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Joined: Nov 2015
Posts: 239
Backyard Mechanic
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OP
Backyard Mechanic
Joined: Nov 2015
Posts: 239 |
I am getting different opinions on how much vacuum I should be getting on my freshly rebuilt 1954 235 powerglide engine. Some say that I should be getting 17-21 inches. I can only get about 15 inches at the wiper port on the manifold. I set the timing to get the greatest vacuum, which is fully advanced. This sets the timing on the mark on the flex plate. (not the BB). BTW I live at about 2500' altitude.
Is this something I should even worry about?
Any ideas or suggestions?
1951 styline deluxe sport coupe w/54 engine and power glide
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Joined: Nov 2001
Posts: 19,758 Likes: 63
ChatMaster - 15,000
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ChatMaster - 15,000
Joined: Nov 2001
Posts: 19,758 Likes: 63 |
The loss of atmospheric pressure at 2500 feet is approx. 1.5 psig compared to seal level. That would give you an equivalent sea level pressure of 16.5 for your engine. I think the range 17-21 psig is the normal range for differences in displacement, stroke and rpm (which all will affect the measurement).
How Sweet the roar of a Chevy four!
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
Thr vacumm may increase after the rings seal better with use.
Gene Schneider
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