Quadrajet Primary Shaft Bushings

hey mister · Dec 9, 2024

JD Miller said:
Why never?
Is that because of sticky goo and hard varnish residue?
Ive seen a WD40 dried varnish when wd40 dries on guns

WD40 is a fish oil based product. Over time it decays and stinks like tuna boat.
If ya doubt me, spray a few of your wrenches with it and close it up in a toolbox. Come back in the spring and be ready to gag.
There are plenty of other penetrating options out there.
In fact, I would use 50/50 of ATF and Acetone as a good penetrating solution. I've seen cast iron piston rings in steam engines broke loose using that 50/50.
Good stuff.

hey mister · Dec 9, 2024

JD Miller said:
I didnt think you can even get that stuff anymore. I live in the boonies and cant get stuff like that anyway
I heard years ago it is all environmentally safe and weak and doesnt work very good. And the price is outrages

Bought a gallon yesterday.
You can order it from Summit...I think.
It was $40. @ Oreilys.

JD Miller · Dec 9, 2024

I dont doubt you on the "dont use spray lube".
Just wondered why.
I dont use it anyway. WD40 turns to a varnish

I have acetone, and Id rather buy another gallon of acetone and use that, than enviro friendly weak carb cleaner gallon

Well this thread is getting me motivated to finish final cleaning and finish rebuilding my q-jet, that got put on the back burner. I do several cleaning sessions cause its never clean enough for me, "Too Picky"

vr1967 · Dec 9, 2024

hey mister said:
If they leak, I can machine new plugs and use a polyester epoxy to seal.

That’s a lot of work to machine plugs when, once removed, we tapped the primary ones for 10-32 plugs and Marine Tex, or Devcon epoxy the threads.

Even Cliff has suggested that over the years.

Guess I’m a dinosaur though, as I was doing that in the 80s and early 90s.

JD Miller · Dec 9, 2024

Was reading HAMB about carb soak cleaners. Few people use Awesome, said it works great... I Had a little spray bottle of the stuff and tried a little spray with a tooth brush scrub on my top plate black carbon. Wow! that stuff works great. Rinsed with hot water and blew dry .
Im going to to the $.99cent store in the next town down river and pick up a gallon or two and do a bucket soak

You must be registered for see images attach

hey mister · Dec 10, 2024

vr1967 said:
That’s a lot of work to machine plugs when, once removed, we tapped the primary ones for 10-32 plugs and Marine Tex, or Devcon epoxy the threads.

Even Cliff has suggested that over the years.

Guess I’m a dinosaur though, as I was doing that in the 80s and early 90s.

I guess it's all in your perspective.
Something like that, I don't consider work. It's a fun little project to fix something.

hey mister · Dec 10, 2024

This is the setup on the mill to bore and ream for the bushing.
Prior to machining, I checked the bore and shaft with gauges and a mic.
The shaft is 0.311.
The bores checked 0.318.
A nice slip fit for a rotating shaft is 0.0015-0.002.
And at 0.002 end, you start to feel play in the fit.
My shaft and bore had a "stand back and toss the shaft in" clearance. (.007)
Had I installed a carb rebuild kit and bolted the carb on, it would have never run right. And just to be clear, you can easily see daylight through a .003 gap.
If light is getting through, so is air.

YakkoWarner · Dec 10, 2024

hey mister said:
This is the setup on the mill to bore and ream for the bushing.
Prior to machining, I checked the bore and shaft with gauges and a mic.
The shaft is 0.311.
The bores checked 0.318.
A nice slip fit for a rotating shaft is 0.0015-0.002.
And at 0.002 end, you start to feel play in the fit.
My shaft and bore had a "stand back and toss the shaft in" clearance. (.007)
Had I installed a carb rebuild kit and bolted the carb on, it would have never run right. And just to be clear, you can easily see daylight through a .003 gap.
If light is getting through, so is air.

I think I need to get this process done on my TBI throttle body - there is definite play on the butterfly shaft. This is also a common problem on the 50 year old SU side-drafters found on British cars (which I also need to get done).

hey mister · Dec 10, 2024

YakkoWarner said:
I think I need to get this process done on my TBI throttle body - there is definite play on the butterfly shaft. This is also a common problem on the 50 year old SU side-drafters found on British cars (which I also need to get done).

Motorcycle carbs were prone to this as well.
In fact the Goldwings had this issue. But if you were a tad ingenous, soft washers could be sandwiched between the throttle body and linkage, on the butterfly shaft. It was a bandaid for a terminal problem.
The main issue is anytime you have a steel rotating shaft in an aluminum housing, in a dirty enviroment, wear is going to happen.
Bushings are the fix, if ya got the room to put em in.

hey mister · Dec 10, 2024

So here is one mod I like and I got the idea from a rebuild kit I had seen.
The float seat had been slotted to assist in fuel flow.
So I cross drill mine, unless the rebuild kit comes with a modified seat.

YakkoWarner · Dec 11, 2024

hey mister said:
Motorcycle carbs were prone to this as well.
In fact the Goldwings had this issue. But if you were a tad ingenous, soft washers could be sandwiched between the throttle body and linkage, on the butterfly shaft. It was a bandaid for a terminal problem.
The main issue is anytime you have a steel rotating shaft in an aluminum housing, in a dirty enviroment, wear is going to happen.
Bushings are the fix, if ya got the room to put em in.

I saw a video of an ingenious guy from somewhere in the Middle East who found valve stem seals that could be used as a stopgap on the SU side drafters.

I want to do bushing in both my Suburban's TBI and the British SUs, but I don't want to risk destroying my only existing ones in the attempt, so the plan is to buy other worn out ones and attempt to rebuild them, and if successful swap over. Downside to that plan is that the bushing kits are expensive and unfortunately a milling machine is way out of my budget.

hey mister · Dec 11, 2024

YakkoWarner said:
I saw a video of an ingenious guy from somewhere in the Middle East who found valve stem seals that could be used as a stopgap on the SU side drafters.

I want to do bushing in both my Suburban's TBI and the British SUs, but I don't want to risk destroying my only existing ones in the attempt, so the plan is to buy other worn out ones and attempt to rebuild them, and if successful swap over. Downside to that plan is that the bushing kits are expensive and unfortunately a milling machine is way out of my budget.

Oh that is brilliant. I would of never thought of valve stem seals..brilliant.

I am offering a service to do the bushings @ $50.+ s/h.
Search my other posts.

hey mister · Dec 11, 2024

YakkoWarner said:
I saw a video of an ingenious guy from somewhere in the Middle East who found valve stem seals that could be used as a stopgap on the SU side drafters.

I want to do bushing in both my Suburban's TBI and the British SUs, but I don't want to risk destroying my only existing ones in the attempt, so the plan is to buy other worn out ones and attempt to rebuild them, and if successful swap over. Downside to that plan is that the bushing kits are expensive and unfortunately a milling machine is way out of my budget.

From what I can tell from pictures, there seem to be enuf meat to install bushings on the SU's.
The real issue would be, are there bushings availavle from a bearing waerhouse.
I did see a SzU carb on fleabay for $45.

JD Miller · Dec 11, 2024

hey mister said:
This is the setup on the mill to bore and ream for the bushing.
Prior to machining, I checked the bore and shaft with gauges and a mic.
The shaft is 0.311.
The bores checked 0.318.
A nice slip fit for a rotating shaft is 0.0015-0.002.
And at 0.002 end, you start to feel play in the fit.
My shaft and bore had a "stand back and toss the shaft in" clearance. (.007)
Had I installed a carb rebuild kit and bolted the carb on, it would have never run right. And just to be clear, you can easily see daylight through a .003 gap.
If light is getting through, so is air.

.007 clearance? OK so what happened ? Why was there so much clearance with the new bushings and shaft? Was the shaft worn junk? How did you fix that? New shaft available :think:

Every seen that video of, Jeff Bradshaw of Elderly Iron, rapping and tying thread around a Carburetor shaft to fix loose shaft vacuum leak?

legopnuematic · Dec 11, 2024

@JD Miller if I’m reading it right, the .007 clearance was pre machining/bushing install.

Quadrajet Primary Shaft Bushings

hey mister

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