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#1 |
newly minted old timer
Join Date: Dec 1999
Location: Hudson WI
Posts: 3,511
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some news on no power saga.
http://67-72chevytrucks.com/vboard/s...d.php?t=365777
that’s the first post.. i pulled off the timing chain cover with great hopes of seeing dots not lined up, but knowing they were.. what did i find? ![]() so i started taking the intake off to prep pulling the cam... i have argued a few times with people far more knowledgeable than me with motors that i thought the problem was a vacuum leak. i always got a..no no no,, wouldn’t cause that.. i did have one friend of mine, a lonnnnnng time race guy motor head say he thought i was what he called a flapper. that is a intake gasket that was not sat right and was hanging in side of the motor. at an idle there was no leak, but under power the extra vacuum would pull the gasket away from the metal causing a massive leak. (the crack is in the paint) ![]() ![]() ![]() i think he may be right. these a photos of the front of the motor, intake gasket. the end twisted up, and was hanging inside. on the underside of the intake there is grease/dirt streaks (i did rub some away when i touched it) ![]() ![]() soooo i guess i go buy a gasket set, and pull all this back together and see what happens.. if its not the problem, still an interesting education.
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____________________________________________ 72 c20 longhorn 65k org miles and counting! 69 k10 Suburban Last edited by mtdave2; 11-09-2009 at 01:55 PM. |
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#2 |
Registered User
Join Date: Dec 2006
Location: Porter Ranch, CA
Posts: 978
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Re: some news on no power saga.
Is that a crack in the block right under the gasket???
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#3 |
newly minted old timer
Join Date: Dec 1999
Location: Hudson WI
Posts: 3,511
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Re: some news on no power saga.
no, its in the paint as far as i can tell. it freaked me out when i saw the photo too
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____________________________________________ 72 c20 longhorn 65k org miles and counting! 69 k10 Suburban |
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#4 |
Registered User
Join Date: May 2005
Location: PA
Posts: 2,696
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Re: some news on no power saga.
turn it over by hand, and watch all the lifters. See if they are all moving up the same amount.
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#5 |
Never Ending Projects
Join Date: Jul 2006
Location: San Diego, CA
Posts: 3,836
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Re: some news on no power saga.
Looks like someone used a cork seal AND RTV. If you use the cork, use gasket tack to hold it, not RTV since it will allow the cork gasket to move when squished down.
I have always used RTV only, a 1/4" thick bead, let it skin over and then set the manifold on squarely. Again, RTV or cork (or rubber) not both.
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. 1965 C10 Panel, ![]() 1968 Chevy C10, Long, Fleetside, Hot Rod Hauler http://67-72chevytrucks.com/vboard/s...d.php?t=313233 SOLD 1965 Chevy C10, Long, Fleetside, Hot Rod C10 http://67-72chevytrucks.com/vboard/s...d.php?t=415702 SOLD We were given two ears and one mouth for a reason... listen twice as much and speak half as often... |
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#6 |
newly minted old timer
Join Date: Dec 1999
Location: Hudson WI
Posts: 3,511
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Re: some news on no power saga.
think everyone has missed the point.
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____________________________________________ 72 c20 longhorn 65k org miles and counting! 69 k10 Suburban |
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#7 |
Never Ending Projects
Join Date: Jul 2006
Location: San Diego, CA
Posts: 3,836
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Re: some news on no power saga.
And what point it that???
You said you think you had a vacuum leak that would happen under load. Since your timing chain looks good, looking at your pics of the intake gasket, it looks like a major vacuum leak would have been happening. I offered info about what I thought was wrong, using RTV and the cork gasket, which would definitely cause the gasket to slip, possibly causing the afore mentioned problem. If I am missing the point, you need to tell us what the real point is then???
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. 1965 C10 Panel, ![]() 1968 Chevy C10, Long, Fleetside, Hot Rod Hauler http://67-72chevytrucks.com/vboard/s...d.php?t=313233 SOLD 1965 Chevy C10, Long, Fleetside, Hot Rod C10 http://67-72chevytrucks.com/vboard/s...d.php?t=415702 SOLD We were given two ears and one mouth for a reason... listen twice as much and speak half as often... |
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#8 |
Registered User
Join Date: May 2005
Location: PA
Posts: 2,696
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Re: some news on no power saga.
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#9 | |
Registered User
Join Date: May 2005
Location: PA
Posts: 2,696
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Re: some news on no power saga.
Quote:
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#10 | |
Registered User
Join Date: May 2005
Location: PA
Posts: 2,696
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Re: some news on no power saga.
Quote:
That's like saying you have a vacuum leak from your dipstick. |
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#11 |
Registered User
Join Date: May 2005
Location: PA
Posts: 2,696
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Re: some news on no power saga.
I always like to keep things basic... so I'll throw this out there anyway
![]() From your first pic -- you do realize with the dots in that position that you are at TDC of #6, not #1, right? |
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#12 |
Registered User
Join Date: May 2005
Location: PA
Posts: 2,696
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Re: some news on no power saga.
Ok, one last post, sorry for all these ideas coming to me in spurts...
Get a new balancer, turn crank one full turn (so both dots are pointing straight up, putting you at TDC #1...). Use a piston stop or some other method of verifying your timing marks. Drop in the dist, so the rotor is aiming towards the #1 cylinder, verify your plug wires aren't crossed, and set your timing with a light (about 36 deg. @ 3,000RPM). Are you sure the cam isn't flat? I didn't know mine was bad until I spun the cam around and watched the lifters. |
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#13 |
chrome makes it go FASTER!
Join Date: Feb 2007
Location: Cleveland Tennessee
Posts: 2,884
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Re: some news on no power saga.
I guess your point is - You are very happy that the problem can be resolved inexpensively?
> > Or maybe this_ i have argued a few times with people far more knowledgeable than me with motors that i thought the problem was a vacuum leak. i always got a..no no no,, wouldn’t cause that.. And you were right all along?
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She can't cook and she won't clean. But she looks good in a skirt and she brings me beer. She can stay for now. EDIT:: But she left me anyway, So forget her. 1962 GMC Stepside V6 4 speed My rolling resto thread http://67-72chevytrucks.com/vboard/s...d.php?t=324226 My old farm truck http://67-72chevytrucks.com/vboard/s...=1#post3465005 |
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#14 |
mini truck racer
Join Date: Aug 2006
Location: Baytown , texas
Posts: 3,010
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Re: some news on no power saga.
I guess i missed the point also , but you can take a punch and divot the gasket surface on the underside of the intake. This will give it something to bite the gasket if it keeps giving you problems
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1949 5-window 1969 Camaro 1976 Chevy Luv yellow 1978 Chevy Luv Blue 1976 Chevy Luv Black 1979 Firebird Flooded in Harvey 1999 F350 Dually 2005 GMC Sierra 4.8 RCSB 2014 Explorer (wifes) My build :http://67-72chevytrucks.com/vboard/s...d.php?t=399148 Build #2: http://67-72chevytrucks.com/vboard/s...d.php?t=653583 Last edited by hotrod 80; 11-09-2009 at 03:36 PM. |
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#15 |
Has more rust than truck...
Join Date: Apr 2005
Location: Ivanhoe, MN
Posts: 2,421
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Re: some news on no power saga.
I agree with Jim on this one, The gasket you are showing has no effect on vacuum it is there to keep oil in the lifter valley. Also if you look at the #1cyl lifters one of them is slightly open when they should both be completely closed (dots lined up on timing set= #1 at TDC). This means one of two things, 1, the timing set is junk/or the crank gear is one of the adjustable kinds and is not set to 0deg or 2, the cam is junk. Hope this helps.
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#16 |
Registered User
Join Date: May 2005
Location: PA
Posts: 2,696
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Re: some news on no power saga.
Double post...
Last edited by Jim_PA; 11-10-2009 at 11:28 AM. Reason: somehow made a double post... |
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#17 | |
Registered User
Join Date: May 2005
Location: PA
Posts: 2,696
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Re: some news on no power saga.
Quote:
When the dots are both facing "up" it's at #1 TDC. But you are right -- the only thing his bad seal will do is leak oil... not a source of a vacuum leak. |
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#18 | |
Has more rust than truck...
Join Date: Apr 2005
Location: Ivanhoe, MN
Posts: 2,421
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Re: some news on no power saga.
Quote:
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#19 |
Registered User
Join Date: May 2005
Location: PA
Posts: 2,696
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Re: some news on no power saga.
Intuition tells us it's the other way around, but we can't all be as smart as the engineers
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#20 |
Registered User
![]() Join Date: Sep 2009
Location: Prescott Valley AZ
Posts: 345
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Re: some news on no power saga.
As far as dots on the cam gear is concerned, it can be installed either way, both #1 and #6 are at TDC. Just be sure #1 is on compression stroke when installing dist. In my experience cam gears that are marked to go in up position do not line up well in the down position. This was probibly off subject. Now to the subject, while the intake is off look at the side gaskets for proper fit, thats where you would find a vacuum leak. Every one keeps saying that a blown end seal would not cause a vac. leak but if the seal was bad enough I don't think the PVC system would work right, hense a vac. leak occurs.
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#21 |
Active Member
![]() Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
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Re: some news on no power saga.
A vacuum leak should be more obvious during idle when you have the highest vacuum in the intake. As you increase the opening in the carburetor butterfly valve, you get more air and that decreases the vacuum.
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