1975 Q-Jet Aux. Power Piston &Rod - ClassicOldsmobile.com

Go Back  ClassicOldsmobile.com > Repair & Restoration > Engine > Small Blocks
1975 Q-Jet Aux. Power Piston &Rod >

1975 Q-Jet Aux. Power Piston &Rod

1975 Q-Jet Aux. Power Piston &Rod

Old January 13th, 2019, 05:48 PM
  #1  
Registered User
Thread Starter
 
Tuffnut's Avatar
 
Join Date: Jan 2011
Location: Paris, Ontario, Canada
Posts: 33
1975 Q-Jet Aux. Power Piston &Rod

I have 1975 Q-Jet 7045250 which comes with an aneroid and auxiliary power piston & rod/jet shown in the picture with the blue arrows.
It came with .067 jets & .041 rods. Today I put new .071 jets with new .044 rods to make it a little more rich at cruise & WOT. I'm running lean because of my engine mods.



With the auxiliary piston first in the primary circuit, will it allow more gas through to the primary dual rods when needed?

I read that these 1975 carbs are a pain to tune because of this set up.

Can I remove the aneroid like they in 76 & 77 and remove the aux. piston & rod and plug both cavities?
I would like to keep the same carb if possible.

Very difficult to find info on the any help would be appreciated.

Thanks

Jeff
Tuffnut is offline  
Old January 14th, 2019, 05:23 AM
  #2  
Registered User
 
olds 307 and 403's Avatar
 
Join Date: Dec 2006
Location: Melville, Saskatchewan
Posts: 4,615
I know Cliff Ruggles mentions it can be plugged in the book. I believe he said it can be plugged and eliminated. I believe the rod adds fuel throughout the whole rpm range. It makes sense .067" is tiny jets for a 350, even 71 jets are probably a bit on the lean side. Contact Cliff Ruggles if you are unsure. I can't see why a plug can't be made and the assembly removed.
olds 307 and 403 is offline  
Old January 14th, 2019, 07:45 AM
  #3  
Registered User
Thread Starter
 
Tuffnut's Avatar
 
Join Date: Jan 2011
Location: Paris, Ontario, Canada
Posts: 33
Thanks for the response. I bought Cliff's book, it talks about it briefly. It says they can be very hard to tune. It doesn't say how to remove the aneroid and how to plug the aux. piston and plug the aux. rod.
I want to test my set up when the weather breaks in a few months with .071 jet & .044 rod. Like you say, I may need to go to .072 jet. I'm .001" closer to range that Cliff wants between the jet & rod at .027 from .026" .
Plus I'm more rich at low end and WOT, it still may not be enough. May have to go the .072 jet with the .044 rod. Would put me .028" difference 15% more fuel at cruise and 18% more at WOT.
I was worried the Aux. rod was restricting the fuel with the new jet/rod set up? I thought I read somewhere the aux. rod meters the fuel at low RPM. I have a slight hesitation around 1300-1500 rpm and it clears out runs real well even at idle.

Jeff
Tuffnut is offline  
Old January 14th, 2019, 08:06 AM
  #4  
Registered User
 
OLDSter Ralph's Avatar
 
Join Date: Sep 2017
Location: St. Paul Minnesota
Posts: 960
Why not just get a different year carb without all that garbage ?
OLDSter Ralph is online now  
Old January 14th, 2019, 09:09 AM
  #5  
Registered User
Thread Starter
 
Tuffnut's Avatar
 
Join Date: Jan 2011
Location: Paris, Ontario, Canada
Posts: 33
I may yet. I know this carb was working great before the engine mods. It was rebuilt 4 years ago. The throttle bracket is modified on it as well on this carb for the 200R4 piano wire attachment. I didn't really want to spend another $400 for a carb or more without tinkering first. I don't want to give up that easy yet...

Jeff
Tuffnut is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
1968_Post
Big Blocks
3
October 12th, 2016 02:09 PM
59Rocket
Electrical
4
June 15th, 2016 04:36 AM
Sampson
Transmission
4
January 13th, 2014 07:36 AM
84oldsDelta88
Transmission
1
March 30th, 2011 09:16 PM
ELECMAN
General Discussion
2
August 17th, 2010 07:13 PM


Thread Tools
Search this Thread
Quick Reply: 1975 Q-Jet Aux. Power Piston &Rod


Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.