If i wanted to run stage 3 heads on a 346 while i waited for the extra cash to drop into a stroker would there be any disadvantages? Current mods in sig.

What I wanna do is get the heads I want and a fast system and run it on my 346 til I build the stroker, then just transfer everything over. Pluss i want to sell the current heads on the motor right now to go toward the stroker. Basically I want to be able to drive the car.

any advice would be appreciated!

 

Sounds like me.. I want a set of AFR 225's but I cant afford to build a motor right now and I'm kinda iffy about puttin them on this 111k mile motor cause if it blows there goes my heads..

But, I dont think you will lose much of anything with the stage 3 heads.. What size stroker are you planning to build later on??

 

i'm doing a 408 for sure....just gonna run it NA with a nice cam and heads. My car has 84k and i'm even wondering if I should. I mean the car runs good and all, I dont drive it tooo often. But really all that would have to be replaced is the valves most likely if the motor went, no?

 

The biggest negative would be for the time being you would have a lower compression setup.
If your doing a 408 in the future I would do the 225 AFR's or a set of 6.0 TEA heads.
Either way do them on a 68cc chamber. If you go much smaller you will have tons of compression when you do the 408.
A 68cc head with a 4" stroke and 4.030 bore and .045 head gasket already puts you in the 12:1 range.

If you do the same combo but with a .040 gasket you will have around 10.5:1 compression.

 

Valves will be too big for the smaller bore.

 

If a piston busts it will tear up all kinds of ****.. The valves will be bent to hell and back and the head will have chunks of piston imbedded in the combustion chamber.. Could also tear up the valve seats, guides, etc..

With 84k you dont have anything to worry about..

 

I wanted to do the TEA / AFR heads which I believe are 67cc or 72cc choices. 67cc would be good with a .40 gasket on the 408, right?

I wouldn't do 5.3's for the 408, I was planning on doing LS6 style.

 

Too big meaning a loss in.....what?

 

I have seen a 2.08 valved head on a stock bore.
Maybe not the best but it works.

 

67 would be a good choice if you want compression.
If your using a flat top with 2cc valve relives you will have around 12.25:1 compression. If you stuck on the .040 gasket and want to have a bit lower compression a 69cc head will hit right at 12:1.


I dont know where you got the 5.3 heads but if it was from my post I wasn't talking about 5.3 heads I was talking about the 6.0 heads.

 

I've had this discussion with my cousins' engine builder before, my cousin races dirt track cars, and has a new 358 built every year......

(you all will have to excuse me if I misuse some terms)

According to him, when it comes to heads, bigger is not always better. He explained it to me like this.... think of your engine as a water spigot, and your heads as a hose. You currently have a wussy little garden hose, but you are wanting that big and bad fire truck hose. So you go out and buy that fire truck hose......do you actually flow more? Well you might be able to flow more, but now since the pathway is so huge you lose alot of velocity, so you end up actually flowing less. The exact term he used is "lazy"... the heads become lazy.

This analogy seems to make sense to me, but Im sure the disparity between stock LS1 heads, and Stage III isnt a garden hose vs a fire hose.

So that analogy leaves a few questions to be answered....

1. How big is too big for a stock LS1? Since you are going to be building an engine I dont think this matters. Chances are you will go with more cubes, and you will need to free up those bottle necks... and go with a healthy cam while your at it

2. Will your performance be hurt? Well one person has already indicated that you will be running a lower C/R, so that is going to hurt you, and spinmonster has indicated that those valves are too big..... as to whether that will hurt performance... I dont know.

I say, why change heads, when you know you are going to tear down the motor and rebuild it anyway?

Stick the money for the heads in a 6month CD, and give yourself sometime to do it all in one swoop.

 

Sorry, but 408 with 67cc and .040" gaskets will net you 11.63:1 CR with a 2cc valve relief in the piston. Not 12.5:1.

Btw, JZ, I get 10.11203656:1 for the LS1 and 10.47781793:1 for the LS6 using my calculations with .054" gasket.

 

Yea, I was gonna question those compression numbers. I'm not the greatest math guy nor do I use those calculators much(compression calcs) but thats pretty high for a 408.

Either way, 225s can be run on a stock cube motor, Tony Mamo has said it himself. Its just setup for a 4.0 bore, which means its going to be shrouding the combustion chamber. You're going to get a lot of turbulence which will result in less power.....but once you get the stroker and it opens up that chamber, you'll be golden.

 

Bore inches 4.030 Diameter of cylinder
Stroke 4 inches Distance piston moves
Head Gasket .040 thickness inches Measure your head gasket tthickness. It's usually 0.040", but not always...for example, on K1200 BMWs it is 0.070". On 113/135" ORCA motors it is 0.00 because they use metal seals and no head gaskets.
Deck Height -.007 inches Move piston to TDC, and measure the distance between the flat top surface of the piston (not the top of a dome or the bottom of a valve relief) and the top of the cylinder. Enter a negative number if the piston's flat surface sticks up past the top of the cylinder. At TDC the piston will "rock" so be careful in your measurements. ORCAs are .035".
Piston top flat top with 2cc valve relives.
volume cc's You'll have to calculate this value the hard way i.e. do it yourself or call the piston manufacturer. Enter a negative number for a domed piston. Enter a positive number for a dished or dimpled piston. If you have a flat piston with no valve reliefs enter 0.00.
Combustion 67
Chamber cc's Get out your 100ml burette, your light, non-nasty grease, your handy dandy plexiglass or lexan sheet, your Marvel Mystery Oil and a six pack and get ready to party. Don't forget to cc the combustion chamber.
Static Compression Ratio:

Static compression ratio 12.15

So what am I doing wrong?
Do I need to change the deck height to a positve number now?
Even if I change it to a +10 I am still at 11.65
Where is the difference at?

 

I have seen this type of statement said in various different configurations time and time again. It is not an accurate one and for the benefit of those who have not read my response pertaining to this I will reiterate. The fact the bore slightly overhangs the chamber (with a 3.900 sleeve) does not pose any problems whatsoever, nor does it cause turbulence and a loss of power. The head will flow more on a larger bore for obvious reasons (less shrouding), but that doesn't mean it's not effective on the smaller bore....it's just not as effective.

Its better to make room around the valve (larger chamber bore) allowing the air to escape and negotiate it's way around the small lip (air is very compressable), than place the wall of the chamber directly next to the valve simply not allowing ANY extra to escape. A 225 will outflow a 205 on a small 3.900 bore by 10-15 CFM's depending on the liftpoint in question....it sounds just as clean on the flowbench and will subsequently make more power when bolted on top of an engine. Before the end of this month, dyno test results from the 383 I'm currently building will prove this point as will the release of the small chamber 225's and the numbers some stock 346 H/C cars start putting up. I feel mid/high 400's will become commonplace and I think you will see a handful of guys clearing 500 RWHP that have all the typical bolt ons, aggressive camshafts, and well thought out and executed combinations.

I'd like to think AFR has delivered on all the promises we have made thus far....hopefully the situation I just described will pan out as well.

Regards,
Tony

PS...Cypher, by no means was I "singling out" what you said....Similar statements just seem to keep popping up here and there and I felt this situation needed better clarification.

 

enter your valve relief number. 2 cc's are being left out of your calculations.

 

I used 1 CC for that.
Brings up a good qustion.
When figuring compression, a 2 cc valve relivef wont effect compression as much as a 2 cc dish piston.
So why do you use 2cc for valve relives?
I normally just use one as there is a loss of compression but a very little loss.
Really a valve relief would be something closer to -.5cc wouldn't it?

 

Hey Tony saying you took a cam like a 230/234 high 500 low 600 lift and ran a 205 and 225 head on a stock cubic inch motor which would make more power?
Using the same compression.

 

So now im confused... 11.63 or 12.x +? I dont want a ratio over 12, too much for the 91 out here in CA.

 

Dude dont listen to me.
I am somehow messing up the numbers in the calc listed below in my sig but cant figure out what I am doing wrong.
Think your confused, I understand everything but am not geting the correct compression somehow.