Hotting up a 502 Crate

[randy331]

...but there others that read this and might, as in novadude and bigblocksontop2 for example seem to at least be entertaining the idea that flow bench cfm doesn't tell us much about an ex port.

Randy

I'm on that list as well, assuming the port isn't jacked up. I do believe, however, that Cd at low lift can be helpful in determining EVC and, thus, influence LSA.


Shawn

I should've worded that better. Actual low-lift flow at a reduced pressure is probably a better way to say it... maybe. First cup of coffee

I think using CD would be much better than just cfm, but you'd need to know actual CSA of the valve window, and not just diameter x pi x lift. Calculating The true window csa would include seat angles/widths/back cuts/widths, and distance from valve edge to the chamber, etc.

That'd still leave out the errors of the higher depressions of the running engine, but it'd better.

Randy

[novadude]

On flowbench numbers....

As a novice who doesn't even know a fraction of what you guys know, I think too many people subscribe to the "mines bigger" theory when looking at flowbench numbers. Just like in 1988. Before flowbench numbers were widely published, and the aftermarket head market existed, everyone needed that Comp 305H magnum cam. Nevermind that they had 9:1 CR, a 2200 rpm converter, and 3.31 gears. CSA, CD, chamber, and all that other fun stuff never enters into the equation - just "what do they flow".

[user-612937456]

40" of depression? I think physics prevent us from going beyond 30" but lets not debate that.

Where did you get this information? Maybe your confusing " of water and " of mercury?

I don't know anyone using 28" of mercury on a flow bench. That would be what about 380" of water?

Well you got me on this one I had my head so far up my ass I I couldn't see the forest for the tree's LOL

I just don't think you grasp my point.

Id say It'd be a fair assumption to say that goes both ways!!!

Enough said

Maybe you knew that lady down in Louisiana that teaches that magical Voodoo formula LOL What was her name Marie Levoe?

I think marie has a new formula. I'd head down there now, but I'm afraid I'd take a wrong turn out of the getto and drive off the edge of the earth.

Randy

I went to her last class but I signed her non disclosure agreement but between you and me I think we can work something out LOL

BTW I may have misjudged you a little but I still think I am right that by using port flow measurement in addition to all other data will improve your chances of choosing an optimal cam grind it may be able to just simplify it by using range categories like poor, good, better, and best. You know like the cave man drawings lol Take it how you will.

[Rokker]

I suggest a lower gear than the 3.73's (whats your rpm through the traps at 118?) even tho its a street car with a 5500 stall you are not concerned about economy plus you will have some more RPM's for you MPH's with a more appropriate cam grind, if you stay with the higher gear the 2" EX may loose you some torque I would consider a set of 1 7/8's primary's, I like the 108-110 LSA for your compression on pump gas but definitely more duration and lift . Have you considered EX cut outs for the timed runs? As you may have read so much about cam discussion don't put too much stock into 14 different guesses as to what you need, grant it some may be close but you will get a more optimal cam if you talk to a competent cam grinder and have them grind one specifically for your combo.

Not 100% of my rpm thru the traps. I try to keep an eye on oil pressure, afr, rpm and my shifter isn`t really great so I´m quite busy. I´m around 5700rpm I think. I like the 3.73´s. It´s a street car and 3.73 let´s me cruise ok on the highway, and I´m getting 13,5mpg with this thing. I like to use the car alot and with gas price here being 9 dollars each gallon I`m ok with the 3.73 erroring on the somewhat low side. I could go to a 28" tire instead of 30" but then I´d have even more troubles trying to get it to hook. Running a th400 and 5500 stall it hits the radial tires pretty hard initially as is.

Yes been thinking about ex cutouts, I`m running the pypes straight thru mufflers, dual - no H or x. Pretty unrestricted and loud. 115db at 3200 in neutral. I don´t think the exhaust is my holding me back, the headers is I think. As I´m at 5500rpm+ all the way from start to finish, I don´t 1 7/8 would be enough ? I don´t need any torque at 4000rpm..
I´m also thinking a cam expert would be the way to go for the next cam change.

[Rokker]

Might be time to go solid roller. I'm thinking:

255/262
.680/.645
108 LSA

I like GVX's exhaust idea. Have you thought about a Sniper intake?


Shawn

thanks for the cam advise. Where would that one peak ?
I`ve been thinking about a victor jr. Don´t know much about the sniper intake. Are they better ?
I

[Rokker]

Back on subject, Rokker, you need more duration to turn more rpm with that many cubes. 242 degrees will be ok at 6000 for a 400 inch motor, you need more cam for your 25 percent larger motor.

How much duration would I need to peak at 6300 ?

[Rokker]

Was the question ever answered about which heads?
are they pocket ported?
rockers?
check the springs
what pressures

The heads are 12363391
They are untouched, but I`m debating with myself if I should give them a gentle touch up behind the valves. Clean and smooth out, no reshaping.
The springs are stock, with 0.060" shim. I don´t have a spring checker. On the investment list for sure. Pretty sure the springs are on the low side. But with valve float occurring at 6700 they can´t be way out of line either ?

[swatson454]

Might be time to go solid roller. I'm thinking:

255/262
.680/.645
108 LSA

I like GVX's exhaust idea. Have you thought about a Sniper intake?


Shawn

thanks for the cam advise. Where would that one peak ?
I`ve been thinking about a victor jr. Don´t know much about the sniper intake. Are they better ?
I

I've got you right around a 6,000 rpm peak with a shift at 6,500 and upwards of 625 hp and 600 ft.lbs. with the flow numbers I got online. If they really only flow in the low 300's, it's probably starving for air.

The Sniper intake was given some pretty good reviews in Vizard's first BBC book. http://www.profilerperformance.com/raci ... bbc-sniper


Shawn

Edit: Going this way is going to require new springs and possibly pushrods.

[swatson454]

You know, buddy, after poking around online looking at those heads, I'm convinced that they're you're log jam. I'm of the opinion that addressing the heads will be much more beneficial than a cam change will be.


Shawn

[wyrmrider]

x2
Heads is where the power is
heads first
cam second
but it's a combination
investigate both (and compression etc) before doing either

[Rokker]

You know, buddy, after poking around online looking at those heads, I'm convinced that they're you're log jam. I'm of the opinion that addressing the heads will be much more beneficial than a cam change will be.


Shawn

This makes sense. I´ve gone thru two different cams, three sets of headers, two carbs. A change in cr from 9:1 to 11.2:1 And I`ve alway felt the engine should have had 500rpm more in it. The cam change helped the most up top, but going from 9 to 11.2 really woke the engine up.

Changing head´s is a big expense, it´s unfortunately not in the cards right now. What can I do myself to help these heads breathe a little better up top ?
Would a spacer help ? I`m gonne try that and 2" for the next outing.
Would you advise me to do some minor porting ? (not experienced)
Bowl blend, work around the guides etc. Mostly smoothing out but not reshaping the ports. Making some room behind the valves.

[user-612937456]

do the mild porting like you described and contrary to popular belief get a cam ground that will be optimal for your not so idea heads and a little lower peak rpm until you can afford some 320cc+ ports. i am inclined to believe that the 2" spacer will not be benificial or at best be neglible. but if you hane access to one its easy to try.

[wyrmrider]

When DIY porting
less is more
the restriction is NOT at the manifold faces
DO NOT port out to intake or exhaust gasket dimensions
DO not make the intake manifold bigger than the head
do not make the head bigger than the header flange
think of which way the gas is flowing in intake IN and exhaust OUT
that's the basics
others may chime in with more specifics for your specific heads
did you ever post up which heads you have Oval or Peanut port- what number
If you posted this I apologies but can't see from here
I've built more than several 454 Oval Port motors
cleaning up the ports and a good valve job will help
I've also installed larger valves to get the seats back where they should be

[Rokker]

I was thinking about a clean up behind the valve. Not going to hog it out. No port matching either.
I posted the head numbers a few posts back. These are the ones that they call rovals that Edelbrock makes for gm and have a matching Edelbrock rpm intake.

[swatson454]

Is there anyone in your area that can work them over for you?


Shawn