best cylinder head

-
I shall admit that i have not read the whole thread but considering how it seems to have derailed alitle i will try to get it back on track.

There are three obvious reasons why a big cam 340 falls on its face at high rpm.
Valvesprings.
Headflow.
Not getting full throtle at the carb.

You dont need a real good head to effectivly turn 7000+rpm with that much cam in a 340,I have done it with some touched up J-heads and it didnt even need a big carb,it did it with a basic 650 holley DP in the past and that engine ran awsome and was real fun on the street,but it might not be the most efficient way at making power these days,its easy to get alitle carried away in these times when it has become kind of easy to make good power with a whole lot less cam and rpm by buying the right parts, lets try to get back to the basics and figure out why that engine wont make power instead.
 
which is why i was saying this engine does not fall on its face at 6800 plus it just quits building more and more power. it acts like it runs out of breath. This engine has valve springs designated for the camshaft in it which should not have any issues up to 7500. the engine will rev up to 7400 easy just under load does not keep pulling as hard up to there
 
Valvesprings can loose a bunch of strenght over time and that can show up as loss of power without valvefloat, but if they are new and they are set at the correct height thats probably not a a problem.
Are your heads ported?
And do you get full throttleopening at the carb?
These are the real questions,since airflow thru the heads will be part of how high you can effectivle turn that engine and make some power and the second question is just something worth checking,its a very comon misstake.
Also regarding the comments that those heads wont flow well enough at maxlift,consider that the valve wont hang at full lift for very long and on top of that i doubt you will see anywhere near a true .650"lift at the valves after lash and that screwed up lifterangle us smallblockpeople are all blessed with add alittle deflection to the pushrods and you are probably closer to .615" or so at the valve.

Its not that i dont understand that you may want a better head on that thing i just think it would be nice if you made that thing run as good as it should before you go to the next level.
I think a W2 topend on that thing would be awsome but better to figure out the basics first.
 
yeah the valve springs are brand new engine has 500 miles on it. has made 2 passes and ran 12.26 at 6000 rpm coming through the lights. needs lower gearing. and this was when the engine was in a different car not belonging to me.
 
now one questions i have is could the degree of the cam affect this issue? they said they have it on a 104 instead of the 106 recommended
 
There is a little Power To be found by having it in as speced. Some guys move it around to suite the need. It does change how and where the power Comes in and goes out.
 
It would be best done in a controlled environment like on a Dyno....otherwise weather and track conditions could give improper data...but as said no two engines are the same..
 
Did you find out what exact piston that is. Part number? The only head I can think to use is annooennchambered W2 if you can find a set.
The OE head can only deliver so much.
 
elitesrock2 said:
as of current the car this 340 is in ran 12.27 at 112. it is a stock suspension car essentially and was going through the traps at too low of an rpm like 5900. RX302S-R6 is the camshaft and they have a ton of portwork done to the heads. my car is a 69 dart which we are building. it will have an all out tub job, frame rail work, 10 point cage, dana 60 with 31x16.5 dot slicks 5.38:1 gears, 4 speed with a scattershield and all that and a vertigate setup. also a cool fact about the dart is it is the number 1 dart off the line from L.A for 1969 sequence number 00001. factory radio delete car with the full trim piece on the dash and everything. turqoise with a white top
Click to expand...

"my car is a 69 dart which we are building." Have you actually driven a car with this engine?
 
If you want to buy a head with closed chambers you can use that piston. But you have to be very careful. You see how far the FLAT OF THE PISTON is out of the FINISHED DECK. It is probably less than .030. Then, putting the piston in a piston vice and doing the appropriate dialing in, mill off the FLAT OF THE PISTON whatever it is out of the hole.

Keep in mind, the dome will still be as far in the chamber as it would have been BEFORE you cut the deck. You can end up with more compression than you want. You can always mill a bit off the dome hole your at it.

If you buy a head with the emissions style chamber in it, you can't use the pistons at all.

Look around for some W-2 heads. Decently prepped W-2 heads will whip most other heads out there, even a W-5 that isn't fixed.

What bore size are the Pistons and what is the compression height?
 
You must log in or register to reply here.
-

Back
Top