thought you might get a kick out of this

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chachi
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Re: thought you might get a kick out of this

Post by chachi » Thu Jun 16, 2011 5:37 pm

...
1974 transporter panel, 2.0 dual solex
1991 vanagon NAHT, RJE 2.3

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Westy78
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Re: thought you might get a kick out of this

Post by Westy78 » Thu Jun 16, 2011 7:55 pm

chachi wrote:
Westy78 wrote:Am I missing something? How are you doing a compression test with no rockers and push rods?

rockers and push rods actuate the valves, but you don't need them to open and close. the crank will actuate the piston so you'll get that compression even without them.
Of course. I was thinking backwards. :blackeye: I should've got that faster since I built my own engine.
Chorizo, it's what's for breakfast.

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RSorak 71Westy
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Re: thought you might get a kick out of this

Post by RSorak 71Westy » Sun Jun 19, 2011 9:50 am

but you don't need them to open and close.
To get an accurate compression test result you DO need them to open and close.!!!!
Take care,
Rick
Stock 1600 w/dual Solex 34's and header. mildly ported heads and EMPI elephant's feet. SVDA W/pertronix. 73 Thing has been sold. BTW I am a pro wrench have been fixing cars for living for over 30 yrs.

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chachi
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Re: thought you might get a kick out of this

Post by chachi » Sun Jun 19, 2011 11:59 pm

...
1974 transporter panel, 2.0 dual solex
1991 vanagon NAHT, RJE 2.3

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chachi
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Re: thought you might get a kick out of this

Post by chachi » Mon Jun 20, 2011 12:09 am

...
1974 transporter panel, 2.0 dual solex
1991 vanagon NAHT, RJE 2.3

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Amskeptic
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Re: thought you might get a kick out of this

Post by Amskeptic » Mon Jun 20, 2011 5:10 am

You cannot get compression results with no valves. The cylinders need that intake fill and they need that exhaust emptying to get any movement of air.
Otherwise you just discover if the rings like to blow-by more on the down or the up.
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Chloe - 70 bus . . . 217,593 miles
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Amskeptic
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Re: thought you might get a kick out of this

Post by Amskeptic » Mon Jun 20, 2011 5:13 am

Westy78 wrote:
chachi wrote:
Westy78 wrote:Am I missing something? How are you doing a compression test with no rockers and push rods?

rockers and push rods actuate the valves, but you don't need them to open and close. the crank will actuate the piston so you'll get that compression even without them.
Of course. I was thinking backwards. :blackeye: I should've got that faster since I built my own engine.
Good eye, Westy78! There is no compression test without proper valve actuation.
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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chachi
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Re: thought you might get a kick out of this

Post by chachi » Tue Jun 21, 2011 6:59 pm

...
1974 transporter panel, 2.0 dual solex
1991 vanagon NAHT, RJE 2.3

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Gypsie
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Re: thought you might get a kick out of this

Post by Gypsie » Wed Jun 22, 2011 4:56 pm

If you are not filling the chamber with air you cannot see how much it will hold in when it compresses or at least not an accurate assessment of compression.

When the piston is moving away from the head a vacuum is forming if the valves are not opening. then when it goes to compress it will pass the vacuum point and start compressing but by that time you won't have enough travel to create an accurate reading.
So it all started when I wanted to get better gas mileage....

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Bleyseng
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Re: thought you might get a kick out of this

Post by Bleyseng » Thu Jun 23, 2011 7:16 am

if you have not installed the rockers etc then just do a leakdown test but without the rings being seated its kinda worthless. Just like a compression test without the valves opening and closing plus the engine should be warm.
Geoff
77 Sage Green Westy- CS 2.0L-160,000 miles
70 Ghia vert, black, stock 1600SP,- 139,000 miles,
76 914 2.1L-Nepal Orange- 160,000+ miles
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