| Slant Six Forum https://www.slantsix.org/forum/ |
|
| Eeny meeny miny.....cam https://www.slantsix.org/forum/viewtopic.php?t=51574 |
Page 1 of 1 |
| Author: | wvenable [ Sun Mar 31, 2013 8:10 am ] |
| Post subject: | Eeny meeny miny.....cam |
Getting my ducks lined up for my son's Demon. Background: 72 Demon w/ stock 74 225/904 auto 3:91 8 3/4 to be changed to 3:23's Upgrades super six, six into one header, DI's recurved dist Looking to put in a cam before engine goes in. Thinking about Doc's RV10 M RDP or RV15m RDP specs on a regrind. What kind of compression would work well with either cam? This thing needs to run on cheapo crappy pump gas. Should I just install the cam or install cam and adjust compression with some head milling after I see where this engine is currently. Engine is low mileage mid 40 thou. I also have a double roller timing chain. Goal is a nice streetable torque(y) ride. Thanks for you help. |
|
| Author: | sandy in BC [ Sun Mar 31, 2013 9:03 am ] |
| Post subject: | |
Decide what your trying to do. Study DCR calculators . Play with different variables till you have a Camshaft Timing Epiphany. My CT Epiphany may differ from yours...... .......better yet have your son do all this. Distributor curve comes after DCR. This will contribute to your final marks....... |
|
| Author: | DusterIdiot [ Sun Mar 31, 2013 9:20 am ] |
| Post subject: | x2 |
Yeah what Sandy said... Either cam will work, the RV 10 would be a good pick if running about 9-9.3:1 static compression and installing 4 degrees advanced. RV15 will also work but may need a little more compression (probably 9.5:1 would be the target). Play around with the DCR calculator and try to keep it no more than the high 7's if running on moose-whizz octane. Distributor should work for those targets since you are going to run street gearing with an automatic. -D.Idiot |
|
| Author: | Dart270 [ Sun Mar 31, 2013 10:04 am ] |
| Post subject: | |
Reality check: Is this car already running and driving? Why not you and he get your racecar running again before taking apart another car? Running cars are valuable and fun. Non-running cars are only good for talking about - much less fun. Mr. Grinch |
|
| Author: | wvenable [ Sun Mar 31, 2013 11:36 am ] |
| Post subject: | Absent minded professor |
Dear Mr. Grinch, I am very worried about your ability to stay focused in class. Remind me to call your mother and set up a conference. Lou, if the Demon was runnin' I would have taken it to Clay City last time. Brief recap. The 10:1, 500ish lift, four barreled long block is sittin' in the Piggie. This came out of the Demon complete with a small register crank! Remember? The engine that was in the Piggie- Bone Stock runner- is going in the Demon. That way my son can put regular gas in the dang thing. Behind it will go a stock auto. The piggie will get the stick that was in the Demon. Except the stick in the Demon was TRASHED. Got a replacement with Zilla's help. The Demon is actually closer. Thanks for the reality check but I just got my sons financial aid forms back for college. The reality is I was hoping you would adopt me. I am house broken. Oh they say that Ginko stuff can help yer memory. Just sayin'. |
|
| Author: | DadTruck [ Sun Mar 31, 2013 4:22 pm ] |
| Post subject: | |
part of the fun when talking cams is understanding what is important and what engine characteristicks work together with the cam varables. This article does a good job explaining all that. http://www.popularhotrodding.com/tech/0 ... ewall.html If I was doing a street motor for an A Body, I would look closely at Agressive Ted's build,,motor set up , electric fan, heat shield...the whole package. remember if you change cams, you will also need lifters, or have em reground.. If you do go the new cam route I have a nice degree wheel and dial indicators that you can borrow,, |
|
| Author: | wvenable [ Mon Apr 01, 2013 3:42 am ] |
| Post subject: | Basic specs w/RV15M RDP |
Quote: ........... till you have a Camshaft Timing Epiphany.
Last time I had an epiphany is when I found out what my "special purpose" was for. Playing with basic DCR calculator. Entered the following: 6 cyl B= 3.40 S= 4.125 Rod length= 6.698 Intake close ABDC 59 deg. I think this is correct for RV15M RDP Alt. 700 ft got the following: 8.8:1 static = 7.21:1 DCR w/ 138.80 cranking press. 9:1 static = 7.38:1 DCR w/ 143.11 PSI 9.5:1 static=7.78:1DCR w/ 153.32 PSI D.I and Sandy, is 153 lbs cranking pressure starting to get into the premium gas area or can this be sorted out by degreeing and dist recurve? |
|
| Author: | slantzilla [ Mon Apr 01, 2013 3:56 am ] |
| Post subject: | |
Hey knuclehead. Call me, I'm pretty sure Bill has a new Comp 262S laying at the shop. Screw it in and call it a day. |
|
| Author: | Dart270 [ Mon Apr 01, 2013 6:35 am ] |
| Post subject: | |
I can't keep all these hundreds of non-running vehicles straight (Cookie, Mater.....), so that's why I asked again. Thanks for refreshing my absent-minded memory. 153 cranking psi should be fine on 87 octane with a good timing curve. Personally, I would not go above 9:1 with those small cams (like RV15M) for 87 octane. Good luck! Lou |
|
| Author: | DusterIdiot [ Mon Apr 01, 2013 7:56 am ] |
| Post subject: | Yes and... |
Quote: 9:1 static = 7.38:1 DCR w/ 143.11 PSI
Under 8:1 DCR = regular gas "87" octane, you should have no problem at the pump.9.5:1 static=7.78:1DCR w/ 153.32 PSI Quote: Personally, I would not go above 9:1 with those small cams (like RV15M) for 87 octane.
I would not exceed 9.5:1 SCR with a short cam, the RV10 would be fine with say 9.2:1 compression, 9.5:1 with the RV15 would be about right (i actually ran 9.66:1 with a comp cam CCX256 for a time and it was fine on the street using regular gas).As Lou stated dialing a good timing curve is a good part of the key to making a peppy mileage maker. -D.Idiot |
|
| Author: | olafla [ Mon Apr 01, 2013 9:30 am ] |
| Post subject: | |
Doc made the following remarks on the RV15m RDP cam, back in spring 2011: Quote: This cam seems to work well with the DCR set to 8.0 to 1 (pump gas)
It was recommended to install it 'straight up'.On the first build, static compression was set at 9.01 to 1 and DCR ended-up at 7.72 Knowing that, we took an additional .040 off the replacement block and doing that put the SCR at 9.33 and the the DCR at 7.994 Bottomline, this cam works well when the static compression is in the 9.3 - 9.5 range... depending on how you phase (degree) the cam. Olaf |
|
| Page 1 of 1 | All times are UTC-07:00 |
| Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/ |
|