I could swear the deck height is exactly 9" but I could be wrong.... I couldn't use the 5.7 rods cause the piston hit the head in clearance mock up.... so the next shortest rod is 5.565..... right? I know that 5.7 rods can be used but it requires specific piston heads right? Also have to include gasket compression height right? Roughly .049 I believe..... I know the 5.7 rods hit with the pistons that are in it now but I could get new rods and pistons.... wouldn't hurt. And with 74cc chambers and flat tops I should be at 10 maybe 10.5 to 1..... but that will cut down any budget I have for heads...... if there is an extra .025" on the deck height then I'm lost..... Lol is it for sure 9.025"?

 

Straight from summit.... it says when using any length other than 5.565 rod to cam clearance could be an issue..... I'm tryin to avoid machine work....

 

Doing some calculations with the deck height of 9.025" and current setup roughly 9.6-1 cr....
Simple answer seems to be dome pistons..... I would like some opinion on it....

 

Hey Bud.Read exactly what they wrote.Rod to cam clearance "could be" an issue.That is they are saying rod bolt to cam.........

Do a search for crank center line to deck on either a 400 or a 350.Here is a sample:

http://search.yahoo.com/search?fr=mc...surface+on+SBC

You could buy "stroker .040 pistons"(althrough I prefer to have the pistons first for the final bore/hone) and get the Scat 5.7 press fit pined ARP bolt stroker clearanced rods.I bought those and thought they are a big bang for your buck.

I haven't plugged any numbers,but I do have my doubts about a c/r of 9.6 with your 76cc heads and current set-up.

Bottom line here is after parts,.040 head gasket,good set of aftermarket 180 or better yet 195cc runner heads,matched cam to the redone c/r,machine work to deck the block to either .010 down or 0 deck,your coming up afew thousand short.

Could you live with your 5.65 rods,76cc heads,cam,well as it is??. Sure.But it isn't just one thing that is a issue.It's a combination of a bunch of things.When you step through that 383 door,you accept GM really never built effective heads for it.Some of the aftermarket stuff is expensive.Remember I said max out all your going to get on a GM standard production head is 170cc intake runners.There are Hi-Po GM heads that cost lots and don't really stand up to what you can get in the aftermarket cheaper,so what's the point??.Even my peanut 383,which I have the wick turned down alot for torque,has a bigger intake runner than 170cc's.Because it needs it.

I'm going to be bold in this next statement.What all of us do is increase the efficiency of production engines.I don't think your set up is doing a good job of doing that.

 

I'm in agreement if the deck height is 9.025" I thought all sbc were 9" I ran the numbers for my rods crank and flat four valve relief pistons and it was 9.6-1 with 74cc heads... so what's wrong with putting in new pistons it's the cheapest most efficient way isn't it? Then after I get my compression back up where it should be, I will get some trick flow heads.... and sometime put a huge cam in..... I Just can't afford it all at once.....

 

Firing order has nothing to do with Volume.. Even if you swap from 1-8-4-3-6-5-7-2 to cut down on crank deflection your volume remains the same.

 

I'm being lazy.Still haven't run the numbers for SCR.A piston swap is opening the debate of long rod vs short rod.I am a believer in the long rod tech.Helps the piston dwell longer at TDC and decreases piston travel with long rods.If your going to replace pistons,basically your only short of the costs of the correct Scat rods which only cost from Competition Products $222.95.Your going to have to pay to re-balance either way.The stroker pistons flat tops or reverse domes to set your SCR I don't think cost anymore.In fact as I set here now thinking about it,a set of domes might cost more.Using the 400 rods is very old tech.That is what we did yrs ago.Also going with a common today's combo,it wouldn't be that much more to deck the block to the two standards of either .010 down or 0 deck.That is one of those things that is a cheap mod and insures a flat deck surface.I want to point out to you that if the c/r is 10.5,you have to swap to aluminum heads as part of your changes for today's gas.Here,I'm trying to say,it's not a option you can do later.The only way to do that is if you set the SCR for a cast iron head as part of your build.It's there where the reverse dome pistons/decked block amount would come into play and where choices of aftermarket cast iron head chamber volumes are important.It is also there where you get to choose which intake runner cc's your going to use as apart of how your going to tailor the torque curve along with cam choices.Of course,you understand the aftermarket cast iron heads are cheaper than aluminum heads.But c/r's are the fast track to power output and you do know you get what your paying for when you buy cast iron over aluminum being the aluminum can be a high c/r for today's gas.For me,we have sold dozens of used aluminum heads and none of them where re-salable without some kind of rework.Valve guides a common thread needing to be replaced.This is one man's opinion,but because of the aluminum material being softer and the way the material handles heat better,I think is also it's down fall.So because of today's gas limits the c/r of cast iron,(9.5)you give up some of the c/r,but again this is one man's opinion,I think over the long term cast iron aftermarket heads are more durable.Here the question is if 9.5 or 10.5 is more important to you.But you have to plan for that in advance.I wouldn't suggest you build a reverse dome cast iron aftermarket headed engine and then later add aftermarket aluminum heads less you where planing for some sort of power adder later along with the aluminum heads.Also with c/r changes a cam/kit swap should happen to match the c/r.

A summary of all this, is just bring this build in-line with commonly used today's tech of 383's.Well sort of.Fact is the tech has moved onto 6" rods or more.If taken care of and built right,there isn't any reason why long term it shouldn't be a consistent turn key strong running long mileage engine.

The question here is if you want to say the heck with it,and just run it as is.

A long,long,run about way of getting back to the original question,you could swap in some Flowmaster 40's to make it sound better.

Gone to the beach for some much needed R & R.TTYL.

 

Well enjoy your r and r...... I'll talk to you later. Thanks again for all the info.

 

This all adds up to me. You're using 350 pistons on shorter 400 rods. This DOES increase clearance in various directions at the expense of more side load on the cylinder bores but it will work just fine. If you want to rebuild the bottom end, then go ahead and get some 3.75 stroke pistons meant for a 5.7 rod. I dont buy that rod/stroke ratios are a big deal, personally. 5.565 rods are way shorter than I would use, but when it comes to choosing between a 5.7 or a 6.0 rod, I think there are a whole lot of far more important factors in making power.

http://www.rehermorrison.com/blog/?p=89

Now if you're in a competitive, displacement limited class in a competition environment and need every edge you can imagine and cost isnt a factor, then yes you optimize that, but for a street car I think you just get whichever quality piston and rod package you can get for the most reasonable price, and if that ends up being a 5.7 or 6.0 or in between length rod then whatever. But the longer rods do get all up into the oil rings on the piston and cause more potential interference issues. Going with a 5.7 H-beam rod should get you a lot more clearance, but you'll pay for it.



With 64cc chambers you will be around 11.0:1 depending on several other factors. With 76cc chambers as on stock smogger iron heads like 882s and 993's, then you should around 9.0-10.0:1. I dont know how you did your math, or how well you measured things like piston volume, gasket thickness, piston to deck clearance, and so on and so forth, but as it sits I would imagine mid 9's in compression sounds about right.

 

I know shorter rods are worse for side drag, but due to limited funds I either get pistons or rods.... can't get both. And to solve the gas mileage issue a higher cr should do the trick.... right? So if I leave the 5.565 rods and install -7cc pistons with 1.56 compression height that should put me right about 10.8-1 cr with the heads I have.... if the extra .025" is there.... but I still haven't gotten a straight answer to the exact deck height. If it doesn't have the extra .025" then calculations show 11.3-1 cr with my current heads....... I'm using summits compression calculator..... so the ? remains if you could only buy rods or pistons and the pistons you have are too tall for longer rods then you must get the pistons.... right?

I know the compression height for the gaskets is .040" so if the extra .025" is there that's .065" of wasted compression space.... I have to make up for that some how, and considering budget and current setup I think pistons are the fix.

If you want to do your own calculations just tell me what other info you need and I'll get it. I plan on building a four bolt 383 later, but right now this is what I have to work with....

I know The mileage is killing me, that's the biggest thing I wanna fix.... I know if I make the motor more efficient ie.... raising the cr that will make it more efficient therefore saving fuel.... correct?

 

Main bolts wont make more power or anything so dont stress over that. 2-bolts are fine even with most moderately tweaked 383's. Once you get past 500hp or so, you will want to move on to an aftermarket block or a splayed 4-bolt setup. Anyone with any factory chevy head on it will be fine with 2-bolts.

Do you have 64 or 76 cc chambers? Im not getting 10.5:1 at all. And I agree the rod length isnt ideal but it will work fine for you. Just get the static compression ratio into a reasonable 9.0-10.0 range.


4.030 bore, .025 piston - deck clearance, .040 head gasket, 76cc chambers, and 5 cc valve reliefs on flat tops will get you, theoretically, 9.3:1. So if you used a thinner head gasket, .025, it would be 9.6. If you had 64cc heads you would be at 10.5:1.

The only way to get great mileage is to go to a modern EFI system like an HSR or go Gen III. An LS1 will do it, so will a 5.3 Vortec, and those things made 300hp FACTORY. Throw a cam in one and some bolt ons and you can hit 350-400 easy.

 

I know mains don't make power.... just meant that eventually I will build a whole new motor so I can get crazy with it ya know.....

I have 882 heads.... I believe that's the casting. Should be 74cc but have seen 76cc stated some where..... so what are You using to get the cr....? Also are You certain that the extra .025" is there?

So You agree best solution is pistons considering my budget and current setup? I know efi would be best mileage, but if the compression comes up the mileage will too.... right?

 

Right now I think I'm at the 9.3 you mentioned.... cause that's the pistons I have 4 valve relief +5cc pistons but the bore is .040" over.... not that it matters with what we are discussing..... but yes 76cc heads 5.565" rods, 3.75" stroke, and .040" gasket. Plus the possible .025" not sure that's there....

 

Deck height is 9.025 inches from crank centerline on a stock sbc. The problem is that production block tolerances arent quite that precise. One piston can be .040 in and another can be .005 in the hole... or sometimes they will just all measure out a little off from there, just depends on the block and the parts. But yes the deck is supposed to be 9.025 inches according to the blueprints.

Your pistons...are they 1.540 or 1.560 compression height? Do you know?

And I dont really understand what you mean by

I think if you're on a budget, and thats what you've already got, then leave it alone, it's fine.

Also, the most common GM head chamber volumes are 58cc, 64cc, and 76cc. 882 heads are 76cc. So thats the number Im using.

 

Ok so with my heads (76cc), 5.565" rods, 3.75" stroke, .040" compressed gasket and .040" over 4 valve relief 1.560" compression height pistons, I should be at roughly 9.3-1 cr according to summit is that what you're getting?

I'm asking if my ratio is 9.3-1 do I need to bring it up and won't that get better mileage if brought to 10.5-1? If yes, the cheapest way to do that is with dome pistons right?

 

just reading through all this, i have some thoughts/opinions.

with a severely tight budget, i would have ran a 350 shortblock with all stock internals. maybe a stock vortec motor from the junkyard. building a 383 and sticking stock heads on it will make a truck motor. putting a big cam in it will make it a bad truck motor. the biggest improvents you could make on this engine at this point is the heads and probably the carb. i would not pull it out to swap pistons, i would swap heads. even at 9.3 compression you would still make a big improvement with a head swap. piston swap would be a small gain.

heads come first. if you can't afford a GOOD set of heads, keep saving. im not talking double hump's, either.

how are you tuning the carb? do you know the a/f ratio while you are driving down the road? how do you know its tuned correctly?
several years ago i was daily driving a cutlass with a 355 oldsmobile engine. it was around 9.5:1, mildly ported stock heads, and the edelbrock performer cam/intake. i had a holley 650 double pumper on it. (spreadbore quadrajet replacement carb)
with a 2004r trans and 3.73 gear i was getting 17mpg hwy, and ran 9.00's @78 in the 1/8 on street tires with a one wheel peel rearend. pretty good running combo, i thought. thats about all the fuel economy i could squeeze out of it, though.

 

boom, i just saw this. get that thing out of there, its not tuned to the engine unless you have swapped metering rods and all kinds of other stuff. i ran at least 6 different quadrajets in my cutlass trying to find gains. did all the tricks you can do to one. however i couldnt find the metering rods needed to make my engine run its best. (i was working with a bunch of smogger quadrajets) i swapped out whatever rods i could find, drilled some air bleeds, and i can't remember what else. had a tuning book i was going by.
then one day i decided to stick that holley on there for the heck of it. i believe the car picked up .2 and a couple mph right off the bat. never messed with the jetting. its a carb that was made by holley to be a direct replacement for the 60's/early 70's musclecars equipped with a quadrajet from the factory.

 

The way it's tuned is posted a few posts up....

 

I don't care for holleys.... and I don't have the funds to purchase one.... but I believe the deck clearance is more important than the carb right now.... so if it's not read through all this and tell me what You would do not would have done.... it's what I have to work with....

 

if the compression is anywhere from 9.0 to 11.5 and you want to make more power, i would swap heads.

if the pistons are completely wrong and the compression height is way off, (.100" in the hole or something like that) then i would swap pistons.

if you want to pick up fuel economy and probably performance, you might want to get a decent carb for the combo. why spend $500 on pistons when the carb will still be wrong? if the carb hasn't been messed with, it is tuned for a 305.
i liked my quadrajets because they had a nice factory hardpipe running up to the carb, and factory linkage to everything. with the holley i had to make all that stuff work, including the fuel lines. but that holley has performed perfectly. even in 20 degree mornings when i went to work.

 

didnt really see where you did anything but turned the adjusters on the carb.... if so, that's not gonna do what you need. you have to physically go in there and change stuff. and its a pain in the *** swapping rods, running it, and swapping rods again.
my holley seemed nicer qualitywise than the quadrajets, also. would not call it junk. but, mine was manufactured in the 70's so its possible things have changed.

when you said it started like it had a dead battery makes me think you have the timing advanced.

 

I'm not tryin to make more power this thing runs hard.... just not doin so well with fuel... or sound.... also I can get pistons to make 11-1 for 250.... but a holly will cost me 300 minimum and that would be the most basic model.... as far as heads I know people have built mean powerful 383s with steel heads like modified stock 882 casting heads.... now the cam is the only thing I don't know anything about.... I was told it was a mild cam but don't have specs.... I want the performer rpm cam but not sure if I should yet.... the specs for it are .488/.510 lift.....

 

What I am trying to do for you is get this 383 in line with the standard 5.7 rod build.Then go on from there.I'm suggesting that anything beyond a 9.5 c/r will require aluminum heads.So your option of using your heads with a dome piston to raise your c/r beyond that 9.5 c/r level isn't in play.It's true about how decks/pistons measure out.Where your sometimes working off the lower average for how you deck a block.

Tell you what.I suggest you chalk this one up to a learning experience.Get the replacement carb in a Holley or for that matter maybe a Edelbrock and leave what you got alone.I'm not going to get involved in a debate of long rods vs short rods.All I am going to say is it is very apparent the industry is making the move to long rods for very good reasons.And that applies to all engines,street or race.

To patchwork fix this with pistons I don't see as viable.I do think it just further makes it worse.I do agree that you do technicality have to fill a chamber with more gas/air given the shorter rods and that "might" play a role in your gas mileage.But first and foremost you air fuel ratio with a carb has to be right.

Now Buell,I think through this thread we have become friends.Giving it to you straight, now three members have spoken to you in a suggestion about a carb replacement.Me now being the third one.Time to take that to heart,especially when you speak about a budget.It is the cheapest option you have leaving it alone and going with the carb swap.

 

I definitely wouldn't tear the build down just to swap out one thing or another to "tweak it". You wait until you have the funds to do everything that needs to be done at once. Properly tuning an engine will make all the difference in the world in how it sounds(because you're changing how it runs, obviously).

 

Ok sounds like a plan..... I just hate that it's so much quieter than it was....

So anyone got another block they wanna donate? Lol....

 

I didn't read EVERY post in this thread, but, you used the same stock heads from the 305? And the same exhaust setup? Is that correct?

 

What holly you suggest? I want spread bore so I don't have to change intakes.... waste gaskets

 

No stock 350 heads.... casting 882... the exhaust should be ok it's 2 1/2" all the way back.... but have been thinking about 3"

 

I put headers on the 305 anticipating the motor swap to a 350 so when I had the y redone I made sure it was 2 1/2 pipe all the way back.... through a gutted cat too.... We all have gotten so far off what I was originally asking but it sounds like I need to start over with this motor..... I had planned on eventually getting a four bolt and building a beast with super charger and all.... but this motor is plenty stout to shell my transmission so power isn't really what I want right now... but efficiency and sound would be nice.... I've always liked the stroker sound and never gotten to build one, and when the opportunity came about I had to built it pretty much over night due to living situation.... so I know it was slapped together, now I have the time to do it but not the money to basically build a whole new motor......

 

Youll be just fine with 2.5 in pipes

With an iron head I think id leave the compression alone at 9.3
You can use cheap gas and gives you more room to play with timing curves/tables

Get towards 10-1 or more with iron heads youll have to pull timing out not to ping that is going backwards in my opinion. If you wanna play with head gaskets and pick it up a few (+5 tops) go for it

 

Ok I know I need to light this motor cause the timing isnt perfect but given all the info above what would you say for advancement?

 

I really think the cam is a problem also... specifically since I don't know the specs......

 

From what I understand, those heads are pretty crappy. Especially if they haven't had any work done to them. You've got a 383 that doesn't have the intake/exhaust ports for it to breathe properly, basically.That would definitely make it quieter than it should be.

You don't know the cam specs?

Are you using the same stock Q-jet from the 305?

 

Yes same carb but its been rebuilt and adjusted... maybe not perfectly but still adjusted..... So heads are the only way to go? I can't get 195cc runners in cast iron though.... and don't have 1500 to drop for heads.....No I don't know the cam specs I was just going to replace it but as I said I had a rush put on me to get out of where a was living at the time and couldn't wait for parts.....

 

So you are using the same computer controlled carb and distributor, with 350 heads(882 casting), and a built 383 bottom end? Just trying to understand the whole situation. Are you using the stock intake as well?

 

performer rpm intake but the rest yes..... I knew I would be looking at the top end later plus the crank for the 350 was all fubared.... so I ordered the crank and was going to build it over the course of a month or so.... the lost my place had to jet.....

 

Might be a silly question, but did you get a tune for the ECM when you did the swap?

 

It's an 85 is there really a tunable ecm? Last I checked if you can't plug in odb you can't tune....

 

There certainly is. That would likely be the source of all of your problems. Especially the poor fuel mileage. The ECM controls also require a functioning o2 sensor.

It controls the fuel and timing. Is your service engine light on?

 

No.... but if there is a computer then it's about to be unplugged. I have a carbed car for a reason... so I need to get a holley and a vacuum advanced dizzy.... so I can loose the computer crap.... no o.2 bung.....

 

If I unplug the connections to the carb will that help till I can get rid of the computer crap?

 

Not sure but a non computer controlled dizzy usually solves a whole lotta "timing" issues.

If you like the spreadbores and know how to work on them go for it
I never learned much about them but have had some well tuned Qjets and imo are superreliable and good performers.

Summit has a replacement type spreadbore that gets rave reviews. Probably a Holley piece with their name on it.

On noise the more power you make the louder it will get.

Ex....my old 350 with the exhaust I just got rid of was about 430chp noise was tolerable. Now with high 5xx chp it was wayyyyy too loud so had to swap. The difference was rediculous. It was loud but was sapping power.

More air you move the more noise. Some turbo cars seem to run quiet though maybe it dilutes it some?!

 

I'm not sure how you not having an o2 sensor didn't turn the service engine light on. The ECM interacts with the dizzy and the carb based on what it reads from the o2 sensor, knock sensor, etc. if the original sensors are not present then you should ditch the carb/dizzy for aftermarket. The air/fuel and timing is being tweaked by your ECM which is running blind, basically. Lol. Someone else can feel free to chime in to correct me if necessary, but that's how it worked on my 1986 trans am with a carbed 305.

 

I never even thought about that.... duh... damn I feel dumb....

 

Well you dont need a Holley necessarily. I like Holleys, other people like other things. Like I said, just pick a platform and learn how to tweak it. Whether its Holley or Edelbrock at this point really doesn't matter THAT much. What matters is you get a carb that you can properly tune to your engine. Holleys are more tunable but a lot of people have a LOT of success with Edelbrocks, especially if you dont want to spend much time tweaking with it over several months to get it right.

Higher compression at this point will make you need to get race fuel. If you want better mileage I presume it's to save money. Having to buy ultra premium hard to find expensive race fuels will NOT save you money. As 1gary and others have said, you do NOT want to go above the high 9's in compression with iron heads. The amount of spark advance you'd have to pull out of it to make it not blow itself up will cost you WAY more power and mileage than what you have now. 9.3:1 is about perfect for a street iron headed mild-cammed chevy. As others have said, you might want to figure out a way to get it up to 9.5-9.8 in a perfect world, but your 882 heads would probably still ping at that ratio. Honestly you've got it just about right if you're at 9.3:1.

The other concern I have is that everyone is telling you to get new heads, and i agree the 882 heads are really, really holding you back, but you're happy with what you've got, and the other problem is that going to factory iron heads that are decent, like Vortecs, will raise your compression ratio to nearly 11:1, but it will force you to buy REALLY expensive race gas just to keep it running AND it will hold you back at the high RPMs. To get 76 cc heads that are actually an improvement over what you've got and will keep the car practical, you will have to spend $800-$1500 for JUST the heads. Thats not bothering with springs, pushrods, coolant, oil, gaskets, etc.

If you're going to change pistons, the BEST thing you can do is go to DISHED pistons of around 12-15cc dish, and then you can run Vortecs that have smaller chambers and keep your compression around 9.3-9.8:1, and you'll probably make another 50 hp over what you've got.

If youre going to go through the trouble of pulling it apart and changing pistons, go dished, and use factory Vortec heads set up for the cam lift you've got. I think the return on your money for that isnt going to be THAT great though, and I think you're better off saving upf or some really nice aluminum heads. Summit 200cc heads are Brodix IK-200's, and JEGs aluminum heads are Pro-Filers, both are excellent products. If you buy name brand, you can keep them probably for the next 2 or 3 builds you make, or sell them for decent cahs and go LS1. They will hold their value or serve you well for years and years. So I will let you make your own choice about that.

GREAT advice, you CAN go Vortecs if you go to dished pistons and make it work pretty well, but you'll spend a lot of money doing that, just save that money and get some nice aluminum heads once, and be done with it. You may never have to buy new heads again if you spend the money once.

If it was spreadbore, it isnt a 650 double pumper.

http://www.bob2000.com/carb.htm


I would either skip the spreadbore intake, or try to find a non computer controlled qjet and old distributor. Trying to make the computer work with your 400 is going to turn out badly. So you're gonna have to spend money to get a new carb setup anyway. I would go ahead and switch to squarebore and be done with it.


You've got a LOT of decisions to make, but you dont have to make them right away. Just take some time and decide what things cost and what you want to do. Replacing pistons is, I think, a fools errand, just like replacing rods. Rod-stroke ratios play a factor, but at this point its already built, I'd leave it alone. It will cost you power, and cost you a little wear and tear over the years, but GM ran their engines like that, your engine can handle it too. It will be fine. You can still make it make power if you want, and you can still get good gas mileage.

Of all the ingredients a good engine has to make a lot of power, rod length is one of the more insignificant ones. Unfortunately the 5.565 length really is REALLY off the scale in the wrong direction, but as I said, GM ran them like that from the factory and warranteed them, you can still make it make power for now if you want to, and when you build your next one you can go to a 5.7-6.0 rod. But its my opinion that spending a bunch of extra time and money and hassle to get the "perfect" rod to stroke ratio just doesn't pay off for a street car. If you're racing like 1gary does with a lot of money to throw at it, optimizing rod length is a no-brainer, but you're a money-challenged hot rodder like most of us, dont worry about it. Proven power makers are heads, cam, intake, and exhaust. Not rod length.

 

What cam and intake you suggest I want a rough idle... and low end torque...

 

Those two things are the opposite of each other. You gotta pick one or the other or a happy medium in between.

 

you can make good power from worked over steel heads , mine does. although I did have a much more aggressive cam in mine. As far as durability for short rods someone built mine many years ago before the 6 inch rods became popular and its holding up fine even though everything else is falling apart. I still don't get why it's so quite though.


Posted from Thirdgen.org App for Android

 

its not a "double pumper", but it does have double pumpers on it.

i think this is the carb:
http://www.jegs.com/i/Holley/510/0-6210/10002/-1

 

Let's not forget the slam cam swaps and forget matching it up with c/r's is a mistake.

Quote from a other thread I did:

I have been ranting about how critical it is to know how to use SCR's and DCR's formulas for cam choices.Richard on another site gave this explanation which I want to share because I think it is well written:

You cannot reach out into thin air and choose a camshaft for a motor. The cam is not a stand-alone piece, it must be matched to the static compression ratio of the motor in order to close the intake valve at the proper time to make the proper amount of cylinder pressure that will work with the fuel you plan to use. The first question that any cam tech at any cam grinder you talk with will be "what's the static compression ratio of the motor"?

The scenario can go wrong either way:
1. You have a low compression ratio motor and choose a killer cam, long duration and high lift. You're looking for that Ricky Racer rump-rump to impress the geeks down at the Sonic. The intake valve closing is extended to a point where the piston has pushed most of the intake charge back up the intake tract by the time the intake valve closes to begin compression and you are left with low cylinder pressure and a weak motor that won't pull the hat off your head.

2. You have a high compression motor and choose a wimpy cam that you think will be just about right for a daily driver. The intake valve closes too early, creating more cylinder pressure than you can use with pump gas. The motor rattles like a can full of marbles from detonation and pretty soon, you've broken all the ring lands off the pistons.

One more time....YOU MUST KNOW THE STATIC COMPRESSION RATIO OF THE MOTOR IN ORDER TO INTELLIGENTLY CHOOSE A CAM FOR THE MOTOR.

And then this article:

http://www.chevytalk.org/fusionbb/sh...php?tid/92966/


Lastly-if you think your money up by using a non roller block you should consider what your giving up: