88 coupe

Take your time. Ask whatever questions you need to. As you can see, there are several of us that can answer them .

Everything will happen 4° later, most importantly the closing of the intake valve, while the piston is moving up in the cylinder. This delay. allows less time/distance for the fuel/air mixture to be compressed.

Norm

captjim

Yeah, all the way down to 9.15, wow!! Still waaaaaay too high. Mp71conv, you either need another cam or lower static compression, and that means different heads or pistons. At what stage are you in this build?

88 coupe

Your "ignore button" is broken.

Norm

mp71conv

Engine still at machine shop. I have the cam already.
Now Im confused. you said 9.15 is still too high. I thought i wouldnt have a problem till 10.5?
Looking at the factory specs. The duration is low like this cam but the lift is much lower.
and all the pre 71 pistons were flat tops.

88 coupe

At the risk of repeating myself: Explain why.

Is this something that you must keep secret, or you not understand the purpose of this board?

Norm

captjim

You are overlooking the fact that in the 70s, you could buy gas with an octane rating over 100, not true today, sadly. 9.15 is the dynamic Cr, not static. You static Cr is around 10 to 1 using a .040 gasket, pistons down .024 and 67 cc heads, but without exact measurements, it is impossible to say exactly. If any milling has been done to the heads or block, your Cr may be higher. In my opinion, and this is just my own belief, with older iron heads with their large, slow burning chambers, 9.5 to 1 is the practical static Cr limit, and 8.2 or so on the dynamic ratio.

" and all the pre 71 pistons were flat tops."
This is incorrect, most had a small dish in them.

captjim

Re-read post #37 in this thread. That cam will make the dynamic Cr too high with an older style head and today's fuels.

88 coupe

9.15 is probably closer to "ideal" than 10, but either can work well, in most instances.

Your choice depends on what you want to accomplish. For most non competition applications, 9 to 9.5:1 CR with (iron heads) are best for use with pump gas.

My latest 468 is 11.9:1 and it runs fine on California's 91 octane, but unlike the "experts" I do not suggest that anyone do the same, unless they are, or know, a competent tuner.

Not so. You should be looking at specs, not years or manufacturers.

Has your shop verified the heads/block dimensions yet? Particular interest, is the deck height as it is a factor in the choice of pistons?

Norm

captjim

I just realized that I used the wrong cam in my calculations. He did not give a part #, just said 219 @ .050. I thought he was referring to the intake. But from his other thread I see he meant the 60801 which is 213 @ .050 on the intake. Now he is REALLY too small on the cam.

88 coupe

What does this have to do with anything?

Not what you said. We can assume it to be a clerical error.

Your opinion?

The key word, here, is practical.

According to the following:

10:1 mechanical CR can be turned in to 8.2:1 effective CR, with a simple cam change.

Which is it?

Norm

88 coupe

Tell us (in your opinion) what cam he should be using, with his 10:1 CR, and why (in your opinion) he should use it.

Norm

mp71conv

Ok I am going to see if they wiil take the cam back for another ( it is unopened so that should not be a problem).
Ill look at there stock performance ones. They have one that is 232int 232 ex.
480 lift int 480 lift ex. 113 lsa

88 coupe

Where does it tell us how a "high performance" cam will lower the cylinder pressure?

Norm

captjim

I have a suggestion, my last on this topic. Measure everything, then determine the true compression ratio of this engine. Call a professional builder/vendor and get their recommendation on a cam. Ask them if the 60801 is a good choice or not with the rest of your combo and the measured compression ratio that you have. Please get back to us with the results so that we can all learn. I would love to find that I am mistaken and that the cam you have will work great in your engine. I am including a link that I wrote explaining how I go about a project, hope it helps. PM me if you like and I will give you my phone # and will be glad to chat and help you in any way if I can, Jim
http://www.oldspower.com/vb/showthread.php?t=36717

Norm, I'm done taking your bait, have a lovely day there in SoCal!

88 coupe

What good would that do, if the pistons are to be replaced?

What a novel approach. Most people would call a cam grinder for advice on a cam choice.

And the following, only addresses a few of its many inaccuracies. https://classicoldsmobile.com/forums/44739-post4.html

As always, I am ready and able to answer any, and all, questions regarding anything I post.

It is not a small stretch, from a simple question to "bait", but the statement itself tends to reinforce my opinion, regarding BS artists.

Norm

Jamesbo

Hey guys he's starting a new thread "Let's start over"

Since I am a cam moron, I think I should add my 2 cents here.

Wouldn't it be easier/better for him to start anew w/o purchasing a cam and first get his shop to help him measure everything to see what he's got. I mean the car could [or could not have] had some machine work done to it.

Just MHO

first things first

Gather the facts.

Isn't that what you guys would do before you made any decision?

Sorry to butt in

captjim

Did I not just state that in my last post?

Originally Posted by captjim
........ Call a professional builder/vendor and get their recommendation on a cam ........
What a novel approach. Most people would call a cam grinder for advice on a cam choice.

The reason I like to use a builder is that they have dealt with the end product and a competent one will have a very good idea of what has worked well in the past. Most have proven combos that they like, ones that they know will perform well in a given circumstance. In most cases, the builder will call his own grinder, get one ground to the specs that they like for the application. By dealing with the builder, you can then go back to him with questions or advice, if needed.

Originally Posted by captjim
........ Measure everything, then determine the true compression ratio of this engine ........
What good would that do, if the pistons are to be replaced?

Because it might be better to replace the cam, especially if he intends on a gear and converter swap. But in reality, you don't want an answer, you just want to prolong the nonsense.

Originally Posted by captjim
I'm done taking your bait ........
It is not a small stretch, from a simple question to "bait", but the statement itself tends to reinforce my opinion, regarding BS artists.

You can call me a "BS artist", that's fine. I build and race Oldsmobiles, I work at a machine shop part time and have access to a couple of really smart guys. I come on these forums to have fun, learn new things, and try to help other guys, if I can. The same cannot be said for yourself. You take the fun out of it and suck the life from this board, it really is too bad.

88 coupe

That is normally how one would begin.

But many DYIs prefer to shoot themselves in the foot" by telling the shop what to do, instead of taking advantage of the experience that is looking them in the eye.

I am working (as we speak) on a new thread that will explain what captjim (and all his "credentials") cannot.

Norm

J-(Chicago)

Jim and Jamesbo, getting the specs hammered out first is a good idea.

Also, Capt Jim.

To properly quote yourself or another poster on the board, once you hit the quote button you must leave the html info in the brackets at the beginning of the text box, then leave the wording that you wish to keep, and finish the last line of the text box with: [/QUOTE]

visual example:

[QUOTEcaptjim######] Texttextquotequote [/QUOTE]

Hope this helps.

88 coupe

It is about as basic as one can get.

Norm

captjim

Sorry, I spend my time actually working on cars, and have not mastered the internet or computers. My bad.

J-(Chicago)

Dang..... I'm just trying to be helpful, not a jerk. Proper quotes will make your information more easily understood, thus getting your valid points across more efficiently.

88 coupe

Yes you did.

Did my reply go over your head?

It did remind me of another that I missed:

Went right over your head, didn't it.

88 coupe

He already knows how.

Like any "BS artist" he does not want to be clear. Proper coding would make it too easy everyone to catch on to his childish games, and it would leave that pesky blue arrow, so everyone would be able to read the post, in its original context.

His rude reply is just another tool used by a "BS artist" in any similar situation.

Norm

88 coupe

Mine do not need any work, because I do it right the first time.

That would be why you have not mastered your "ignore button"? And why you cannot answer simple questions about your own statements?

But you do seem to have plenty of time to flame anyone (and/or trash an entire thread) who asks a question that you cannot answer.

Isn't it interesting that I am ready and willing (if not eager) to answer any and all questions pertaining to my own posts.

How can it be, that, with few exceptions, my statements are never challenged.

Could it be that (in spite of my lack of "credentials" I might have reasonable cause to challenge yours? Maybe, that you have based your "opinion" in on some misinformation you have acquired? No, that cannot be possible.

Or did it occur to you, that I might be looking for some knowledge you have that I do not have?

Also not possible, because, according to you, and your minions, I already know everything there is to know, and my only purpose here, is to torture captjim.

Norm

88 coupe

Found an interesting statement, while working on my new thread.

Isn't 9.8 getting dangerously close to 10:1?

Norm

mp71conv

http://www.empirenet.com/pkelley2/DynamicCR.html
This some good information and some specs

88 coupe

Looks like it is. I'll know, when I have time to read all of it.

Good to see you are searching on sites other than forums. Shows you are one who can think for himself.

Norm

captjim

That article was a link I provided him in post # 37 of this thread, glad you found it useful. Hope it helps explain why I think the cam would be too small for your application.

mp71conv

Well I did not know all the points to look at when getting a cam.
I learn something new all the time.
But it does seem to be that it is not just the duration but
the degree after bottom center that the intake closes.
And the cam is at the mid 30's. That is not good.
And it make sense to me. so off to get a different one.
Thanks to all
I will keep everone up to date on what happens.

83hurstguy

I would either go for a Harold grind (from an Olds vendor or Harold directly), or call Bill Trovato. Those guys know what they are doing.

captjim

"I learn something new all the time."

Don't we all? That is part of the fun, when we stop learning, it isn't nearly as exciting.

Jokers69

I'm only qualified to comment on what's in my car, which works well for what I do with it. My parts were recommended by an engine builder whom I trust. But I'm sure you would have some better way to do it.


Adios..

88 coupe

In other words, you cannot answer the question?

Because I asked a simple question?

A question that captjim would, trash an entire thread, just to avoid answering?

Norm

88 coupe

https://classicoldsmobile.com/forums...wreply&p=50285

Norm

83hurstguy

And I wouldn't order it from Terry... if you can get him to return a call you are lucky, let alone ship parts out. He's a nice guy, but his business has been on a pretty bad slide.

Call Rocket Racing or Smitty... or go directly to Harold.

88 coupe

Yes it is.

My response to it, was in post #53.

Norm

88 coupe

Thanks, I was not aware of that.

Norm

Jokers69

you trashed the thread big guy..

and, no, I cannot answer you question, so am I thrown off the island *******?

88 coupe

Thank you, for your honesty.

Norm