agree for the most part...
Really?? Hmm.......(I'm not picking on your thread, BTW) Let's go over this real quick. Overlap- the time during the camshaft cycle in which the intake & exhaust valve are both open; overlap is increased the closer the centerlines are together. Centerline decreases and overlap increases. So, you may have "fixed it" with the new cam (hopefully), but an increase in overlap will always lower cylinder pressure. Because the piston is higher in the bore by the time the exhaust valve takes a seat. Good Luck! |
|
| Author: | Dart270 [ Sun Jul 29, 2007 4:12 pm ] |
| Post subject: | |
I have so far never talked to a cam grinder who I thought understood the Slant 6 on cams. I'm not saying they're not out there, but the standard places (Erson, Crane...) do not have the background or testing behind them. I agree with those above who say you need LESS LSA. I run 106 LSA 250 @ 0.050" and it works very well on 10-10.5:1 comp. Not too big at all. 108 would be the max I would even consider getting custom ground. Dave Vizard had a nice article in Popular Hot Rodding recently about LSA, and I used his figures to calculate that the Slant should have 105 deg. The guy making the most HP in a drag car in the whole US uses around 104-106 for best power. Best of luck, Lou |
|
| Author: | Joshie225 [ Sun Jul 29, 2007 8:48 pm ] |
| Post subject: | |
Lou, I followed Vizard's formula for calculating LDA and came up with 108° for a 225 with a 1.78" intake valve and 114° for a 170 with the same 1.78" intake. Were you calculating LDA with stock size intake valves? |
|
| Author: | Sam Powell [ Mon Jul 30, 2007 6:17 am ] |
| Post subject: | |
I would think two ,three, and even four times before I put that cam in there. In fact, I would not put that cam in there. It might improve it some, but it is not what you are really looking for. Why believe a counter guy at a cam company over a group of serious racers who have been playing with slants for 40 years? All the work you have done, and will do to change it, and you are not optomizing your engine still. There is no doubt that the 108 or even Lou's 106 centerline is what you need to wake that engine up. If you drove Lou's '64 you would never long for a V-8 again. I'm telling you, his car is strong, and I think you are only the correct camshaft away from getting the same kind of ferociousness out of your engine. Cams are not that expensive, compared to the install and setup time. I would either send it back, ask for a replacement from them (Is it a Comp Cam?), or sell it on this site. That cam would be great in any number of other slants on this forum. You're just going to be mad again if you put that cam in there. I think you got "sold" that cam shaft, just the same way you were "sold" the rebuild. The guy talked a good line, and you signed off on his word. Sam |
|
| Author: | argentina-slantsixer [ Mon Jul 30, 2007 7:51 am ] |
| Post subject: | |
Quote: I have so far never talked to a cam grinder who I thought understood the Slant 6 on cams. I'm not saying they're not out there, but the standard places (Erson, Crane...) do not have the background or testing behind them.
hey lou, any link to that article? thanks!
I agree with those above who say you need LESS LSA. I run 106 LSA 250 @ 0.050" and it works very well on 10-10.5:1 comp. Not too big at all. 108 would be the max I would even consider getting custom ground. Dave Vizard had a nice article in Popular Hot Rodding recently about LSA, and I used his figures to calculate that the Slant should have 105 deg. The guy making the most HP in a drag car in the whole US uses around 104-106 for best power. Best of luck, Lou |
|
| Author: | Bren67Cuda904 [ Mon Jul 30, 2007 10:02 am ] |
| Post subject: | |
Humm, where do I start.  Whats amazing is how many different directions one can be pulled with convicing aguments. 1. "The Slant6 is completly different than any other motor." This is true, but it still has a piston that moves back and forth and two valves that open and close. 2. "You need to increase lobe seperation (ei. 110 to 114) to decrease cranking pressure" According to some dyno software this is true, but it will make it lazy out of the hole. Dyno software compairison: My orignal 240@50 110 lobe sep installed 3* advanced cranking pressure is 235psi Installed straight up its 217psi So far the software agrees with what I am seeing. I just bought a 250@50 110 lobe sep. This cam installed straight up its cranking pressure according to the software will be 202psi. If I advance it 3* it will push it to 213psi. If its retarded 3* it should drop to 191psi. This same cam installed straight up with a 106 lobe sep will have according to the software, 218psi cranking pressure. It seems to me that for my situation the 250@50 110 installed straightup is right for me. A few more miles on the roller chain and it'll retard slitely anyway. "I should tare down the motor and take some compression out" I agree that is right way to fix this, but that not going to happen. If I tare it down, it getting parted out. Your dealing with someone that just looking for a reason to abandon this Slant6 stuff. Don't push me. I held on pretty long even withall the abuse. 
|
|
| Author: | SlantSixDan [ Mon Jul 30, 2007 10:39 am ] |
| Post subject: | |
Quote: Humm, where do I start.
Well, Brennan, that depends on your goal. If what you're after is an engine that runs right, then you need unbiased advice given from the benefit of experience with the engine you're working with, so you ask a question on here, then do as you're told. If what you're after is spending as much money as possible, then you need biased advice given by someone who has a financial interest in selling you a particular camshaft or whatever, so you ask every camshaft vendor you can find and then start spending money. Quote: It seems to me that for my situation the 250@50 110 installed straightup is right for me.
Astounding. You have multiple people telling you "Stop, that's the wrong cam for your engine". They've been down this road with this engine, and have nothing to sell you. And you — of all people — are telling them they're all full of it, because some piece of software told you and some cam company sold you. I say again: Astounding.Quote: I held on pretty long even withall the abuse.
Oh, yeah, for sure, all the abuse. How do you stand it? Yours is a heavy burden, it is.  If anyone's abusing anyone, it's you abusing the kindness and generosity of those who carry on responding to your disingenuous cries for help, despite your utter lack of intention to follow the good advice you're given.Quote: Your dealing with someone that just looking for a reason to abandon this Slant6 stuff.
Door's right over there. Don't let it hit you on the way out.
|
|
| Page 4 of 9 | All times are UTC-08:00 |
| Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/ |
|