how do I know the power valves working?

[grumpyvette]

Grumpy??
how do I know the carbs power valves working?

why not use the correct test tools?
as a general rule you take engines cruise vacuum at about 2000 rpm average it with the idle vacume , lets say ones 17 " of vacuum and the others 19" you take the average which in this case would be 18" add about 2" to the average so you have 20" divide that in 1/2 and youll pick the next higher power valve or in this case a #10.5
lets say the readings are 9" and 11" average is 10" add 2" get 12" , 1/2 thats 6" so you start with a #6.5
http://forums.holley.com/entry.php?430-Holley-Power-Valve-Tuning
theres a vacuum number on the valve test it!
http://forums.holley.com/attachment.php?attachmentid=264&d=1340225776
http://documents.holley.com/techlibrary_power_valves.pdf
http://www.summitracing.com/parts/MOR-62295/?rtype=10

http://www.mityvac.com/pages/products_hvp.asp

 

[Grumpy]

$41 to check a power valve? I have never actually found a blown one, and for $9 I'll put a new one in.

yeah! $41 plus the vacuum test pump and your up near $70 which to most guys I'm sure seems rather high, but its a valid tool and a one time expense, its not how far the valve moves, its if it seals and opens when its supposed to that matters and verifying its not leaking when closed or restrictive once open, but the vacuum pump hand tool has other uses and actually knowing that the power valve does or does not function at the listed vacuum rating and is not leaking or failing to seal is well worth the one time cost (at least to me)and if you tune cars you need several power valves so you also need to know they both function and function at the intended vacuum reading to tune the car effectively, and you also need to test that they don,t leak.
and a bit of clear plastic hose with the vacuum hand tool plus the correct container makes bleeding brakes a easy one person job

beats bleeding brakes the old way with two guys

years ago I purchased two of these assortment packs when they cost about 1/2 the current price , Ive tried hard to keep 4 jets in each size in inventory as I use those, 72 jets in assorted sizes for $52 is still a good deal , and it gets better if you buy the pack or two of them, when summit posts a discount code
I don,t know how anyone else feels but I like having the correct parts to tune on hand
http://www.summitracing.com/parts/hly-36-181