Edelbrock Carburetors?

-
I am in the process of rebuilding the Holly 80508 750 CFM with kit 37-754 and I have this question for you Holly guys. I am getting fuel between the main body and the metering block with the car not running. Primary fuel bowl is leaking down sitting there, the float is set correct and a little to low side. Could the new power valve that came in the kit be leaking?? Thanks a bunch...
 
I am in the process of rebuilding the Holly 80508 750 CFM with kit 37-754 and I have this question for you Holly guys. I am getting fuel between the main body and the metering block with the car not running. Primary fuel bowl is leaking down sitting there, the float is set correct and a little to low side. Could the new power valve that came in the kit be leaking?? Thanks a bunch...


If the fuel is leaking internally (into the engine) it can be the PV. It can also be the main body or the metering block isn't flat. Or both. I've had them where I had to remove the boosters, fit the main body into the mill, indicate it in and cut .040 off to get it flat. I've heard of some being off .060 but I can't verify that.

If it's leaking externally it's probably that the MB isn't flat.

Sometimes the $850.00 for a BLP B4X is worth every penny.
 
If the fuel is leaking internally (into the engine) it can be the PV. It can also be the main body or the metering block isn't flat. Or both. I've had them where I had to remove the boosters, fit the main body into the mill, indicate it in and cut .040 off to get it flat. I've heard of some being off .060 but I can't verify that.

If it's leaking externally it's probably that the MB isn't flat.

Sometimes the $850.00 for a BLP B4X is worth every penny.

Not leaking externally, I will look at the being flat issue. Thanks for the input...
 
Not leaking externally, I will look at the being flat issue. Thanks for the input...


I also forgot to mention that sometimes the power valve can hit on the boss that sticks up into the cutout on the main body where the bolt from the base plate bolts on. Does that make sense?
The best way to check for interference is to take the gasket off the metering block and with the power valve in the main block stick it on to the main body and make sure the metering block doesn't rock on the main body.
If it does you can grind that boss away until you get clearance.
Don't know why I forgot that until now but I is very common.
 
Well this is not a normal Holley, it has a 80508 main body, Quick Fuel float Bowls front and back and the vacuum secondary is also Quick Fuel... Beside leaking I have never been able to get the choke fast idle to work. Thanks for your input....

Sounds like a hermorphadite POS. No wonder it leaks.
 
No, Buckwheat. That's not how it is. The boosters are even different between the 1405 and 1406. You cannot turn one into the other because the passageways in the carburetors themselves are different. The 1405 is a performance tune while the 1406 is the economy tune. Edelbrock even backs that up. There's a thread around here somewhere splainin all the differences. There's a good bit. Alot more than just rods and jet and sprAngs.

I would also have to say with all else being equal, the 1405 would have more power, since it is the richer carburetor.

But like me, YESTERDAY, before I even put my brand new 1405 on my Scamp, I converted to the 1406 mains, rods, springs, and the pump shot was already on mid. So, I effectively have a 1406 with manual choke. I didn't get finished as I have to replace part of a fuel line tonight. But I will finish tonight. We'll see how it runs, hopefully tonight.

Does the 1405 have more power? In my opinion: No. It is a jetting difference only. Same carb. Does the 1405 jetting make more power? That depends on a whole lot of variables.

Unless you put an AFR gauge on it (or run it down the dragstrip looking at the trap speed) and tune for ~12.5 at WOT or highest trap speed, 1406 / 1405 doesn't matter. Different engines require different things. I don't necessarily think the 1406 set-up I put in the 1405 will make the most power. But, I've been fighting rich on Power Mode and Cruise Mode with the 1407. I should be lean enough (if not too lean) on the 1406 jetting. Either way if it runs great down low, but doesn't hit the AFR I want (12.5) at WOT, I will simply throw a bigger secondary main jet on it, until I get there. That way, I can have my cake (good low rpm (street) manners), and eat it (WOT) too! :D


7milesout
 
I also forgot to mention that sometimes the power valve can hit on the boss that sticks up into the cutout on the main body where the bolt from the base plate bolts on. Does that make sense?
The best way to check for interference is to take the gasket off the metering block and with the power valve in the main block stick it on to the main body and make sure the metering block doesn't rock on the main body.
If it does you can grind that boss away until you get clearance.
Don't know why I forgot that until now but I is very common.
I will check it. Thanks
 
NEVER had one leak.

I like the HP series holleys now a days.

I am stumped on this. The rebuild kit fit great, it would just sit there and leak the float bowls into the intake. It was so bad I drained the oil yesterday, smelled gas on the dipstick. I put it back together, set it on the intake with two sheets of paper underneath it, two bolts holding it down on the intake gasket, filled the float bowls to the proper level and let it sit over night. Nothing on the paper this morning. I took the Carb off today and I am letting it sit on a bench. If all is good I will put in the oil and reinstall the Carb and try again. Thanks for your input....
 
Sounds like you might be ready for a new carb or to take that one to a carb shop.
 
Sounds like you might be ready for a new carb or to take that one to a carb shop.

The latest is I put the carb back on, turned the electric pump on, gas was everywhere, overfilled the float bowls. I have a fuel regulator set at 4.5 psi and it just pumped right through it I am going to put a gage on the pump and see what is going on these electric pumps are supposed to shut off when a certain back pressure is met. Pump shut off pressure is 5 to 9 psi.
 
No, Buckwheat. That's not how it is. The boosters are even different between the 1405 and 1406. You cannot turn one into the other because the passageways in the carburetors themselves are different. The 1405 is a performance tune while the 1406 is the economy tune. Edelbrock even backs that up. There's a thread around here somewhere splainin all the differences. There's a good bit. Alot more than just rods and jet and sprAngs.

I would also have to say with all else being equal, the 1405 would have more power, since it is the richer carburetor.

Rusty - If by "boosters" you mean the accelerator pump, I agree they are different. The 1405 has a 0.028" pump nozzle diameter, while the 1406 has a 0.031" diameter. A bigger diameter on the 1406. Course that could be a typo because one would think the 1405 "performance" tuned carb would get a bigger squirt, but comes right out of the Edelbrock carb manual. Course there could be differences in the plunger of the pump that would squirt out more volume, but through a smaller orifice.

As for the rest of the "passageways" in the carburetors, unless I saw factual data, I would NOT believe they are different between the 1405 and 1406. The primaries of both the 1405 and 1406 are a quarter inch smaller (both the venturi and the bore) than the 750 CFM carb. Hence the CFM difference. I've searched for the thread you're referring to, but haven't been able to track it down.

The reason I don't believe them to be different is, it looks like a cast part to me (I didn't look at specifically to determine, just recalling what it looks like from memory). And quality casting tools are EXTREMELY expensive. So I doubt Edelbrock would double up on their tooling costs. Not saying you're wrong, but unless I saw evidence of the contrary, I believe the differences to be: accelerator pump, primary main jet sizes, metering rods, manual / electric choke.

Either way, if the passageways are better (more power) on the 1405, good for me. That's what I purchased. And on top of that, the AFR gauge removes all the wondering of what's going on carburetion wise. I think I have the carburetor set-up as optimized as it can be. Only hand sanding metering rods would allow me to go further than I am. I doubt I'm going to bother.

Tonight I'm going to go home, swap the AFR gauge to the other bank, and dial in the idle AFR to be as exact to the other side as possible. Then drive it and double check WOT AFR. After that, I move on to hurdle the next challenge.


7milesout
 
-
Back
Top