What should my heads flow with this cam?

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Badart

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My zero deck 360 shortblock is getting finished up with KB 107s and have decided on a cam. It's a Comp XE-284H. Here are the cam specs.

240@50 on the intake
246@50 on the exhaust
.507 lift intake
.510 lift Exhaust
110 LSA
Hydraulic Flat Tappet Cam

I have already had my J heads rough cut for 2.02 valves has the smaller valve guides already installed and will taking them to the head porter in the next couple of weeks in Salt Lake and I need to give him some flow numbers to shoot for. (Yes I know that I should have gone with RHS heads, but I already have some money tied up in these and want to use them). I know stock J heads should flow around 220 from the factory, but what should I shoot for?

I am shooting for 10-1 compression ratio and this is a street car. The rest of the combo is Eddy air gap, 3K stall convertor, 3.89 gears (Furd 9") and running through hooker comp headers to 3" exhaust.
 
Thats nearly identical to my setup 'cept the furd niner. No reason to think those heads shouldnt go over 250 cfm. should make a nice combo (i hope so for my sake!)
 
That is a weird question and one I never came across, but, when we were early 20somethings, we used to say, 1 cfm per degree of duration. Of course, today, getting all that cfm into a port at the cams max lift may not be possible for all heads in question and/or possible without a over kill of a porting to achieve it since this level of flow may not be possible by your max lift unless you open the head up further than really need be for the application.

Also, just get as much as possible in the low lift areas no matter what.

Exp. head porters/engine builders should answer this.
Not Joe-hotrodder and his bag of doughnuts.
 
rumblefish360 said:
That is a weird question and one I never came across, but, when we were early 20somethings, we used to say, 1 cfm per degree of duration. Of course, today, getting all that cfm into a port at the cams max lift may not be possible for all heads in question and/or possible without a over kill of a porting to achieve it since this level of flow may not be possible by your max lift unless you open the head up further than really need be for the application.

Exp. head porters/engine builders should answer this.
Not Joe-hotrodder and his bag of doughnuts.
Click to expand...

LOL. I hear you, but when you guys start talking about velocity and stuff it gives me a headache. I just want to go to him with a little knowledge and see what he has to say also. Apparently he is a mopar guy, but have never used him in the past. I would ship them to one of you guys on here, but the last time I shipped heads it cost me $120 one way. Too rich for me.
 
They will flow lots of air and fuel.
 
Badart said:
LOL. I hear you, but when you guys start talking about velocity and stuff it gives me a headache. I just want to go to him with a little knowledge and see what he has to say also. Apparently he is a mopar guy, but have never used him in the past. I would ship them to one of you guys on here, but the last time I shipped heads it cost me $120 one way. Too rich for me.
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120.00 one way! Utah should only be 80-90.00 one way for both heads. Still not cheap but alot depends on what you get for what you pay.
The hard part is getting alot of work done for a reasonable amount of money. Stock heads are probably the most difficult to port heavily, and most expensive. So the return HP per $$$ is poor. But I know how it is to work with what you have so just be carefull.

Are you using stock type 3/8 valves?
 
ou812 said:
120.00 one way! Utah should only be 80-90.00 one way for both heads. Still not cheap but alot depends on what you get for what you pay.
The hard part is getting alot of work done for a reasonable amount of money. Stock heads are probably the most difficult to port heavily, and most expensive. So the return HP per $$$ is poor. But I know how it is to work with what you have so just be carefull.

Are you using stock type 3/8 valves?
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Brian the 120 was to ship them to Florida, so shipping them to you would be cheaper in Cali, but I would still have to pay for the ride back. I am no engine builder by any means, but my machinist/engine builder recommended the smaller diameter valve stems for the build and that is what we are going with.
 
You should expect at least high 240's and at middle 260's with best being 280-290cfm

Here are some pics of heads I did myself, 2.02/1.60 11/32 valves and off 'n on porting for over 2 months after work, I can bust it out in a week now.

It's tight between the guide/wall area and you need long shank bits do it al out.
It's mainly removing the excess guide material, getting it wider between the guide and straight wall along with removing the guides kink that comes off and across the roof to the straight wall and straight so thats it's more flowing then the short side/straight wall-where the straight side comes in to the floor/shortside, then thee ol pinch and valve cover bolt bumps.

Theres a whole lot of meat in the J head ports, thats for sure,btw the taller & longer you leave the ssr, the better for all around .500 & under flow it will be, at least thats what I've found with the way I shape the port.
 

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1wild&crazyguy said:
You should expect at least high 240's and at middle 260's with best being 280-290cfm

Here are some pics of heads I did myself, 2.02/1.60 11/32 valves and off 'n on porting for over 2 months after work, I can bust it out in a week now.

It's tight between the guide/wall area and you need long shank bits do it al out.
It's mainly removing the excess guide material, getting it wider between the guide and straight wall along with removing the guides kink that comes off and across the roof to the straight wall and straight so thats it's more flowing then the short side/straight wall-where the straight side comes in to the floor/shortside, then thee ol pinch and valve cover bolt bumps.

Theres a whole lot of meat in the J head ports, thats for sure,btw the taller & longer you leave the ssr, the better for all around .500 & under flow it will be, at least thats what I've found with the way I shape the port.
Click to expand...

So what kind of $$$ would you put on those heads with all the machine work plus porting if someone were to pay for that?
When you have the means to port your own heads then it becomes much cheaper to do.
 
Nice work, Justin. I may get you to do my big block heads if you're game.
 
Those are a thing of beauty wild&crazy. So do you guys think this could be something that I could do? I do have an electric die grinder, shop vac and access to machining bits from our machine shop at work. I do have a couple of sets of 318 heads laying around to practice on. Hmmm
 
ou812 said:
So what kind of $$$ would you put on those heads with all the machine work plus porting if someone were to pay for that?
When you have the means to port your own heads then it becomes much cheaper to do.
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The parts & machine work was $890 'lots of miling' + me porting $80 & worth of bits and yeah it was cheaper alright.lol
I did all I cared to do at the time, was wore out...and there was a point when I thought they looked really good..and to go into water at that point after all this time would be a raw deal. Though I did the major port work before the machine work.
They are good heads though.

I'd say that much porting could cost 400+$'s

how much 'per stage' of porting do you usually charge?


StrokerScamp said:
Nice work, Justin. I may get you to do my big block heads if you're game.
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what heads?, I have a friend that ports bb heads closer to you, pm me.

dodgetkboy78 said:
Looks good Justin......... I can see why it took two months. LOL, your faster than me, took me a year.
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yeah it's time consuming.
There's a massive amount removed, I had to do complete make over on them 'the whole port' and was also going for cc increase since they're on top of 410 cid. but I did keep it standard intake rock, could tube'em and pick up after re working the far side/push rod wall.

here's an exhaust pick, btw heds R/L as to port to the header bends
 

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Badart said:
Those are a thing of beauty wild&crazy. So do you guys think this could be something that I could do? I do have an electric die grinder, shop vac and access to machining bits from our machine shop at work. I do have a couple of sets of 318 heads laying around to practice on. Hmmm
Click to expand...

If you are gonna consider doing this...you should find a head of the same # and practice on it. The J head has a way different shaped port then a 318.

Mainly you need to look at 'in person' the bowls of after market ported heads, stick yer fingers in there and get a feel of the ssr and far side bowl is just as important.

the ssr/pocket-bowl to seat is where you can really fk up, no launch ramp sht.lol
 
what did they flow? looks nice! i'm getting ready to do a set for a 427" did you widen the lower port just before the ssr to slow down air flow to make the turn?
 
Rumble Quote:
Exp. head porters/engine builders should answer this.
Not Joe-hotrodder and his bag of doughnuts.
Click to expand...

Nice.==D>LOL
When the heads get done at the shop, then your answer will be right in front of you in the form of flow number's.
Your max lift at the valve, will be your max cfm.

I think 220cfm is a little high in stock form.
The peak # is not as important as the lower lift #'s.
Being a little conservative is a good thing, as far as head porting.

Velocity is key at pulling more air into the motor.
Velocity also mixes the fuel and air better because of it's air speed.
Just because a head flows more cfm, does not mean it will make more power.
A good head porter will increase the cfm, but only enough so that the velocity is not lost ,but improved.
When he get's done, and hands you your flow sheet,you will then get a better idea of what your engine will make for power with the cam you have.
I would have done the heads first, and then picked the cam second ,so that the cam is blue printed to the heads.

That"s a pretty big cam for your converter.
If you look at most cams with 240 @50 and up duration ,they make max torque above 3800 rpm's.
The torque band is lowered in bigger cube engines above 391 cid,but with a 360 cid, i would think it would be a little over 4000 rpms.

I think a converter with a minimum stall speed of 3800 rpm's would be a much better choice for your 360.
I don't mean to say anything bad about your combo, but that was the only thing i thought, was kind of a mismatch.
If that"s what you have, then use it.
You have good compression, so your torque will be strong.
Sounds like a great engine.
Maybe he can flow the heads before he ports them, so you have a better idea of what he did for you in the end.
good luck........:thumbup:
 
Hey BaDart,thats the same cam I have in my stroked 340(372ci useing a 3.58 crank)in my 73 Dart Sport,4 speed.My engine ws dynoed at 452hp 440ftlbs.The best I could get out of it was a 12.53@108,was just too hard on the car with a 4 speed.You should be good to go useing an auto.Good luck.
 
Thanks T67 (I take a bow) LOL, I'm Joey hot rodder, I dabble in the sci. of it all. But I will quickley hand over the stage to those who know. No sense of bullshyatin like I know.
 
EL5DEMON340 said:
what did they flow? looks nice! i'm getting ready to do a set for a 427" did you widen the lower port just before the ssr to slow down air flow to make the turn?
Click to expand...

270 cfm int/187 cfm exh @.500 lift
It flowed just over 270 @.5 but I can't find the sheet at the moment, I know I have it posted in one my threads, maybe the 410 thread,
But the flow at .300 was 198cfm, @.400 was 244 cfm and peak was 284 @.530, see they are working good down low and in the upper range for a flat tappet of .450 or .500+ lift. and I'm sure there's plenty of velocity with these kind of gains every .050 lift increase. The exhaust flows in the 160/170''s low/mid lift and jumps to 180's by .500 and then actually went to 190's but it was @.600, thing is...Those numbers were had with NO flow pipe, so add a flow pipe and they go up!
Also, the radius I used was just a thin lil string fingered to shape....no cnc radius fixture like the 'pros'....so I could make them look better if I used one I'm sure.

below is not directed at EL5demon340

Sorry, but I'm just a wee bit above that ''joe hotrodder'' bs.
And flow equals power, don't know what planet it is where it doesn't...

It's when the heads pick up only tinzy weenzy every .050 that makes a slow port, thats when you NEED a roller or better yet, new heads.
distribution is something to look at, but what port actually does that complete ly even?
Wet flow is neat thing to play with.
 
Hey wild&crazy,
I did not even think about you when i responded to this, so don't take what i said as any kind of cheap shot.
Your heads flowed good #'s and they look good.
I did not mean that higher flowing heads mean less power.

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I tend to be on the conservative side when making changes.
 
I really hope that this guy knows what he is doing. When I take them to have them ported I will have him flow them before and after. Then post the results.
 
I wouldnt spend much on porting beyond cleaning the bowl areas up and gasket matching. The cam's not going to open the valve past about .485 at best and you are looking for max flow from the seat to .400. It's not worth spending to get more than about 240-250 IMO.
 
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