Re: Evolution of Victor Gen 2 chamber
[Re: BradH]
#2714541
11/10/19 02:23 PM
11/10/19 02:23 PM
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Joined: Oct 2007
Posts: 4,206 New York
polyspheric
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master
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Posts: 4,206
New York
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Why do they leave all of those sharp edges? It's the cheapest way to do it.
Boffin Emeritus
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Re: Evolution of Victor Gen 2 chamber
[Re: BradH]
#2714560
11/10/19 03:54 PM
11/10/19 03:54 PM
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Joined: May 2011
Posts: 4,489 northern,Ohio,USA
Clanton
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master
Joined: May 2011
Posts: 4,489
northern,Ohio,USA
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I wanted to clean up around the valve seats but never got too it or the chamber unshrouding "Stuff" swirling around inside my quasi-empty head...
E Victor Gen 2 (72 cc advertised) chamber & seats OOB
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Re: Evolution of Victor Gen 2 chamber
[Re: Clanton]
#2714591
11/10/19 06:02 PM
11/10/19 06:02 PM
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Joined: Jan 2003
Posts: 14,492 So. Burlington, Vt.
fast68plymouth
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I Live Here
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So. Burlington, Vt.
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Here’s the “heads with valves” vs the “bare heads”.
With the bare heads the seats are left uncut. The ID of the seats/diameter of the bowl where the relief cut ends/OD of the as delivered 45* angle that’s made into the seat insert: In - 1.970/1.770/2.100 Ex - 1.575/1.420/1.700
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Evolution of Victor Gen 2 chamber
[Re: BradH]
#2714601
11/10/19 07:00 PM
11/10/19 07:00 PM
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Joined: Jan 2003
Posts: 14,492 So. Burlington, Vt.
fast68plymouth
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Depends on what shape the burr is at the end of the wand.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Evolution of Victor Gen 2 chamber
[Re: fast68plymouth]
#2715119
11/12/19 01:04 PM
11/12/19 01:04 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
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Taking time off to work on my car
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OP
Taking time off to work on my car
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Val-haul-ass... eventually
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Here’s the “heads with valves” vs the “bare heads”.
With the bare heads the seats are left uncut. The ID of the seats/diameter of the bowl where the relief cut ends/OD of the as delivered 45* angle that’s made into the seat insert: In - 1.970/1.770/2.100 Ex - 1.575/1.420/1.700 Very curious to see how both style of chambers look after the new seats are cut... Feel free to post "after" pics, too.
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Re: Evolution of Victor Gen 2 chamber
[Re: BradH]
#2717509
11/19/19 01:07 PM
11/19/19 01:07 PM
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Joined: Jan 2003
Posts: 14,492 So. Burlington, Vt.
fast68plymouth
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I Live Here
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So. Burlington, Vt.
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What was the bare head looks like the area around the seats in the chamber is more filled in. As they are in those pics, the valve drop between the two heads is within a couple thou.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Evolution of Victor Gen 2 chamber
[Re: BradH]
#2717511
11/19/19 01:11 PM
11/19/19 01:11 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
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Taking time off to work on my car
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Val-haul-ass... eventually
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I know there are people thinking: "Big deal, it's just a valve job..." Yes, yes it is. However, there's been something of a learning curve w/ this style of head (Victors and the Procomp "clone"). Therefore, the goal w/ this set is to start off w/ the least amount of material removed from the as-cast chambers to have a basically "unmolested" chamber as a baseline.
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Re: Evolution of Victor Gen 2 chamber
[Re: powertrip]
#2717797
11/20/19 10:38 AM
11/20/19 10:38 AM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
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Taking time off to work on my car
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OP
Taking time off to work on my car
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This will be part science experiment AND the heads are expected to be used on a live engine. "When" depends upon which century they get finished. Ideally, they'd be done in time to do a swap w/ the current heads on my RB 452 to see what's what. Otherwise, they'll be tested on my RB 451 build that will eventually replace the RB 452 that's been through multiple rebuilds / freshen-ups over the years. The current heads' chambers being opened up to gasket line as shown is the result of Hughes Engines CNC chamber program, which I had Hughes do after getting the heads from Brian at IMM (member ou812). I'd prefer to not have any overhang at all, if possible, but won't know how far to take it until I finally get around to porting & flow-testing. One hypothesis about why the current heads back up starting about .750" is because this CNC'd chamber program takes too much out between the intake valve and the adjacent bore, as well as removes too much material from the plug-side of the chamber (too concave). So, that's where the "science experiment" part of this factors in. Also, I've never notched the top of my blocks' bores, so maybe this is one of those scenarios where the head is "happier" if the chamber is pushed out a bit beyond the bore, as long as the bore is notched to eliminate the resulting ledge. There are a couple of beliefs I've seen debated on engine tech forums such as SpeedTalk. One is (basically) that improving the area below the curve of the peak valve lift is the goal, even if the port stalls or backs up (flows less) at lifts higher than the cam being used. The other is that having a port that is more stable across the lift curve and continues to increase in flow well after the peak valve lift will help power across the RPM range, even if the flow #s that fall under the valve lift curve aren't as good as a head that fits into that first category. My current head seems to fit pretty well into that first category w/ solid flow #s, but backs up starting around .100" above peak valve lift. My desire for the second set of heads is to come up w/ something that fits into that second category. An apples-to-apples comparison of both sets of heads would be very interesting... well, at least to a few(?) people.
Last edited by BradH; 11/20/19 10:51 AM.
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Re: Evolution of Victor Gen 2 chamber
[Re: BradH]
#2717976
11/21/19 01:23 AM
11/21/19 01:23 AM
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Joined: Mar 2018
Posts: 114 NW Indiana
powertrip
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member
Joined: Mar 2018
Posts: 114
NW Indiana
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I'd prefer to not have any overhang at all, if possible, but won't know how far to take it until I finally get around to porting & flow-testing. One hypothesis about why the current heads back up starting about .750" is because this CNC'd chamber program takes too much out between the intake valve and the adjacent bore, as well as removes too much material from the plug-side of the chamber (too concave). So, that's where the "science experiment" part of this factors in. Also, I've never notched the top of my blocks' bores, so maybe this is one of those scenarios where the head is "happier" if the chamber is pushed out a bit beyond the bore, as long as the bore is notched to eliminate the resulting ledge.
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At one time, I considered notching the bore fixture for my flow bench. My bore fixture has removeable sleeves from 4.100" to 4.500", so to gauge the effectiveness of bore notching, I compared the flow between a 4.350" and 4.500" bore on a well ported BB RPM head. This was a long time ago, but I was surprised to discover the large bore was worth nothing flow wise, at least on that head! So, I never notched my bore fixture. I have also tried opening up the chambers similar to the Victors on the plug side, and again found little to nothing on an RPM style head.
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Re: Evolution of Victor Gen 2 chamber
[Re: BradH]
#2717982
11/21/19 01:33 AM
11/21/19 01:33 AM
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Joined: Mar 2018
Posts: 114 NW Indiana
powertrip
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NW Indiana
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There are a couple of beliefs I've seen debated on engine tech forums such as SpeedTalk. One is (basically) that improving the area below the curve of the peak valve lift is the goal, even if the port stalls or backs up (flows less) at lifts higher than the cam being used. The other is that having a port that is more stable across the lift curve and continues to increase in flow well after the peak valve lift will help power across the RPM range, even if the flow #s that fall under the valve lift curve aren't as good as a head that fits into that first category.
Back in the bad old days of 516, 915, and 906 iron head porting, I subscribed to that first theory, mostly because I couldn't keep them from stalling at high lifts anyway! They still ran good for what they were. Nowadays I'm all about consistent port areas and air speeds, which favors the latter theory. These heads run better, but they are higher flowing, better heads to start with.
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Re: Evolution of Victor Gen 2 chamber
[Re: BradH]
#2717986
11/21/19 01:56 AM
11/21/19 01:56 AM
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Joined: Mar 2018
Posts: 114 NW Indiana
powertrip
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NW Indiana
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My current head seems to fit pretty well into that first category w/ solid flow #s, but backs up starting around .100" above peak valve lift. My desire for the second set of heads is to come up w/ something that fits into that second category. An apples-to-apples comparison of both sets of heads would be very interesting... well, at least to a few(?) people.
Don't know about anybody else, but very interesting to me indeed! Reminds me of when I used to build in-line four drag bikes, I built two cylinder heads for a 1327cc GS Suzuki, one epoxied dump port style, and one tumble port. They each had their strengths, but the best head ended up being a hybrid of the two. My next cylinder head project is a set of Stealths. A preliminary look reveals significant chamber shift, with some valves much more shrouded than others. Sounds like these are a prime candidate to duplicate your science experiment!
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