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Old 11-11-2010, 09:54 PM   #1
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Car: 92 Pontiac Firebird
Engine: 305 TBI L03
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416 heads.

Hey guys about a week ago i was at a car show that is hosted every friday night here in broward county florida and stumbled some guy with a pickup full of smallblock parts, he had everything there to assemble a motor, well he had a complete motor ready to run , he also had a pair of 416 heads rebuild with everything installed and ready to run, he was only asking 100 dollars for them wich if u ask me is not a bad deal for a pair of heads that are like new with everything installed on them.

Are these heads really worth it for a 305? I think these were installed on the L69s or LG4s i dont really know.

Does anyone got any flow numbers on these heads stock ? I already have seen what they flow ported and i must say im amazed at how good they flow with just some porting done. If im lucky and find that guy at that car show again with the heads im gonna buy them, at most i will gasket match them and polish the exhaust and do some minor porting on the intake just to remove cast inperfections etc.
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Old 11-11-2010, 10:34 PM   #2
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Re: 416 heads.

In stock form they really aren't anything impressive but they do have potential because of the intake port design, intake port volume, and chamber volume.

They were common on the LG4 and L69's from day one until they switched bolt patterns in '87.
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Old 11-12-2010, 11:16 AM   #3
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Re: 416 heads.

Quote:
Originally Posted by Doom86 View Post
In stock form they really aren't anything impressive but they do have potential because of the intake port design, intake port volume, and chamber volume.

They were common on the LG4 and L69's from day one until they switched bolt patterns in '87.
So what do u think of them ? I guess anything is better than a swirlport head , for a 305 there arent many options to go with and these heads seem to be really cheap on ebay, i can also get a pair of vortecs wich sometimes are on craiglist for 250 a pair average, but since they are 350 heads i would have to machine the surface to lower the combustion chamber, i can find both pair of heads very cheap but 416s seem to be a better deal since i can avoid all the hassle of the machine shop, theres also my stock heads wich DynoDon and Fast355 ported a pair of the l05 ones and came out with some pretty nice results, for the amount of power im looking to get out of the 305 i think stockers with some mild porting would work just fine since theres also the swirl ramp wich creates nice torque at low rpms wich is always kind of nice on a street/DD car.
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Old 11-12-2010, 12:44 PM   #4
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Re: 416 heads.

I think with minor work they are perfect for a strong street/strip SBC.

If you are keeping the 1.84 intake valves don't remove much metal because they are already big for that valve size. With the 1.84 valve limit your work to bowl blending and valve guide work. Don't dig out the bowls just blend down the edges made by the bowl cutter, don't touch any other metal in the bowl if you can help it.

The port entrance does not need to be touched at all do not do this the CSA of a stock 416 head is perfect for a 6,222RPM peak on a 305 already and making it bigger will raise this peak.

They have the volume, they have the CSA, you just need to make them flow better.
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Old 11-12-2010, 06:09 PM   #5
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Re: 416 heads.

Quote:
Originally Posted by Doom86 View Post
I think with minor work they are perfect for a strong street/strip SBC.

If you are keeping the 1.84 intake valves don't remove much metal because they are already big for that valve size. With the 1.84 valve limit your work to bowl blending and valve guide work. Don't dig out the bowls just blend down the edges made by the bowl cutter, don't touch any other metal in the bowl if you can help it.

The port entrance does not need to be touched at all do not do this the CSA of a stock 416 head is perfect for a 6,222RPM peak on a 305 already and making it bigger will raise this peak.

They have the volume, they have the CSA, you just need to make them flow better.
Were should i focus on the runners ? So ur saying to not even try to gasket match the entrance ? Since everyone does that hey why not, so i should just try and remove as little material as possible from inside the runners just remove casting inperfections etc. The exhaust i will polish it and work around the ports a bit to try and make them better.
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Old 11-12-2010, 07:38 PM   #6
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Re: 416 heads.

Quote:
Were should i focus on the runners ?
That depends, do you plan to build the motor to peak over 6,222RPM? Do you want a bigger valve?

The only restriction in the runner if you are porting for a 1.84 valve will be the common wall where the head bolt goes through between the two ports. Just blend it lightly into the wall up near the roof and touch it less and less the closer to the floor. It should not be straight but it should curve smooth and generously into the floor. Do not remove much metal here focus up near the roof. If this doesn't make sense I have pictures that show it. After that just remove the casting bumps in the roof, blend them in and leave it at that.

Quote:
So ur saying to not even try to gasket match the entrance ? Since everyone does that hey why not, so i should just try and remove as little material as possible from inside the runners just remove casting inperfections etc. The exhaust i will polish it and work around the ports a bit to try and make them better.
Yep that's exactly it. It's a waste of time and again you don't want more volume. Don't follow the common mistake here. I have measured the stock port my self this isn't McDonalds parking lot spank. Go to summit and tell me what size valve the 165cc SBC heads have in them. Do you still think you want more volume with your 1.84 valve?

1.736 CSA, 165cc runner, 55cc chamber.

That's enough volume for a 1.94 valve and perfect CSA for 6,222RPM peak HP on a 305. This is exactly why I say;
Quote:
Originally Posted by Doom86
"They have the volume, they have the CSA, you just need to make them flow better."
If you use a bigger valve you can remove more volume in the right places as long as you don't increase the choke, unless you are wanting to peak HP higher then what stock supports (6.2k).

More volume isn't always the answer it depends greatly on the application they are intended for. If you increase volume with-out increasing flow you kill air speed. That is exactly what happens when you cut out the PRP. It's not even close to being a restriction so you're increasing volume, decreasing air speed, and not increasing flow; and always keep in mind the further away from the valve the less it effects flow.
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Old 11-12-2010, 07:50 PM   #7
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Re: 416 heads.

Quote:
Originally Posted by Doom86 View Post
That depends, do you plan to build the motor to peak over 6,222RPM? Do you want a bigger valve?

The only restriction in the runner if you are porting for a 1.84 valve will be the common wall where the head bolt goes through between the two ports. Just blend it lightly into the wall up near the roof and touch it less and less the closer to the floor. It should not be straight but it should curve smooth and generously into the floor. Do not remove much metal here focus up near the roof. If this doesn't make sense I have pictures that show it. After that just remove the casting bumps in the roof, blend them in and leave it at that.



Yep that's exactly it. It's a waste of time and again you don't want more volume. Don't follow the common mistake here. I have measured the stock port my self this isn't McDonalds parking lot spank. Go to summit and tell me what size valve the 165cc SBC heads have in them. Do you still think you want more volume with your 1.84 valve?

1.736 CSA, 165cc runner, 55cc chamber.

That's enough volume for a 1.94 valve and perfect CSA for 6,222RPM peak HP on a 305. This is exactly why I say;


If you use a bigger valve you can remove more volume in the right places as long as you don't increase the choke, unless you are wanting to peak HP higher then what stock supports (6.2k).

More volume isn't always the answer it depends greatly on the application they are intended for. If you increase volume with-out increasing flow you kill air speed. That is exactly what happens when you cut out the PRP. It's not even close to being a restriction so you're increasing volume, decreasing air speed, and not increasing flow; and always keep in mind the further away from the valve the less it effects flow.
Awsome, thanks for the advise , and no this is mostly going to be a street engine if ever ill take it to the local 1/8 mile track like once or twice a year lol, or never. I dont think this motor will see near 6k rpm anyways, afterall its an 18 year old engine and i dont want to blow a cylinder the first time i floor the thing lol, im just looking for a nice DD with around 230 to 250 rwhp with some nice low end torque, i dont wanna push the motor too much cuz you know its 18 years old even if the thing when running u cant even feel it. Hell with these heads an lt1 cam and a nice flowing intake paired with Robs EBL i should be good to go, with a nice 3.23 posi rear i think this car should feel pretty nice. Also if u do have pictures of your port work can u share them could be nice to see were to concentrate the work on, tho i get what ur saying to just blend the walls of the runner so the flow more nicely, i guess this can also be applied to the runners of the intake manifold.
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Old 11-13-2010, 01:42 PM   #8
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Re: 416 heads.

If you are building for a low spinner really try hard to only remove what you have to in order to improve flow. You need more velocity through the choke to get what you want. The way you do this is either, more displacement, or increase flow with little increase in volume. Obviously volume will have to increase so keep it where it counts.

I have no pictures of a properly ported head for 1.84 valve but I do have a 416 head I just took off of my LG4 sitting here. I took one of the valves out and got some pictures to show what I was trying to explain before. The dots are the casting bumps that need blended in. The line is the cut I was talking before in the common wall. It should run that height and be adjacent to the valve guide and run along the wall just past the length of the valve guide heading towards the port opening at the pushrod pinch. What's pictured is everything you should do in the runner for your application.

Click the image to open in full size.
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Old 11-13-2010, 01:42 PM
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