Secondary metering rod size?

[74 Shortbed]

Hopefully he threw them in the trash and ordered a non-shiny Holley lol

LMAO....

 

[74 Shortbed]

Just typical Square Body Nuts... We answer the questions, give opinions, and give solutions to the problem.... Then it's on with some serious hijacking..

LOL...

 

[RustyPile]

Yankees yes, and as a Masshole that makes me an original rebel........ya know the Boston Tea Party thing. Lol

Yep... Pretty good little undercover operation.. For a while, folks thought the Indians did it.. People over in kalifornacation need to pull something like that.. Word is their taxes are higher than a pissed of cat's back.. lol.....

 

[3504boltmain]

Get rid of the EGR. Don't just disconnect it, toss the sumbitch in the trash and block off the ports in the manifold!!!!. Those things are nothing but a pain in the ass.. Their operation effects everything about an engine.. When faulty, they cause hesitation, poor performance, poor gas mileage, rough idle, stalling, pinging,-- just about everything..

I have always adjusted the air valve simply by "feel".. There's no way I could put in writing and explain the technique to someone with not a lot of "seat time" on Q-jets.. Air that's sucked in by the engine is what opens the valve.. That plunger/piston connected to the metering rod hanger is a power valve.. It needs the correct spring under it for proper operation..

90# of compression tells me either you have mighty big combustion chambers or the rings are quite leaky.. Either way, the volumetric efficiency of the engine is way down.. You need some resistance in the "delay" spring, don't want the valve just flopping open.. "In the green" manifold vacuum doesn't tell me much, give me a number.. With the vacuum advance disconnected the average SBC likes about 32 - 34 degrees total advance, Depending on the engine something between 4 -- 10 initial, with all of it in around 2,000 -- 2500 RPM.. With the vacuum advance connected, you should see around 46 - 50 degrees at light load cruise speeds.. With a healthy engine, you can push these numbers somewhat...

I have headers and The EGR seems to hold vacuum... But I agree, I'll see if I can fab up a block off plate. I also have some gasket material laying around too. The bolts are probably very rusted and I'm guessing I should soak them in some penetrating lube for a couple days first. I am also guessing with ALL of the other smog stuff removed other than PCV and charcoal canister, that the EGR is serving little or no purpose... other than a reduced engine performance if it is faulty and or routed incorrectly (Vacuum).

I will speak truthfully and say I have a LITTLE understanding of the functions of a carburetor and I am familiar ONLY with a Quadrajets mechanical and vacuum systems... This is the first SBC I've owned (sad to say) But I intend to learn a wealth of knowledge... So I thank all for the input.

I am not exactly sure how to test the power valve spring tension... I've heard a back up carburetor would be Ideal for this... I will look further into this...

The LT9's have low compression heads from what I hear. I do agree 90lbs is really low, but I am not sure how low for this configuration. I think I recall "In the green" being in the green zone and good for an sbc's volume... But I'm not sure of the actual number... When the snow melts I'll look at all these things and report back on this stuff.

I have yanked and cranked that distributor all around... I have set it as low as 0 and as high as 38 degrees advance (initial with vac. advance disconnected) yes that low and that high, and all in between... Why? Because I got aggravated one day and decided that's what I was going to do. I've done it again and again since then too. It sits at 12 degrees initial as of now.

 

[Honky Kong jr]

Paper gasket material won’t hold up so well. It will get cooked and blow out. As far as carbs Holleys are so much simpler then a slobberjet. Shiny or not.

 

[RustyPile]

That’s a minimum lol

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The pit is 7’ wide

Might scare a few cows, but no people close enough to see that little ol' thang..

 

[Honky Kong jr]

Might scare a few cows, but no people close enough to see that little ol' thang..

I generally don’t do stuff for attention. I’m just me and do **** when the mood strikes.

 

[3504boltmain]

Hey, what happened to the metering rods.

WTF? I saw (1 new alert) when I got on here this morning... It took me back to page 4!!! I didn't see all this **** till after I started replying to one of y'all Yuk-Yuks from yesterday!!! A damn party popped off while I was out getting my driveshaft lubricated last night!!!

 

[3504boltmain]

Paper gasket material won’t hold up so well. It will get cooked and blow out. As far as carbs Holleys are so much simpler then a slobberjet. Shiny or not.

I've used bubble gum on an engine seal (you could see the connecting arm moving back and fourth) on a leaf blower... It worked... I don't know if it lasted... I don't care to use it...
Simple is as simple does right? heheh

 

[RustyPile]

I have headers and The EGR seems to hold vacuum... But I agree, I'll see if I can fab up a block off plate. I also have some gasket material laying around too. The bolts are probably very rusted and I'm guessing I should soak them in some penetrating lube for a couple days first. I am also guessing with ALL of the other smog stuff removed other than PCV and charcoal canister, that the EGR is serving little or no purpose... other than a reduced engine performance if it is faulty and or routed incorrectly (Vacuum).

I will speak truthfully and say I have a LITTLE understanding of the functions of a carburetor and I am familiar ONLY with a Quadrajets mechanical and vacuum systems... This is the first SBC I've owned (sad to say) But I intend to learn a wealth of knowledge... So I thank all for the input.

I am not exactly sure how to test the power valve spring tension... I've heard a back up carburetor would be Ideal for this... I will look further into this...

The LT9's have low compression heads from what I hear. I do agree 90lbs is really low, but I am not sure how low for this configuration. I think I recall "In the green" being in the green zone and good for an sbc's volume... But I'm not sure of the actual number... When the snow melts I'll look at all these things and report back on this stuff.

I have yanked and cranked that distributor all around... I have set it as low as 0 and as high as 38 degrees advance (initial with vac. advance disconnected) yes that low and that high, and all in between... Why? Because I got aggravated one day and decided that's what I was going to do. I've done it again and again since then too. It sits at 12 degrees initial as of now.

I'm talking STOCK low performance engines such as LT9s here. Some of what I'm about to say doesn't apply to all engines..

Headers don't magically convert a 160 Hp engine into a high output one.. Mid 80s SBC especially the truck engines were bad about cams going flat.. Have you mounted a dial indicator and checked this?? The very first thing you need to address is that low compression.. The LT9 truck engines start off at 8.5 (or something close to that) C. R... They need every ounce of compression possible..

You mentioned something about the gasket interfering with the power valve plunger?? A proper gasket that's properly installed will NOT interfere.. Never, ever sand or scrape the power valve plunger.. Same thing applies to the bore it sits in.. It's vacuum operated and any change in it's O.D. (wall clearance) will affect it's operation.. As with all carburetor parts, soak the damn thing in industrial strength parts cleaner solution..

There is a way to check the spring, but as long as it's not broken or damaged, or been replaced by something not intended for that purpose, it will probably be ok.. The metering rod taper, shape, and general configuration are very critical as their purpose is to precisely meter the fuel.. Even the installed height is just as critical.. The worst thing a person can do is jack with the hanger and rods..

No disrespect meant here, but I think your problem didn't originally lay with the carburetor.. But the "experiments" you conducted on it have created more problems and only made the problem worse..

 

[RustyPile]

WTF? I saw (1 new alert) when I got on here this morning... It took me back to page 4!!! I didn't see all this **** till after I started replying to one of y'all Yuk-Yuks from yesterday!!! A damn party popped off while I was out getting my driveshaft lubricated last night!!!

That'll learn ya, dern ya.. See what happens when you run out the door....

 

[3504boltmain]

I'm talking STOCK low performance engines such as LT9s here. Some of what I'm about to say doesn't apply to all engines..

Headers don't magically convert a 160 Hp engine into a high output one.. Mid 80s SBC especially the truck engines were bad about cams going flat.. Have you mounted a dial indicator and checked this?? The very first thing you need to address is that low compression.. The LT9 truck engines start off at 8.5 (or something close to that) C. R... They need every ounce of compression possible..

You mentioned something about the gasket interfering with the power valve plunger?? A proper gasket that's properly installed will NOT interfere.. Never, ever sand or scrape the power valve plunger.. Same thing applies to the bore it sits in.. It's vacuum operated and any change in it's O.D. (wall clearance) will affect it's operation.. As with all carburetor parts, soak the damn thing in industrial strength parts cleaner solution..

There is a way to check the spring, but as long as it's not broken or damaged, or been replaced by something not intended for that purpose, it will probably be ok.. The metering rod taper, shape, and general configuration are very critical as their purpose is to precisely meter the fuel.. Even the installed height is just as critical.. The worst thing a person can do is jack with the hanger and rods..

No disrespect meant here, but I think your problem didn't originally lay with the carburetor.. But the "experiments" you conducted on it have created more problems and only made the problem worse..

Oh, I can only agree with making the problem worse... I can put everything back to normal though... I think one of the guys called me "Secondary Rods"... I guess I should change my name haha! I know the hand made rods were junk when I made them, and I'll put it back... I was just being bored. Anyway, Yeah, I am considering pulling the carb back out and inspecting the power valve and comparing it to others. The problem I thought I saw is that it didn't seem to seat correctly (It slid in and plunged, but something seemed off)... Like it was too tall and the gasket couldn't get around it to well... and it was a nightmare holding it and the accelerator pump down to put the next part on (air horn?).
Before I do that I should go find myself a dial indicator... I think you are probably right on this. Come to think about it, this truck is so jacked up that I have considered already to scrap it but keep the block and trans. The bed, floor boards, kick panels and fenders all have rust holes in them... Even the frame near the rear wheels has a hole where an exhaust hanger used to be. I planed to pick up new panels for the rot and get some plate steel to reinforce the frame... But if the cam is flat there's no reason to continue dikin with this truck.
The hanger was bent to hell when I bought the truck... I didn't find this out till I went to go disassemble the carb... I did my best to straighten it.
What should I google to figure out how to check the cam for flatness? I have no Idea how to do this. I did also adjust the rockers... I used the "on the fly" method.

 

[RustyPile]

In all your explanations, you've not mentioned the accelerator pump operation.. When addressing a hesitation, it's the quickest and easiest to check.. Doesn't even require the first tool -- eyes and hands only..

You may have the wrong plunger or it's worn or damaged.. Without seeing it, I can't say.. When I build a Q-jet, I put the plunger and metering rods in before the gasket goes on.. There is a plastic ring at the top of the plunger just below the rod hanger.. With the plunger removed from it's bore, this plastic piece just flops around.. Drop the spring in, and install the plunger with the rods attached.. Then press on the hanger to shove the plunger to the bottom. Using a small screw driver, gently push the plastic piece into the bore until it's even with the top of the bore.. It should fit tight enough to hold the plunger in place.. The plunger should move up and down freely when finger pressure is applied to the top of the hanger.. The gasket fits around all this but none of it touches the hanger or rods..

We're zeroed in on the carburetor, but I honestly believe your problem lies elsewhere... If stuff has been bent, modified, exchanged with other parts, fabricated, or otherwise jacked with, I'd suggest you discard the carburetor and get another one..

 

[3504boltmain]

In all your explanations, you've not mentioned the accelerator pump operation.. When addressing a hesitation, it's the quickest and easiest to check.. Doesn't even require the first tool -- eyes and hands only..

You may have the wrong plunger or it's worn or damaged.. Without seeing it, I can't say.. When I build a Q-jet, I put the plunger and metering rods in before the gasket goes on.. There is a plastic ring at the top of the plunger just below the rod hanger.. With the plunger removed from it's bore, this plastic piece just flops around.. Drop the spring in, and install the plunger with the rods attached.. Then press on the hanger to shove the plunger to the bottom. Using a small screw driver, gently push the plastic piece into the bore until it's even with the top of the bore.. It should fit tight enough to hold the plunger in place.. The plunger should move up and down freely when finger pressure is applied to the top of the hanger.. The gasket fits around all this but none of it touches the hanger or rods..

We're zeroed in on the carburetor, but I honestly believe your problem lies elsewhere... If stuff has been bent, modified, exchanged with other parts, fabricated, or otherwise jacked with, I'd suggest you discard the carburetor and get another one..

Right on. With regard to the accelerator pump... I meant that putting the air horn on was a pain because of having to hold down the pump and power piston at the same time while installing the air horn.. The little plastic piece that you are talking about is what I think the issue was (maybe)... Because it was different from what I had seen in my learning to rebuild these. My installation was exactly as how you explain yours from what I can remember.
Also, I am looking at a Haynes manual on camshaft inspection... It looks legit on its explanation on how to inspect for a flat lobe. Chevy and Gm Trucks 67 thru 87. Pg. 2A-11 "Camshaft Lobe Lift Check".

 

[3504boltmain]

I will also go back and check out the low compression... I will check it again to make sure I did the test correctly in the first place. If I am correct, I think I remember seeing that it was a slow gradual rise to 90 psi after a few strokes. (4 or so) If all the piston rings are worn, I was guess this truck was pushed to the limit a few to many times.