F0x Slaughter

Just because the heads flow awesome doesn't mean they are for your setup.

To much flow without supporting it will cause you to lose power, just like to much lift.

93v8clone

Ok , I bought a set of a.f.r 210,s last yr to compliment my 383 solid roller going into car this yr . Well I got a case of whatevers and wanted to see what the car would do with them on my 355 . I put em on and the car loved it esp up top I did lose a little low end but that's what the high stall conv is for ! So after tuning the setup and what not I went to the track and on the a.f.r 210 setup that most on this board said would slow me down , I did a 10.82 on a 100/150 shot with a 4k stalled performabuilt 4l60 . That was a little faster than my 11.2 I bested with my stock ported and the were ported by l/e . Those same heads now are goin on my STREETCAR s.r 383 with a stalled 4l80 behind it .

ElkySS

iTrader: (6)

it started as a golen motor i bought used. it put out 520 flywheel when new. when i got it, the heads wer untouched 195cc street afrs, the intake was a factory stock lt4. cam was a 238/242 .575/.575 112. it trashed a 1.5 rocker so i replaced them all with comp ultra mags. u cant get them in 1.5 so i went with 1.52 which brought the lift up to .582. the local porter i had more than exceeded my expectations. if you want his contact info, ill pm you. guy is god with a dremel. 6 speed car, numbers made through a moser 12 with 4.10s.

I miss anything?

ElkySS

iTrader: (6)

oh yea, its got a mail order tune too.

bowtienut

iTrader: (1)

I have nothing against AFR heads. No doubt at all they're capable of producing amazing power with the right work applied to them. The tone of the OP's first couple of posts sure indicated to me he had unrealistic expectations of "out of the box" heads.
I was trying to get information to offer advice for a so called weekend street car. When that led to a 500 rwhp goal for a car to "putt around town with", I clearly have nothing to offer.
I'm sure you'll enjoy the car either way, Steve. Sounds like budget isn't a big concern. Good luck with it

Wicked94Z

iTrader: (26)

insert unhelpful post highlighted by nuthugging, regurgitated bullshit, and ignorance.

Seriously.

Wicked94Z

iTrader: (26)

See post above.

See post above. Its one thing to nuthug and not post from experience. Its another to spout completely incorrect information, leading the uneducated to "slaughter"

I have a hard time accepting a 238/242 cam making anywhere close to 600hp. You don't get 80+hp from a rocker change and taking 10cc out of a head. Without seeing your heads... generally you couldn't get enough cross section from a 205cc 23° port to make that much power with such a small cam. Not enough time/area.

ElkySS

iTrader: (6)

dont know what to tell you, supprised me too. its not an off the shelf cam, i can tell u that. it was pulling 5 degrees of timing at peak torque so its pretty low (455rwtq) it was still pulling .5 degrees at peak hp tho

Puck

iTrader: (17)

While you can over-head an engine, too much lift wont cost you power unless your heads were poorly ported and instead of plateauing they plummit or go turbulent.

Speccing a cam a bit past max lift is beneficial, since it increases the valves dwell time at max lift instead of only spending a fraction of a second there.

ElkySS

iTrader: (6)

he also did the combustion chambers and back cut the valves. we also found the intake gasket was hanging into the runner and who ever ported the intake for the 58mm tb didnt open it up far enough. those may have contributed

F0x Slaughter

If your head flows the best at .650 there is no reason to put a higher lift in it. Its doing nothing for you but causing more strain on the valvetrain.

A head can't flow more air than its max flow.

Puck

iTrader: (17)

You are incorrect, and show a common misconception about valvetrain events.

If your head peaks at .650 and you spec, say, a. 675 cam, the valve will be at or above Max flow for longer, and make more power.

F0x Slaughter

Sure go for it.

Its called run a longer duration.

Lift

Lift and duration are the two cam specs that get the most attention. Lift is simply how far the cam lobe will open the valve at its peak. More lift generally equals more flow, but too much lift is very hard on valve springs and lifters and if your heads have a definite flow peak then lifting the valve beyond that point usually does not give increased power. Lift is generally expressed as a decimal value of less than an inch, and a distinction must be made between lobe lift and valve lift. Lobe lift is the physical measurement of the lift of the actual cam lobe. Valve lift will always be higher because the rocker arm multiplies the lobe lift through the use of the fulcrum. Valve lift can be calculated by multiplying the lobe lift by the rocker arm ratio (e.g. .300 lobe lift x 1.6 rocker = .480 valve lift). Valve lift in excess of .600" is usually not worth any extra flow on a street Small Block Chevy head.

www.lt1howto.com/articles/camshafts.htm
http://www.hipermath.com/engines/intake_valve_lift

Apparently you are one who believes "bigger is better".

1961ba427

iTrader: (26)

Well said. Most people don't think about it. If your head flows
300 cfm @ .600",
310 cfm @ .625",
315 cfm @ .650",
then starts falling to say - 300 cfm @ .675" and drops all the way to
280 cfm by .700", you will still move more air through that port by having it open the valve past the peak flow lift.

This is why class racers with lift restrictions find ways to "vault" valves off the nose of the lobe even with uported crappy heads. That's a whole other subject and it is all very controlled chaos, but it's very common practice.

F0x Slaughter

The problem is if you run a high lift low duration the ramp speed will be high tearing parts up. High lift high duration will have a lower ramp speed giving a more gentle lift, thus keeping the valve open longer.

1961ba427

iTrader: (26)

Who said anything about low duration? (Or duration at all?) With a goal of 500 rwhp, I'd think the OP would be looking for a decent amount of duration and lift.

RamAir95TA

iTrader: (2)

Quick...Google whatever you can find to support your case!

Puck

iTrader: (17)

Apologies if my first response was overly simple or blunt - I was posting from my nearly dead cell phone.

You suggest adding duration, but I am somehow the one who thinks "bigger is better"?

Duration is one method of increasing the valves time at higher lifts, but you can only run so much duration for any given application based on desired peak, engine rpm, engine size, idle, streetability concerns, etc. Increasing lift will generally not have the same negative effects of increasing duration. People then bandaid their too high duration cam by widening the LSA to get back the drivability issues they got by going to high duration in the first place. Although its not the correct way to do things, this is a common practice among shelf and "house" grind cams.

Its not a hard concept to understand. Increased dwell time @ max lift = more air per valve event, which equals more power. Wearing down parts is a completely different problem, caused by poor part selection.

Only if you don't run the proper valvetrain - which many people do not. Valvetrains are often waaayyy underappreciated and overlooked, since most people are hesitant to spend close to what their heads cost in "just" valvetrain parts, and they skimp on extremely important things like springs and pushrods since they are not considered a power mod. Then, when their pushrods turn to spaghetti and their cheap springs let the valves bounce off the seat, they end up peaking way too early, making crappy power, and breaking stuff.

Wicked94Z

iTrader: (26)

1961ba427

iTrader: (26)

Not sure if that was pointed at me.....or directions for replying to what I said, but either way that cracked me up. LOL I'm gonna try to get outta this one so not to clutter up the OP's AFR cylinder head thread any more.