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A Little Disappointed--Victor Heads
#1275280
07/28/12 11:12 AM
07/28/12 11:12 AM
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Joined: Sep 2007
Posts: 427
Cascade, CO
reknapp52
OP
mopar
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OP
mopar
Joined: Sep 2007
Posts: 427
Cascade, CO
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Last spring I removed my MP .590 cam, and mildly (non-professionally) ported 915 heads, and replaced them with a set of the Edelbrock Victor heads and a used Comp Cams roller that I have had for a couple years (see attachment for specs). Also installed a set of the Hughes offset rockers (1.6 ratio) to go with the new heads. The intent was to gain a few MPH from my 447 low-deck in Super Gas (throttle-stop) racing. The old combo would run 137-138 in Denver, with a best of 150 in Topeka. Althoough I haven't had time to really flog this new setup, the initial outings are not very impressive, with speeds of 139 in Denver. I swapped out my 4:30 gears for a set of 4:56s, which netted 100-200 more RPM in the lights, and no difference in MPH. I realize that the 850 DP carb may be a little on the small side for what I am trying to do, and the cam being degreed at 106 is not the best (wanted to retard it some, but I couldn't cut valve reliefs as deep as I wanted because of the close proximity to the top ring land). Any thoughts/input would be appreciated.FWIW--I know that low-end and mid-range have improved because I have added .3 to .4 to my throttle-stop timer.
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Re: A Little Disappointed--Victor Heads
[Re: reknapp52]
#1275281
07/28/12 11:52 AM
07/28/12 11:52 AM
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Joined: Jan 2003
Posts: 31,248
Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,248
Oregon
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My guess is that the cam is way too big. Unless everything else on the car is matched up to a huge cam, you've probably killed off the mid-range power so much that the car just can't get moving. For comparison, take a look at a few of the tech articles on my website. My 505 dyno mule made 800 hp with a cam that was only 266 at 050. Your cam is 280 degrees with a smaller displacement. ( www.arengineering.com is the site, then click on tech articles.) That cam will work in a super stock type motor with tons of rear gear. Or lots of compression, lots of converter, lots of gear, etc. Give Dwayne Porter a call and have him spec you a different cam. I bet that if you drop 20 degrees off the duration that combo will pick up a bunch.
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Re: A Little Disappointed--Victor Heads
[Re: reknapp52]
#1275283
07/28/12 01:09 PM
07/28/12 01:09 PM
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Joined: Jan 2003
Posts: 16,941
NC
440Jim
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,941
NC
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Quote:
The intent was to gain a few MPH from my 447 low-deck in Super Gas (throttle-stop) racing...
I swapped out my 4:30 gears for a set of 4:56s, which netted 100-200 more RPM in the lights, and no difference in MPH.
What compression ratio are you running? What is the shift point and finish line rpm you are seeing?
In a "small" 447 CID and that much duration (280 at 0.050"), it should like 7500+ rpm. But the tight LSA (106) will favor mid range rather than peak hp (hp corresponds to mph). You added almost 10 deg at 0.050"
MP590: 303/303 at 0.020", 271/271 at 0.050", 106 LSA, 1.5 rockers
Roller: 308/308 at 0.020", 280/280 at 0.050", 106 LSA, 1.6 rockers
The unported Victor heads should flow better than your ported 915's (310 cfm vs 290 cfm?). But it is a shame to have heads with potential that is not used since the porting was not done. I assume these are the standard port (not max wedge) heads.
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Re: A Little Disappointed--Victor Heads
[Re: reknapp52]
#1275292
07/28/12 03:57 PM
07/28/12 03:57 PM
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Joined: Dec 2006
Posts: 3,667
Arizona
Chris'sBarracuda
master
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master
Joined: Dec 2006
Posts: 3,667
Arizona
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Quote:
Last spring I removed my MP .590 cam, and mildly (non-professionally) ported 915 heads, and replaced them with a set of the Edelbrock Victor heads and a used Comp Cams roller that I have had for a couple years (see attachment for specs). Also installed a set of the Hughes offset rockers (1.6 ratio) to go with the new heads. The intent was to gain a few MPH from my 447 low-deck in Super Gas (throttle-stop) racing. The old combo would run 137-138 in Denver, with a best of 150 in Topeka. Although I haven't had time to really flog this new setup, the initial outings are not very impressive, with speeds of 139 in Denver. I swapped out my 4:30 gears for a set of 4:56s, which netted 100-200 more RPM in the lights, and no difference in MPH. I realize that the 850 DP carb may be a little on the small side for what I am trying to do, and the cam being degreed at 106 is not the best (wanted to retard it some, but I couldn't cut valve reliefs as deep as I wanted because of the close proximity to the top ring land). Any thoughts/input would be appreciated.FWIW--I know that low-end and mid-range have improved because I have added .3 to .4 to my throttle-stop timer.
And your mph got better last weekend in Denver.. The DA was around 9400-9700' all weekend.
I would say you are doing fine.. 
Run it all out, then see the difference.. And put the 4.30's back in, or maybe even 4.10's..
Bigger carb?? Yes.. Most likely more mph..:tounge:
If I remember, your car is light.. 
Chris.. 
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Re: A Little Disappointed--Victor Heads
[Re: d-150]
#1275294
07/28/12 05:04 PM
07/28/12 05:04 PM
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Joined: Jan 2003
Posts: 1,361
Wild West
M_D
pro stock
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pro stock
Joined: Jan 2003
Posts: 1,361
Wild West
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I agree with jamesc and 440Jim, more information would help. The intake manifold is one thing I would be interested in, as well as car weight with driver.
You netted about 20+ more hp. In analyzing the before and after numbers the real wildcard here in my opinion is; how good really were your 915 heads? I don't know what your car weighs, but if they went 150 mph they probably weren't terrible for o.e. iron heads, but I have a hunch the Victors and cam should have shown some more than they did unless the iron heads were very good.
But, I think to make substantial gains (8-12 mph) a good port job on the Victors and tweaking of other parts (intake, larger carburetor, and possibly different cam) need to be done. I am a little surprised as your stated compression ratio of 15.3 on that displacement is not common because it generally takes a fair amount of determination and effort to make it happen.
Are you sure the valve springs on the Victors are able to handle the roller lobes?
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Re: A Little Disappointed--Victor Heads
[Re: d-150]
#1275295
07/28/12 05:08 PM
07/28/12 05:08 PM
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Joined: Oct 2005
Posts: 976
ontario canada
mac56
super stock
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super stock
Joined: Oct 2005
Posts: 976
ontario canada
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Quote:
carb way to small you moved the powerband up with cam gears and heads
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Re: A Little Disappointed--Victor Heads
[Re: M_D]
#1275297
07/28/12 05:38 PM
07/28/12 05:38 PM
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Joined: Jan 2003
Posts: 5,875
communist bloc of new jersey
jamesc
master
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master
Joined: Jan 2003
Posts: 5,875
communist bloc of new jersey
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Quote:
I am a little surprised as your stated compression ratio of 15.3 on that displacement is not common because it generally takes a fair amount of determination and effort to make it happen.
that's one of the things i was thinking. i didn't try to crunch any numbers but that would take a very small chamber volume and/or dome piston which i avoid if at all possible.
as mentioned heads like those don't usually shine until they're ported but they should still put the 906 to shame
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Re: A Little Disappointed--Victor Heads
[Re: AndyF]
#1275298
07/28/12 06:21 PM
07/28/12 06:21 PM
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Joined: Sep 2007
Posts: 427
Cascade, CO
reknapp52
OP
mopar
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OP
mopar
Joined: Sep 2007
Posts: 427
Cascade, CO
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One thing I should clarify is that I am not bashing the Victor heads--I am probably expecting too much too soon with the new combination. I probably have no more than a dozen passes down the track since the changes were made, and as Chris pointed out, most all were made in D.A. numbers above 8000'. I know that as I get more runs in, and do some tweaking here and there, I can get some more MPH out of it. That said, here are some more particulars:
Old combo:915 heads with very mild back-yard port job, Venolia domed pistons, Howards aluminum rods,MP .590 flat tappet cam, Crane 1.5 rockers,Torker manifold, Holley 850 DP carb, Dedenbear base-plate T-stop, 2" primary headers, 4:30 gears, PG trans w/1.76 low. Car weighs 1940, add me and 75 lbs ballast, race weight is about 2200.
Changes made:Edelbrock Victor heads, Hughes 1.6 rockers, Edelbrock Victor 2886 intake, the above mentioned Comp Cams cam, Dedenbear linkage-style T-stop. Have tried both 4:30 gears and 4:56s.
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Re: A Little Disappointed--Victor Heads
[Re: jamesc]
#1275299
07/28/12 06:49 PM
07/28/12 06:49 PM
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Joined: Jan 2003
Posts: 1,361
Wild West
M_D
pro stock
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pro stock
Joined: Jan 2003
Posts: 1,361
Wild West
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If I were building an engine (race and high power street) for Denver or any high altitude only street use such as Flagstaff AZ I would certainly add a couple points of compression ratio over the usual, it really helps when the air is thin.
I re-read the o.p. where it was stated the heads have a mild non-professional port job, to me that indicates the flow is likely 250 or under, and compared to the Victors at 310-320 it seems there should be quite a bit left on the table.
Flow numbers aside, for a super gas level engine I believe the larger cross section max-wedge size intake tract is better. I don't have any real experience with the Victors, is the port between the 2 versions the same except the standard port is necked down at the manifold area? I suspect that is the case after looking at the published port volumes. If so, opening them up (assuming the heads are "standard" port openings) and using a different intake manifold with larger runners could really wake it up.
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