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I just want to do a double check and make sure I am not crippling this build before I start.
This style head, from what I researched, supposedly has some weak points. Mostly tearing off rocked studs with stiff springs and being tough to weld. And dropping valve seats.
I have been assured these will be leak free, welds smoothed out, intake port re-ported etc.
Std mounting holes have already been deepened and is not what broke.
These things had tremendous roller cam springs on them and ripped off an intake stud.
I have been assured they'll be reliable and strong enough for stock strength factory LS6 solid cam springs.
At most I might run 540/60/90 lift, not the .740 roller these things had on them before.
You won't be able to see any repair work with the valve covers on.
Best part he is one of my best friends and for $1600 they'll be ready to install.
So is this a great deal or I am I letting my friends favor blind me to a problematic set of heads?
If the heads are too shaky, reliability wise, it puts my whole build at risk.
Any other things I should consider?
Fire away.
leigh1322:
I would kinda be curious as to the extent of the port work that was done on the heads and to what lift they flow to. Having a .740ish lift cam in there doesn't necessarily mean that they flow to that but those factory heads already had pretty big intake runners to begin with. May want to "cc" the intake runners and see what you are working with at the least and see if your buddy maybe has a flow bench sheet for the heads laying around (unlikely). I still think the heads will be a nice piece to build your motor around. It would be nice to know what kinda flow numbers they put out to help you pick the cam (or are you going with an LS6 cam?). I also commented in the other thread that the one picture of the combustion chamber almost looked like it had a crack between the two valve seats. Hopefully that is not the case and it is just the way the picture looks, just trying to look for any potential problems you may run into. Other than that, I like the look of the heads. For $1600 ready to install that is a pretty nice deal, the other positive is that you are buying them from a friend (less likely to have someone trying to pawn their junk off on ya). Keep us posted!
Last edited by bence13_33; 07-05-2018 at 03:11 PM.
I did something very similar to your build...i found a pair of heads that had been polished, as in outside shined, snowflakes gone...had Jerry MacNeish look them over, he put the proper finish back on gave them a thumbs up and now I have them running stock L88 springs...my build is a sorta L88 tribute...anyway the engine has been running fine for over a year, and I am not gentle....my advice would be to have a very knowledge chevy aluminum engine parts guy look at them.
I did something very similar to your build...i found a pair of heads that had been polished, as in outside shined, snowflakes gone...had Jerry MacNeish look them over, he put the proper finish back on gave them a thumbs up and now I have them running stock L88 springs...my build is a sorta L88 tribute...anyway the engine has been running fine for over a year, and I am not gentle....my advice would be to have a very knowledge chevy aluminum engine parts guy look at them.
Great Idea.
Anyone you could suggest within driving distance of Philly?
My buddy Jeff owns a speed shop and machine shop and has probably built 3000 motors. Obviously a lot of BBC. These were his personal heads. He's very good, and he has a full machine shop, but he's a drag race guy. Can anyone recommend someone with more chevy aluminum head experience?
I'd love to hear an L88 run hard again someday!
Yeah we could get them flowed, that's probably a pretty good idea. I am not sure of the extent of the porting. They were on a pretty serious drag car, like low 9s. They might be a little too much flow for the LS6 cam, and I know new aluminum oval ports would make more torque and run harder, but I am more into the nostalgia aspect of it.
I'm thinking of the mid-range torque sacrifice and skinny tires as 1970s torque-management and transmission life insurance!
leigh1322:
Probably not a big deal to get them flowed either way. I have a feeling regardless of the "sacrificed" low/mid range torque it will be a non-issue because these things already have a ton of torque to start with. The flow numbers will just be interesting to know what you are working with and perhaps for later down the road if a cam change is something that interests you. I would just stick with your buddy Jeff's opinion and expertise, it sounds like he knows his stuff. It also makes it much nicer because it's like a one-stop-shopping deal.
Last edited by bence13_33; 07-05-2018 at 04:11 PM.
Call Fonse performance in Erial NJ. Dunno if he does flow bench work, but he will know who does around here. Clymer PA? Wouldn't you be better off in the Pittsburgh market?
Last edited by derekderek; 07-05-2018 at 04:49 PM.
Richie zul is in your neck of the woods,I'd call him and ask if he would look em over for you.another really good guy would be "General" Lee Edwards.but he's in virginia.and also in virginia is Carlton Phillips all those guys were pro stock racers that used those heads in years gone by and know the limitations.I haven't messed with that stuff in years and likely forgot alot of what I knew,but then again stuff happens that I suprise myself all the time.
good luck and keep us posted
I can tell you by looking at this photo you posted that there is quite a bit to be gained with work in the bowls, short side radius, chamber and seat work. The seat throat on the intake looks like it has a high throat diameter to valve size ratio. It's kind of how heads were done way back. The problem is it really hurts low and mid lift flow. A little larger valve and some seat work could fix this though.
Doesnt take much to not only flow, but if someone already took a grinder to them have them poured, if that head is too big you wont like nostalgia, the car may be sluggish everywhere.
If it were me put a more modern SFT grind in, get some modern aluminum heads, nice difference. Those old heads werent that great.
No compared to today's heads they aren't that good,but back when they were the hot ticket (mostly due to the weight savings) experienced engine builders would get around a thousand horsepower with alot of work.but that was an engine designed to run wide open throttle for a quarter mile at a time leaving the line at 8k R.P.M .it depends how much work has been done that will determine how suitable they will be. I agree fully that a set of aftermarket heads would be a better route. But remember those new heads are a direct result of what Lee Edwards,Richie Zul, Bill Jenkins and Warren Johnson learned with those old snowflake heads.
I have a complete late 70's era pro stock engine with those heads fresh in the wrapper and it's not for sale, one day maybe I will use it,but definitely not in a street driven car.
They are the equal to iron rectangle heads flow-wise. Easier to port and weigh less. They are expensive because they are collector items. The really valuable ones are with the correct date codes for 68-69 cars. Then they are usually used to try to be passed off as genuine, not tribute engines. Personally, I feel 800 for 1 unhurt 1978 head is ok. 800 for the other that ripped entire stud boss off the head? Not so much...
Ok, what is this LS6 being built for. ET? or for sitting next to the engine in a lawn chair at events? These are good heads for the second option. Get a zz502 roller cam and retro hyd or solid roller lifters. Nice idle. Good power. And can run with 120 seat-350 over nose spring pressures. 544 lift. The thing I like about this cam is GM designed it. They don't like to lose money. Replacing a warranty engine cuz the cam was too aggressive trying to get 25 more hp costs them money.
Thanks for the input. Great discussion. I agree these things have passed their prime as the "hot ticket" for a race motor. I intend to build a pretty authentic LS6, as a nostalgia tribute, and not try to pass it off as an original. Hence no need for any matching dates, etc. I'll more than likely race it once just to see what it does, period. It's basically be a driver and a cruise-in car.
My problem is that there are just so few of these heads around, and they have all been raced, I need to make certain these haven't been so heavily ported during their prior life, that they ruined any semblance of streetability. (Remember I think a 30-30 cammed DZ 302 or LT1 is perfectly streetable). Stock ovals and rectangular ports both flow about the same at .500 and under, around 270-280. It's only at .600 that the rectangular ports start to pull away. And then the porting jobs or newer heads can add 17-20% or more to that. AFRs are around 330 or so, unported. So I think we'll just examine them closely and make sure the port job isn't too extreme, killing the low rpm flow velocity. My BBC experience is much more limited than SBC but I only want to build this beast once.
I think people are being a little over critical of these heads. Are there aftermarket options that will run better, yeah probably all of them, and they should....we are talking about around 40 years of engineering advances. So when you factor that in, how poor are these heads really? To say that they are only good for shows and won't produce good ET/MPH is a bit hyperbolic. These heads came on one of the most powerful engines Chevy ever produced. They are a bit more than show pieces, they were the badest factory heads of the time. I like your idea for the motor, I would stick with what you really want. Yes a roller cam idles nicer and will produce more power. There is just something that I love about a solid flat tappet camshaft. It might be the simple/raw nature of what it is and what it was that I find so appealing. Build what you want, and what you know is going to make you happy. I would not be too worried about a lack of horsepower with those heads though.
They can make decent power..and if I'm not mistaken...the ports are actually a little smaller than iron rectangular ports. You've identified the issues with them....they got abused over the years, the aluminum in them is nothing like a Brodix/AFR etc....lots of broken studs and damage.
I know you're probably not running tall covers...but maybe some of those sneaky ones that looks stock but are just a little taller could allow a stud girdle to be installed to add some reliability even with a solid flat tappet.
They are going to start coming alive around 4500-5000 RPM or so......they will drive fine...but flat footing it at 3000 RPM is going to be a little weaker.
I'd use a dual plane intake on it...factory 427/425 style one is fine if you have hood clearance.
Sounds like you're planning a reasonable cam...so that will help things....
Thanks 427 Hotrod
I actually loved the way my 30-30 cam'd LT1 came alive at 3500.
Here's hoping this one is similar, just way more of everything all around.
I'm definately Not planning for a motor like you have!
I'm willing to give up 25-30 here and there, as long as I wind up with 75-100 more than the small block.
Jeff's and my estimate is between 530-570 with the headers.
Just gotta watch 427HR's point of view. You said a DZ 302 is perfectly streetable. His idea of perfectly streetable does low 9's.
LOL...it's all relative right?? My current turbo setup is so mild to drive......but truthfully even the N/A versions weren't bad.
You already know a killer set of ovals would do better....but these will do OK too. In fact....it can often help traction down low by not having so much bottom end...but come on like a freight train once rolling. Just remember to drop a gear or two before punching it from a roll with someone!
I've mentioned it before, but one of the best flat tappet cams I ran in my 427...and in some 396's and 454's too...is an ancient Crane. Part number #134691. It's a 256/266@.050 with .580/.600 lift on a 110 LSA. It "looks" fairly big...but in practice it is very easy on parts, runs like a Mo Fo and will rev to the moon. I ran a gazzilllion flat tappets through my old 427 and at the end of the day on the street...this one did very well. Very old school...but proven.
# 131311 and #131111are another couple of options if you want a little thumpier.
07-05-2018, 12:48 PM
Snowflake Aluminum Head Questions
