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.

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66 Lil' Red Piggie Valiant (Mater Crusher) - Thanks Zilla!!!!! 72 Demon (Number 1 Son's)

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.......

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Yeah....Im the one who destroyed this rare, vintage automobile.....

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

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

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Home of Slant6-powered fun machines since 1988

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'.

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66 Lil' Red Piggie Valiant (Mater Crusher) - Thanks Zilla!!!!! 72 Demon (Number 1 Son's)

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,,

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?

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66 Lil' Red Piggie Valiant (Mater Crusher) - Thanks Zilla!!!!! 72 Demon (Number 1 Son's)

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.

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Official Cookie and Mater Tormentor.

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

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Home of Slant6-powered fun machines since 1988

Under 8:1 DCR = regular gas "87" octane, you should have no problem at the pump.
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

Doc made the following remarks on the RV15m RDP cam, back in spring 2011: It was recommended to install it 'straight up'.

Olaf

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Aspenized