Used camshaft selection for stock short block 360
#318408
05/14/09 10:40 PM
05/14/09 10:40 PM
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Joined: Feb 2004
Posts: 3,934 Nova Scotia Canada B2Y 1E4
SANDYinNS Canada
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Nova Scotia Canada B2Y 1E4
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I'm putting a budget 360 together for my 84 shorty truck. Street and stip use no hauling or towing. just a bracket rig and tire burner. Getting tired of the current slant6! The truck has 3:55's and a sure grip 833 od tranny. The 360 short block is a mid 70's low comp version that will only be treated to a re-ring and bearing. I'm using a set of ported heads of the same vintage only they have 202 valves in them. Again left over from another project that was upgraded to eddy heads.... I'm going with an edelbrock performer as the truck a/c and it is the only intake I have fits with that. Here is my real question. I have 3 camshafts left from various other projects all are used but in fine shape with lifters in order. One is comp cams 268 and another is comp 272. The wild card is an old purple shaft I once took out of a 340. It has to one of those old 108 centerline cam as we had an issiue with detonation and swappimg it out for a wider centerline cam solved the problem. Wouldn't this work well in my low comp 360 by building up the cyl pressure? Or would one of the more modern comp cams be a better choice. This is basically a junk motor with me using up some old parts that are laying around.
Sandy in Nova Scotia formerly drdodge340 68 coronet wagon, 68 formula s 340 fb barracuda-69 super bee-72 aussie charger-72 aussie vh dodge ute -76 feather duster-76 duster-77 street van - 98 ram 1500 SS/T-99 ram 1500-13 ram red express truck- 2015 hellcat challenger
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Re: Used camshaft selection for stock short block 360
[Re: SANDYinNS Canada]
#318410
05/15/09 12:02 AM
05/15/09 12:02 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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I dont know the LSA on the 268 or the 272 but if they are wider than the purple I would use the purple and install it at 102 to 104 centerline just for the purpose you stated... upping the cyl pressure
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Re: Used camshaft selection for stock short block 360
[Re: goldmember]
#318412
05/15/09 12:36 AM
05/15/09 12:36 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
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Romeo MI
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Quote:
The only problem is the MP hyd cams with 108 lsa are over 290 degrees(I know they don't list them as such),so you can advance them all you want and not produce cylinder pressure with under 8 to 1 comp. The old standard comp 268high energy is ground on a 110lsa and most install it around 106lca,much closer to usable than the larger duration MP cams,IMO.
Your talking 290 advertised which is about a 246 at 50 then advance it to 102 CL then you still have enough RPMs to play with, as you advance the cam you kill the upper rpm range. If you use the 268(which I am guessing its a 268 advertised) which would be about a 228 at 50 and if you advance that you dont have much for top end RPM... JMO BUT it will have better low rpm cylinder pressure for torque
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Re: Used camshaft selection for stock short block 360
[Re: goldmember]
#318414
05/15/09 08:04 AM
05/15/09 08:04 AM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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the 268H is 218/218 .050 dur, .454" lift
the 272? do you mean the magnum 270H? is 224/224, .470 lift
I have an XE262 in my stock long block 360, pulls real good from about 1800-2000 up to 5500. if you've got a loose (2500-2600 stall converter, and don't care about idle quality, I'd probably go 270H. if your converter is more in the 2200-2300 stall range or lower, the 268H
use comp 901 springs with either.
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Used camshaft selection for stock short block 360
[Re: patrick]
#318415
05/15/09 08:21 AM
05/15/09 08:21 AM
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Joined: Feb 2004
Posts: 3,934 Nova Scotia Canada B2Y 1E4
SANDYinNS Canada
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I'm going to check what I have I think both were xe cams? The mp is an old 284/484 purple shaft/108 I'm fairly sure of that one! Truck is 4 spd..no worries on stall speed.
Sandy in Nova Scotia formerly drdodge340 68 coronet wagon, 68 formula s 340 fb barracuda-69 super bee-72 aussie charger-72 aussie vh dodge ute -76 feather duster-76 duster-77 street van - 98 ram 1500 SS/T-99 ram 1500-13 ram red express truck- 2015 hellcat challenger
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Re: Used camshaft selection for stock short block 360
[Re: SANDYinNS Canada]
#318416
05/15/09 09:06 AM
05/15/09 09:06 AM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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Grand Haven, MI
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what first gear ratio is it? unless it's a 3.09 first gear tranny, I'd stick with one of the two comps, probably the smaller one.
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Used camshaft selection for stock short block 360
[Re: SANDYinNS Canada]
#318418
05/15/09 01:16 PM
05/15/09 01:16 PM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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I Live Here
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Grand Haven, MI
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Quote:
Quote:
what first gear ratio is it? unless it's a 3.09 first gear tranny, I'd stick with one of the two comps, probably the smaller one.
I have no idea what the 1st gear is? whatever came in a slant 833 od 84 truck?
I looked it up somewhere on the net and it does look like a 3:09 1st gear
The cams i have are a 268 h could be an xe not sure but i think it might be
Second one is a 274 xe which looks like it is discontinued?
both appear to be on a 110 center line
Is there much difference? I know the old 108 dc shaft detonated badly with a 9.7 :1 motor ( I measured it before and after the rebuild )
268H is 268/268, 218/218@.050, .454" lift, 110 LSA, 48 deg overlap
XE274 is 274/286, 230/236@.050 .488/.491 lift, 110LSA 60 degrees overlap.
268H will make more torque, XE274 will make more HP. using comp's camquest6 software, assuming 7.8 compression, 600 CFM carb, dual plane intake, headers, and flow data taken from hughes website for '576 heads w/2.02's, it's predicting:
308HP@4500 & 387 TQ@2500
switching to an XE274 yields
331HP@5000 & 382 TQ@4000,
one thing to remember is your gear spread and RPM drop. A833 OD's are 3.09, 1.67, 1, so your 1-2 shift will drop RPM's 46%, 2-3 will drop RPM's 40%. ideally you want to shift at or slightly above your HP peak, and drop to near your torque peak.
I think the numbers & RPM's are off on the comp simulation, I'd wager the 268H will peak HP at ~5200 & TQ at ~3000, and the XE274 more like 5800-5900 and 4000-4500. with the wide gear spread and the heavy weight of the truck I think I'd still look at the 268H, and shift ~5700 RPM (will recover at ~3100 & 3400...with the XE I'd say you'd probably need to shift near 7k to get to a decent shift recovery point for the cam (7k shift would recover at 3800 & 4200) and by then I'd wager you'd be too far past your HP peak that you wouldn't be gaining anything. if you had a closer ratio 4 speed with deeper gears, or an automatic with a loose converter, I'd go with the XE.
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Used camshaft selection for stock short block 360
[Re: goldmember]
#318421
05/15/09 06:01 PM
05/15/09 06:01 PM
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Joined: Apr 2007
Posts: 375 NE Oklahoma
71valiant
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I built a simliar engine for my valiant. Stock 360 pistons and heads. I used a 480/480 lift 292/292 duration 230@.050 109 centerline. It runs well with 4:30 gears and a 2600 stall.
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Re: Used camshaft selection for stock short block 360
[Re: emarine01]
#318423
05/15/09 07:24 PM
05/15/09 07:24 PM
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Joined: Apr 2007
Posts: 871 WA 98043
thecarfarmer
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Got an OD; gears can be changed. Go big cam and don't look back! Bet if you had 5.13's that purple shaft would be the clear winner... Then again, I'm NOT known for having anything resembling common sense regarding comfort/drivability. -Bill
Seduce the attractive, and charm the rest.
******
489 C.I.D., roller cam, aftermarket heads, tunnel ram, stock '54 Dodge rear axle assembly: which of these doesn't belong?
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