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12/11/13 1:18am - Original Message: 'Big cam vs. vacum needs....'
HighDesertDave
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
Hey is there a minimum recomended amount of vacuum to properly operate the headlamps and wiper door? Kinda wondering how much cam is too much cam. I'm thinking in terms of inches on a vac gauge....as in a power brake booster needs 18 / 16 minimum. Thanks, Dave

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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

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12/11/13 5:59am - Reply: 'Re: Big cam vs. vacum needs....'
apasbigal
Former Member
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goldens bridge, NY - USA

Vette(s):
1972 T-Top 350 auto, matching numbers,Blue, ac

Joined: 11/3/2003
Posts: 498
15 -20 inches of mercury will operate everything quite well . I read this spec somewhere in a tech article, but can't find the article now. I'm believe it was in a troubleshooting headlight/wiper door problem .Congradulations on your find , love the color and the last year of 2 steel bumpers. Happy holidays Big Al

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12/11/13 1:12pm - Reply: 'Re: Big cam vs. vacum needs....'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19458
 Yer lucky if you can pull 18" on a stock engine. That's why these cars have vacuum reservoirs. As long as you don't get something with a lot of duration, cam-wise, you may be otay. If you go with a lumpy, rump-rump-rumpity-firtzfirtz-rump cam, all bets are off, even with a larger vac reservoir. They do make vac pumps for stuff like that, tho.
They also have electric conversions for the head lights....LOL

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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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12/11/13 2:53pm - Reply: 'Re: Big cam vs. vacum needs....'
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
Good to know. My vac parts seem to operate ok...a little slow at start up but I wasn't sure if there was a reservoir someplace or not. If I let her run a minute then they seem to open/close well. But, I forgot this part, the wiper door always does this little partial dance when the engine starts. Opens a smidge and then closes back up. I'm not fooling with any of the controls...just starting the car. Is this normal? There is a rumbly cam in her and I have not been able to retrieve the specs from the PO. I want to put a power brake booster on her. I hope I don't need to swap out the cam to run the booster. I'm kinda hoping since the headlights work that the booster will work. Of course I could take a vac reading but I can't start the car when its -4 every day now. Cry

____________________________________
My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

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12/11/13 3:03pm - Reply: 'Re: Big cam vs. vacum needs....'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19458
HighDesertDave said:But, I forgot this part, the wiper door always does this little partial dance when the engine starts. Opens a smidge and then closes back up. I'm not fooling with any of the controls...just starting the car. Is this normal? 

Normal? No.
Common? YES! Ouch
Usually that is a sign that the check valve is leaking. The check valve is the metal, pie shaped valve in the vacuum line about 6" from where it comes out of the port on the engine. There will be a small round plastic filter, and then the check valve. If the valve is ok, then the next most common reason for that happening is a leak somewhere. I can send you some vacuum tech if ya want. Good for both the headlights and wipers.



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Joel Adams
C3VR Lifetime Member #56    
My Link


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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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12/11/13 3:16pm - Reply: 'Re: Big cam vs. vacum needs....'
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
Sure send it over or post or....all this was supposedly replaced. The lines and diaphragm look new....I have not looked at the valve your referring to though. So a leak is possible. Hey the right hand headlamp goes up after the left. One time I had to go and pull it up. Other times it works like it should (which is a guess cuz what do I know). Does this point you towards something?

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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

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12/11/13 3:18pm - Reply: 'Re: Big cam vs. vacum needs....'
Case75
Former Member
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230

Joel, should both headlights go up at exactly the same time or is it normal for say the driver's side to go up slightly ahead of the passenger side? That is the condition that I have. I have a delay of a couple of seconds on the passenger side.

Greg.




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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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12/11/13 3:35pm - Reply: 'Re: Big cam vs. vacum needs....'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19458
Both headlights are supposed to open/close at the same time, at the same speed.It rarely happens, but it s'posed to. A leaking actuator, relay valve, hose, switch, over-ride....anything can cause one to open/close before the other. Might even simply need to be lubricated...ya never know.
Dave, I'll e-mail the info first chance I get...Wink  I really should be werking right now, but....I'm slackin off..... LOL

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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12/13/13 3:56pm - Reply: 'Re: Big cam vs. vacum needs....'
Tom the 69
Former Member
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Blairstown, NJ - USA

Vette(s):
69 Vette.LeMans blue w/383 stroker- AED 950 HO modified carb -Weiand team "G" intake -AFR 210 heads- solid roller cam- 21/2 in side exhaust. Muncie M-21 trans and 4.56 rear. Used for dragracing and cruising,

Joined: 3/28/2003
Posts: 3
I am running a big solid roller in my '69. I'm pulling 7 to 8 in. of vacuum and all my lights, brakes and wiper door operate fine,a little slow,but they all work.

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