Hello, I'm thinking of a cam swap for my L74 10.25:1cr 350, but want to retain stock 2.56 gears and pull at least 12 in of vacuum in gear. My last Olds 350 had 10.25:1 pistons #7 heads with stock valves w/ 3 angle job. The cam I chose was a SSI from PAW .472"in/.496"ex lift 214/224@.050" 112LS. It needed 14 degrees of initial timing to run up 10 in. of vacuum in gear. The car had a B&M Holshot converter and 3.36 gears, and ran well enough to give a 16mpg average. I would like a noticeable lope idle and around .470" lift. Any suggestions appreciated.

Tony

 

I just finished up a 10.45 to 1 355 and used a Voodoo 60803 .510/.522 227/233 on a 110. Runs great, plenty of vacuum at idle. No ET yet, it is miserably hot down here and rains most afternoons. I installed it at 104.5, 2 degrees advanced. But, I think there is a flaw in your question. An engine that needs a large cam is not going to like those 2.56s out back. You are going to want more gear, IMO. After you did the valve job, what head gaskets did you use? If the Fel-Pros, Cr is going to be lower, like 9.6-9.8 or so. That is with the assumption that the stock pistons are in it. If not, all bets are off as to the true Cr.

 

A engine does not need any particular cam. The cam dictates to a large degree what rpm range the engine operates at. A street car range is say off idle to maybe 6000rpm. So what cam would improve low to midrange power in a 350 Olds L 74 and play nice with a tall 2.56:1 gear.
By the way how much vacuum does that Voodoo cam pull in gear...

 

I am going to disagree with your comment about "an engine needing a cam" basing it on the ability to run pump gas. Sure, put a low lift low duration cam in a 10.25 to one engine with 2.56 gears, and the car will make a ton of torque, vacuum, and be fun to drive. But, you will darn near need to run straight 100 octane. IMO, a certain cam NEEDS a specific cr range to work. And, it is the whole combination, engine, cam, gears, converter, weight, etc.

"A street car range is say off idle to maybe 6000rpm."

I disagree with this, too. IMO, most engines do not have an effective operating range of 5400 rpm. An engine that pulls hard to 6 grand is not going to have great idle characteristics. It will want some gear and converter. An engine that idles great and has instant low rpm throttle response is going to be done at 4800. This in old-school carbureted engines, not modern EFI stuff.

In all honestly, if the engine is truly at 10.25, you will have a hard time finding a cam that works well with those gears and runs on pump gas. Now, if it turns out that the true cr is like 9.7, go with a cam like the Voodoo 60802 218/227 and it should work, but still might be a little soft down low. Mine pulls 16" of vacuum and idles very smoothly. Why not just put a decent gear in it and make life easy?

 

what exactly is an Olds L 74 HC 350 Rocket?

 

It is just the option code, like LS6 was a 454 Chebby.

 

I've never seen the reference before..

 

We just don't use those option #s live the Chevy boys do. Couple of examples, there are many,
http://www.442.com/oldsfaq/ofocd.htm
http://www.fusick.com/rallye350.htm
It is just the code for a 4 bbl high compression 350

 

Ok lets say cylinder pressure of around 180 psi. that will run on pump gas. Losing maybe 10-15 psi would be acceptable, simulating a low compression engine correct. By the way the stock cam works fine with its 250/264 short duration on pump gas. Re curve the distributor to pick up the low end and ad a little more total ignition timing, and you have your low end back and not turning high rpm's while cruising. I'm thinking between 210-218 degrees @ .050" and around .480" lift with LS between 108-112. Any more thoughts... A street engine would not pull hard at 6000rpm it would be winding out redlining correct...

 

My 9 to 1 355 with an Engle 210/216 .472/.488 cam has 165 lbs cranking pressure. I personally do not think you could run a cam that mild with 10.25 to 1 on pump gas. Adding more total timing will just make it worse. Once again, using an appropriate cam to run on pump gas with 10.25 to 1 cr will not work well with 2.56s. IMO. Why are you so hung up on using a gear ratio that is not suited for the application?

 

Ok, I did not say my stock cam (187/198 @ .050") engine with 180psi runs fine on todays premium. But it does, and I have built a 72' 355 Olds using 10.25 pistons that had a 175 psi cylinder pressure with a 214/224 @.050" duration cam, a quick advance curve that ran without detonation on pump 91 octane with 2.73 stock gears. These are both clean carbon free chamber engines with 6cc dished pistons. A excellent combustion chamber. It can be done...

 

OK, 2 things and I'll leave it be. First, 6cc pistons sitting .025 down (which is what the ones I have had did) a .040 gasket and 68 cc chambers gives you 9.2 to 1, not 10.25. Those "advertised" cr #s are usually off. That is why I kept saying "true Cr" If you milled the heads, decked the block, or used the Corteco or Cometic gaskets, it will be higher.

Secondly, just because you can't hear detonation, does not mean it isn't there. The silent killer. Several cam grinders I spoke with said that 9.5 is about the limit with an old iron head on pump gas. These guys know a lot more that I do.

Good luck with it and let us know how it turns out.

 

Consider the use of the car when determining the compression ratio. Your camshaft profile probably has the most significant impact on what mechanical compression ratio you should run. A longer duration camshaft will allow you to use higher mechanical compression ratio pistons because it lowers the effective compression ratio by keeping one or both valves open slightly into the compression stroke.

 

What you are calling "mechanical" compression is called the "static compression ratio". How the cam affects it is called the "dynamic compression ratio" You are correct, using a cam with more duration will allow you to run a higher static Cr on pump gas. But, by bleeding off some cylinder pressure, you make the bottom end softer. You WILL lose some low end throttle response, thus the need for more gear and converter. As always, IMO. The gear part is just where we will have to agree to disagree. I don't think a high compression engine with a lot of duration matches up well with a 2.56 gear.

 

Both are correct.

Norm

 

Both of these, are also correct.

Norm

 

First time I ever saw it was on this site. This was the second, or maybe third, time.

"Gearhead" that I am, I would expect it to be used by the "numbers matching" Guys.

Norm

 

First order of business:

I don't see a problem with that.





http://fcrparts.com/Our_Products.html

Call Terry at: 1-402-596-1800

He will need the information about your vehicle, engine specifications including heads and flow numbers if available, and your specific intention of what you want your motor and car to do.

Norm

 

Ultradyne = Good for you

 

Yes. Good for any Olds.

Harold (the UD cam grinder) will not bore you with a description of an entirely different application:
Or tell you to change yours, so it will fit a cam in his catalog:
And he will not tell you, based on his own limited experience, that you have something that you do not:
He will simply design the best possible profile, based on the information you give him, for your unique application.

Norm

 

this thread went to hell

 

All for a cam recommendation...

 

There is a single common denominator regarding threads that go to hell on CO. You figure out what (who) it is.

I thought Wireman and I were having a friendly discussion, polite and civil. No? As to the cam, it is just my personal opinion that there is no right cam for a car with 10.25 to 1 and 2.56 gears. Not with today's crappy fuels. JMHO. By all means, give Dave at Engle, Tim at Bullet, Terry at FRC, John at RR, and get their advice. I have spoken and dealt with all 4 and they are great guys. They do it for a living and most surely will give you some expert guidance. If they do recommend a grind, please share the specs with us!!

 

Most threads go to hell when a person who will remain nameless ( I have taken a vow to myself to never utter it), gets involved. Think about it guys. Talk to the mods. Get him off of here before you die of boredom and inanity. I find myself looking at Capn's threads and you know who pops up. Just to cause trouble. UGH!

 

The mods have given norm free reign to be himself, somewhere there's a thread that says his vast godlike knowledge trumps his abrasive 'tude, so don't expect any changes.. As a matter of fact, I can remember someone commenting on his style in a thread a while back and he linked the mods approval thread.

 

Yeah, he has taken a special interest in me. I feel special!! LOL Seriously, though, he costs this board membership, which is too bad, because there are a lot of great guys. Look at the DX build thread. He ran off raadon, who simply stated that he has a DX block with .842 lifters. From his few posts, raadon seemed to be an experienced Olds guy, but like many others, he is gone and Norm is here. This also from that thread,

Originally Posted by gearheads78
........ I noticed no sarcasm in that post
No stupidity in the post = No sarcasm in the response.

Norm

The problem is that Norm gets to decide who is stupid, what is stupid, etc.
In the 350 upgrade thread he takes a smart a$$ shot at me with his "oops" remark, then posts a link to RobbMcs website. Well, that pump does not clear the E-brock head, according to their own website. I am not sure if he is saying that it will, his goofy posting style makes it difficult to understand sometimes. IMO. I'll do what I usually do, get tired of his nonsense and quit posting. Of course, I have nothing of substance to add, so that will be a good thing, right? Its not like I have an Olds that I race or work at a machine shop that builds race engines or anything.

 

Could be part of the misunderstanding.

I'm glad that you have experience many of us don't (myself included) and value your contributions, just as I do Norm's. I nor any of the moderators or administrators are here to ban someone because they offend some people. I cannot think of any members that have been banned for any reason other than spamming. We have had no members that constantly use vulgar language, or flame others, or try to preach religion, or politics. These are the most common reasons usually cited as bad behavior that deserves discipline. My own son (Olds64) does not like Norm or get along with him. You know what he has done? He has put Norm on his "ignore" list, problem solved. If I were to ban Norm because some people don't get along with him and dis-like his posting style, then who goes next by what standard? Sorry guys, he won't be banned because you don't like him any more than you would be banned because someone didn't like you. And as far as not having as many members because he scared them off or offended them so they quit, this site isn't here as part of a popularity contest. Besides, I can only think of a few anyway. I don't spend much time over at ROP or the HAMB because those places are really clique-ish and can be brutal. No skin off my back, I go there occasionally and visit, maybe post once in a while. No big deal, I don't need to try to get someone banned there because I don't like them. I am saying this in part to get some things off my back, and in part to defend my in-action (according to you). I just don't think it is right. By the way, your posts have been informative and useful and I appreciate them, don't have anything personal against you, nor do I have anything personal in the interest of Norm. I don't know him any more than I know you, certainly don't consider anyone here (except Jesse, my son) as a friend. Friends require some personal one to one experience and time invested in my opinion.
By the length and fractured nature of this post anyone can tell I am letting it all go as I type. I apologize for it's poor construction and it may be difficult to read. Anyway....

 

I appreciate you taking the time to reply, but it is not the posting style so much as the attitude. Take post # 20 in this thread.

"Harold (the UD cam grinder) will not bore you with a description of an entirely different application"

He asked about vacuum in a 10.25 to 1 engine. I relayed my actual (not theoretical) experience in a VERY similar (yes, it has .2 more compression) engine. Why use the word "bore"

"Or tell you to change yours, so it will fit a cam in his catalog"

I don't have a catalog. When I need a cam, I call one of the 4 vendors mentioned above.

"And he will not tell you, based on his own limited experience, that you have something that you do not"

That was in response to this by me,

"After you did the valve job, what head gaskets did you use? If the Fel-Pros, Cr is going to be lower, like 9.6-9.8 or so."

Over estimating Cr is a big problem and results in many engines being over cammed. That's why I asked. The piston catalogs are famous for it.

Why use the phrase "limited experience"? Both that and the "bore" are clear intentional insults, not imagined, and not necessary. He goes out of his way to do this stuff constantly. Not just to me. Look over threads where he is involved and look at the direction that the thread takes afterwards. He does not assail my facts, he just adds his own interpritations. And, all due respect, if you don't think that he costs you members, you are mistaken.

This from the "350 upgrade" thread'

Originally Posted by captjim
........ You will need to port match an RPM intake ........

Port (not gasket) match is always a good idea, regardless of the head/manifold combination.

Quote:
Originally Posted by captjim
........ fuel pump clearance is an issue ........

Shouldn't be. How many are using an OEM type pump at, or near, 400HP?

If any are, how many experience a "lean" condition, at the big end?

Norm
__________________
Quote:
Originally Posted by Texascarnut
........ I think you are more of an irritant to everyone here, and most certainly not nearly as smart or knowledgeable as you seem to think you are.


88 coupe






08-03-2008, 05:28 PM #20 (permalink) 88 coupe
Junior Member

Join Date: Oct 2004
Location: Southern CA
Posts: 992


Oops.

http://www.robbmcperformance.com/products/olds550.html

Someone probably is, but it did not exist, when the Edelbrock head was designed.

Norm
__________________
Quote:
Originally Posted by Texascarnut
........ I think you are more of an irritant to everyone here, and most certainly not nearly as smart or knowledgeable as you seem to think you are.


88 coupe







08-03-2008, 06:38 PM #21 (permalink) captjim
Senior Member

Join Date: Aug 2007
Posts: 136


"Shouldn't be. How many are using an OEM type pump at, or near, 400HP?

If any are, how many experience a "lean" condition, at the big end?"

The Master/Airtex 40736 will support that Hp level just fine, and costs $40, but will not clear the E-brock head.

Hey smart-a$$ Norm, this, from RobbMc's website,
"Will Not Clear Edelbrock Heads"

Oops.



This exchange could have (and should have ) gone this way,
Norm;
"While true that a stock pump won't clear the E-brock heads, the point really is moot as and SBO the uses an E-brock head will require more fuel than a stock pump can deliver. Here is a link to the RobbMC pump (link). It will support well over 500 hp.

Jim;
"That is a valid point about fuel delivery. That is a first class pump, however, after visiting the site, I see that their pump does not clear the E-brock head, either. Perhaps you are aware of a modification that allows that to be used on a SBO"

It did not solely due to Norm as his arrogant and insulting attitude.

 

I just added Norm to my ignore list. It is unfortunate that somebody as knowledgable as he is has to have the attitude he has. I am thankful I do not know him and even more thankful I do not live next door to him. He does drive members away from this board. There is no excuse for his style. Being crusty is one thing. I am 62 and know something about crusty. Just about every thread he is involved in goes to hell. Just go back and look at them. Nuff said.

 

I put said person on my ignore list as well. It's like a breath of fresh air. Oldsguy is right. It's a free country. We are also free to leave this board if we are offended by any member. I posted I was leaving and a member suggested I just put the person on my ignore list. I laughed because I had no idea this function existed. Like I said, it's like a breath of fresh air. You check a post and voila! No posts by ignored member. What a great function. Keep posting Capn, I like your stuff. I hope you guys enjoy mine too.

 

captjim and all you other guys, don't give up posting on this site. Do the same thing z11375ss and I have done and put said person on your ignore list. Then you get the pleasure of knowing that you have igonored him because you get a message when he post that the message is hidden because said person is on your ignore list. Life will be better and we still need your knowledge.

 

So Jim, since you and I think alot alike and we both have butted heads with other know-it-alls, I assume I might have another opponent? I don't try to start Shyt but if I feel they are wrong I am prepared to do battle. If I'm proven wrong, I will admit it. I hope I can contribute in a positive way to this site.

Ya Jim you gotta start hanging around a few racers and engine builders

Nick

 

Nice to see you here, Nick. I'm sure you can contribute a lot. There are a lot of big talkers on the internet, but not many guys with 10 second N/A small blocks Oldsmobiles.

So, I have added a member (the only one) to my "ignore" list. Theoretically, if everyone else does too, he will be talking to himself.

 

Now let us all join hands and sing Kumbayah!

Someone is roasting their tires lord... Kumbayah

Someone is smoking a ricer lord... Kumbayah

Someone is running 12s lord... Kumbayah

Oh lord... Kumbayah

 

10 second small block. Big deal. Mine runs 10s too. Just not in the quarter. Welcome 380.

 

Exactly what is expected of any participant on these boards.

I've read some of your posts, on those other forums. Looking forward to more of the same.

Norm

 

Did someone just say something? I coulda sworn I heard something.

 

ROTFLMAO!

Allan

 

HaHa! And to think I get on here to get away from my girlfriend's drama TV!!!!

 

Lock this thread already.