just brought home the new 555 bigblock from the machine shop today for my vette. i know what he says to use for heads but i thought id sniff around a lil bit . the motor has flat top pistions. custom grind solid roller . rear cut for iron gear . its a 688int 645 exhaust 262/268 @50 . i am sold on cnc heads . the problem is who to buy from. my thoughts have been on the fully cnc versions from eaither BMF/ AFR / DART PRO 1. my machine shop says to run 350 or bigger runners ? what do you all say . street use no racing keisler 5 speed od withy 373 gears all info appericiated. thanks
ps / who do you think makes the best heads theese days and what do you use and your combination and your end results good or bad...

I think a 350 or bigger head on a low rpm street motor might be too much. I would suggest maybe a 335 cnc head for better low speed torque. I run the Dart 325 Pro 1 heads on my motor and they work fine.

Max rpm of combo will determine how much runner volume / cross section you need for the inches.

I've used the Darts on many motors from street to race and they work.

i use afr 357's on my 468 pump gas motor and they work great .i had my canfield 310's which i ported on there and switched to the afr's and still picked up 3 tenths and 3 mph.the only real diff is to pick up the et the i had to shift 600 rpm's higher.they still drive on the street fine.:thumbsup: :D

yes just street use . so the dart 325,s or the afr 335,s is the best choice for
my applacation. ? nobody has any experiance with the bmf heads. ? should i stay away from bmf. and go with dart or afr ? i used some afr,s in the past 2 times and they had lots of oil leaking problems and taking off the valve cover always seemed to have lots of oil pooled and it always ran down my heads onto the block and floor. not to mention premature guide wear . and on the last set i took them to a well known performance shop to repair and he flowed them on his bench 3 times to check his machine cause they didnt live up to there flow numbers so i stopped using afr,s . the other problem i had was the support ribs on the rocker stud bosses always seemed to develop cracks . this was 4 years ago. maybe afr ahs improved this area. and i dont do any extreme racing most of my hot doggin is done on winding back roads so i couldnt figure out why i had so many problems with the afr,s .
anyways im still open to info and sugestions . this motor will proally sometimes see rev,s as high as 7200-7500 but not often . thanks

BMF are by Carl Foltz of CFE one of the most respected cylinder head guys in the business. He has nice stuff.

I would not go any larger then a around a 320 cc head for a street car.

even with 555 cubes you think his cnc 330 head is to big ? according to his flow numbers he posts 398 on the 330 head are almost as good as darts and afr,s 404 with 5 cc,s more volume in the runner of there 335 heads. that is.
so it seems with all things considered the bmf 330 head is a rockin head even with its loss of 5 cc port volume down from dart and afr,s 335 heads . i see a 6 cfm loss in air flow on the bmf head at 330 intake runners as opposed to the dart and afr 335,s . so wich does a guy choose for max all around performance. ? thanks

I recently saw a set of the BMF's..they were very nice looking. They reported good #'s at the shop. They've done several motors with the 385's and liked them.

That said, we've tested quite a few heads over the last couple of years. The AFR's came close....but didn't match advertising. But they were also flowed on a couple of different benches with pretty different readings on the same heads. the exhasuts were way low..but it only took a little work to drastically improve them. We used them on a 540 with hyd roller and under 10.0 compression. Main reason he went so large was eventually he was going to do a 632. They drove fine on the street and actually did better down low on the chassis dyno than the very nicely set of ported GM/Edelbrock rectangular ports, even though the GM heads had almost a point more compression. The best part was the "hung on" as rpm climbed and didn't nose dive.

Another buddy has a set of 335 AFR's on his pump gas 548. They seem to do great and made 670+ RWHP at only 6200 rpm! He has since made some changes to get them to go a little higher.

Then there was a set of Brodix -3 CNC's that also provided varying results on different benches..but we're building a heck of a database! The intakes were pretty close, but exhaust was down. Again....a little work straightened them out.

I have Brodix 2xtra's on mine. They have been ported and are out to 377 cc's. But there is no issue with bottom end..at least to me. You have plenty of bottom end and depending on what you're doing..it's pretty hard to hook these things up. In my case moving powerband upwards has helped tremendously as far as getting power down to track. Killing bottom end has been good!


I would hesitate to put 325 cc heads on a 555. I agree with the engine builder...I'd be out on the 350 plus range if you are looking to make power above 7000 rpm.


JIM

thanks jim seems to me you know quite a bit about head s and flow testing.
given the fact of exhaust needing some work to bring them up to par i was wondering did you happen to remember the bmf exhaust numbers or did they to need work. ? i am gathering that my best choice is eaither a bmf head or a dart if i want to get the most flow for my dollar. ?

umm

AFR 335!! My engine builder never used AFRs till he built my motor. The 335s on my street/strip 540 worked so well on the dyno and the street, he dumped his Brodix heads and got some 335AFRs for his street/strip 540. AFR says the 335s like 555 c.i. even more because of unshrouding the valves effect. Get the AFRs. you wont be disappointed!

AFR 335!! My engine builder never used AFRs till he built my motor. The 335s on my street/strip 540 worked so well on the dyno and the street, he dumped his Brodix heads and got some 335AFRs for his street/strip 540. AFR says the 335s like 555 c.i. even more because of unshrouding the valves effect. Get the AFRs. you wont be disappointed!
try reading the entire post i have been the afr route and from waht others say in this post they dont make the number like i found and another found.

I have AFRcnc'd335's on my 540 10:1 267/273 714/714 112LSASolid Roller Special grind Isky; T&D Shaft Rockers spec'd out a little over 1.7, net lift after lash .711

Dyno'd last month 753.8 HP @6700rpm 673.4 TQ @5200rpm
Mike Lewis (Wolfplace) put the heads on his flow bench, I don't have the figures in front of me, but I know for certain that the intake was well in excess of 400cfm and the exhaust in the 250 neighborhood.

This was Dyno'd with 2" primary Headers.....Anything larger would certainly have seen higher peak HP, probably near 7500RPM

I feel most of the "CNC" type heads are close to the same size for size in the power department. Our new motor has AFR 357cc heads and they are making tons of power. If you have a street only engine the 335cc's might be best but with compression the bigger 355cc heads make more power. It all kinda depends what you want the combination to do. My son's 13 to 1 compression 540 ran 9.56 @ 140 with the Dart "335 CNC" heads, 4.11 gears, Turbo 350 Trans and 8" ATI converter. The newer 598" with 13.7 to 1 compression has run 9.31 @ 145.6 with the AFR's, 3.50 gears, Turbo 400 Trans. and 10" ATI nitrous converter. A friend has a 598" with 14.8 to 1 compression, Powerglide Trans., 3.73 gears, with Brodix -2 Xtra CNCs and an 10 or 11 inch very tight converter and has run 9.42 @ 145. So it seems to me all make about the same power when the combinations are nearly the same.

even with 555 cubes you think his cnc 330 head is to big ? according to his flow numbers he posts 398 on the 330 head are almost as good as darts and afr,s 404 with 5 cc,s more volume in the runner of there 335 heads. that is.
so it seems with all things considered the bmf 330 head is a rockin head even with its loss of 5 cc port volume down from dart and afr,s 335 heads . i see a 6 cfm loss in air flow on the bmf head at 330 intake runners as opposed to the dart and afr 335,s . so wich does a guy choose for max all around performance. ? thanks

Yes. Your comment of an occassional 7000 rpm peak tells me that for the most part this engine is going to see 6000 to 6500 rpm 80 to 90% of the time. That's what you build for, what your going to be doing most of time, not what you do once in awhile.

Velocity Vs. Volume. Both are need to feed a NA, but Velocity is king when it comes to championships. Correct port Cross Section along with port volume are critical aspects to building an engine. Under head an engine and either you have to have one huge cam to compensate or the power won't be where you need it to get down the track. Over head an engine and you'll have to leave harder to take advantage of the port flow and unless you got deep pockets your wear and tear on driveline parts just went up exponentially. Compound this by putting in a large camshaft and you have a miss matched bunch of parts that you just spent big buck's on.

Engine accelleration. Two equal HP engines, the one that rpm's the quickest will win the race. Velocity is key here.

320cc head will support 557 CID to 6800 rpm no problem.

i'd recommend you check with the guy who built your shortblock before you actually spend money. he knows what he built and how it's built, he may have some input that might be valueable. like maybe "I don't think the intake valves on those heads will clear the pockets on these pistons." or similar. these big motors are not always just a cut-and-dried, bolt on whatever you want and go deal. never hurts to ask.

The BMF heads are cast by Canfield and Carl Foltz of CFE has an excellant reputation. Given that this is a street car I'd look to something around 325-340. Don't overlook Brodix.

okay took everyones advice and decided to go with the dart 335 cnc heads with some shaft mount rockers. considering i will see shifts and rev,s as high as 7,500 sometimes when road race foolin around . so with this choice does it seem like the right choice or do i need to re think port runner volumes ? and thanks so much you have all been real helpful and i have learned a lil more to date. also i dont quite agree with my shop builder on the 350 or bigger runners as he is all about 1/4 mile stuff and i think he might not be up to demand of the more trans am type pro tour thing i am into . any comments or further suggestions welcome....

Just to throw out another option the 540" BBC I'm building will be sporting Ray Franks 24* Profiler heads that were prepared by Steve Schmidt Racing Enterprises. These are oval port heads vs. rectangle ports of the ones that have already been mentioned. SSRE has a few different CNC programs for these heads. The program he ran on mine has the runners at ~325cc. The intake flowed just shy of 400CFM at .800 with a 4.530 fixture AND with the intake manifold on the head. All the mid lift numbers were good as well ;)

http://www.steveschmidtracing.com/cylinder-heads/pro-filer-24-bbc.html

HTH...

that all sounds good except i have never seen a set of oval ports pull much past 6000 although todays tech on heads is pretty good . the other thing is my intake is rectangle and with 555 cubes i really think i need to stay rectangle , but i could be wrong.

that all sounds good except i have never seen a set of oval ports pull much past 6000 although todays tech on heads is pretty good . the other thing is my intake is rectangle and with 555 cubes i really think i need to stay rectangle , but i could be wrong.
Here's one of SSRE's engines (555ci oddly enough;) ) with the same head I'm running: How does 950hp at 7,500 tickle your oval port fancy?

http://www.steveschmidtracing.com/engines/dyno-charts/555-pro-sportsman-dyno.html

Hell, for that matter our own Todd Geisler has his 3,500lbs Malibu running in the 9's with a set of 049 GM oval ports on his 468ci BBC, and rest assured he's shifting/trapping higher than 6k.

it dosent as i was once in advertising and i know how over blown advertising is to make sales . i think i will call there tomorrow and ask because ovals dont produce they never have they are torque heads. will honestly post my conversation on 900 plus hp from them.

it dosent as i was once in advertising and i know how over blown advertising is to make sales . i think i will call there tomorrow and ask because ovals dont produce they never have they are torque heads. will honestly post my conversation on 900 plus hp from them.
Don't waste your time calling anyone. You've already made up your mind and have all the answers!

I'd bet that oval ports would work better in a pro-touring car, quicker shift recovery, and mid gear accelleration. Even the Pro Stock boyz are running oval ports, granted they are BIG oval ports :thumbsup: I guess if you're running 6 gears and 7k+ all the time, the rectal ports will work.

after doin some searching on this site i found a post by member bb485 titled 703 hp from brodix ovals. and in that post a member named wolfplace says he would like to see them ovals make 703 hp on his dyno and from looking at wolfplaces web site i can see that he appears to be quite knowledgeable based on his site and his equipment . as for pro touring i think you should look at most of the big inch pro tour guys on lateral g net and pro touring . com site none of them big inch motors use ovals. like this sites own wolfplace says id like to see ovals make that on my dyno. EVER LOOK AT PRO STOCK OVAL HEADS THEY REALLY RESEMBLE RECTANGLE MORE THAN OVAL .

that all sounds good except i have never seen a set of oval ports pull much past 6000 although todays tech on heads is pretty good . the other thing is my intake is rectangle and with 555 cubes i really think i need to stay rectangle , but i could be wrong.

In KY/IN/TN there is a Pull Truck series that has a class where you are allowed to run a max of 470CID, flat tappet mechanical cam, and you must OEM heads. 2 past champions have run 781's and 049's on there engines. These are 14.5 to 1 engines with net lift around .700" and make on the dyno 715 to 730HP at 8200 rpm. Most of the trucks run a final gear of 30 and turn these engines to 9000 rpm.

What most forget we have to see alot of "other" rpm before we see our max rpm. Air speed and proper runner volume at these other rpms allows the engine to accellerate. To accellerate quickly the air volume needs to be moving.

Square ports, round ports, whatever ports are just generic words to designate a type of head and really have nothing to do with performance. Correct port cross section and adequate flow numbers to feed a given combination for a given rpm range is what matters.

Since you were an advertisting I will tell you a little story. A cylinder head company mentioned on this thread release a BBC head for sale several years ago. The runner volume is a true 300 cc's. It flopped. No body bought it. All the owner did was change the label on the head and his adverstising to reflect a larger runner volume and heads flew out of the building and is still a successful head today.

A built engine is a good engine, A built combination is a champion.

I'd have to either leave the oil plug out or one plug wire off to only make 700 hp on ANYBODY'S dyno - stock intake gasket fully ported merlin oval port heads / 13.7:1 / roller cam under 700 net lift.

I think Wolfy was taken out of context.

MAT

MAT, with the oil plug out and that duralube in there, won't it make MORE power???

Yet another under performing BBC oval port head:

http://www.brodix.com/PB%202005.html

Wonder what rodbolt knows that the rest of the world is so clueless about? Do tell, rodbolt. Maybe you should change your screen name to "rodknock" since you're "knocking" down all the oval port suggestions after asking:

my machine shop says to run 350 or bigger runners ? what do you all say . street use no racing keisler 5 speed od withy 373 gears all info appericiated. thanks
ps / who do you think makes the best heads theese days and what do you use and your combination and your end results good or bad....

Just messing with you. Seriously, you need to check all the availble options. Technology has changed quite a bit in the past 40 years. As Chris pointed out a properly sized runner/combo will perform well with either port shape. Deciding on one over the other is matter of what you're trying to accomplish for a given combination. Don't get sucked into the bigger is better trap whatever you do. Personally, I would never build such a large engine for a purely street driven manual tranny car. IMO you would be much happier with a hi revving SBC of smaller BBC. You won't be able to use 50% of the power that 555BBC will be capable in a street car with a stick and 3.73 gears unless it's a pro street back halfed deal. As they say, "different strokes for different folks." Have a good day :thumbsup:

well i do have 14 inches of skin on the pavement out back and the 555 is a step up in cubes after the 540 that was in the vette wore out and i was makin at the rear wheels 729 hp with 676 tq with unported 345 heads . since the heads are now unusable i thought id look around . like i said i dont know everything im here to learn . and after talking to the people at schmidt racing the tell me they make no such 900 plus hp motor with oval ports . my past experiance with oval port heads was not verry mentionable and that is that .
i came here for learning not to put anyone down or get put down . i just beleave that in the end result rectangle ports make more end power. as for the manual keisler hasnt broken yet and there is alot to be said when comin off a banked turn at 6500 rpm laying into the throttle to 7 ot 7500 before upshifting .

Ken, is this the oval port package you were referring to?

http://www.steveschmidtracing.com/engines/555-pro-sportsman.html

Ken, is this the oval port package you were referring to?

http://www.steveschmidtracing.com/engines/555-pro-sportsman.html
Yeah, that's the one John.

Rodbolt, look at the oval ports they are talking about. These are NOT chevy oval port heads. They are 325 cc custom cnc ported heads. No one is saying you need to put 781's on a 555. The fact that the shape of the port is oval has nothing to do with it. The cross section and cc of the port is what you need to look at to compare them. I personally believe you will have a great running 555 with the 335cc heads you have chosen. They are only 10cc bigger than the ones kjett is talking about. I'll bet you lunch that they won't flow 400cfm with the intake bolted on though. My guess at what kjetts heads will flow without the intake is in the 420+ range. Anyway, you will be fine with the heads you chose. Good luck. And don't take things so personal.

and if you call there and ask them he will openly admit that the oval so named port heads more closely resemble a square port design neither an oval nor a rectangle. we can argue this all year long oval means just that egg shaped . not square named ovals