View unanswered posts | View active topics It is currently Sun Jun 25, 2017 6:30 pm



Reply to topic  [ 5 posts ] 
 Seperating out Power Piston Springs 
Author Message

Joined: Tue Aug 23, 2016 10:38 am
Posts: 84
Well, after tearing apart 7 q-jets with most of them being spares I have built up an amazingly different group of power piston springs. For my mild build I doubt I will need a super soft one but it would be handy to have an idea of the point where each overcomes a specific vacuum. I was thinking of tapping a spare body power piston cavity for a vacuum nipple and attaching it to my car which currently has 20in/hg at idle. If I used 2 tees, first a tee with a needle valve, then closer to the carb body a second tee to plumb in my vac gauge. Then I could slowly crack the needle valve allowing it to bleed vac until the power piston moves.

Has anyone done anything like this?


Tue Sep 20, 2016 2:14 pm
Profile

Joined: Sat Mar 29, 2014 10:27 am
Posts: 42
Try this:

http://www.nastyz28.com/forum/showthread.php?t=216888


Tue Sep 20, 2016 3:22 pm
Profile

Joined: Tue Aug 23, 2016 10:38 am
Posts: 84
Ya, I saw that. I wonder if we should simply be rating springs by the vac they move or if we should also consider the rate at which they over come the vac. Like a mechanical advance spring. It has a rate and not simply a point of start. I wonder if it would be worth figuring the force the vac applies to the power piston are and figure the spring rates or simply track movement. Probably have to use a spring force calculator to get K though, I doubt if I can find that light of spring tester.


Wed Sep 21, 2016 5:14 pm
Profile

Joined: Tue Aug 23, 2016 10:38 am
Posts: 84
This is one of the reasons I didn't understand Roe's suggestion to cut a spring (though I did it in my 2gc). Spring force has to do with active coils and coil thickness. When you cut a spring it will actually have a greater rate at the same level of compression because there will be less active coils.


Wed Sep 21, 2016 5:26 pm
Profile

Joined: Sat Aug 24, 2013 7:57 pm
Posts: 152
Location: Frostburg, MD
Too bad the z28 fellow didn't test to something like .200" movement.


Wed Sep 21, 2016 9:50 pm
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 5 posts ] 

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
Designed by ST Software for PTF.