modified 455 iron intake & stage 1 heads.

Finally finished it.
Also did some upper runner work.
Now onto the heads.

 

Could you describe what you did and what you expect from it?

 

When i go back out into the garage i will take some pictures of the intake runners.
I always wanted to build an all iron stock appearing 455.
This motor is going into my 69 Electra 225 custom.
Yes, 4 door 278 posi & TCI break away converter with anti balloning plate.
Stock ported exhaust manifolds.
2 1/2 dual exhaust.
1970 ported stage 1 heads.
464 wiseco forged dished pistons, 9.6 to 1 compression.
Worked over 800 quadrajet.
Expecting to increase some flow & HP.
When done I will take it to the local drag strip and see what it runs.
I will post how I went about modifing the intake & what tools I used tomorrow.

 

Subscribed

 

That middle divider is really low. What HP motor is that going on.

 

I was thinking same thing. You can't really make a dual plane into a single.
I did that to an Edlebrock and had to weld back in.

 

The middle divider is milled 3/4" down from the top.
I used a 3/8 & 7/16 end mill in a drillpress to cut everything out.
Then used 6 inch ferrous oval, ball, cylinder, flame burs to do the rest.
I left the floor & sides of the intake alone.
Only worked & ported the roof & opened the runner ports a little but kept them smaller then the runners on the heads.
Gasket matched of course.

 

This intake will be on a 464 with well ported stage 1 iron heads.
All iron motor 500 HP.

 

How heavy is car?

 

Its heavy.
1969 buick electra 225 custom 4 door, spare tire & Jack included.
I am going to put it on the scales soon.

 

I would lean more for torque then.....at least use a 4 hole spacer.

 

I have a reed custom ground camshaft.
Club cam.
218 intake & 228 exhaust @ .050 /491 & 512 lift with a 1.6 rocker.

 

Would love to hear a lot more about this build and dyno numbers if they happen. I have a very similar combination coming together for my 430.

 

I don’t like to take the divider out on a dual-plane. If anything,just a notch. I just cut the bottom of the intake out,do the work to the runners,and weld back together like some of the pure stock and FAST guys do.

 

You can waste a lot of time trying to get more out of a stock iron Intake that would be better spent else where on the motor other then doing a bit of work in the Plenum for example, or installing a oversized Carb for strip use only.

Things need to be considered as a whole , that is the whole Intake tract from the Manifold Plenum to the valve seat exit in the combustion chamber of the Head.
This needs to be looked at in a linear fashion to see what's going on.
If you reference my quick sketch up here's what needs to take place in regards to making the most power with a given amount of port area.

First off the minimum amount of port area or the port choke as it's called needs to be 1 stroke lenght back up stream from the ass end of the Intake valve .
If your mind is working now you can see that there is a big difference between where ideal point should be for a 215 cid motor and a stroker 455, no?
The next consideration about the choke point is that the port area it contains sets up the maximum rpm where the motor will make Hp.
Another factor is that when this choke point is located anywhere else but where it ideally should be the effect on the motors power band will be to narrow it up and shift it up into a higher rpm level.
This last factor can be benifical to a full race motor , but for any type of street motor is a train wreck!

Next up is the port taper or expansion rate for maximum power which in most cases is a rate about 1.5% per inch of port lenght or so.

Putting all of these factors in play and then diving into a stock iron Intake Manifold with one or two inside snap gauges will quickly show how hindered a stock Intake is.
If you do this in terms of port width and height through out the Manifold and then draw it out in a linear way you will quickly see how comprised the port area is in a stock Intake.
Also consider the fact that a 90 degree bent anywhere in the whole Intake tract can reduce flow numbers by up to 2o% , or even 25% if the bend is in a high velocity area of the whole deal we are talking about!
A 45 degree bend will chop off some 15% in flow numbers on average.
Looking at a stock iron Intake to can see how unless we chop it open in places where the runners join up to grind them into a better form then there's not much to be gained .

The worst flow impeadment is the bend of the low side Plenum runners coming back up to the Intake flange .

 

I like the way you think.
I have not altered the pinch points on the intake or heads.
But only did some smoothe blendings & bowl work & pocket porting.
When I get the heads completed, I will take some pictures of them before I lap the valves in.
Reason for cutting the center divider down a little on the intake is to take some of that bottom end bite out.
So I can launch this beast on a radial tire & be consistente.
Expecting to increase the flow a little.

 

I will say this.
It takes a lot of time to modify a stock intake.

 

Also from your photos I have seen what looks like polish work done to the ports and whatever, you are shooting yourself in the foot if you do that in terms of mixture control which tie's right into the power being made.

What I do is polish to get my ruff / course porting work blended in nice and then I go back in and add texture back on the port walls with a fine cut football shaped Burr.

Here's a shot of a ruff cut Intake port and then the same port polished out and then gone over with a fine cut Burr.
Note that in the last shot I have not bothered to even touch the floor of the port and that's the way these 275 cfm heads got bolted to the motor.