FWilliams
07-11-2006, 01:00 AM
Ahhh the camel hump...camel back...double hump ....double bump....fuelie.....known by a number of names and casting numbers, this GM head is either coveted or despised.
with the introduction of the vortec heads, the camel hump is becoming a once again popular choice for a hot little small block mill, and in my opinion is the head of choice for a screamin small journal mill.
I am not going to try and cover all the variations and styles that were made , but concentrate on the ones most likely to be found at the swap meet or the local paper. And try and cover some things to look for while checking out that "just rebuilt " piece.
known mainly by the last 3 digits of their casting number, the most common ones to be found will be the
461
462
186
291
492.
the ones I am going to cover here are the 461 and the 462 and also the 291...the 492 is not as common but still found, it was the factory replacement for the camel hump and is virtually the exact same as the 462 casting ...in fact most of the heads are the same configuration as the 462 casting except for the 461.
what i like most about the head is the fact that it flows OK out of the box, around 160 on the intake....can be made to flow much better with a little work...will except most any intake manifold that you can throw at it, and will also accept a whole slew of spring and retainer packages to custom tailor to any cam.
the vortec while still a popular choice, has limited spring options ...and while having a newer burn combustion chamber, is still limited to lift and flow parameters....as well as limited intake choices. There are some new ones hitting the market all the time , but in my opinion if building a older style motor they just don't cut it. most of the write ups you read about them any more are in mags where you turn the page and there is a big ad selling said heads.
I classify the head with the craze that surrounded the use of the 305 casting in circle track motors, the small combustion chamber instantly bumped up the compression in a stock rules class....the intake tract didnt flow worth a crap, but it was an easy and cheap way to boost compression.
any way...enough of my .02....lets look at some heads.
here are a few that have I have been working with as of late.....
204043
the first thing I look at when I go to look at a set is what size valves do they have?....they will have either a 1.94/1.5 or a 2.02/1.6 valve set....either factory or machined afterward....a lot of the 1.94's that have had multiple or bad valve grinds, end up gettin cut bigger for the 2.02. in some very rare instances where a drag racer has had them, they could have a 2.05 intake, but it will be very rare to see this
the 1.94/ 1.5 will have a definite area between the valves that you can plainly see
204044
the 2.02/1.6 will look like the valves are touching....virtually no area visible between them.....when you see this you know that you have the big valves
204045
the next thing to look at is what shape the valves and seats are in
if the valves are sunken down into the valve seats, they have either been ground to much or to deep , or have pounded the seats down......the problem with sunken seats , are that they create all different valve stem heights.....especially if someone has been over agressive with the valve
grinder..
here is an example of sunken valves and then using a straight edge on the valve stem you can see the difference in the heights
204046 204047
what you would like to see are the valves sitting up, where you can actually see the valve edge or margin above the seat area.
204053
next I look at the valve springs, have they been modified? and to what extent.
a stock set up will have cast iron guides and valve springs with oil shields installed. they should have a small O ring style valve stem seal on the valve stem.......the oil shield is to help control the amount of oil the the O ring has to deal with...insureing enough oil gets to the valve guide ,but not to much
the springs will look like this
204054
most times when a valve job is done the valve guides are changed to either a thin bronze liner or a new thick wall bronze guide is installed.... a lot of times a positive type valve stem seal is installed when this is done...I do not like to see the positive type seal used if the stock oil shields are gonna be reused, you are not going to get the proper amount of oil to the valve guide by using this combination
204055
if you are gonna use the postive type seal you should go to an after market retainer at least.
204056
next thing to look at is the rocker stud set up . It will be stock pressed in stud.....
pressed in stud that has been pinned......
tapped for a screw in stud......
.tapped and machined for a guide plate and screw in stud. I dont have any pictures of pinned studs....it really isn't done much any more...the first pic is a pressed in stud. You can see the boss the stud sits on is tapered at the top.
in the next pic you can see where the boss has been machined to flatten it off and give a little more surface area then drilled and tapped
finally the last pic you can see the boss has been milled down to accept the thickness of the guide plate and screw in stud.
204061 204062 204063
it's nice to at least have the screw in stud for a performance application.
a couple of other things I want to touch on briefly, if you are running the 2.02 valves and the valve area of the combustion chamber has not been unshrouded , you are more than likely flowing worse than of you had the 1.94 valves...there is nothing wrong with the 1.94 in a hot little street motor....you can usually pick these up cheaper , because everyone wants the 2.02.
most of the ones that I find at swaps and what not have been done by racers that have moved up to a better head for their paticular class...they want to get little money back out of them . but in most cases they have had excellent machine work done......and you can get it at a fraction of the cost.....walk by the guys with the 600.00 dollar core heads ...matching corvette numbers,,, yada yada yada, these heads are not getting those kind of prices any more...
lets go find a set of heads........
with the introduction of the vortec heads, the camel hump is becoming a once again popular choice for a hot little small block mill, and in my opinion is the head of choice for a screamin small journal mill.
I am not going to try and cover all the variations and styles that were made , but concentrate on the ones most likely to be found at the swap meet or the local paper. And try and cover some things to look for while checking out that "just rebuilt " piece.
known mainly by the last 3 digits of their casting number, the most common ones to be found will be the
461
462
186
291
492.
the ones I am going to cover here are the 461 and the 462 and also the 291...the 492 is not as common but still found, it was the factory replacement for the camel hump and is virtually the exact same as the 462 casting ...in fact most of the heads are the same configuration as the 462 casting except for the 461.
what i like most about the head is the fact that it flows OK out of the box, around 160 on the intake....can be made to flow much better with a little work...will except most any intake manifold that you can throw at it, and will also accept a whole slew of spring and retainer packages to custom tailor to any cam.
the vortec while still a popular choice, has limited spring options ...and while having a newer burn combustion chamber, is still limited to lift and flow parameters....as well as limited intake choices. There are some new ones hitting the market all the time , but in my opinion if building a older style motor they just don't cut it. most of the write ups you read about them any more are in mags where you turn the page and there is a big ad selling said heads.
I classify the head with the craze that surrounded the use of the 305 casting in circle track motors, the small combustion chamber instantly bumped up the compression in a stock rules class....the intake tract didnt flow worth a crap, but it was an easy and cheap way to boost compression.
any way...enough of my .02....lets look at some heads.
here are a few that have I have been working with as of late.....
204043
the first thing I look at when I go to look at a set is what size valves do they have?....they will have either a 1.94/1.5 or a 2.02/1.6 valve set....either factory or machined afterward....a lot of the 1.94's that have had multiple or bad valve grinds, end up gettin cut bigger for the 2.02. in some very rare instances where a drag racer has had them, they could have a 2.05 intake, but it will be very rare to see this
the 1.94/ 1.5 will have a definite area between the valves that you can plainly see
204044
the 2.02/1.6 will look like the valves are touching....virtually no area visible between them.....when you see this you know that you have the big valves
204045
the next thing to look at is what shape the valves and seats are in
if the valves are sunken down into the valve seats, they have either been ground to much or to deep , or have pounded the seats down......the problem with sunken seats , are that they create all different valve stem heights.....especially if someone has been over agressive with the valve
grinder..
here is an example of sunken valves and then using a straight edge on the valve stem you can see the difference in the heights
204046 204047
what you would like to see are the valves sitting up, where you can actually see the valve edge or margin above the seat area.
204053
next I look at the valve springs, have they been modified? and to what extent.
a stock set up will have cast iron guides and valve springs with oil shields installed. they should have a small O ring style valve stem seal on the valve stem.......the oil shield is to help control the amount of oil the the O ring has to deal with...insureing enough oil gets to the valve guide ,but not to much
the springs will look like this
204054
most times when a valve job is done the valve guides are changed to either a thin bronze liner or a new thick wall bronze guide is installed.... a lot of times a positive type valve stem seal is installed when this is done...I do not like to see the positive type seal used if the stock oil shields are gonna be reused, you are not going to get the proper amount of oil to the valve guide by using this combination
204055
if you are gonna use the postive type seal you should go to an after market retainer at least.
204056
next thing to look at is the rocker stud set up . It will be stock pressed in stud.....
pressed in stud that has been pinned......
tapped for a screw in stud......
.tapped and machined for a guide plate and screw in stud. I dont have any pictures of pinned studs....it really isn't done much any more...the first pic is a pressed in stud. You can see the boss the stud sits on is tapered at the top.
in the next pic you can see where the boss has been machined to flatten it off and give a little more surface area then drilled and tapped
finally the last pic you can see the boss has been milled down to accept the thickness of the guide plate and screw in stud.
204061 204062 204063
it's nice to at least have the screw in stud for a performance application.
a couple of other things I want to touch on briefly, if you are running the 2.02 valves and the valve area of the combustion chamber has not been unshrouded , you are more than likely flowing worse than of you had the 1.94 valves...there is nothing wrong with the 1.94 in a hot little street motor....you can usually pick these up cheaper , because everyone wants the 2.02.
most of the ones that I find at swaps and what not have been done by racers that have moved up to a better head for their paticular class...they want to get little money back out of them . but in most cases they have had excellent machine work done......and you can get it at a fraction of the cost.....walk by the guys with the 600.00 dollar core heads ...matching corvette numbers,,, yada yada yada, these heads are not getting those kind of prices any more...
lets go find a set of heads........