What is Big Deal w Big Chief Heads ??
02-23-2018 | 03:28 PM
#1
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What is Big Deal w Big Chief Heads ??
I have been reading about heads and some people talk about the big chief heads as if those heads are the big chief of all heads.
Do these heads require race gas or is there some catch to using those?I want a pump gas boat
Do these heads require race gas or is there some catch to using those?I want a pump gas boat
02-26-2018 | 11:21 PM
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From: Tennessee
You don't see them that often in offshore boats for a few reasons. We need longevity. Big Chief heads do move a ton of air, but they do it by rolling the valve angles. That, and the port placement, calls for offset rockers and/or offset lifters. That puts more then desirable side load on the guides. The guides just won't live as long as they will in a 24/26* head. The other thing is that there are some KILLER flowing 24* heads out there. They are flowing as much or more than an 18* Big Chief head without all of the issues.
The Big Chief heads also require a specially designed piston. That piston, along with chamber design, seem to be more detonation sensitive then a more standard piston and chamber. They don't like very much timing at all. A lot of guys don't know that and time them like a normal head. They wind up with WAY too much timing and end of beating the bearing out of it. If you are running race gas, like you would in a race car, detonation isn't an issue anymore. That why you see them in race cars way more then in pleasure boats.
We've made almost 1800 hp with 24* heads and certainly could have made more. There really is no reason to use an 18*, or lower, head.
Eddie
The Big Chief heads also require a specially designed piston. That piston, along with chamber design, seem to be more detonation sensitive then a more standard piston and chamber. They don't like very much timing at all. A lot of guys don't know that and time them like a normal head. They wind up with WAY too much timing and end of beating the bearing out of it. If you are running race gas, like you would in a race car, detonation isn't an issue anymore. That why you see them in race cars way more then in pleasure boats.
We've made almost 1800 hp with 24* heads and certainly could have made more. There really is no reason to use an 18*, or lower, head.
Eddie
02-27-2018 | 02:01 PM
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You don't see them that often in offshore boats for a few reasons. We need longevity. Big Chief heads do move a ton of air, but they do it by rolling the valve angles. That, and the port placement, calls for offset rockers and/or offset lifters. That puts more then desirable side load on the guides. The guides just won't live as long as they will in a 24/26* head. The other thing is that there are some KILLER flowing 24* heads out there. They are flowing as much or more than an 18* Big Chief head without all of the issues.
The Big Chief heads also require a specially designed piston. That piston, along with chamber design, seem to be more detonation sensitive then a more standard piston and chamber. They don't like very much timing at all. A lot of guys don't know that and time them like a normal head. They wind up with WAY too much timing and end of beating the bearing out of it. If you are running race gas, like you would in a race car, detonation isn't an issue anymore. That why you see them in race cars way more then in pleasure boats.
We've made almost 1800 hp with 24* heads and certainly could have made more. There really is no reason to use an 18*, or lower, head.
Eddie
The Big Chief heads also require a specially designed piston. That piston, along with chamber design, seem to be more detonation sensitive then a more standard piston and chamber. They don't like very much timing at all. A lot of guys don't know that and time them like a normal head. They wind up with WAY too much timing and end of beating the bearing out of it. If you are running race gas, like you would in a race car, detonation isn't an issue anymore. That why you see them in race cars way more then in pleasure boats.
We've made almost 1800 hp with 24* heads and certainly could have made more. There really is no reason to use an 18*, or lower, head.
Eddie
I want the best for my twin 602 s
02-27-2018 | 03:04 PM
#5
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From: Pa
I'm not an engine builder, just throwing this out there, the symmetrical heads, 18 degree and less have less variation between cylinders, the intake runners will flow within a couple of CFM versus 10, 20 sometimes 30 CFM on the conventional head. I believe the LS motors run a symmetrical port head.
03-03-2018 | 03:48 PM
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You don't see them that often in offshore boats for a few reasons. We need longevity. Big Chief heads do move a ton of air, but they do it by rolling the valve angles. That, and the port placement, calls for offset rockers and/or offset lifters. That puts more then desirable side load on the guides. The guides just won't live as long as they will in a 24/26* head. The other thing is that there are some KILLER flowing 24* heads out there. They are flowing as much or more than an 18* Big Chief head without all of the issues.
The Big Chief heads also require a specially designed piston. That piston, along with chamber design, seem to be more detonation sensitive then a more standard piston and chamber. They don't like very much timing at all. A lot of guys don't know that and time them like a normal head. They wind up with WAY too much timing and end of beating the bearing out of it. If you are running race gas, like you would in a race car, detonation isn't an issue anymore. That why you see them in race cars way more then in pleasure boats.
We've made almost 1800 hp with 24* heads and certainly could have made more. There really is no reason to use an 18*, or lower, head.
Eddie
The Big Chief heads also require a specially designed piston. That piston, along with chamber design, seem to be more detonation sensitive then a more standard piston and chamber. They don't like very much timing at all. A lot of guys don't know that and time them like a normal head. They wind up with WAY too much timing and end of beating the bearing out of it. If you are running race gas, like you would in a race car, detonation isn't an issue anymore. That why you see them in race cars way more then in pleasure boats.
We've made almost 1800 hp with 24* heads and certainly could have made more. There really is no reason to use an 18*, or lower, head.
Eddie
I am building a catamaran with hopefully twin 602 procharged engines.Can you gt me the heads? I dont want to just buy some heads online I want to get them complete with port polish, valves installed, gaskets everything ready to go
03-04-2018 | 06:34 PM
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From: Tennessee
No, the heads that I'm referring to are not Dart's. Edelbrock sells what they call a Pro Port head. It's just a bare casting and nothing more. The ports are not finished, no guides, no seats....nothing. That way, you can make them whatever you want. You aren't working with a mediocre port that you are trying to get big flow numbers from. You can make whatever you want as far as port size, configuration, etc. There are no compromises. I would be glad to supply them for you. However, I need to get quite a bit of info on the rest of the engines so that we can get what you need. I need to know how big the chamber needs to be, how much cam so we can set up the springs, etc. It would be best if you just called me at the shop. You can reach me anytime at 615-216-7449
Eddie
Eddie
03-05-2018 | 09:52 AM
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