What have you done to your square lately??

[ChuckN]

How perfect does it need to be? Would you actually know it wasn't right if you did not have that new monitoring system in place?

I know that we all want our trucks to run the best that they can but sometimes close enough is...well, close enough. Of course if you can feel it stumbling or bogging or whatever it is doing then you would absolutely need to fix it. I would guess that there used to be a bunch of carbureted vehicles that were not Perfect at all throttle openings or RPM. There are still quite a few out there actually, I can smell them at pretty much every car show I attend.

Well, it’s “not-perfect “ enough that it falls on it’s face until the power mode finally catches up with it.

 

[ChuckN]

@Redfish think I’ll spray around and double check for vacuum leaks, but it seems unlikely that the one spot it runs lean and everything else is good. Time to go back to the drawing board.

There is a procedure that a guy can do to partially decrease air flow to the bleeds- but it’s a little witchcraft-like and I’ll probably give Edelbrock a call before I do that.

 

[legopnuematic]

Well, it’s “not-perfect “ enough that it falls on it’s face until the power mode finally catches up with it.

What CFM carb is on your truck? Engine specs? Heads, cam, intake, etc? Base timing? Are you using a vacuum gauge along with the wideband?

What can happen is too big of a cam and not enough engine, or too big of a carb can create symptoms like you describe. Off idle lean spot.

What happens is when the throttle blades open, there is too much air and not enough response to properly draw fuel and atomize it. Low velocity.

Then begins the attempt to correct it by adding more and more fuel from the accelerator pump typically.

Just something to consider. Also, remember carbs are pretty forgiving, ignition is not. Idle speed is to be set by timing, then using the idle speed screw to fine adjust. More base timing will increase idle speed, allowing idle speed screw to be lowered, keeping things in the idle circuits at idle.

 

[Sgt Gus]

Same.

Mine are 20's, just fyi.

 

[ChuckN]

What CFM carb is on your truck? Engine specs? Heads, cam, intake, etc? Base timing? Are you using a vacuum gauge along with the wideband?

What can happen is too big of a cam and not enough engine, or too big of a carb can create symptoms like you describe. Off idle lean spot.

What happens is when the throttle blades open, there is too much air and not enough response to properly draw fuel and atomize it. Low velocity.

Then begins the attempt to correct it by adding more and more fuel from the accelerator pump typically.

Just something to consider. Also, remember carbs are pretty forgiving, ignition is not. Idle speed is to be set by timing, then using the idle speed screw to fine adjust. More base timing will increase idle speed, allowing idle speed screw to be lowered, keeping things in the idle circuits at idle.

Hey, well, maybe you can shed some light.

355 SBC, about 10:1. Cam unknown, runs about 15-16 mmHg at 750 rpm. Timing is set to 35 total at about 3000, initial is 14 deg. Edelbrock 650 CFM AVS2. 461 60s era Camelhump heads.

I bought the truck with the engine already set in and not running, fresh rebuild. The guy I bought it from (of course) swore he was confident that he knew what it was but then confessed that he bought it from someone else already done and didn’t know what was in it.

It may very well need a smaller cam, but I can’t vouch for whatever is in there. Truth gone ahead and been told, I’d planned on getting some 195cc AFR heads this year and while I had the heads off, pulling the cam and looking at the number to see what it is.

I do have a dial indicator that I haven’t used yet, but I don’t think it would tell me any useful information that would be accurate enough.

 

[TotalyHucked]

Same.

I'm just getting caught back up here on the gas tank discussion. Are you saying your senders are under the bed? Every shortbed 16 gallon tank I've ever seen has the sender under the cab like soundmound's truck. Mine are that way as well. Only the longbed trucks got had the sender under the bed (20 gal tank, not sure where it landed on longbeds optioned with the 16gal tank/tanks)

 

[TotalyHucked]

Hey, well, maybe you can shed some light.

355 SBC, about 10:1. Cam unknown, runs about 15-16 mmHg at 750 rpm. Timing is set to 35 total at about 3000, initial is 14 deg. Edelbrock 650 CFM AVS2. 461 60s era Camelhump heads.

I bought the truck with the engine already set in and not running, fresh rebuild. The guy I bought it from (of course) swore he was confident that he knew what it was but then confessed that he bought it from someone else already done and didn’t know what was in it.

It may very well need a smaller cam, but I can’t vouch for whatever is in there. Truth gone ahead and been told, I’d planned on getting some 195cc AFR heads this year and while I had the heads off, pulling the cam and looking at the number to see what it is.

I do have a dial indicator that I haven’t used yet, but I don’t think it would tell me any useful information that would be accurate enough.

I have never done it so take this with a grain of salt, but I've seen several videos (youtube and on whatever PowerBlock is called these days) showing how you can get rough cam specs with a dial indicator off the rocker arm rolling the motor over by hand. Then you can google and see if you might get lucky and find the cam you probably have. Might be an option

 

[legopnuematic]

I'm just getting caught back up here on the gas tank discussion. Are you saying your senders are under the bed? Every shortbed 16 gallon tank I've ever seen has the sender under the cab like soundmound's truck. Mine are that way as well. Only the longbed trucks got had the sender under the bed (20 gal tank, not sure where it landed on longbeds optioned with the 16gal tank/tanks)

Ditto, long bed with a 20 gallon tank puts the sender right in the gap of the bed and cab (great place for it lol), the front bracket location should be the same from long to short (not 100% on that however), with the rear of the tank being the difference.

 

[Frankenchevy]

I get rain-x wipers at dollar store for like $9. Might as well save a little $

Or Costco for $7… wiper prices are ridiculous these days.

 

[Frankenchevy]

But spectra off rockauto.com an google a 5% code if there isn't one floating around on the forum. Doubt you'll find a better deal.

LMC should be last resort for something only they carry. You can usually get anything they have cheaper somewhere else. Just my .02

I used 20% off coupon at advanced when I bought my spectra tanks. Less than $100/tank and ahipped to store for free.

That was five years ago or so…

 

[ChuckN]

I have never done it so take this with a grain of salt, but I've seen several videos (youtube and on whatever PowerBlock is called these days) showing how you can get rough cam specs with a dial indicator off the rocker arm rolling the motor over by hand. Then you can google and see if you might get lucky and find the cam you probably have. Might be an option

If it’s a hydraulic tappet, is there a way to account for the “squish” of the lifter?

I’ll check that out.

 

[TotalyHucked]

If it’s a hydraulic tappet, is there a way to account for the “squish” of the lifter?

I’ll check that out.

Oooo, good point. That I'm not sure of. Maybe if you knew what lifters you had, you could use those specs but without knowing what lifters, I'm not sure you could

 

[Grit dog]

Did you see Soundmounds pic? His tanks look like the senders are tucked under the cab...am I wrong? I assume they were all like mine until I saw the pic he posted in this thread with the bed off.

I just went back and looked. Yes they’re 100% under the cab. Longbeds are basically centered on the gap between the cab and bed.
Of little consequence though. Still gotta fish around up there under the cab/bed with the tank dropped down a little.
Good point though.

 

[legopnuematic]

If it’s a hydraulic tappet, is there a way to account for the “squish” of the lifter?

I’ll check that out.

If you remove the rocker from the equation, thus removing the valve spring and set your indicator on the pushrod itself, or use extension rods on the indicator itself to reach down to the lifter without the push rod. The spring tension of a dial indicator is almost nothing compared to a valve spring.

Then multiply by your rocker ratio to determine lift at the valve.

Or remove the valve springs and install a pair of checking springs and read at the valve itself.

 

[Chevrolado]

Y'all are bad influences.. all this tank talk..

Just placed an order for 2 new ones.

How do I tell my wife what I've done?