SBM Edelbrock/Speedmaster Head Data

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Earlie A

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Here's a little data on out of the box small block mopar Edelbrock 6077 and Speedmaster 1654 heads, side by side comparison, intake port for cylinder 2 or 7.

Port volume: E-172cc, SM-175cc
Average intake throat diameter: E-1.816, SM-1.827
Throat diameter to valve diameter ratio: E-89.9%, SM-90.4%
Port area at pushrod pinch: E-1.783 sq in, SM-1.869 sq in
Port area at head bolt pinch: E-1.997 sq in, SM-2.040 sq in
Intake port centerline length: E-4.875", SM-4.875"
Combustion chamber volume: E-62cc, SM-64cc

Attached is a picture of the intake port molds. There is very little difference between the two ports. The Edelbrock is a little smoother on the short turn. The Speedmaster is a little smoother at the pushrod pinch. The Speedmaster is a very close copy of the Edelbrock.

Flow numbers are also attached. The flow numbers for a stock 1973 Mopar 587 head with 1.88" intake valve are included for reference.

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  • EPSON032.PDF
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One more bit of information that I find fascinating. Look at the difference in the shape of the valve seats. The Edelbrock has a radius on the entry and a 0 degree top cut in the chamber. The Speedmaster goes from a 90 degree to 60 degree bottom cut on entry and has a 15 degree top cut in the chamber.

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  • Edelbrock & Flowmaster Seats.PDF
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pittsburghracer said:
Are you going to port them now.
Click to expand...
That is my plan. I've already done a few things to the Speedmaster head. Working on it first because it's the cheapest. The head bolt and push rod holes are tubed. I worked on the push rod pinch area on one port and gained 20 cfm @ 0.600 lift. I removed the head bolt bulge on the same port and gained 10 cfm at 0.750 lift, but lost a little at 0.600. Even after the mild porting the velocities are 320-350 around the pushrod and 340-380 over the SSR, so I know there's more work to do there.

I'm not going to touch the bowl area until I can work on the seats. Next move is to add a small 75 degree cut between the 90 and 60 degree bottom cuts. Only have a few hours here and there to work on it.

I've learned a lot from your posts and pictures. Thanks for sharing so much.
 
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Here's some recent test results on the Speedmaster head. First modification is a small 75 degree bowl cut between the factory 90 degree bowl hog and 60 degree bottom cuts. Results are shown with an Edelbrock 1 angle valve.

Second test was just experimenting with the shape of the stock combustion chamber. Clay was added in the combustion chamber to form a 35 degree top cut 'cone' around the perimeter of the intake valve. The picture shows the clay in the chamber with a 35 degree plastic 'squeegee' that was used to form the clay. Where shrouded (the cylinder wall side), a 4mm radius was also added to smooth the transition to the chamber wall. The spark plug was completely covered, and clay was also extended over the quench pad. Obviously not a usable design, but it made for an interesting test. Results shown with Edelbrock 1 angle valve.

Last test was adding a Ferrea 30 degree back cut valve to the head with the 75 degree bowl cut and the clay chamber.

This post is for information sharing only. I am not qualified to interpret the results.

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  • EPSON035.PDF
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Some more flow test results on the Speedmaster - this time with a 39 degree pressure recovery 'cone'. As in the last test, clay was added in the combustion chamber to simulate a top cut to try to improve on the factory 15 degree top cut.

Three sets of flow numbers are included, all tests run with a 30 degree back cut intake valve. First is the stock 15 degree top cut (with sharp inside corner on the shrouded side). Second is the 35 degree clay top cut with 4mm radius on the shrouded side (this is the test from the previous post). Last is the 39 degree clay top cut with 4mm radius.

Again, I am not qualified to interpret the results, but for this head, on the flow bench, it seems that the stock 15 degree top cut angle is not optimal. It also seems that the 35 degree angle flows better at lower lifts and the 39 degree angle flows better at higher lifts.

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  • EPSON036.PDF
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The clay should come out to replicate real world air flow within the chamber/past the valve, out of the head, into the chamber & cylinder. The clay is helpful if you’re welding to the head later to reshape the chamber for better/ set results. Allowances should still be made for the spark plug. Hinderance or not to air flow and fuel dispersion/collection.

The pictures are a bit hard to read.
 
rumblefish360 said:
The clay should come out to replicate real world air flow within the chamber/past the valve, out of the head, into the chamber & cylinder. The clay is helpful if you’re welding to the head later to reshape the chamber for better/ set results. Allowances should still be made for the spark plug. Hinderance or not to air flow and fuel dispersion/collection.

The pictures are a bit hard to read.
Click to expand...
Can you open the PDF?
 
Can you post a larger and clearer picture?
 
My man, I’m asking a simple question.
Can you post a bigger picture? That’s it. Nothing more nothing less.
 
rumblefish360 said:
The clay should come out to replicate real world air flow within the chamber/past the valve, out of the head, into the chamber & cylinder. The clay is helpful if you’re welding to the head later to reshape the chamber for better/ set results. Allowances should still be made for the spark plug. Hinderance or not to air flow and fuel dispersion/collection.

The pictures are a bit hard to read.
Click to expand...
Weld the chamber, or sink the valves.
 
rumblefish360 said:
I’m not understanding this reply to what I wrote.
Click to expand...
If the valve job is cut about 0.090" deeper, the top cut angle of 35 degrees can be achieved without welding.

As far as pictures - this is about as good as I can do. Maybe there's a trick to posting pics that I do not know.

IMG_2223.jpg


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Earlie A said:
If the valve job is cut about 0.090" deeper, the top cut angle of 35 degrees can be achieved without welding.
Click to expand...
OK, well, that still does t make sense to what I wrote but at least I now understand it and how it applies. Thanks.
Earlie A said:
As far as pictures - this is about as good as I can do. Maybe there's a trick to posting pics that I do not know.
Click to expand...
When I’m on the iPhone, I open the picture up from the photos icon and click the edit button and use the crop feature. Once the cropping is done the picture automatically resizes larger. In this way, I can cut out all the sides of the photo that need not be in the picture. I’ll demonstrate below/ next post.

Similar idea on the PC on the desk top. It’s also an Apple computer.

Thanks for the bigger picture and efforts.
 
I’m not sure what you are trying to do here. Why not fully port the head to the 285-290 cfm capable with a 2.02 valve then start your mods.
 
pittsburghracer said:
I’m not sure what you are trying to do here. Why not fully port the head to the 285-290 cfm capable with a 2.02 valve then start your mods.
Click to expand...

I'm trying to learn. I could be totally wrong in my approach, but my thinking is this:

Looking at small block mopar heads the Edelbrock style head is an improvement over the factory heads. The TF head is an improvement over the Edelbrock. Part of that improvement is a better combustion chamber with different top cut angles and pressure recovery designs.

Why does one head flow better than another? How can efficiency be improved? How can I achieve the proper port size, velocity and cfm for the particular engine?

For instance: I bought one Speedmaster head and one Edelbrock head. I tested them both in stock form. The Speedmaster had higher cfm numbers, but it also had a larger port volume and a larger push rod pinch area. It also seemed to me that the Edelbrock had better seat angles below the valve, but the Speedmaster had better angles on the top cut. The top cut on the Edelbrock is 0 degrees. So, the air sees a 45 degree seat, then a 45 degree angle change. That can't be good. So, I'm trying to get a feel for how 'bad' it is and if it can be improved.

So why am I posting this stuff? Again, education. I'm sure there are a few other nerds out there like myself who will be fascinated with numbers. I'm also willing to take (some) abuse that comes with posting to get my thoughts and ideas challenged and corrected. Painful learning seems to have worked for me in the past.

Oh, and I am hoping to get to the 290-300 cfm range. I just want to understand how and why I got there.
 
I understand that and trust me I’ll be reading along but a 170 cc chamber will only flow so much so why not port the head then try to find the extra 10-15 cfm I guess you are hoping to find. Look closely at the chamber around both the Speedmaster and Edelbrock head and you will see why the speedmaster flows more. Valve shrouding. A man way smarter than I will ever be preached 15 max on the valve angles and hopefully under that number. That number seems to really come into play up top. Ex: 90-70-60-45-30-15
 
pittsburghracer said:
I understand that and trust me I’ll be reading along but a 170 cc chamber will only flow so much so why not port the head then try to find the extra 10-15 cfm I guess you are hoping to find. Look closely at the chamber around both the Speedmaster and Edelbrock head and you will see why the speedmaster flows more. Valve shrouding. A man way smarter than I will ever be preached 15 max on the valve angles and hopefully under that number. That number seems to really come into play up top. Ex: 90-70-60-45-30-15
Click to expand...
I'm currently at 182cc. I have opened the PRP up a little, flattened the head bolt bulge, increased the bowl area width to 1.89 by working on the cyl wall side, and smoothed the SSR.

I've been probing with flow balls and flags to try to identify the source of the turbulence at .500/.550. I know there is SSR work to do and width to gain there.

Thanks for the tip on the shrouding.
 
pittsburghracer said:
I understand that and trust me I’ll be reading along but a 170 cc chamber will only flow so much so why not port the head then try to find the extra 10-15 cfm I guess you are hoping to find. Look closely at the chamber around both the Speedmaster and Edelbrock head and you will see why the speedmaster flows more. Valve shrouding. A man way smarter than I will ever be preached 15 max on the valve angles and hopefully under that number. That number seems to really come into play up top. Ex: 90-70-60-45-30-15
Click to expand...
One more comment/observation about the top cut angles. Again, recognizing that I could be wet behind the ears, in a perfect chamber the top cut off of a 45 degree seat should be in the 35-39 degree range. This applies to valve angles of less than 14 degrees (mopar is 18 so some concave cutting must occur on the spark plug side to reduce shrouding). This allows for the slow expansion and pressure recovery once the air is past the valve. Even a 15 degree (so a 30 degree top cut) turn after the 45 degree seat is too much and turbulence will occur and shut down part of the flow area.

This information is from two of the top cylinder head developers in the country. But, I recognize my interpretation and application could be wrong.
 
Try not to over complicate things. Try to look at everything at every angle especially the short turn. Think about how it relates to the cylinder and where you would like the air to go. Short side sizing and shaping on these heads is a pain in the butt and get more time consuming as you go to a bigger valve. I use snap gauges to get me close height wise ( I won’t discuss that figure. Lol) then I do final sizing and blending after I do the valve job.
 
Question. Would t the valve seat angles of the seat and valve change with valve size and/or port shape?

I was thinking it would since what is good at one valve size and port shape may not work well with a larger port size and valve.
 
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