cam advice
#3133071
03/28/23 05:26 PM
03/28/23 05:26 PM
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Joined: Oct 2014
Posts: 174 louisiana
musclecarman15
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OP
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Joined: Oct 2014
Posts: 174
louisiana
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need cam advice...building stroked 383(3.75 stroke),30 over block,pistons flat top with 4cc valve relief,(440 source kit,with balancing and special bearings), 346 heads(they have been CnC ported,2.14,1.81 valves,unshrouded,milled .007,etc,),ductile iron adjustable 1.5 bushed rocker setup by rocker specialities,stock intake has been extrude honed,original holley carb has been blueprinted , stock high performance exhaust manifolds and ecs correct exhaust system,blueprinted oil pump and distributor,steel shim(.020 )head gasket,stock oil pan and valve covers,fuel pump,balancer,factory 727 automatic trans with 3.23 gears,engine in 71 cuda convertible with air conditioning and power brakes,etc(need vacuum)want low end torque...pistons .025 in hole, want to use hydraulic flat tappet cam...like xe 525....need opinions....car is original so want to maintain original look for engine componets...thx keith
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Re: cam advice
[Re: calrobb2000]
#3133122
03/28/23 09:10 PM
03/28/23 09:10 PM
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Joined: Jan 2003
Posts: 20,826 A collage of whims
topside
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 20,826
A collage of whims
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I'm a fan of Engle's hydraulic FT cams - haven't heard of issues like Comp apparently has. My 406" SB street Duster with AC ran K54 intake lobe (214 @.050, .470 lift) & K56 exhaust (224 & .504) - plenty of vacuum, great throttle response, and sounded meaner than it was. For my 448" RB street B-body, scaled up to K56 (224/.504) Intake and K58 (230/.520) Exhaust; same effect, though a 4-speed non-AC car. Can't recall if 110 or 112 LC, though. Worth a call to Engle for their advice. Johnson EDM lifters in both, zero problems. 406 was iron head @ 9.5:1CR, a bit marginal on octane until I dialed some timing out; 448 had Eddy heads & 10.3 CR, perfectly happy on pump 92. As stated, CR matters on pump gas street cars; ya need to measure that.
FWIW, K60 is 238/.534. Those are their older grind #s; their numbering has changed, but last I heard they'll grind whatever they've made in the past.
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Re: cam advice
[Re: musclecarman15]
#3133145
03/28/23 10:40 PM
03/28/23 10:40 PM
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Joined: Jan 2003
Posts: 31,050 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,050
Oregon
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Pick something on the small side and keep the overlap low. You have to be really careful with cam selection when running exhaust manifolds. If the cam is too big the back pressure from the manifolds will cause reversion and bottom end torque will suffer. To make matters worse, the big cam won't make more power up top either. On the flip side if you go with too small of a cam then the torque will be great and you'll only give up a small amount of top end power. I used to do a lot of cam testing before I figured out that it was costing me a fortune and I wasn't getting paid for it! http://www.moparts.org/Tech/Archive/bb/Lobe.html
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Re: cam advice
[Re: AndyF]
#3133196
03/29/23 08:13 AM
03/29/23 08:13 AM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
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usa
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i've been messing with a similar combo in one of my cars for several years trying to find a sweet spot; still searching. my engine is a stock 440 and basically your putting together a physically smaller 426-440 wedge. my car has a midland ross power brake booster and it just doesn't like anything 15" of idle vacuum or less. the booster does fine with 16"-17" of vacuum at idle. the cams I've tried thru the years are the stock magnum, comp cams 21-305-4, 272/.455 mopar, hughs/engle 23/30 and summit 6401. the comp cams cam will make vacuum but runs out of steam rather quickly (probably due to 106cl installed). the 272 mopar looses vacuum, summit and engle even more. going from a true 1.5 rocker to a true 1.6 rocker will loose 1" of vacuum. the faster the lobe profile with the same duration will loose some vaccum. currently i have the stock mopar cam (actually a sealed power cs661, same as stock) in the engine and vacuum is up, brakes work, drives nicely, but performance has been better. that 275hl is going to give you about .560" lift at the valve, about 15 degrees overlap at .050" (something i'd never do with stock parts).
if you insist on the 275 type cam i'd suggest an xe274 ground on something like a 113 or 114lsa. the 275 is a 274 with the added area under the curve that a 274 has with 1.6 rocker. with all the tappet/cam problems people are having i'd error towards the gentler side. the faster the lobe, the higher the rocker ratio the more spring you need. the more spring you have can kill a hydraulic tappet and cause lobe failure.
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Re: cam advice
[Re: lewtot184]
#3133199
03/29/23 08:38 AM
03/29/23 08:38 AM
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Joined: Jan 2003
Posts: 9,876 Weddington, N.C.
Streetwize
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master
Joined: Jan 2003
Posts: 9,876
Weddington, N.C.
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If they still have it available the Crower HDP 271 is a great cam it's like 224/232 @.050 and .486/496 lift on 112 in at 108
Everybody I've ever recommended that cam to loves it.
BTW: The vaccuum pump from a Chevy cobalt 1.4 turbo makes for a great brake booster. I run one on my Rocky drag car. You can find them cheap on Ebag
Last edited by Streetwize; 03/29/23 08:55 AM.
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Re: cam advice
[Re: musclecarman15]
#3133268
03/29/23 12:25 PM
03/29/23 12:25 PM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
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master
Joined: Jun 2008
Posts: 3,916
usa
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thanks everyone on the advice...first i have a 1.5 rocker ratio as i had rocker specialities blueprint and true my rockers up, yes in need vacuum for power brakes and ac and dont want to use a pump,so i believe i will move my lobe seperation to 112, and my compression ratio should be in 9.2 to 9.4 range with the steel shim head gasket....next question becomes to go with a 224/230 or a 230/236 at 50 cam. remember my heads have been CNC ported,2.14/1.81 valves,etc.....thx everyone keith neither. going from 110 to 112 isn't going to buy you that much. i've found that increasing overlap by 5-6 degrees at .050" will reduce vacuum by 1". i'm pretty sure that rocker specialties doesn't correct ratio. to do that means moving the adjuster location. find a way to check your rocker ratio before assuming it's correct. the scrub pattern on those iron rockers is fairly long when compared to a roller, and the more lift you have means more scrub travel. be sure to check geometry.
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Re: cam advice
[Re: Streetwize]
#3133449
03/29/23 07:16 PM
03/29/23 07:16 PM
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Joined: Feb 2003
Posts: 1,646 Ontario,Canada
firefighter3931
top fuel
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top fuel
Joined: Feb 2003
Posts: 1,646
Ontario,Canada
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A Cuda with 3.23 gears I'd go with the Crower 271 hdp because I know it works well.
It's basically one step hotter than a 440 magnum cam and it'll give you more torque and roll on power without killing drivability. If you were running shorty headers or a little more compression and a better intake I'd go up to the Comp 232/237 or the old Ultradyne 231/239 but honestly that Crower is a great cam. Agreed We installed this cam in my buddy's 67 Charger ; 440 with 9.2:1 compression, CH4B intake, 750DP, HP ex manifolds, 2.5in exhaust with UltraFlo mufflers, 12in factory TQ converter, 3.55 SG running 275/60's out back. No problemo boiling the hides and pulled really hard to 5800 rpm. Recurved the distributor for 16* base timing and 36* all in @ 2500. Idle vacuum was 18-19 hg @ 900rpm idle. Power brakes worked like a charm. Has a nice mild rumble at idle as well. Ron
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Re: cam advice
[Re: musclecarman15]
#3133459
03/29/23 07:38 PM
03/29/23 07:38 PM
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Joined: Feb 2003
Posts: 2,810 Sobieski Wi
bee1971
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master
Joined: Feb 2003
Posts: 2,810
Sobieski Wi
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Motor that I built Factory block 383 / 432 .030 over 3.75 Crank 10.4 - 1 Compression 440 Source Kit Edelbrock E Street 75CC Heads Comp Cams XE275 HL Cam and Lifters 200 PSI Cold Cranking on all 8 cylinders 16 initial - 18 Mechanical - All in by 2400 RPMs Run ported vacuum advance on the street Edelbrock AVS2 800 - Rejetted on the mains and rods Idles at 650/700 RPMs all day long - 13.5" Vacuum Factory power brakes , disc front , zero issues Never mind the wrong dancing dipstick Been running for about five years now https://www.youtube.com/watch?v=gjFG6l_Whh8
Last edited by bee1971; 03/29/23 08:04 PM.
1971 Dodge Charger Superbee 2011 Ram Sport 1500 Quad Cab Deep Water Blue Loaded Siberian Huskies
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Re: cam advice
[Re: lewtot184]
#3133463
03/29/23 07:58 PM
03/29/23 07:58 PM
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Joined: Feb 2003
Posts: 2,810 Sobieski Wi
bee1971
master
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master
Joined: Feb 2003
Posts: 2,810
Sobieski Wi
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i've been messing with a similar combo in one of my cars for several years trying to find a sweet spot; still searching. my engine is a stock 440 and basically your putting together a physically smaller 426-440 wedge. my car has a midland ross power brake booster and it just doesn't like anything 15" of idle vacuum or less. the booster does fine with 16"-17" of vacuum at idle. the cams I've tried thru the years are the stock magnum, comp cams 21-305-4, 272/.455 mopar, hughs/engle 23/30 and summit 6401. the comp cams cam will make vacuum but runs out of steam rather quickly (probably due to 106cl installed). the 272 mopar looses vacuum, summit and engle even more. going from a true 1.5 rocker to a true 1.6 rocker will loose 1" of vacuum. the faster the lobe profile with the same duration will loose some vaccum. currently i have the stock mopar cam (actually a sealed power cs661, same as stock) in the engine and vacuum is up, brakes work, drives nicely, but performance has been better. that 275hl is going to give you about .560" lift at the valve, about 15 degrees overlap at .050" (something i'd never do with stock parts).
if you insist on the 275 type cam i'd suggest an xe274 ground on something like a 113 or 114lsa. the 275 is a 274 with the added area under the curve that a 274 has with 1.6 rocker. with all the tappet/cam problems people are having i'd error towards the gentler side. the faster the lobe, the higher the rocker ratio the more spring you need. the more spring you have can kill a hydraulic tappet and cause lobe failure. I run the Factory Power Disc Brakes Midland Ross Booster Interesting differences
1971 Dodge Charger Superbee 2011 Ram Sport 1500 Quad Cab Deep Water Blue Loaded Siberian Huskies
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Re: cam advice
[Re: bee1971]
#3133494
03/29/23 09:16 PM
03/29/23 09:16 PM
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Joined: Oct 2014
Posts: 174 louisiana
musclecarman15
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OP
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Joined: Oct 2014
Posts: 174
louisiana
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So I believe I'm down to two..1. crower 271 cut on 112 or 113 lsa...2....comp xe274...cut on 113 or 114 lsa...I need the vacuum and a nice idle...just want to make sure these cams will give me a low rpm starting torque curve ,knowing that this car won't see hardly any rpm above 5k...it's an original (restored, matching number) 71 cuda convertible that I want to have some fun with....keith
Last edited by musclecarman15; 03/29/23 09:32 PM.
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Re: cam advice
[Re: lewtot184]
#3133500
03/29/23 09:40 PM
03/29/23 09:40 PM
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Joined: Jan 2003
Posts: 4,733 Moved to N.E. Tennessee
GomangoCuda
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Joined: Jan 2003
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Moved to N.E. Tennessee
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looking at the 440source website it shows some compression ratios in the low nines which is what i have. anymore i look at overlap at .050" for these scenarios. a stock cam is -11 degrees at .050". from the cams i've used I've found anything at zero degrees and above will noticeably effect low rpm vacuum. the summit 6401 has about +1 degree overlap at .050" but can reduce idle vacuum by 2". the mopar 272 has zero degrees at .050" and will reduce vacuum. my favorite performer was the engle 2330 but at 110lsa it will noticeably reduce vacuum at idle. adding a higher ratio rocker to a stock cam will add some area under the curve plus some lift but will reduce vacuum a little. enhancing the timing curve only marginally helped vacuum. there're no free lunches here or magical cams. it all needs to be thought out. of course, a vacuum reservoir canister can be added; i just couldn't find a decent place for the black lump in my engine bay. Engle will grind it with your choice of LCA.
In theory, there is no difference between theory and practice. In practice, there is.
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