mp71conv

I am building an olds 350.
new flat top pistons .30 over
vodoo cam .486 ex .499 in lift/ 219 dur at 50.

would I be better off with the performer rpm or just the performer?

Danny Wiseley

One vote for the Performer RPM!

J-(Chicago)

RPM
x2

joe_padavano

What car, what trans, what gears and tire size, what intended use and RPM range?

Redog

I'd go with the RPM for a few reasons

1. The Performer is just a lighter version of an Olds mani:
2. The RPM is only $10 more
3. The RPM is a much better mani for a small block

The only reason I'd go Performer is if hood clearance is an issue

88 coupe

And which flat top pistons?

Norm

mp71conv

The pistond are speed pro flat top.
350th trans
2:53? rear somwhere in that area. Maybe going to change to 3:42
O it's a 71 cutlass converible
Rpm range 1000-5000
going to use the orginal carb unless I find something better
hooker headers
2 1/2 flowmaster exhaust
cam is a voodoo 213 int/ 219 ex dur at 50
485int/ 499 ex lift
stock rockers

will the stock touque converter be good enough?

captjim

That cam is going to be way too small for you to run that on pump gas, IMO. Cr will be up over 10 to 1, too much, again IMO. Those Voodoo cams "act" smaller than they really are due to the fast ramps. I have the 60803 227/233 in a very similar 355, Speed Pro flat tops #7 heads, but a .027 gasket, my Cr is 10.45 to 1 and I mix the fuel. Your dynamic Cr/cylinder pressure will be very high. I would re-think things at this point or you will either have the hassle of mixing in 110 octane, or de-tuning it to the point that it is no fun to drive. Since your handle is 71conv, I am guessing you are using the original #7 headed engine. This assumes that you are using a #5, #6, #7, or #7a head. If you are using a #3A or #8 head, you are OK.

mp71conv

I don't think that I can get that high of a cr. my head gasket is around .040.
why would the small cam give me problems?

88 coupe

I am also interested in the answer.

And I believe I may have a couple of follow up questions.

Norm

joe_padavano

I'm guessing this is a reference to using a long-overlap cam to reduce dynamic CR. This was a strategy used by some cam grinders in the mid to late 1970s to get high compression cars from the 60s to run on the crappy low-lead gas of the 1970s.

88 coupe

I'm, guessing the same.

It's a concept I've read about on the internet. Problem is, many people make the statement but none of them explain what makes it happen.

Logical extension is: Any "wannabe" can make the statement, but anyone who actually understands the physics of it, will explain it in a heartbeat.

I'm assuming captjim (from his many conversations with famous "camgrinders" and from his many years of machine shop experience) would understand how it works, and be able to, rationally, explain it.

Norm

mp71conv

WOW. Well I'll hope for the best with I got..Thanks
After I get it running Ill let everyone know wht happened.
Probably have more questions.

88 coupe

OP did not say anything about milling his deck and/or heads. Normally, unless prior to machining, some abnormality was discovered, there would be no reason to do so.

That seems to be the consensus among our resident "cam experts". Internet education?

The question that was posed to captjim was: How?

"Faster ramps" would allow more time for cylinder filling, which would (in theory) cause a higher dynamic CR. Isn't that the opposite of what you (and captjim) are advocating?

He is not using dished pistons.

What CR do you think he will have, with the parts he is actually using?

Define "hydraulic intensity" and explain how it might contribute to this "bleed off" theory.

So now, the OP should use a "stock cam" instead of a "performance cam" to accomplish this "bleed off"?

How does "maintaining cylinder pressure" cause a " modern performance cam" to "bleed off" compression?

That a bigger (higher lift and/or more duration) cam should, make more power, is a given.

Wouldn't it take more cylinder pressure to accomplish it? If so, how could that happen, if the cam was "bleeding off" compression?

In this case, is "low end cylinder pressure" a good thing? If so, why?

What does this calculator have to do with anything in this thread?

Norm

88 coupe

Use the RPM, and you will be fine.

Norm

88 coupe

Would it be a "valve job" if it had less than "3 angles"?

1) Taking "tolerance stack" into consideration, how would a machinist go about finding whether the block is already "true" or not?
2) How do you know that this one is not?
3) How do you know that his existing "piston to deck" dimension is not .024" already?

Not the first time you have deleted all of your posts, when someone asked you to clarify some of your own statements?

I would expect such a tactic from a common BS artist, but not from someone as knowledgeable as yourself.

Norm

Wireman134

There is a 2 angle standard valve job and there is a 5 angle also. I guess if the block is at the shop and it is squared and true, w/ the pistons around .025" in the bore. Then he is ahead of the game. Norm you really have no mechanical knowledge do you? Why so many questions that stress you so much? You need to relax and think a little, not being so critical of others. Maybe find a hobby...

88 coupe

The last post that was deleted:

This thread has nothing to do with "engine building" and I am not interested in becoming an "engine builder".

Not interested. But, I have "rebuilt" a couple.

At the risk of repeating myself, I have since learned (from the internet) that I have been doing everything wrong.

We all could "get it" if you, and/or captjim, were able to clarify your own statements.

Wireman: If you cannot stand the heat, stay out of the kitchen.

Norm

captjim

My Speed Pros sat .024 down on my non-cut 350 block. That with a .040 gasket and 67 cc heads puts you right at 10 to 1. MP71conv, you do whatever you like, but IMO, and only my opinion ( it has been established by Norm, the Classic Olds expert, that my opinions are completely worthless) that at 10 to 1 that cam will have too much cylinder pressure and you will have detonation issues, whether you hear it or not. PM me if you like and I will give you a recommendation on a cam that I think will work better for you.

Norm, post whatever you like, give your fingers lots of exercise, but keep in mind this is what I see (and from other posts here, quite a few other guys see)

"88 coupe This user is on your Ignore List."

88 coupe

Not in any machine shop, I would use.

Yes, there is. The heads on my most recent 468, are living proof.

He did not say his engine was in the shop, and he did not post his dimensions.

How did you know what they are? Are you a "remote viewer"?

Here it is, again:

Still no answer?

It is not a coincidence that the pistons he chose, were designed to be .024" under the deck when used with a factory block

But what do I know?

Not a bit.

Why so few answers?

You need to get over the silly notion, that you can read minds.

If you actually think I'm being critical, that is your choice. Whether it is fact, or not, has nothing to do with this topic.

What is fact, is that turning a simple discussion into a pizzing contest, is another way for a BS artist to divert attention from the fact that he/she is unable to handle an adult discussion.

I already have several.

One of them, is waiting for captjim to answer the same questions, that you are unable to.

If you would like to stay on topic, do so. If you wish to continue your pizzing contest, you can do it by yourself.

Norm

Wireman134

RPM

Jamesbo

88 coupe

Norm did not establish anything, as captjim has been doing the establishing, for himself.

Again you are spreading this internet myth. I know nothing about "classics" and not a lot more, about Oldsmobiles.

What I do have, is a working knowledge of the basics.

They are only "worthless" if you refuse (or are not able) to discuss them. What you do not realize, is that they could be valuable learning tools, if you would take the trouble to defend them.

If, indeed, your "bleeding off" theory is supported by the laws of physics, it should be easy to defend.

And a "high performance" cam will make it all better, but you do not know why.

Not if the advance curve is tailored to that specific engine.

Yes. You have a recommendation, that will cure a problem that does not exist.

And to showcase your credibility, you will take that valuable information "Private" so the membership cannot learn from it.

As if I need your permission.

Yes. Put your head in the sand.

It did not change anything the last time you said it, and it will not change anything this time, or next time.

Norm

Jokers69

another ruined thread by our resident expert

tonycpe

As you all know I don't post very often and whenI do , my response is short . I was enjoying this thread at first and then ,,, well enough of that. .........

Here is what I do know. I started playin around degreeing camms on Triumph motor cycles while twisting a wrench for a dealer in 1973. I have had many cams in my 350 over the last 40 years . 2 years ago i put in the performer rmp matching cam. I had 195 lbs. cranking compression and it was on the edge of running properley on 93 octane. the following year i changed 2 things heads were milled .030 and i put in a in a ultrudyne 288/296 part # cam. Of cousre this cam has much more duration . My cranking compression went down to 175. I know it was happier on 93 octane and it was 1 second quicker in the quarter mile.. Hopefully this may have helped some of you fellow olds guys. and if you did not like what i had to say .... I don't want to hear about it. which is what i sugest to some of you .....If you don't have anything good to say or just don't say anything.

88 coupe

Two "experts".

This is a legitimate question, on topic, asked by by the thread owner, in response to a statement made by one of those two "experts".

No one, including the author (captjim) of that statement, has been able to answer it.

Maybe Jokers69 will be able to answer it for us.

Norm

captjim

So what else is new? Whenever I give an opinion, I say IMO, or in my experience, or whatever. I never say my way is right and yours is wrong. I hesitate to post here for this exact reason. Whenever I do, my "buddy" chimes in with his normal crap, criticizing everything I say. I suppose he has taken every 4 word phrase and broken it down, telling everybody how wrong it is. Did he call me a "BS Artist"? That is one of his favorites. Whatever, I block him and don't have to read it. Too bad it clutters up threads. It is probably better if I just quit posting here, like so many other guys have done before me, it just isn't worth the nonsense.

redoldsman

Come on guys and keep posting. I have the resident self proclaimed expert on my ignore list so I see him on this thread without seeing his BS. It gives me pleasure knowing I ignored him. If you quit posting, he wins and that is exactly what he wants. He don't give a ratsazz about helping anybody and you guys do. Don't let him win. I know some things but when it comes to cams and motors, I rely on you all for help. I will probably redo the 350 in my 72 Cutlass this winter and will need your help. I can put it together but I will need good advice when it comes to picking components.

88 coupe

Your input is always welcome.

Duration is only one of the factors that affect the effective CR. If nothing else was changed, you should have seen an increase in pressure.

What other specs were different? Any changes in ignition timing?

Following might explain my curiosity:

Overlap occurs between exhaust and intake. It is increased, for better scavenging, in order to promote increased cylinder filling, which would increase cylinder pressure.

By coincidence, it is similar to my reply to a previous (now deleted) statement:

His silence (and deletion) is a clear indication that my reasoning is sound.

Do you still have the tags for those two cams?

Norm

88 coupe

Yes. My opinion, based on my own personal experience with numerous "BS artists".

If you dare question that opinion, I will launch the "mother of all personal attacks" which will get you "banned" from this site.

Norm

88 coupe

Yes:

Join the bashing/trashing party, and show everyone how mature you are.

Norm

J-(Chicago)

Simple questions are being asked here.

Why the long winded responses?

There was a lot to be learned from this thread before everyone started pointing out how Norm is a jerk.

Tonycpe.....
Thank you for your experience based input. I hope others will follow your example of useful information.

Danny Wiseley

I did all my own head work (except milling) back in the 60's and early 70's, and maybe I've forgotten a lot, but what two angles are involved in a 2 angle valve job? Are you referring to the 1 degree difference in the valve face and the seat? I generally just used a 60-45-30 treatment on the seat and 30 and 44 on the valves, after I polished them.
DW

joe_padavano

You are correct and I misspoke in my previous quote. What I should have said was not "long-overlap" but delayed intake closing.

88 coupe

That would do it.

Along the same lines, RV cams used earlier intake closing to get more power from the low compression engines, of the 70' and '80s.

Norm

Wireman134

Angles are referred to cuts on the seat. A picture is worth a thousand words and I am a man of few of them. We will learn together fellas. http://www.enginebuildermag.com/Arti...alve_jobs.aspx

captjim

Nice pics, Wireman!

Using this calculator, which isn't perfect, but pretty close
http://www.projectpontiac.com/ppsite...nt/view/16/30/
I get 9.29 to 1 dynamic Cr using these cam specs installed straight up.
https://www.lunaticams.com/Product.aspx?id=1722&gid=287
9.29 to 1 is simply too much to run on pump gas, as always, IMO. Read this if you care to, pretty good article.
http://www.empirenet.com/pkelley2/DynamicCR.html
Another, shorter one,
http://www.hotrod.com/pitstop/hrdp_0...ion/index.html

I never base my build decisions on advice given over the internet, by me or anyone else. I work with a builder/vendor, with a budget and goal in mind. The advice he/she gives based on their valuable experience is well worth the few extra dollars you might spend on parts over Summit or Jegs. I used John at Rocket Racing, but there are several good Olds vendors with solid reputations. Perhaps this site has a "favorite" or sponsor that a moderator can recommend.

On another matter, someone will have to convince me that these 2 statements made by Norm in this thread do not constitute internet bulling and how they encourage and promote the exchange of ideas in a fun, friendly environment.

"If you dare question that opinion, I will launch the "mother of all personal attacks" which will get you "banned" from this site."

" Wireman: If you cannot stand the heat, stay out of the kitchen."

mp71conv

What if I retard or advance the cam. Would the change when the intake valve closes and change the dynamic cr?

88 coupe

Yes it would.

4° of retard, would lower your effective CR.

I see you are learning, in spite of the trash.

Norm

mp71conv

Its alot of information to take in.
I just want to get it right.
What other things will happen when I retard the cam?