I was wondering if 15* heads are streetable. what makes me wonder is I was playing with my DD2000 and put together a 357 sbc with a single plane intake, open headers, comp 280hr (dual pattern 280* @ .050 .525 lift), 750 carb, 11:1 compression, etc. this was using the Bowtie 15* heads which made a huge differance in power with a reasonable (i think) compression ratio. the motor made peak power at 7500. could a similar setup be used as a weekend driver? why don't more folks use these type of heads?

The valve angle will not really affect streetable performance IMO. What will though is the intake runner volume. Many of the race type heads have intake runners which are gonna be too large for any bottom end/mid range performance. That and most all GM castings require porting to optimize their performance. A local race runs GM 18 degree stuff. His old heads were worn out with decks way too thin from many many rebuilds. He bought a new set of castings, but nobody could port the heads in a timely manner. He didn't want to miss the end of the season, so they did the needed machining, guides, seats, etc. and bolted them up unported. He claims this is as slow as his truck has ever run...equal or maybe a bit slower than his previous 23 degree combination.

Also, if that 7500 rpm hp peak was accurate, figure on needing to shift that puppy at 7800-8000 for peak on track performance (not based upon given cam timing). Given that high of a power band would likely yield a mushy sluggish low/mid performance.

What you want to do is doable, but it won't be a mild docile combination. It will wind up being a somewhat radical combination with marginal street manners.

You're far better off with conventional 23* heads, which are easily capable of over 650hp even with a streetable intake port volume. I have a set of home-ported Canfields that started life as the 197cc version and now they are about 215cc and flow 305cfm @ 28" at .700". A very fair and possibly conservative equation is 2.2hp/cfm of intake port flow, so 650+ is there with these heads. And, the ports have a fairly small cross section which gives good engine acceleration and velocity. The race-oriented stuff with rolled valve angles typically require oddball intake manifolds and shaft rocker systems as well. I did use Jesel stuff but normal stud-mount rockers would have worked for a more docile street cam profile instead of the 288/296 @ .050" .700"+ roller used.

Originally posted by young gun '71:
I was wondering if 15* heads are streetable. what makes me wonder is I was playing with my DD2000 and put together a 357 sbc with a single plane intake, open headers, comp 280hr (dual pattern 280* @ .050 .525 lift), 750 carb, 11:1 compression, etc. this was using the Bowtie 15* heads which made a huge differance in power with a reasonable (i think) compression ratio. the motor made peak power at 7500. could a similar setup be used as a weekend driver? why don't more folks use these type of heads? =
My own opinion of Desk top whatever is it's more fun then PacMan was many years ago :D

When you use these programs if you want any kind of real world results,, as real as they get, ;) you need to use a little discretion with input.

Sometimes they will come out pretty close in HP estimates but with some real world combinations they are not even close. :(

Yours is a perfect example of what not to do.
Just as you would not build an engine with 8000 rpm heads & a 5500 rpm cam you should not input these values into the program except for amusement ;)

The hyd roller is not going over 6-6500 max & is not going to be 280 @ .050, that is probably the seat timing. It is probably closer to 230 @ .050.
The heads you input are going to start working real good at about 5500-6000 or so on a 350.

BTW, what are 15 deg bowtie heads??

I dunno what 15* bowties are, it's in the list of heads. I guess it is kind of a mikey mouse deal though.
you cought me again on the cam stuff though mike graemlins/waving.gif I always get those scrambled. and are the hydrolic lifters rpm limited *guess* because of that little spring in them bottoming out? I guess just leave the nascar parts websites alone huh? tongue.gif thanks for explaining this stuff guys!

Hi Wolfy, Looks like the head he is refering to is a partially machined 18 degree, high port head that is rolled 2 degrees by angle milling the head and changing the valve angle by 1 degree for a total of 3 degrees. It is part number 24502615 in my 2002 G.M. Performance Parts Catalog and is one of six variations of the casting 10134363 and has no seats or guides according to this book. It also has a 210 cc intake runner and 35-37 cc combustion chamber. Sounds like a lot of work doesn't it?

Originally posted by Harold Sutton:
Hi Wolfy, Looks like the head he is refering to is a partially machined 18 degree, high port head that is rolled 2 degrees by angle milling the head and changing the valve angle by 1 degree for a total of 3 degrees. It is part number 24502615 in my 2002 G.M. Performance Parts Catalog and is one of six variations of the casting 10134363 and has no seats or guides according to this book. It also has a 210 cc intake runner and 35-37 cc combustion chamber. Sounds like a lot of work doesn't it? =
Hey Harold,
Thanks, didn't even know GM had a head they called 15 degrees,,,guess I gotta bone up on my trivia ;)

I guess that makes the last set of 363's I did 17 degree heads as I rolled em 1 deg :D
which is in itself a bunch of work by the time you are done.
Had to redo the intake face, spotface the bolt tops & ream the the bolt holes so the studs were still straight.

Always a pleasure visiting with you Mike, i bet that 15 degree would be a bundle of work and expense because it didn't have guides or seats!

Why bother?? Why not go with 10 degree Buick style SBC heads and be done with it...

pdq67

The 18 degree Chevy stuff is better than the Buicks are for ultimate power. Early on though, some Comp guys liked the Buick heads on smaller motors as they seemed to perform better in hot summer weather compared to the 18s due to the port and chamber design. Now that Nascar guys use SB2 heads you can find some good deals on old 18 stuff that is still in awfully good shape, but as time has gone by the supply of the heads has all but dropped off from the Nascar guys. But, you are back to needing matching cam, lifters, headers, intake, valve gear, pistons, etc. again with any of the rolled valve angle heads. My Canfields are a 22 degree after doing the same as Mike has with the other heads, but it is worth it since the intake port angle is improved along with other benefits of a more shallow valve angle.

Actually the only reason I do it is strictly a compression issue with the least dome possible & when building engines with head rule constraints.

This engine is a 332" SB & it is very hard to get over 14.0 compression in these smaller engines when running cams with about .700 lift.
I don't feel given the same casting that there is any real advantage to angle milling regarding port angle as you are not really changing anything except the chamber itself.
the port & port entry angle to the valve is essentially identical ;)

Also, if your headers are close to the engine now, 1 deg will move them pretty good. You can figure it by taking the sine of 1 deg (or whatever angle you cut them)times the length so if your headers are say 24" from flange down to collector in height you will move the collector in almost 7/16".
More of them stupid little details :(

That was the primary reason I did it too in 331" and 341" motors with deep valve pockets and some hope of decent flame travel as well with 23* heads and their chamber limitations. It slightly improves the angle of the intake port as it meets the intake manifold. I know that the guys here locally at R&J who did the design work for the Mopar B-1 head years ago started with some pretty specific thoughts on port roof angle to valve angle numbers that they wanted to stick to, but they had a clean slate to work with. smile.gif

whoa! you guys lost me :eek: . so your talking about angling the heads toward the intake making to headers pop outwards towards the framerails, so you have to trim the headers/intake? and, are we trying to promote quench or the overall compression? graemlins/beers.gif

Originally posted by young gun '71:
whoa! you guys lost me :eek: . so your talking about angling the heads toward the intake making to headers pop outwards towards the framerails, so you have to trim the headers/intake? and, are we trying to promote quench or the overall compression? graemlins/beers.gif =
Sorry about that smile.gif
Angle milling is done by cutting the head across the chamber or head gasket sealing surface zero at the intake side & all off the exhaust side to a certain amount.
1 degree on a small block is a little over .130" taken off the exhaust or chamber side of the surface.
The reason for angle milling is you are limited by the intake seat as to how much you can flat mill the head.
Then the intake surface has to be cut back to 10 degrees which is the stock angle from the chamber side to the intake side on a 23 degree head so the intake manifold will still be at the correct angle to seal.
The tops of the bolt holes need to be spotfaced so they are flat to the new chamber surface & on large cuts like the one above you will need to ream the bolt holes out so the bolts will line up with the holes in the block.
You also need to either cut the bottom of the intake or top of the block as the intake will now be lower.
The reason the headers can become a problem is because you have "tilted" the head slightly which brings the headers in towards the engine.

Sounds like a lot of fun huh :D

The main reason is to make the chamber smaller for compression.
It has nothing to do with quench as this is the flat part of the head & piston & it is still flat, this doesn't change.

Have I confused you enough yet ;)

You know, Powerhouse is selling a cast-iron, 50 cc big valve SB head for not much money!!

I wonder if they are any good??

And Mike, I'm saving your above post b/c it might come in handy later..

pdq67

ya know, after reading a lot of posts from you guys, i realize that if this were baseball instead of engines, you guys would be throwing 110 mph fastballs and i would still be trying to hit the dang thing off the tee! but it is definitely an interesting education. thanks

Hi Wolfy, Ford and Mopar flattened the valve angles out a lot on their small blocks which should give those engines quite an advantage with the standard type heads. When you angle mill these down to 22 degrees i'd guess it would require changing the valve relief also, right? How hard is it to get the head bolt holes honed to the correct angles?

I always get confused when Wolf starts talkin' bout angle milling. How about a picture show, MIke? I can't visualize where it is that the milling is happening.

Even a pic of a head and lines going through or pointing to where the heads are cut.

So lost without visuals, lol.

I'm just glad Mike uses the correct terms for this instead of the confusing crap like angle machining and angle milling or whatever they were called that got me ta scratching my head once.......

You know, even pointy headed old me can understand "flat and angle milling"!!!

pdq67

Originally posted by Slowpoke70:
I always get confused when Wolf starts talkin' bout angle milling. How about a picture show, MIke? I can't visualize where it is that the milling is happening.

Even a pic of a head and lines going through or pointing to where the heads are cut.

So lost without visuals, lol. =
Hey Enrique,
No pics but I'll see if I can make it easier ;)
Picture putting a head into a surfacing machine & the cutter is over the head so the chamber side would be facing up.
You level it as if you were just going to cut it for a nice flat new surface.
Now you tilt or raise the exhaust side up say .100" by attaching a dial indicator to the cutting head & "sweeping" it across the head & lock the head in this position.
Now when you surface it the cutter is going to start cutting at the exhaust side & will not reach the other or intake side of the head until you have cut the .100 off that you tilted or "angled" the head.
You have just angle milled the head .100thou smile.gif

Now you get to remount the head in the machine with the intake face facing up & set the machine so you are cutting this surface back to the original 10 degrees to the deck or chamber side you just finished assuming we are talking about a standard 23 degree small block head.

Harold,
The bolt holes will "straighten" pretty easy with a reamer in the Bridgeport & you usually don't need to mess with them until you get over about .070 to .080 thou in angle, just spot face the tops.
The piston depends on how much room you have but if I need to cut it yes I change the angle.

Now I'm catching on. graemlins/hurray.gif

graemlins/thumbsup.gif Got it.

would you need shorter/longer pushrods?

Originally posted by young gun '71:
would you need shorter/longer pushrods? =
Probably,, & piston to valve clearance can get interesting :rolleyes: