I do believe your correct Lou.
Not sure what I was thinking last night.
(Probably the upcoming campaign trail for the Possum-Bagel ticket.)
CJ
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| Author: | ceej [ Wed Jan 19, 2011 10:37 pm ] |
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It sounds like you've got quite a bit of retard on that cam. You may be able to improve the vacuum by advancing the cam a bit. I'd think three or four degrees should do it. It still should get to 5000 OK. Check with some cam gurus like Josh and Doc and see what they think. CJ |
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| Author: | Dart270 [ Thu Jan 20, 2011 10:19 am ] |
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99 deg intake centerline is not retarded in almost anyone's book. Maybe I'm missing something. Usually, I recommend people degree their 225 performance cams around 99-102 for best power, which is what pretty much all the serious racers have figured out. Retarding will give more top end, advancing more low end. It could be this cam is just too big for your CR... $100 for a good regrind cam matched to your engine CR and driving desires might be the way out of all this. Regrind might sound cheesy, but the highest HP 225s on the planet use them (Tilley). Lou |
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| Author: | ceej [ Thu Jan 20, 2011 5:12 pm ] |
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I do believe your correct Lou. Not sure what I was thinking last night. (Probably the upcoming campaign trail for the Possum-Bagel ticket.) CJ |
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| Author: | wjajr [ Sun Jan 23, 2011 9:41 pm ] |
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Sorry to have dropped off on this project. We have had my sister in-law, wife’s sister, here since New Years while her hubby languished in the hospital suffering from diabetic complications. Friday night we lost him. She has returned home, and things are getting back to normal here. Now the cam. I will install a factory steel head gasket replacing the current Fel-Pro gasket in use. Calculations predict compression to increase from 9.5 to 9.9:1 using factory gasket. This is closer to what the original builder had told me he was running when he was racing this car, years ago. From what others have indicated I should get additional benefit from this increase. Would I see higher idle vacuum, smoother idle, more top end, or what? By increasing compression, will the torque curve drop down a few hundred rpm, or is moving torque curve only achieved by retiming the cam? Is the intake lobe center line the one that cam timing is set to? Lou said that 99-102 degrees is sweet spot for this size cam, I’m a little confused at this point, but is 99 the more advanced position? Trick Flow Directions states a 4 degree advancing of cam moves “Power Curve†down approximately 200 rpm. 200 rpm lower torque curve would help her off the line with a 2600 rpm stall converter. As cams go, where dose this one land in the pecking order of stock to wild? Lift at valve before lash is: Exh. .324†x 1.5 = .486†Int. .321†x 1.5 = .481†Bill |
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| Author: | Joshie225 [ Sun Jan 23, 2011 10:37 pm ] |
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Raising the compression ratio will increase the torque, but will not change the peak torque RPM. Intake centerline at 99° ATDC is more advanced than a higher number. A higher number means the piston has traveled farther. If the intake valve is at peak lifter sooner it closes sooner so it's advanced in relation to the piston position. I would not advance the cam any more. If you need a better idle you need less overlap. If you need more low speed torque you need an earlier intake closing. Both these things happen with less duration. |
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| Author: | emsvitil [ Sun Jan 23, 2011 11:42 pm ] |
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Quote: Raising the compression ratio will increase the torque, but will not change the peak torque RPM.
And the whole power curve moves higher, everywhere............ |
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| Author: | Dart270 [ Mon Jan 24, 2011 5:51 am ] |
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If those duration @ 0.050" numbers are right, then this is what most people call a Big cam. 9.9:1 Comp will help some, but not a ton. 3000+ RPM stall is needed, likely 3200-3500 best. You could also retard about 2 deg more, but no more than that. I have 96 deg in my '64 Dart with a very similar cam and 10.5:1 and it is good down low but runs out around 5500 where with the cam at 101 it would pull hard over 6000. I will re-degree that one to 99. If you are determined to use this cam, I would mill head to raise compression to 10.5:1 min. With a good ign timing curve, this should be fine on 91 octane. I'm not totally clear on your intended usage and tolerability on the street, but I feel you might be better off with a smaller cam - only around $100-130 with shipping from Oregon! Lou |
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| Author: | wjajr [ Mon Jan 24, 2011 7:49 am ] |
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[quote]If you are determined to use this cam, I would mill head to raise compression to 10.5:1 min. With a good ign timing curve, this should be fine on 91 octane. I'm not totally clear on your intended usage and tolerability on the street, but I feel you might be better off with a smaller cam - only around $100-130 with shipping from Oregon![/quote] Lou, Mostly this car is a daily driver, sun out, putzing around town, weekend trip to car shows, and once a year drag for the hell of it machine. An occasional tire roast to tame the V8 unbelievers would be nice, and or just for the hell of it because it is fun. Now that we know the cam’s secrets, I’m trying to find a way to tame it a bit or better its street manners, and drop torque curve lower. This is all looking like a tall order to fill. As I mentioned earlier, Doc’s RV 15 is looking real nice with its low end torque production. As long as that RV 15 can produce enough rpm to cohabitate with a 3.55 rear and 24.5†dia. tires that produce a 60 mph cruse rpm of 3000 I think it is the way to go. In a conversation with Ceej last week, he said his Hooptie is running a RV15, and it runs out of wind at 5000 rpm. That would give me 2000 rpm under 3000, and 2000 rpm over my cruse rpm so it looks to be a decent fit in that respect. Currently I need to have the rpm up over 3500 before this engine starts to pull hard. That translates to a manual down shift at 60 mph way past the 904’s automatic 3-2 shift at 46 mph, cranking it 1500 rpm over transmission’s programmed normal up shift point of 4000 rpm to get her going---not real street friendly, and quit noisy as well. In some strange way, that loping idle, on looking disbelievers asking if it’s a 340 4V head trip is hard to stifle as impractical this engine is for street duty. There is something to be said driving an untamed beast, I’m not sure what it is as one moment I’m in love, the next is what a PIA this thing is. I’m seriously considering replacing the turbo mufflers with Ted’s set-up, and enjoying some silence, and perhaps the radio as well while motoring down the road. So perhaps it is time to put the race engine out to pasture, reprogram it for a more sedate demeanor / sleeper duty. Bill |
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| Author: | Dart270 [ Mon Jan 24, 2011 12:48 pm ] |
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Thanks for your explanations. I have a clearer picture now. I like bigger cams myself, and am not afraid of a bit of a bumpy idle. To me, the RV15 specs look basically like a stock cam, and I personally would not bother with that for a "performance" application. Doc is a mild cam kinda guy. Since you have a 2600 RPM stall and 3.55 gears and 9.5:1 comp, I would really recommend something like the Oregon 234/226 @ 0.050" cam, or at least the (slightly smaller) Erson 280/270 (230/220 @ 0.050") cam. These should be pretty much ideal for your app, give a throaty sound, and make good power without pinging on pump gas. Degree at 99-100 and smoke the tires. FWIW, I am about to install my Oregon 234/226 cam into an engine for testing, but it may be several months before I get it into a car. Sandy has the 280/270 in his Valaint with about your comp and gears and he says it has great low end. Lou |
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| Author: | wjajr [ Mon Jan 24, 2011 2:34 pm ] |
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Lou, of the cams you listed, do you have any idea what one would expect for idle vacuum from them? My current cam dose not produce enough vacuum at idle in gear (4 to 6 inches), and only 10 to 11 inches at 1100 rpm in P which rises hell with signal to carburetor, making selecting a power valve almost imposable for my Holley 390. Which in turn causes over enriching at low rpm, and run-on at engine shut down. I generally kick the transmission into “N†at a light to keep from going rich I don’t mind a loping idle at all if there is good drivability at low engine rpm when putting around town in traffic. I guess I need to hear from others that are running any of these cams in a similar drive train combination to my configuration. Bill |
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| Author: | sandy in BC [ Tue Jan 25, 2011 6:40 am ] |
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I get a great signal with the 280/270 cam.......but I run a BBD ,,,,and that alone gives me a good signal. Getting the right cam timing is as important as getting the right cam. |
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| Author: | Dart270 [ Tue Jan 25, 2011 6:57 am ] |
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I would expect 10-12 in Hg or more for the 234 cam and 12-14 in Hg or more with the 280 cam, both around 700-800 RPM idle. These are NOT big cams for a 225. Lou |
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| Author: | THOR [ Tue Jan 25, 2011 8:21 am ] |
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Its awesome that youve finally got it figured out. How long has it been now? Might you be interested in getting rid of that cam? I have a manual transmission, so it would likely be alot easier to deal with... ~RDE~ |
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| Author: | wjajr [ Tue Jan 25, 2011 10:24 am ] |
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Yeah THOR, finally decided to spend the bucks on a degree wheel. I would have to say the cam saga started shortly after the car got on the road May of 2008 when I started plaguing the board over tuning the Holley 8007, still ongoing. At the time I didn’t realize that my cam was causing so much anguish while trying to get this heap of iron road ready. Perhaps you remember post after post pertaining to run ability, vacuum level, and idle speed. The last year has not been old car friendly because of our home construction project sucking up time, energy, and bushels & bushels of 100 dollar bills covering over runs...and while-we’re-at-it’s. I have a few small low buck projects are slated while the snow builds & than melts. Better handling, cleaner looking engine compartment & trunk, and stronger performance are some of them. Now that I know what is going on with the cam, performance up grades can now be made more efficiently & scientifically, such as just changing head gasket for a 0.5 compression increase for next to nothing. I still have to decide on changing the cam this winter, and if I do, what to replace it with. I have been giving some thought to ditching the old Holley for a BBD, but these projects start the old Spend-o-meter spinning out of control. I’ll be posting project progress, so stay tuned. Bill |
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| Author: | 66aCUDA [ Wed Jan 26, 2011 4:57 am ] |
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Bill I run the 280/270 with an Aussie Speed Hurricane and Eddy 500. I have 12" at idle. Frank |
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