Quote:
Originally Posted by Argess
2/ Power valves from each car were not "blown". However, they had a microscopic stamp ( number about 1/32" high...very small) on the brass piece that holds the spring that said 5.5. Don't genuine Holley Power Valves have the number on the aluminum part you put the wrench on?
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no. the only number is on the back & very tiny
Quote:
Originally Posted by Argess
3/ Testing with a Mighty Vac showed operation around 3 in Hg for both valves. Mighty vac was checked against another guage and shown to be accurate.
Thank-you.
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a mitty vac is not an accurate way to check. the power valve.
Quote:
Originally Posted by Argess
Now, for a light car that has a 290 adv Cam, and I am getting close to 16 in Hg with my current intial ignition timing at idle. According to what I read, shouldn't 8.5 Power Valves be a better choice? According to my 1966 Ford Manual, the twin Holley set-up used #85 PVs.
2/ If I purchase replacements, wouldn't 8.5s be a better choice?
Thank-you.
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your idle vacuum is not the number to go by. What is the vacuum at cruising with a very light load, like up a slight grade ? For example, if that number is 9, then a 6.5 is what you want for a power valve rating.
also, your float level is very important. Too high can cause a multitude of problems. Be sure all the floats are set the same. A little low is much better than a little high. Unless you are on the Bonneville Salt Flats
Z. Ray