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| sliding | Big cams vs vacuum | ||
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Senior Guru
 
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I'd like to see or hear how much vacuum are your engines with
bigger than stock cams making at idle?! |
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Posted on: 2010/7/15 10:20
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'90 L98 auto with a lot of mods |
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| Matatk | Re: Big cams vs vacuum | ||
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Webmaster
 
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Is this just out of curiosity or are you concerned with braking, etc? I don't have a vacuum gauge, but I'll have to get a video of my motor running later. I have something like a 224/232 cam and it has a nice lope, good braking, no issues at 800 rpm idle.
Matthew |
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Posted on: 2010/7/15 11:35
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| Trae1976 | Re: Big cams vs vacuum | ||
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2012 Memorial Day Car Show Winner!
 
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Mine's pulling 11-12in with a Comp 270H. I believe the stock system in mine was about 18in.
Quote: 12-211-2 - Comp Cams 'Magnum' Hydraulic Flat Tappet Camshafts Details |
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Posted on: 2010/7/15 11:47
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| sliding | Re: Big cams vs vacuum | ||
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Senior Guru
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I'm just curious, for comparison purpose. I'm still
having idle issues and I'm not sure if vacuum is as should be, or is too low. MAP readings (Datamaster or some other logger) at idle (it doesn't have to be vacuum gauge) is what I'm interested in. |
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Posted on: 2010/7/15 11:49
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'90 L98 auto with a lot of mods |
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| sliding | Re: Big cams vs vacuum | ||
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Senior Guru
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Quote:
Thanks! What is your idle set at? |
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Posted on: 2010/7/15 11:50
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'90 L98 auto with a lot of mods |
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| Trae1976 | Re: Big cams vs vacuum | ||
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2012 Memorial Day Car Show Winner!
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Quote:
sliding wrote: About 700. |
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Posted on: 2010/7/15 12:02
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| flyboy | Re: Big cams vs vacuum | ||
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Elite Guru
 
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15"@ idle, 700rpm, 19"@1500rpm.
LT4 "Hotcam", 218/228@.050,.492/.525w 1.5X1.6 rockers. LSA 112*, 6*timing, stock was 19" vac. @ idle. |
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Posted on: 2010/7/15 12:13
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'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
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| Weavsvet | Re: Big cams vs vacuum | ||
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Senior Guru
 
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12" @ idle, 900 rpm
226/230.565.565/111lsa Lobe Lift .3533 .3533 duration @ .006 280 284 |
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Posted on: 2010/7/16 6:57
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1996 Corvette Coupe,AFR 195 street Eliminators,Edelbrock LT4 Air Gap intake manifold,9.5" 2800 stall,TPIS LT headers,Bullet 226/230.565.565/111 lsa cam,1.7 Scorpion rr's,EWP, X Pipe, Stock Exhaust,Elec.Cutouts,Dana 44/3.45, Tune by Wester's Garage |
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| sliding | Re: Big cams vs vacuum | ||
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Senior Guru
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Please let me know if my math is correct!
Let's take Weavsvets cam for example. He's making 12" (it's inHg, right?) at idle. If we convert that to kPa, that makes ~40 kPa. So if we take 40kPa off of ~101kPa(atmospheric pressure), does it mean that his MAP reading at idle should be arround 61kPa? Also, does compression have effect on vacuum? |
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Posted on: 2010/7/16 10:19
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'90 L98 auto with a lot of mods |
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| pr0zac | Re: Big cams vs vacuum | ||
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Elite Guru
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i don't know what its vac reading is at idle. its around 800 rpm and my cam is a 245/253 @ .050 .612/.612 on a 107lsa, 300/308 @.006 and my brakes work fine.
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Posted on: 2010/7/16 15:34
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96 lt4. 357ci, 11:1, LE 226/232, LE2 LT4 heads, ported LT4 intake, EM Gladiator44, EM LT's, stock exhaust, NX kit. |
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| sliding | Re: Big cams vs vacuum | ||
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Senior Guru
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What CID engine do you have? Stroker?
That cam is way bigger than mine and I'm getting comments that my cam is too big. |
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Posted on: 2010/7/16 18:42
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'90 L98 auto with a lot of mods |
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| biggrizzly | Re: Big cams vs vacuum | ||
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2011 Memorial Day Car Show Winner!
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OK here some more specs for you.
My cam card is shown below: This is an emissions legal cam profile designed by Brett Bauer to run with my LE2 heads and pass Maryland emissions so its not too big but supposed to develop better torque and power than the GM Hot Cam. Based on one of my early scans that I can open and look at today it shows my MAP KPa jumping between 50.0-55.7 at idle around 800 rpm. At high RPM between 5400-5600 RPM it was registering between 11.8 and 14 Kpa Cam Specs  |
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Posted on: 2010/7/16 20:00
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| pr0zac | Re: Big cams vs vacuum | ||
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Elite Guru
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385
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Posted on: 2010/7/16 20:43
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96 lt4. 357ci, 11:1, LE 226/232, LE2 LT4 heads, ported LT4 intake, EM Gladiator44, EM LT's, stock exhaust, NX kit. |
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| iCorvette | Re: Big cams vs vacuum | ||
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Senior Guru
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13.5 inches 850 idle, still lousy brakes
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Posted on: 2010/7/16 21:07
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| pr0zac | Re: Big cams vs vacuum | ||
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Elite Guru
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Quote:
you have something wrong with your brakes then. i ran that cam for years and never had a brake issue. |
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Posted on: 2010/7/17 4:24
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| Aboatguy | Re: Big cams vs vacuum | ||
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Senior Guru
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Quote:
From checking my datalogs/vs my vacuum gauge your are correct manifold vacuum will reflect in the differential between MAP and BARO at idle. Baro-MAP = manifold vacuum |
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Posted on: 2010/7/17 14:15
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| sliding | Re: Big cams vs vacuum | ||
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Senior Guru
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Quote:
 Thanks!Thank you all guys! |
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Posted on: 2010/7/17 15:28
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'90 L98 auto with a lot of mods |
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| Weavsvet | Re: Big cams vs vacuum | ||
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Senior Guru
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Sliding
Just so you know I have plenty of brakes at 12" of vacuum. Hope you get it squared away. EDIT: urns out I had a intake leak. I believe it was the grommet for the PCV. I fixed that and my vacuum went to 14". |
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Posted on: 2010/7/17 20:15
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1996 Corvette Coupe,AFR 195 street Eliminators,Edelbrock LT4 Air Gap intake manifold,9.5" 2800 stall,TPIS LT headers,Bullet 226/230.565.565/111 lsa cam,1.7 Scorpion rr's,EWP, X Pipe, Stock Exhaust,Elec.Cutouts,Dana 44/3.45, Tune by Wester's Garage |
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| dan0617 | Re: Big cams vs vacuum | ||
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Senior Guru
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12" of vac at idle, 230/236 cam on a 110 lsa. Only time brakes don't work right is when the vac booster is toast. My car is a MAF car so I don't have any MAP info for you.
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Posted on: 2010/7/17 20:23
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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| pr0zac | Re: Big cams vs vacuum | ||
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Elite Guru
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Quote:
when you going to step up to a HR cam? i wanna see what you can make that car run.... |
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Posted on: 2010/7/18 0:07
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| iCorvette | Re: Big cams vs vacuum | ||
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Senior Guru
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Quote:
new booster 5k miles ago, does not hiss.... |
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Posted on: 2010/7/18 3:19
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| Josh | Re: Big cams vs vacuum | ||
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Guru
 
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230 / 236, .57X/.57X, 113 LSA. It's a comp cams 280 XFI cam. No problems, 750-800 idle.
45-50 KPA at idle, measured with Data Master. Car is an M6. A tuner I know and respect thinks that you could go 240/250 or more and still make it work. If mine ever comes apart again, that's the route I'm going. Probably something in the upper 240's and upper 250's. Don't worry about the guys saying your cam is too big, that's the Corvette mentality it seems like. 99% of those guys haven't ever done a cam swap. They're just regurgitating what they've read on the net. |
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Posted on: 2010/7/18 4:36
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"Have ya paid your dues, Jack?" "Yessir, the check is in the mail." - Jack Burton |
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| tpi421vett | Re: Big cams vs vacuum | ||
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Registered Vendor
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I have 11" of vacuum with a 252/260SR and the brakes work great. But it is a 450ci engine.
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Posted on: 2010/7/19 3:06
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AFR Dealer, can sell at prices too low to advertise. 801-953-6391 08 C6 LS3,3LT,Z51,A6,NPP 91 vette,450ci, AFR 220, miniram,FAST, Crane 252/260 solid roller, 200 shot nos, ZF6, 4 link, 9", DA corrected to 1300 ft 9.65@145.xx 450ci now with AFR 235... |
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