A Little Disappointed--Victor Heads
#1275280
07/28/12 12:12 PM
07/28/12 12:12 PM
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Joined: Sep 2007
Posts: 427 Cascade, CO
reknapp52
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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 12:52 PM
07/28/12 12:52 PM
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Joined: Jan 2003
Posts: 31,078 Oregon
AndyF
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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 02:09 PM
07/28/12 02:09 PM
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Joined: Jan 2003
Posts: 16,932 NC
440Jim
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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 04:57 PM
07/28/12 04:57 PM
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Joined: Dec 2006
Posts: 3,667 Arizona
Chris'sBarracuda
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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.. ![](/ubbthreads/images/graemlins/thumbs.gif)
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.. ![](/ubbthreads/images/graemlins/biggrin.gif)
Chris.. ![](/ubbthreads/images/graemlins/wave.gif)
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Re: A Little Disappointed--Victor Heads
[Re: d-150]
#1275294
07/28/12 06:04 PM
07/28/12 06:04 PM
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Joined: Jan 2003
Posts: 1,361 Wild West
M_D
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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 06:08 PM
07/28/12 06:08 PM
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Joined: Oct 2005
Posts: 976 ontario canada
mac56
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Quote:
carb way to small you moved the powerband up with cam gears and heads
![](/ubbthreads/images/graemlins/iagree.gif)
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Re: A Little Disappointed--Victor Heads
[Re: M_D]
#1275297
07/28/12 06:38 PM
07/28/12 06:38 PM
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Joined: Jan 2003
Posts: 5,875 communist bloc of new jersey
jamesc
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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 07:21 PM
07/28/12 07:21 PM
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Joined: Sep 2007
Posts: 427 Cascade, CO
reknapp52
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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 07:49 PM
07/28/12 07:49 PM
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Joined: Jan 2003
Posts: 1,361 Wild West
M_D
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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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