My home inspection of Speedmaster heads
- Thread starter 318willrun
- Start date
-
What’s your setup for porting intakes? I resort to backwoods improvising using a couple of 2x4’s screwed into the bench top in such a way as to be able to prop the intake up at angles, it works but not ideal
Intakes are harder to get placed right but I use those V-blocks in the one picture and then place wooden blocks I save for this job to shim higher when needed. My shop is lite up well but I almost also use bifocals when porting as I usually sit pretty close to my work.
PRH
Well-Known Member
And I thought the point of buying these was to not spend as much as, or very close to, what you’d have into a set of TF’s.
The throat diameter is 1.890, which is 93% of the 2.02 valve.
Way too big for the lift range most everyone using these will be running.
They cut right up to the 45 on the vj.
Maybe PBR can measure the throat of the unported head.
My guess is, it’s bigger than it should be as well.
They want the porting to be “pretty”, with a minimum of drop outs...... Imo they’re porting below the seats for appearance...... not for flow.
In order to have the throat percentage be more in line with the valve diameter and lifts most will run with these heads you’d need to run a 2.08 valve.
Then you start to run into valve shrouding issues....... more $$$ to fix.
For what many buying these heads are looking to do....... for the $$$ they spent on the CNC version over the bare head, I think you’d be better off buying the bare heads, have the seats cut for 2.055/1.60 valves, and the bowls blended.
My guess is that would have you ahead of the ootb cnc version, flow wise, through about .550 lift....... for similar $$$.
Last edited:
I will try to
Measure that today. As far as valve shrouding I tested that on my flowbench and was kinda surprised at the results myself. My bore fixture measures 4.010 and using a 2.08 valve maxed out slightly of 315cfm. My fixture is drilled and the head is mounted with a head gasket and four studs so it’s not shifted away from the bore fixture like some guys do with C-clamps. I’m thinking most guys go 4.030 on their blocks. I know I do.
j par
Well-hung Member
I think buying these heads "loaded" with anything more than a "mild" Street/strip build in mind is counterproductive...
PRH
Well-Known Member
John, I was referring to whatever extra shrouding you’d get from the as cast chamber after swapping out the 2.02’s for 2.08’s.
If the chambers needed reworking after the swap..... then that’s added time/$$$ being put into the heads.
I’ve only done any kind of heavy porting to a few sets of SBM RPM heads, and none with 2.08 valves....... so I don’t know if the chambers are really an issue with these heads or not.
The one set I had here for freshening that had 2.08 valves in them did have the chambers reworked(cnc from Hughes).
If the chambers needed reworking after the swap..... then that’s added time/$$$ being put into the heads.
I’ve only done any kind of heavy porting to a few sets of SBM RPM heads, and none with 2.08 valves....... so I don’t know if the chambers are really an issue with these heads or not.
The one set I had here for freshening that had 2.08 valves in them did have the chambers reworked(cnc from Hughes).
The chamber on any Edelbrock or Edelbrock copy Head sucks big time. And honestly it can’t be fixed. At least not by me because I don’t want to pay even more money recutting the Head deck surface to get my compression back.
Krooser
Building Chinese Free Engines since 1959...
Anyone ever measured the RA of the deck surface or the heat treat on these heads?
j par
Well-hung Member
I like where this thread started and where it's going at least I'm not the one....
PRH
Well-Known Member
Besides the obvious "home inspection" lol..... I guess I'll say it this way. IF I pull the stock, untouched 360 heads (1.88), will I gain any performance by bolting on a set of these unported, SM heads? If I don't, they are not worth their weight in aluminum. IF they bolt on 25-45 hp over my stock heads, my 40% discounted heads were "mission accomplished".
PRH
Well-Known Member
I still think the unported bare heads like PBR bought are a great deal.
You couldn’t do much of anything with stock castings for under $450.
With a nice valve job and a quickie blend...... they’ll be better than 90% of the bowl blended iron stuff that’s currently out running the streets.
Even though I think they’re a good deal....... I don’t think they’re all that special ootb.
But, I am looking forward to 318wills results.
Whatever the outcome....... as long as he doesn’t swap a whole bunch of other stuff along with the heads....... it should be a pretty good real world back to back test.
You couldn’t do much of anything with stock castings for under $450.
With a nice valve job and a quickie blend...... they’ll be better than 90% of the bowl blended iron stuff that’s currently out running the streets.
Even though I think they’re a good deal....... I don’t think they’re all that special ootb.
But, I am looking forward to 318wills results.
Whatever the outcome....... as long as he doesn’t swap a whole bunch of other stuff along with the heads....... it should be a pretty good real world back to back test.
PRH
Well-Known Member
I agree.
Honestly the only reason I bought them was because right before the sale I finally got off my butt and did some sorting of my old parts laying around in unmarked boxes. Having more Edelbrock valves, .550-.620 lift capable springs, and 10 degree retainers and keepers than I would ever use it made it a win win. Now whether I sell them or throw them on a spare engine for matt or I after they get ported will be the big question.
Ok I took some measurements and my throat numbers look better than the ones above. Both of my small block heads are dated 3-24-17
Intake throat measures 1.830
Exhaust throat measures 1.395
Time for some bench numbers. Fire up the motors. Lol
Intake throat measures 1.830
Exhaust throat measures 1.395
Time for some bench numbers. Fire up the motors. Lol
PRH
Well-Known Member
1.830...... 90.6% with a 2.02 valve.
Still on the big side, especially if you weren’t planning on running much lift.
And it doesn’t give you much room for reshaping.
Although, the RPM bowl is probably pretty close to that ootb.
Still on the big side, especially if you weren’t planning on running much lift.
And it doesn’t give you much room for reshaping.
Although, the RPM bowl is probably pretty close to that ootb.
Last edited:
skrews
Well-Known Member
Will these things take a 2.08 valve seat wise?
PRH
Well-Known Member
They should.
Keep in mind the “throat” is big...... the “bowl” isn’t all that big........ 1.925”
I’d be pretty surprised in the TF head didn’t have the intake bowl at 100% of the valve....... or very close to it.
The BB TF head has the throat at 91% and the bowl at 100%.
Keep in mind the “throat” is big...... the “bowl” isn’t all that big........ 1.925”
I’d be pretty surprised in the TF head didn’t have the intake bowl at 100% of the valve....... or very close to it.
The BB TF head has the throat at 91% and the bowl at 100%.
Last edited:
-
