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I just bought a used set of alum. bowtie heads (049 casting), have a few questions
They look like they were heavily modified, but I don't know how they looked stock so I can't really tell. In each intake port there is some black epoxy to smooth the transition from the valve guide to the back of the intake bowl.
I don't have a camera, so this was the only similar pic I could find on the internet, I think this is a pic of AFR heads:
But the intake port looks exactly like that, only it was done with epoxy to give it that shape behind the valve guide.
Also, the combustion chambers have lots of little dimples in them, is that normal?
Anyways, they came bare when I bought them, I need a set of valves, springs, retainers, and seals. What's a good set, and how much lift can these heads handle?
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Ruiner, without seeing a picture of the heads, it is hard to say what the dimples in the chamber are. They are most likey just porosity from when the heads were cast, but they could also be the result of some sort of debris entering the chamber.
The epoxy is commonly used to repair a section of a head that has been ported excessively.
As for the valve springs required, this relies on several factors. The main one being what camshaft you have. Refer to the cam manufacturers recommendations for seat pressure and open pressure for a starting point. Also, your maximum desired rpm depends on your choice of valve spring- choose springs with too light a pressure and your valves will float. Thirdly, the type of tappet (hydraulic, hydraulic roller, etc) you are using helps to determine the spring you need, as heavier tappets require the used of stiffer springs. For general use, stick with the cam manufacturers recommendations. I hope this helped to answer some of your questions.
well the epoxy is in all 8 intake runners, looks like it was put there just to smooth the back of the intake bowl, make the valve guide a little more aerodynamic as air flows past it
as for the dimples, it looks as if somebody took a center punch and made a bunch of very small holes in each combustion chamber, they're spaced in a regular pattern about 4-5mm apart, abut 1.5mm in diameter
From what I can tell, these are pretty wild heads. I'm not trying to build some crazy 600hp race engine though, I'm hoping I can take advantage of the efficiency of these heads and use it in combination with a relatively mild cam, and get some good usable power. They're going on a rebuilt 355
They do sound pretty wild. The biggest problem I see is heads that are so radically ported to require Epoxy will usually have pretty crappy low lift flow numbers and not work very well with a mild cam.
BTW, I have a set of bowtie 049's on my autocross car that look to have some very nice port work without Epoxy. Looks to be close to a felpro 1206 intake gasket 1.25X2.25 ports. 2.10 and 1.65 valves and these make some decent power with a relativly mild .530 lift, 246 at .050 duration solid cam.
The Bowties are pretty outdated though and there are better heads on the market but since you have these allready it dosen't hurt to try them and see how well they do. I am pretty impressed with mine.
yeah I'm just trying to use them since I got a really good deal on em
Did some more research, apparently the dimples I saw is called center-popping, supposed to increase fuel atomization and reduces detonation. Anyone know more about this?
I've heard of it. I have a feeling you may find some other odd things if you know what to look for if someone bothered with that. You will likely never know if it actually works right for those or not, just have to assume so.
The center popping in the chambers is interesting, not what i had in mind when you were talking about dimples...i thought you were talking about some type of casting mark. it can't hurt to try 'em out since you have them; at least it'll look cool, but they're probably going to kill your bottom end on a low compression, mild cammed engine. have fun and good luck man.
Thats totally random dimpling. Likely completely worthless for its intended purpose.
Not that I believe the dimpling offers any advantage but may I ask why you feel it's worthless just because it's random? Maybe it just dosen't matter how it's spaced. BTW the dimples don't look totally random to me.
Yeah they are definetely equally spaced and all run together in diagonal lines. I don't know if they work or not, as this is the first time i have seen this, but like everything else in the hot rod world, innovation and progress are sometimes the result of just trying something completely random and different. It would be interesting to see some testing to see whether or not it helps to better atomize the fuel (which would yield better fuel economy) and if it helps to reduce detonation.
It shouldnt look like someone took a measuring tape and put a grid across the chamber. Someone read about the procedure, and thought they knew the idea.
Yeah I just took the heads over to my local shop for a valve job, he said it was an old school racing trick, that those heads most likely came off a circle track car or something of the like. The guy was really impressed with the porting though.
Also noticed that the widest part of the combustion chamber is more then 4 inches across (kinda explains why it has steam holes drilled, was on a 400), will this cause a problem on a 4.030 inch bore?
I noticed that your exhaust ports are numbered just like mine and the exhaust ports look identicle to mine. Same guide plates(stamped with SGM) and I also have 7/16 studs. I should have took some pictures before I reinstalled the heads. I can still get pictures of the intake ports, studs and guide plates but that is about it.
Is there anything stamped on the ends?
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One more question. Is this the same Ruiner that post's on 3SI?
Last edited by rayar; 11-16-2008 at 10:46 PM.
Reason: Automerged Doublepost
Ok it's been a while I've been short on cash and taking my time with my engine build
I just went yesterday and picked up the short block, it's a 70's 014 casting, bored 30 over, stock crank/rods, with TRW flat top forged pistons (they say L2256F .030).
Been doing the math, want to make sure everything's right.
I measured the heads, the combustion chambers are 59cc (plus they have "59" stamped on the ends)
piston to deck clearance at TDC is 0.019, -6.1cc valve reliefs, so with a .041 thick head gasket I should be at 10.3:1 static compression ratio
so my question is, what's a good cam to get for this motor? It's hydraulic flat tappet, need something compatible w/ TPI
I was looking at something like the crane 114142, or COMP 260XFI, would that work well? I'm looking for good low and midrange, not going over 5800-6000rpm. Currently stock 700r4 and 2.73 gears from '91 RS 305 TBI
