Ok heres the deal.

I have

355, Bottom end balanced, New flat top pistons
Stock rebuilt heads 75cc chambers 72-73 on the year
2800 stahl 3000 flash on a 350 turo trans
2:73 stock posi
MSD 6A
MSD Wires
750 Edelbrock 4 barrel Carb
Air Gape intake

Tell me why you think I cant use this cam

Comp Cams Magnum Cam

253/253 525/525 3000-7000

Ive been told It wont work well Let me know why you think it wont.

 

Any work done to the heads? 253/253 seems like a alot for stock heads.

 

Thats what I,m afraid off. There just stock rebuild. New Valve and springs. and there only 1.94's Ive been told that the motor will be a turd with those heads. Which seams to be all I need to make this a good running engine.

Here's another question. Could I get away with a set of 2.02 heads Rebuilt. Or what CC heads whould be recommended ???

 

what about your 2.73 gearing?

 

Yes Yes those do suck too. I,m not going to change those till they break or I get some suspension done to the rear end and some Drag Radial's or slicks. Right now the low gearing helps me off the line, I dont spin one bit. I,m still not under 2 seconds in the 60 foot but if I had say 3.73 with the suspension and tires I have now I,d spin real bad and have about a 3 second 60. So I,ll take what I can get for now. The only rear suspension work I have now is Panhard Bar.

 

Why won't the cam work? Beacuse on factory heads, at .525" valve lift, the bottom of the retainer will slam into the top of the guide boss, bending a pushrod, flattening a cam lobe, something destructive of the sort.

 

http://www.crower.com/misc/cam_spec/...00231&x=13&y=5



IROCZ86

youll be far happier in the long run with a cam like this in that engine with those 2.73 rear gears and cpr,but ID give SERIOUS concideration to adding a set of 3.73-4.11 rear gears as the cam I sellected will run far more effectively with them installed, the cam you sellected will be a total miss-match

 

That cam is way to big and will not run well in that motor. First, the stall converter is to low. Second you don't have enough gear. Third the heads will not flow enough air to support the cam. It will not be streetable and will be a pain in the a$$ to tune. Look for something smaller.

 

I realize all of that. Right now I just want to get it back up and running agian before summer. The Cam I had before ( JUNK NOW ) worked good. It was a Crane Energizer Cam

2000-5,000 216/216 .454 lift.

I want to go a little bigger but not TOO big. So what can I get thats a little bigger than that but not TOO much for what I have now. I know Gears would help but I cant do both right now. Remember I,m on a tight Budget with a wife and two kids. Things come slow if at all. I dont have alot to work with at the moment. If I really have too, I could buy a set of Richmond gears but wouldnt be able to afford to have someone put them in for me.

 

use Comp Cams #12-209-2 275DEH -10 cam
275-277 .462"-.482" 219-229- @.050" 110LSA

You need to remove the cylinder heads and "home port" them.
Have .060" shaved off the decks and reinstall with thin .015" steel shim head gaskets.

This will get the compression ratio and air flow up.

 

UM, Ive already got 10:1 Compresion, at least thats what the Machine shop that rebuilt the motor said. And I dont want to mess with the Heads. To tell you the truth I think they were decked. I,m not sure, I didnt own the motor or the car when the Motor work was done to it.

But to have 10:1 compression with Flat tops It would almost have to be Decked dont you think. And I already have the .015 steal head gaskets.

 

I'd go with the Isky 264 Mega Cam with 1.6 stamped steel long-slot rockers installed "straight up" ICL 108, ECL 108. Advertised duration 264/264, 214/214 @.050 lift, .480 valve lift with 1.6 rockers (check for clearances) It will have about the same vacuum as the other cams suggested, but the tight centerline and small single pattern duration will let the power curve and peak power come on quick. All good things for stock 1.94 valve heads and numerically low rear gears.

 

"And I dont want to mess with the Heads."

This is what will give you the effect you're looking for by wanting to select a big cam like the 305H Magnum.

Yes you have to remove them and do all the dirty grinding and porting but it's all worth it.
This will wake the motor up quite a bit.

By home porting the heads you'll get the big top end power and rpm you're after even with this relitively modest cam.

Just installing a big cam like the 305 magnum will turn it into a mutt. (missmatch)

 

Well I do have someone that could do that for me professionaly at no charge I believe. Or he has 2.02 heads laying around I could get off him too. But I didnt really want to do anything at all to the heads, b/C in a year or two ( depending on money ) I,m just going to by a set of Iron Eagle Dart heads most likely 2.05 or 2.08 64CC. Right now I just want to go as Big as I can on the Cam with what I have currently just to get it going again. I understand fully that the Heads Ither need to go or have some port work done to them, I,ll check with my guy and see what he says. If I dont want to mess with them AT ALL, give me a Cam Dur and Lift that I can manage well with what I have.

 

MY 350 has 64cc vortec heads and flat tops, and the block was shaved enough to get it straight. Unless they shaved the heads I dont see 10-1 there. Espically if they say they were 75cc. Mines is still probably just at 10-1.

 

I didnt see how either. I,m going to take one of them off tommarrow and take it to a guy to have him look at them. Maybe seewhat he can do with porting and what not. ( not my line of expertness ).

 

Not sure if this helps y'all but I have a L-98 350 +.020 and with a 64 cc head and my speedpro flat tops I have 9.74:1 C/R .

 

I don't think so.

It's always amusing to see these funny numbers tossed around without any basis in fact.

Speed-Pro pistons are "rebuilder" items, not a "performance" product. They were originally intended as replacement truck pistons. They're a good heavy-duty product, but they are optimized for "rebuilder" purposes, not racing; in spite of the fact that they work pretty well for racing, when properly applied. But regardless, their "design intent" has not changed.... they're NOT racing parts, they're REBUILDER parts.

One of their optimizations for fleet service, but non-optimizations for racing, is their compression height. Their compression height spec is 1.54", compared to 1.56" stock (or "racing" parts). Since a common failure in hard-worked motors is blown head gaskets, and when a head gasket blows and the jobsite monkey keeps driving the truck anyway, the block gets eroded, and has to be decked. Therefore, since it's usually preferable in a "rebuilder" application to give up a little compression, as opposed to having pistons crash into heads, these pistons are located .020" further down in the hole than stock, to allow for repair to the deck surface.

Therefore, in an undecked stock block with the usual 9.025" deck height more or less, you end up with about .045" of deck clearance. That means, the piston misses coming up to the top of the block, by that amount. Which is to say, you've got to add that much volume to whatever other volumes you have, in order to accurately calculate compression. Whether it's a pleasant dose of reality or not.

People who quote these ludicrous CR figures usually aren't taking that into account.

Those pistons also have 4 valve reliefs; they cc about 6 ccs. People usually leave those out too.

Using a .039" head gasket (Fel Pro or equivalent), .045" deck clearance, 6 cc valve reliefs, and 64cc heads, the true CR is 9.27:1..... not 9.74:1.

Using the same numbers except with 75cc heads, the CR is a rompin' stompin' 8.37:1.

That is WAY WAY WAY WAY too much cam for a motor with smogger compression like that. It will be beyond gutless especially at low RPMs. The gears will about guarantee that the car will be slow with that combo.

A cam with a .050" duration in the mid teens to low 20s is as high as you want to go.

It is mighty stupid to build a severely mismatched motor like that, with the totally wrong cam, because someday you "might" upgrade the heads. Look at it this way: your head upgrade, from drive-in to drive-out, will set you back AT LEAST $1500. What's a $100 cam, compared to that? Is is worth forcing yourself to tolerate a slug-slow gas-sucking pig in the meantime, to "save" that $100? That misfit cam will cost you that much just in gas, within a few hundred miles; and you'll hate driving it, every second. Don't do it.

 

ummm I do think so . You don't even have a clue WHAT speedpro's I have . Did you know there is more than one 20 ever piston they sell ? When stock was 9.0:1 with a dished piston adn I have the stock deck hieght on the block I have 9.72 :1 cr

Here is the stats on them from Jegs


844-L2256F20 350ci Stock-Type Piston, .020'' Overbore
Piston Dia.: 4.020''
Piston Top: Flat Top, 4-Valve Reliefs
Pressed Pin
Comp Ratio: 9.72:1 w/64cc Head, 8.62:1 w/76cc Head
Ring Grooves: 5/64'', 5/64'', 3/16''
Sold as Each



I believe what jegs put there over a really rude jerk who knows it all But you were right these were a stock type replacment piston . But they are forged and yield a higher compression ration than you CHOOSE to believe.

What say you ?

 

I don't have to. They're SPEED PROs after all. I'm thinking (although of course I can't really know for sure) I've been building engines with them since sometime before you were a gleam in your momma's eye, and maybe, before your momma was a gleam in your grandma's eye. I've LONG SINCE lost track of how many different part numbers of TRW / Speed Pro pistons I've used over the years, EVERY ONE of which had .020" less compression height than stock.

And of course, the reality is, you have the single most popular part number they sell.

You're wrong about your CR. Period. Go right ahead kidding yourself, but I assure you, your engine is not fooled.

Go look up the compression height for them, and you'll see that the numbers I'm quoting, are RIGHT STRAIGHT OUT OF THEIR CATALOG, and can be verified with a micrometer and a buret (or even just a dropper); no matter what Jeg's put on their site.

Those CR figures you're quoting assume that ceratin block work has been performed. They ARE NOT accurate for an unmodified stock block.

It's all numbers dude. You can protest all you want, the numbers won't change. 2 + 2 cannot be made to equal 5, even for UNUSUALLY LARGE values of 2. You just make yourself look like some kind of .... well, let's not go there.... by screaming and hollering and calling me names, because you don't like the numbers. They're not going to change for you.

So, go right ahead and believe whatever you want. Some people still believe that the Earth is flat. Somehow I doubt the Earth is listening to that and adjusting itself to their bias, any more than your engine is reading the Jeg's catalog and changing its compression to go along.

It's always amusing when people take offense at reality. Especially known, measurable, physical reality about a mass-produced product with several decades of history, that can be observed with common household instruments. It shows something about a person's inner character when they do that.

Go look up the compression height of your pistons, and you will find that it's 1.54". Go look up the stock compression height for the CHevy SBC, and you'll find that it's 1.56". Go find a compression calculator - ANYBODY'S - and use those numbers, and don't forget to inculde the .025" of deck clearance that a stck block already gives you. After you humiliate yourself by discovering the truth, I believe you'll see you owe everybody here an apology for that outburst.

 

I don't think I do . You come off as a jerk plain and simple . So you got a response that reflected that .

Let me see my engine builder, and the jegs book is wrong . where do you get off saying you are right and they are wrong ? Maybe YOU owe the appology .
As far as yelling and screaming stop trying to hype this up to more than it is . A disagreement.


The only appology I owe is that to the origonal poster , for haveing to type this stuff in his thread .

BTW you heads are gonna be a problem with that cam . What are the casting #'s it may help .

 

L2256F pistons seem to show compression height as 1.563"

http://www.sdpc2000.com/cart.asp?act...id=362&pid=397
(read down, below the moth ***** BS)
http://www.derbypro.com/bbs2/topic.a...e&TOPIC_ID=346



I am in the market for relatively cheap pistons now, and i'm picking Speed-pros, but i've noticed they're sources are not always right. I wanted to get H345NP's, and some sources showed a 1.56 compression height, some showed 1.54".
But! They're advertised compression ratios are right, *IF* you use the "correct" compression height.

if you use a compression ratio calculator, and use a "normal" .039" thick gasket, 4.166" gasket bore, then try and get their advertised compression ratios. If you get the correct compression ratio as in their catalogue (9.7:1), using a .025" deck height, then it's a safe assumption that the compression height is 1.563.... (unless they published both wrong)


IROCZ, have the head casting # yet? Everything kinda holds in the balance without it....

 

I have a skinnier gasket . But not sure of the thickness .


Head numbers head numbers. We need head numbers.

 

Oh no, no apology needed here. I,ve been amused by the whole thing. And learned a little bit in the process.

As far as my Cam options go. Here are the plain and simple facts you have to decide on for me.

1. I,m not moding or grinding or decking or anything else to my stock heads. Other then maybe 1.6 Roller Rockers its all staying like it is. ( Casting Number 3998993 E83 72-73 year Heads. )

2. I had previously a Crane Energizer Cam 216/216 454/454

3. I can but dont have to use a 2800/3000 flash B&M Stahl.

4. I dont want and am not looking for a specific kind of Cam, I WILL buy a Comp Cam.

5. All I want from you guys ( Asking Nicely ) is what Duration and Lift will work well with what I have.


Say for instance a Comp Cams Magnum Cam 2500-6500 244/244 501/501

Is this lift too high or is the RPM to high?? Things of that nature.

I am willing to call Comp Cams and order a special order MADE Cam specific to what I want.

So there have at it and play nice all of you.

 

first off, those heads are crap. Had to be the first to say it.
Now that you know it, and you're set on using them, be prepared for a disappointment....

Flat tappet cam right??

magnums aren't amazing, look at the extreme energy. the Xe274 is VERY popular on these boards. Perhaps look at an extreme energy solid. Toss in some BTE stud girdles ($59, no joke), and you can have a very powerful valvetrain, with less maintenance then you think.

do you know EXACTLY what was done to the heads? I think it'd be HARD to have 10:1 compression with those, plus you don't know what the max lift the heads will take, until you measure it, and if it's low (ie, you want more lift), you'll need to take the heads off and have something machined so....
(unless you use .050" offset retainers, keep those in mind...)

 

Second off, I know those Heads are crap. Third OFF I,m not a rich spoiled ***** that can just go and buy whatever I need. What I need right now is what WILL WORK THE BEST with what I have regardless of how Crappy my heads are. The previous Cam was good other than a slight hesitation, The Previous Cam kicked in at 2000 and the Stahl on the convertor was only about 1800.

Future mods withing the next two years include new Heads and a ROLLER CAM. Right now All I want is what will work the best. And since I already know a 2000-5000 216/216 454/454 works good ( Ran a 13.90 in the 1/4 with 2.73 gears ) I just want to know if I can go a tad bigger or not. What is so hard about this guys???

These heads are 75 CC heads with Stock new valves and springs. Other then I dont know if they were decked to get this magical 10:1 compression I dont know anything else about them, I didnt have the work done the previous owner of the car did.

 

IMO the cam you have now, is already as big as it can possibly be for the rest of the combo; i.e., the car might go faster if you went down a bit, instead of up, with the cam. Which also means, if you put a bigger cam in it, it's entirely possible the car would go slower, rather than faster.

I cannot begin to tell you how many times I either built (under duress... not my idea, I assure you) that identical motor for other people, or watched them build it, all through the late 70s and early 80s, after that combo of stuff started becoming plentiful in junkyards and used cars; and the results really haven't changed very much since then.

Honestly, I think the fastest the car might go with that combo, would be with a Comp XE256 or XE262. Neither of which is a very big change from your current one, and IMO not worth the money and trouble of making the change. The cam you have now (HE268) was designed in about 1980, for motors EXACTLY like the one you've got, part number for part number; and while newer cams may "make more power" at their HP peak, the fastest car isn't always the one whose engine "makes the most power" on the dyno (Desktop or for real). It's as much about the engine's torque curve matching the RPMs the drive train forces the engine to operate in, and the "area under the curve", as it is about pure peak HP.

My recommendation would be, to just leave it alone, and save up your money, and get to the point where you can do what you REALLY want to do, that much sooner. Consider that every dime you spend on what you have NOW, delays getting what you REALLY WANT, by however long it takes you to save another dime. I don't see you getting a whole lot more out of it without more $$$ than just a cam swap.

 

True true true. I do hate the combo. But I still have to get something, as I dont have a cam at all right now, the motor isnt even in the car. I might go with the option of leaving it as is just going with a Comp Cams of the equivalant to the Crane I had in it. ( Crane = soft which is how I rounded two of the loabs.)

I really appreciate all the comments and Ideas, and the arguing off topic. I,ll let you all know what I plan on doing, I might still do something with heads, I,m not sure. It all depends on money and how much I have to blow.

 

I recomended a cam for you setup in a previous post above.
It's a tad hotter than what you had, without getting silly.
it will work well and will work well for ya when you improve the heads and rear gear ratio also.

 

Originally posted by F-BIRD'88
use Comp Cams #12-209-2 275DEH -10 cam
275-277 .462"-.469" 219-229- @.050" 110LSA

This is the Cam you recomended I get and do some Home Porting to the heads??

Whats the RPM Range on this?? You wrote the Specs different than I,m used too. I get the 219/219 as the Intake exhaust Duration and the Lift at >050 but what is the .462"-.469" or am I reading it all wrong??

Sorry if I sound like a dumbass but this is not the part about Building a Rod I like the best.

And what would happen if I used this cam and didnt home port the heads or anything?? Would it still be decent or a Mutt??

 

Never mind, I am an Idiot. .462 is the lift and 219-229 is the duration, now what is the 275-277??

 

advertised duration, don't worry about that.

porting the heads will make more power difference, then if you just swapped to that cam.

did you consider it decent, or a mutt, before you wiped that cam?

 

No not a Mutt at all, faster than most thought it would be. Ran 13.90's in the 1/4 just over 2 seconds 60 foot times. I had a friend with a 89 Firebird with almost the same setup and he would run a second slower than me at the track. We could never really figure that out, he had 3.42 rear gears and I had the 2.73's

Here's another question, could I go with a 2000-5500 224/224 .460/.460 Its a Lunati Bracket Cam. I could get a 2000 stahl to go with it if it would help.

 

Go with a Comp XE262 cam. Your way over camming your combo.

 

XE262, does XE stand for xtreme Energy??

So far two of you have recommended that same Cam.

 

Yes, XE = Xtreme Energy.

 

XE 272 or XE272 which one should I get??



Well all thanks again, I think I know now what I,m gonna do. Get the XE262 or the XE272 Cam and have the Heads Ported and decked.

Oh ya one more thing.. Should I stick with the Stock Convertor or get a stahl of somekind?? Say a Holeshot 2000 from B&M

And what are the Specs on the XE262 Cam and the XE 272 Cam.


Oh and I,m looking at a Hydrolic Cam if there are no objections.

 

XE262 http://store.summitracing.com/partde...CL12%2D238%2D2

DE275 http://store.summitracing.com/partde...CL12%2D209%2D2

These 2 cams aren't terribly different from each other; except that the XE will give a little better cylinder pressure at low RPMs (more torque), where the DE will give a little less valvetrain noise. My personal preference is for the XE cams, but that's just me; either one will work well.. as well as anything can... in the combo at hand. You won't go wrong with either one.

That's what cam selection is about: evaluate the rest of the combo AS IT STANDS (cams being as cheap as they are, and their match to the combo as critical as it is), and avoid the pitfalls of "someday" "maybe" "I might" "plan to" whatever. The cost just in gasoline - green cash money, bleeding out of your wallet on a daily basis - from an overly enthusiastic cam choice, will more than pay for replacing it when that "someday" finally comes.

"There's no such thing as too much cam, only not enough motor". And I might add, not enough CAR (gears, converter, weight).

 

stop saying "stahl", there's no "H". It's "stall". Like if you didn't know how to drive a standard, what you would be doing. There, I had to say it, I thought it was just a typo, but you said it too many times.

Once you pull off the heads (not off now right?), find out what pistons are in there, and cc the heads. That'll tell if you need the heads decked much.

 

WELL SORRY MR. Crabby pants.

 

 

Just so you all know, I went with the XE 262 and LOVE IT. Next week we start the LT1 head Conversion. Heads are at the machine shop now should get them back by monday. Got a show to go to Tuesday and then tear down.

 

sorry wrong thread.