Edlebrock RPM head clean up

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DC Dart

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Swapping out the hydraulic roller springs in my heads to solid roller. While apart I am debating smoothing out the intake and exhaust ports. Is there much gains in just clean up? Not really changing port size? Or maybe gasket match? Edlebrock RPM is on top and TTI 1 3/4 headers are on the other end. Cam is a XR 280 and engine is a 451. I also ordered + .050 keepers to increase installed valve height. May get close to rocker? This project stalled and I started working on it again.
I know it will look better LOL.

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You can see small to moderate gains with smoothing out the port ceilings and bowls. 65
 
I am thinking I may spend a few hours doing that. On the exhaust side the milled to cast transition seems rough. I am just looking at the minimal gains. I am not wanting to risk messing the heads up. If I go to the next level I will do trick flows or send these heads to the guys that know what they are doing. Ahh sorry for the double photos
 
If I remember correctly, the best improvement per dollar spent is getting a nice valve job and backcut the intake valves if not already done.
 
DC Dart said:
I am thinking I may spend a few hours doing that. On the exhaust side the milled to cast transition seems rough. I am just looking at the minimal gains. I am not wanting to risk messing the heads up. If I go to the next level I will do trick flows or send these heads to the guys that know what they are doing. Ahh sorry for the double photos
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I wouldn't touch the exhaust port, keep the velocity up. Smooth ports allow wet flow to stick to the walls. Rougher the better for atomization. Also I'd advise buying the Hughes intake gaskets and port match to that gasket size and blend into the intake port.
 
Thanks for the ideas and thoughts guys. I am still deciding how far I want to go. I have to disassemble the heads anyway soo?
I am very good with a die grinder. I am thinking if I do anything at all it will be minimal. I have a performer rpm manifold.
 
If you’re not going to have the seats recut, then all I’d do in the bowls is blend away any ridges in the transition from the seat to the bowl.
Exhaust opening: blend away that ridge near the flange……doesn’t need to be any bigger.
Intake opening: opening size is fine as cnc’d, pinch width is usually inconsistent and can be a bit lumpy.
Open it to about 1.140”, and smooth out the lumps.
#3 & #6 will be close to 1.140 as cast, but I still make the curved wall similar to the shape of the other 3 ports, but the pinch in those two will end up bigger when you do it that way.

None of that will move the needle very much on the flow bench.

An important thing to keep in mind with those heads is…….there aren’t really any big gains to be had by doing a minor clean up.
The basic shape of the heads are fine.
The “bigger“ gains out of those heads come from making them bigger, not by changing the basic shape of the ports.

As an example, the MCH cnc’d std port version ends up at 255cc’s(but flow a bit less than the TF240).
That’s a fair amount of material to take out of a street head(210cc up to 255cc).
 
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PRH said:
If you’re not going to have the seats recut, then all I’d do in the bowls is blend away any ridges in the transition from the seat to the bowl.
Exhaust opening: blend away that ridge near the flange……doesn’t need to be any bigger.
Intake opening: opening size is fine as cnc’d, pinch width is usually inconsistent and can be a bit lumpy.
Open it to about 1.140”, and smooth out the lumps.
#3 & #6 will be close to 1.140 as cast, but I still make the curved wall similar to the shape of the other 3 ports, but the pinch in those two will end up bigger when you do it that way.

None of that will move the needle very much on the flow bench.

An important thing to keep in mind with those heads is…….there aren’t really any big gains to be had by doing a minor clean up.
The basic shape of the heads are fine.
The “bigger“ gains out of those heads come from making them bigger, not by changing the basic shape of the ports.

As an example, the MCH cnc’d std port version ends up at 255cc’s(but flow a bit less than the TF240).
That’s a fair amount of material to take out of a street head(210cc up to 255cc).
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Mch head ?
 
Thank you for the insight PRH. I think at the most, I will do what you mentioned. I may do something different at a later time.
The car will be mostly street. I have a lot of car to assemble yet.
I should get the springs, retainers, and locks next week. Just went with what comp cams recommended.
 
Seeing that your heads had the red Viton seals on them, those normally come on the heads with the dual HR springs.
If you’re going to run a HR cam, they are fine for most Comp HR shelf cams.

If your new cam is a SR, then yes, you’ll need a spring upgrade.
 
The heads are the 60925 for HR cam with dual springs. The springs comp recommended were the 953. They are discontinued. They were 473 spring rate. The new improved springs are 26953 @500 spring rate installed at 1.95. I think what they mean by improved is having one spring work on more applications. LOL
I originally assumed a solid roller would have lighter springs due to less parts in the lifter. Yep. I was wrong on that.
The locks I ordered are machined 10 degrees. The +.050 locks seem odd to me. I assume they have been proven.
 
DC Dart said:
The heads are the 60925 for HR cam with dual springs. The springs comp recommended were the 953. They are discontinued. They were 473 spring rate. The new improved springs are 26953 @500 spring rate installed at 1.95. I think what they mean by improved is having one spring work on more applications. LOL
I originally assumed a solid roller would have lighter springs due to less parts in the lifter. Yep. I was wrong on that.
The locks I ordered are machined 10 degrees. The +.050 locks seem odd to me. I assume they have been proven.
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Hopefully you got chromoly locks.
+ .050 is fine, that's what shims are for.
I assume the springs 943-16 .
Look around for ti retainers from another source.
Comps are about $100 more.
 
I’m not a fan of running springs that light(953’s) on a BB SR cam.

Also, I like using stuff I’ve had good results with in the past.

Lastly, +.050 locks may cause some interference issues between the retainers and rockers.

My go to spring for street/strip SR cams on those heads is an Isky 9315 @ a nominal 1.900” installed height.
Paired with Comp 741-16 retainers & 611-16 locks.
 
PRH said:
I’m not a fan of running springs that light(953’s) on a BB SR cam.

Also, I like using stuff I’ve had good results with in the past.

Lastly, +.050 locks may cause some interference issues between the retainers and rockers.

My go to spring for street/strip SR cams on those heads is an Isky 9315 @ a nominal 1.900” installed height.
Paired with Comp 741-16 retainers & 611-16 locks.
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What locks do you recommend for a drag race only engine?
 
Well at least I know the retainers will work. That's what I ordered. My picks of the rocker were to show my concern how close the retainer is. The vertical edge is the retainer is around .050
Sliding the retainer up without locks to guess. Is hard. I will have the ordered parts early next week to see if I have retainer clearance.
If I don't have the clearance. It should be easy to return. The springs won't have to leave the box.
Comp cams and edlebrock are under the same roof. So I can say your recommend parts are not playing nice together. LOL
I would have gone that isky spring if I saw it.
 
Comp cams and edlebrock are under the same roof. So I can say your recommend parts are not playing nice together.
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Like I said, if/when possible, I like to stick with stuff I know works.
If that means Comp misses out on a few spring sales…….oh well.

The Comp 954’s are basically an equivalent to the 9315’s, I just like the 9315’s better.
 
The 9315s are still on mine. I like the lower seat and over the nose pressures and less spring rate than the 943s. Still good valve control to 6800.
 
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So I got my keepers and locks. First impression is that it won't provide the .050 extra installed height. It clears the rocker. I have not ordered the spring height mic yet so everything is speculation. That should have been first step I recon.
That extra .050 might be a hassle. the 9315 installed at 1.9 looks like a nicer way to go.

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First impression is that it won't provide the .050 extra installed height
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There is no industry standard for exactly what the “std height” is for retainers & locks.

Generally, when they’re calling them plus or minus .050 heights, it would be relative to std parts from the same manufacturer.
And then, sometimes the claimed height differences from standard(+50/-50, etc)are close to reality, and sometimes it’s not that close.

But, you can get frustrated/lost trying to compare IH’s with parts from different manufacturers.

Also, first install with new parts, I recommend tapping the top of the valve being measured with a small brass hammer to seat everything.
Sometimes that yields nothing, sometimes it can add .020-.030 installed height.
 
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I’m getting ready to assemble a pair of heads, and happen to have the locks being discussed on hand.
As it turns out, the ones in this sample set are very close to .050” from each other.

611(std)- 1.903
630(-50)- 1.848
614(+50)- 1.951
 
DC Dart said:
So I got my keepers and locks. First impression is that it won't provide the .050 extra installed height. It clears the rocker. I have not ordered the spring height mic yet so everything is speculation. That should have been first step I recon.
That extra .050 might be a hassle. the 9315 installed at 1.9 looks like a nicer way to go.

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The spring OD itself may be closer to the rocker, than the retainer.
 
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