Heads question
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 952
Likes: 44
From: NC
Heads question
Hey guys
I have probubly a simple question about the heads I have
I bought a rebuilt set of heads with the 1.94 intake valves that have been ported and polished. I would like to find out of the heads have been milled (ultimatly to find out what size compression chamber I have), what type (pound?) springs I have. Should I just take the heads to a machine shop and have them checkout the heads for me? do you think they will charge me?
Also, i will probubly put them on a motor sometime in the next year. The heads have 1500 miles on them. Should i replace the valve stem seals before I put them on the motor? Is there anything else I should do?
I dont have the heads with me, Im at college so I cant do any sort of measurements right now.
Thanks for the info
James
I have probubly a simple question about the heads I have
I bought a rebuilt set of heads with the 1.94 intake valves that have been ported and polished. I would like to find out of the heads have been milled (ultimatly to find out what size compression chamber I have), what type (pound?) springs I have. Should I just take the heads to a machine shop and have them checkout the heads for me? do you think they will charge me?
Also, i will probubly put them on a motor sometime in the next year. The heads have 1500 miles on them. Should i replace the valve stem seals before I put them on the motor? Is there anything else I should do?
I dont have the heads with me, Im at college so I cant do any sort of measurements right now.
Thanks for the info
James
Team Owner
Joined: Feb 2005
Posts: 32,519
Likes: 1
From: central America
St. Jude Donor '08-'09
If you're not sure what you have, definitely take them to a shop to have them checked. Someone here might be able to tell you how to do it at home, but a good speed shop should have that equipment. Yes, they will charge you, but I can't imagine it being that expensive (you aren't asking for machine work, just use of their calibration tools).
Valve stem seals are cheap insurance, so it probably isn't a bad idea if they have been or will be sitting for some time.
What kind of heads are they?
trw
Valve stem seals are cheap insurance, so it probably isn't a bad idea if they have been or will be sitting for some time.
What kind of heads are they?
trw
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 952
Likes: 44
From: NC
They are GM 1973 heads that have been fully rebuilt and ported/polished. I bought them because they were cheaper than getting mine rebuilt. The only problem is. Like i said, I dont know exactly what was done because I just bought them as rebuilt. They look great, I wish i had pictures.
Team Owner
Joined: Feb 2005
Posts: 32,519
Likes: 1
From: central America
St. Jude Donor '08-'09
993 heads have 76cc combustion chambers, 165 cc intake, that flow around 200cfm stock. With being ported and polished, that may flow around 225-230 cfm. There was a business online that sold ported and polished 993 heads, and those are the numbers I remember. This should give you a rough idea of what you have, obviously have it checked out before you put them on the motor.
I'm runnning 993 heads on my 355. I didn't have them ported and polished (was low on cash) but I did have them put in 2.02/1.6 valves in them. I'm happy with how it runs now, but plan on upgrading to aluminum heads that will work better with my relatively high lift cam. With .125 domed pistons, my CR is 9.5:1. What kind of motor are you putting together?
trw
I'm runnning 993 heads on my 355. I didn't have them ported and polished (was low on cash) but I did have them put in 2.02/1.6 valves in them. I'm happy with how it runs now, but plan on upgrading to aluminum heads that will work better with my relatively high lift cam. With .125 domed pistons, my CR is 9.5:1. What kind of motor are you putting together?
trw
Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 952
Likes: 44
From: NC
TRW, you have been a great help so far, Thank you very much!
I am planning on putting together a 355. It will be my first engine so I am still learning about how things work and how everything works with eachother. I Idealy I would like a motor that makes good power but That can still run off of 87 octane just because it is cheaper and I drive my vette alot. However, I do not know what makes a motor able to run on lower grade gas. I thought it was lower compression. So I was going to try to aim for 9.2-9.5 compression ratio because that is what i have "heard" is boarderline on running 93 octane. However If i have to run 93 i might as well bump my compression to 10 or higher.
I would like to have a the biggest cam that will run well with my compression ratio ( which I havnt decided on). And i also have not decided on what type of pistons I would like, whether they are flat top or dome. So there are lots of things I need to decide on before I start picking out parts. I would like to have 300 at the wheels but that may be a stretch.
Thanks again for the info TRW, I gotta go to class now.
James
I am planning on putting together a 355. It will be my first engine so I am still learning about how things work and how everything works with eachother. I Idealy I would like a motor that makes good power but That can still run off of 87 octane just because it is cheaper and I drive my vette alot. However, I do not know what makes a motor able to run on lower grade gas. I thought it was lower compression. So I was going to try to aim for 9.2-9.5 compression ratio because that is what i have "heard" is boarderline on running 93 octane. However If i have to run 93 i might as well bump my compression to 10 or higher.
I would like to have a the biggest cam that will run well with my compression ratio ( which I havnt decided on). And i also have not decided on what type of pistons I would like, whether they are flat top or dome. So there are lots of things I need to decide on before I start picking out parts. I would like to have 300 at the wheels but that may be a stretch.
Thanks again for the info TRW, I gotta go to class now.
James
Melting Slicks
Joined: Apr 1999
Posts: 2,010
Likes: 3
From: Moon Twp. PA USA
Originally Posted by James B
TRW, you have been a great help so far, Thank you very much!
I am planning on putting together a 355. It will be my first engine so I am still learning about how things work and how everything works with eachother. I Idealy I would like a motor that makes good power but That can still run off of 87 octane just because it is cheaper and I drive my vette alot. However, I do not know what makes a motor able to run on lower grade gas. I thought it was lower compression. So I was going to try to aim for 9.2-9.5 compression ratio because that is what i have "heard" is boarderline on running 93 octane. However If i have to run 93 i might as well bump my compression to 10 or higher.
I would like to have a the biggest cam that will run well with my compression ratio ( which I havnt decided on). And i also have not decided on what type of pistons I would like, whether they are flat top or dome. So there are lots of things I need to decide on before I start picking out parts. I would like to have 300 at the wheels but that may be a stretch.
Thanks again for the info TRW, I gotta go to class now.
James
I am planning on putting together a 355. It will be my first engine so I am still learning about how things work and how everything works with eachother. I Idealy I would like a motor that makes good power but That can still run off of 87 octane just because it is cheaper and I drive my vette alot. However, I do not know what makes a motor able to run on lower grade gas. I thought it was lower compression. So I was going to try to aim for 9.2-9.5 compression ratio because that is what i have "heard" is boarderline on running 93 octane. However If i have to run 93 i might as well bump my compression to 10 or higher.
I would like to have a the biggest cam that will run well with my compression ratio ( which I havnt decided on). And i also have not decided on what type of pistons I would like, whether they are flat top or dome. So there are lots of things I need to decide on before I start picking out parts. I would like to have 300 at the wheels but that may be a stretch.
Thanks again for the info TRW, I gotta go to class now.
James
Compression ratio is not the only thing to be concerned with, if you want to run lower octane gas.
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Thread Starter
Burning Brakes
Joined: Nov 2002
Posts: 952
Likes: 44
From: NC
Originally Posted by glen242
Compression ratio is not the only thing to be concerned with, if you want to run lower octane gas.
James
Melting Slicks
Joined: Apr 1999
Posts: 2,010
Likes: 3
From: Moon Twp. PA USA
Originally Posted by James B
Could you give me a few pointers of what I need to be concerned with in order to be able to run 87 octane. Also, How much power would i be sacrificing by make sure my motor could run on 87 octane. and what do you think would be the max compression ratio I could run. Im sure i am really showing how much I still dont know by asking these questions. thanks for the help guys.
James
James
Since you say you are learning, get a couple of books on rebuilding sbc. More general answers there than can be given on forum posts.
