Aluminum Bowtie heads
#1
Junior Member
Thread Starter
Join Date: May 2008
Location: Austin
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
Car: '91 Camaro RS
Engine: 355 TPI, Comp 268xfi, bowtie heads
Transmission: 700r4
Aluminum Bowtie heads
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:
http://www.maximumraceengines.com/im...alve%20job.jpg
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?
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:
http://www.maximumraceengines.com/im...alve%20job.jpg
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?
#2
Member
Join Date: Sep 2007
Location: Baltimore
Posts: 169
Likes: 0
Received 0 Likes
on
0 Posts
Car: '82 Z-28
Engine: 355
Transmission: TH-400, 8" ATI MRT
Axle/Gears: Moser 9", 4.56's
Re: Aluminum Bowtie heads
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.
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.
#3
Junior Member
Thread Starter
Join Date: May 2008
Location: Austin
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
Car: '91 Camaro RS
Engine: 355 TPI, Comp 268xfi, bowtie heads
Transmission: 700r4
Re: Aluminum Bowtie heads
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
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
#4
Junior Member
Thread Starter
Join Date: May 2008
Location: Austin
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
Car: '91 Camaro RS
Engine: 355 TPI, Comp 268xfi, bowtie heads
Transmission: 700r4
Re: Aluminum Bowtie heads
also I'm trying to figure out what size valves I need, the heads came with no valves.
I'm assuming valve size is measured from the O.D. of the valve seat?
If so I'm getting 2.10" x 1.60" with my digital calipers
I'm assuming valve size is measured from the O.D. of the valve seat?
If so I'm getting 2.10" x 1.60" with my digital calipers
#5
Member
iTrader: (1)
Join Date: Oct 2008
Location: Bozeman MT
Posts: 230
Likes: 0
Received 0 Likes
on
0 Posts
Car: 83 Camaro
Engine: 4 Bolt 350, Bowtie aluminum heads
Transmission: TH350
Axle/Gears: 3.42, superior axles, Torsen diff
Re: Aluminum Bowtie heads
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.
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.
#6
Junior Member
Thread Starter
Join Date: May 2008
Location: Austin
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
Car: '91 Camaro RS
Engine: 355 TPI, Comp 268xfi, bowtie heads
Transmission: 700r4
Re: Aluminum Bowtie heads
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'll try to get a pic
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'll try to get a pic
#7
Guest
Posts: n/a
Re: Aluminum Bowtie heads
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.
Trending Topics
#8
Junior Member
Thread Starter
Join Date: May 2008
Location: Austin
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
Car: '91 Camaro RS
Engine: 355 TPI, Comp 268xfi, bowtie heads
Transmission: 700r4
Re: Aluminum Bowtie heads
well I'm going to try and sand them down some, just to get rid of the roughness in the chambers
dremel time
dremel time
Last edited by Ruiner; 11-12-2008 at 10:36 AM.
#9
Junior Member
Thread Starter
Join Date: May 2008
Location: Austin
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
Car: '91 Camaro RS
Engine: 355 TPI, Comp 268xfi, bowtie heads
Transmission: 700r4
Re: Aluminum Bowtie heads
another pic
Edit: also a random question, but #10066036, is that a good block? It's a 350 4 bolt 2pc rear seal, bought it freshly bored 030 over for $100
Edit: also a random question, but #10066036, is that a good block? It's a 350 4 bolt 2pc rear seal, bought it freshly bored 030 over for $100
Last edited by Ruiner; 11-12-2008 at 11:06 AM.
#10
Member
Join Date: Sep 2007
Location: Baltimore
Posts: 169
Likes: 0
Received 0 Likes
on
0 Posts
Car: '82 Z-28
Engine: 355
Transmission: TH-400, 8" ATI MRT
Axle/Gears: Moser 9", 4.56's
Re: Aluminum Bowtie heads
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.
#11
Member
iTrader: (1)
Join Date: Oct 2008
Location: Bozeman MT
Posts: 230
Likes: 0
Received 0 Likes
on
0 Posts
Car: 83 Camaro
Engine: 4 Bolt 350, Bowtie aluminum heads
Transmission: TH350
Axle/Gears: 3.42, superior axles, Torsen diff
Re: Aluminum Bowtie heads
10066036...350...........2 or 4...Target Master/Goodwrench crate motor, 2-piece rear
seal, "Hecho en Mexico"
#13
Member
iTrader: (1)
Join Date: Oct 2008
Location: Bozeman MT
Posts: 230
Likes: 0
Received 0 Likes
on
0 Posts
Car: 83 Camaro
Engine: 4 Bolt 350, Bowtie aluminum heads
Transmission: TH350
Axle/Gears: 3.42, superior axles, Torsen diff
Re: Aluminum Bowtie heads
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.
#14
Member
Join Date: Sep 2007
Location: Baltimore
Posts: 169
Likes: 0
Received 0 Likes
on
0 Posts
Car: '82 Z-28
Engine: 355
Transmission: TH-400, 8" ATI MRT
Axle/Gears: Moser 9", 4.56's
Re: Aluminum Bowtie heads
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.
#17
Junior Member
Thread Starter
Join Date: May 2008
Location: Austin
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
Car: '91 Camaro RS
Engine: 355 TPI, Comp 268xfi, bowtie heads
Transmission: 700r4
Re: Aluminum Bowtie heads
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?
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?
#18
Member
iTrader: (1)
Join Date: Oct 2008
Location: Bozeman MT
Posts: 230
Likes: 0
Received 0 Likes
on
0 Posts
Car: 83 Camaro
Engine: 4 Bolt 350, Bowtie aluminum heads
Transmission: TH350
Axle/Gears: 3.42, superior axles, Torsen diff
Re: Aluminum Bowtie heads
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?
----------
One more question. Is this the same Ruiner that post's on 3SI?
Is there anything stamped on the ends?
----------
One more question. Is this the same Ruiner that post's on 3SI?
Last edited by rayar; 11-16-2008 at 09:46 PM. Reason: Automerged Doublepost
#19
Junior Member
Thread Starter
Join Date: May 2008
Location: Austin
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
Car: '91 Camaro RS
Engine: 355 TPI, Comp 268xfi, bowtie heads
Transmission: 700r4
Re: Aluminum Bowtie heads
yeah they do have markings on the end interestingly enough, they both say "H.V.H. 93220"
#20
Junior Member
Thread Starter
Join Date: May 2008
Location: Austin
Posts: 88
Likes: 0
Received 0 Likes
on
0 Posts
Car: '91 Camaro RS
Engine: 355 TPI, Comp 268xfi, bowtie heads
Transmission: 700r4
Re: Aluminum Bowtie heads
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
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
#22
Supreme Member
iTrader: (1)
Join Date: Jul 2000
Location: Carson, CA
Posts: 1,290
Likes: 0
Received 0 Likes
on
0 Posts
Car: '88 GTA, 90 Formula
Engine: 5.7 TPI, fed growth hormones
Transmission: 700r4 4u2?
Axle/Gears: 9bolt
Re: Aluminum Bowtie heads
The punch marks were fashionable in racing about 15 years ago, if done properly they help swirl and keep fuel from condensing on the metal. On a street engine, they will carbon over, but they do work and will not hurt anything.
The addition of epoxy in the intakes to smooth the transitions is actually an excellent sign, it means that the person working on the ports did not want to enlarge everything to create smooth transitions, but instead wanted to conserve cross section changes and make smooth transitions while keeping the port volume as low as possible. I saw many heads ported by the best builders in the world during "Engine Masters Challenge" teardowns, and many of the top-placing engines used epoxy in strategic places. Those that used them in the exhaust ports saw it start to peel away, but in the intakes they held up fine.
Your heads are legit. Circle track engines are tuned for torque and drive off corners, thus use smaller ports. Drag race engines are all about max flow and max RPM, so go with the biggest ports possible. Run the xfi260 and about 10.2 compression, and don't forget you will need get your intake base/runners/plenum ported, or your engine will be starving for air. Especially the base.
The addition of epoxy in the intakes to smooth the transitions is actually an excellent sign, it means that the person working on the ports did not want to enlarge everything to create smooth transitions, but instead wanted to conserve cross section changes and make smooth transitions while keeping the port volume as low as possible. I saw many heads ported by the best builders in the world during "Engine Masters Challenge" teardowns, and many of the top-placing engines used epoxy in strategic places. Those that used them in the exhaust ports saw it start to peel away, but in the intakes they held up fine.
Your heads are legit. Circle track engines are tuned for torque and drive off corners, thus use smaller ports. Drag race engines are all about max flow and max RPM, so go with the biggest ports possible. Run the xfi260 and about 10.2 compression, and don't forget you will need get your intake base/runners/plenum ported, or your engine will be starving for air. Especially the base.
Last edited by TA; 09-06-2012 at 06:28 PM.
Thread
Thread Starter
Forum
Replies
Last Post
ambainb
Camaros for Sale
11
04-25-2016 09:21 PM