from one side it seems like there is something sticking out from between the carb and intake. I’m not 100% sure there is a gasket as I didn’t install the carb. Since I’m opening it up anyway, may as well just take it off completely and change or add a gasket.

do I need to use a Holley 4150 carb gasket or can I use some of that high temp form a gasket?

do you think I would have anything to gain if I removed the carb spacer? It’s a rpm air gap intake.

 

You have to use 4150 gaskets and that spacer, based on color, looks like a heat insulator.
You still haven't posted the list number of the carburetor.

 

this is the number on the horn.

 

When I feel around underneath the spacer there is something rubbery there. It’s something black, not sure if it’s a gasket or some sort of sealant. You can sort of see it in this picture. I also attached a zoomed out version of the photo which shows what looks to possibly be fuel leaking and staining the intake?






this is the spacer I got.

 

Keep the heat spacer if you have the hood clearance with your Eddy 7501. It all helps with hot fuel issues.
I do see something under the spacer and it looks like something that should not be there. Using a RTV to seal the carb to an Intake will come back to haunt you later. Don't do it. The sticky stuff could end up in some fuel passages and raise havek with the carbs functions.

Your plan was to swap out the metering & bowl gaskets, plus maybe the Power Valve. You have to remove the fuel supply line at the carb anyway, so why not just disconnect throttle linkage & vacuum lines and put the Holley on your work bench. So much easier than on the car. As you disassemble carb parts, spray everything down inside with Gumout Carb Cleaner. (Walmart)

You will need to order TWO FelPro # 1900 carb base gaskets. They run around $7 each and can be had at about any parts store. One gasket under the spacer, one above.

You need to do this right and fix what somebody else did wrong, that RTV needs to be scraped off.

I will add then with your Holley on your workbench, fuel bowl is off, what a great time to swap out the accelerator pump diaphragm too. Its easy, four screws, 20 seconds labor.

 

you should have looked up the specs on the 90770 before buying parts.
It has a power valve only on the primary side and it uses a 2.5.
The secondary has no power valve but uses large 99 jets versus the primary side 74.
click on the specs tab
https://www.holley.com/products/fuel.../parts/0-90770

 

i only want to change the power valve. I have the blue gaskets since I don’t know if I can reuse the ones currently on the carb. From what I read online, I have to remove the 4 bolts and pull of that section in order to have access to the power valve.

that rtv or whatever is under there is concerning. I will have to remove and see what’s there. In case my parts store doesn’t have fel pro, can I use either of the first two gaskets from the attached photo?

I will also get the accelerator pump diaphragm as you suggested. On the website I see a few different kinds of diaphragm 30cc, 50cc etc. Would I need to remove the one from the carb and match it up that way?

The carb was rebuilt last year is what I was told. The two end pieces do appear to be newer than the main body.

 

i don’t believe the carb is stock, it was rebuilt according to my motor specs at the time. This was before the aluminum heads and air gap. I can always exchange the power valve, I’m pretty sure the installer said it was 6.5. But in any case I will open it up and verify what power valve is in there.

 

The odds are the old Bowl & M. Block gaskets will rip when you remove them. But that's ok, you have new, better, reusable ones.
I Googled that air horn model number also. Showed Holley truck avenger carb. But the picture looked nothing like yours.

The diaphragm you need is the 30 cc. Those 50 cc are for all out, wheel-standing bad boys double pumper carbs.

Use NOTHING BUT HOLLEY PARTS EVER !!!! No substitutions. Trust me. (maybe QuickFuel sometimes)

When you go to drain your fuel bowl, remove a bottom bolt first and drain into a cup. They sell a special cup just for this procedure.
When you turn your bowl up-side-down to swap-out the diaphragm, make sure the float is hanging correctly when you flip the bowl back up-right.

For several decades the rule on power valves was to install a unit about half of your vacuum at idle. Lots of SBC with cams run around 12-14 inches of Vac. So half would be 6.5.
New research has shown that a PV a couple notches below Vac at idle might be a better deal. IDK.

The FelPro 1900 base gasket could be swapped for a Mr. Gasket unit instead. You want the "open style" for a square -bore Intake bolt pattern.

I would do some research on the stock power valve rating. If you put a 6.5 PV in a 2.5 carb . . . . . . . . ?????
Something tells me that 2.5 is too low.

 

HeadsU.P. noticed that the carburetor pictures dont match the link for the 90770. It appears somebody removed the side hung float bowls and installed center hung float bowls so it's anybody's guess as to what is inside this carburetor.

 

Obviously, that is not the same carb as what Titanie has. Same trouble I had with Google, wrong picture.

 

Just noticed something else. Had to turn my Lap-Top up-side-down but . . . .

Not knowing what model this carb is, I did see it could possibly be a "Four-Corner" idle mixture screw carb. If it is, the secondary screws are missing.
Sometimes there is a just a hole that does not go all the way through into the metering block.

 

I took some more photos of the carb and the holes that don’t have anything in them. There is only two idle mixture screws that I can see and they’re on the primary side closer to the front of the car. The horn corresponds to a truck carb but the bowls on either end are new and don’t appear to be from this carb originally.

 

Ok. I did some research and Holley says only the mechanical secondary carbs have the four corner mixture screws. Not the Vac secondary like yours.
So holes are plugged.

I did get a pretty good match of pictures from Summit. But the horn number was 80770 and theirs is a Holley 770 CFM, Vac secondary, performance square-bore with center-hung floats.
Close, but no cigar there. Like Melwff said. Its a hodge-podge of parts. Different colors of main body compared to the rest. I have seen where a overnite soak of carb parts in Chem-Dip will change the color too.
So, back to the drawing board. Do you know what your last vacuum reading was before you started working on this? That will help with the new PV choice.

You should be alright with your fuel bowl gasket purchase. But look really-really close at the old metering block and new gaskets for a perfect match.

Don't you just love it when people mix-n-match parts together?

 

yup nothing like getting a freshly rebuilt Frankenstein carb lol. I got a vac tester coming, will take a reading. I don’t recall what is was previously.

if I end up removing the carb to do all this work, at that point I wonder if it would be easier to just bolt on the 670 aluminum ultra street avenger I have sitting in the garage.

 

Well the 670 cfm would have better throttle response. But the 770 cfm would do a longer burnout.
Decisions - decisions.

I don't know anything about those ultra street avengers, but new carbs are so pricey anymore. Looking at $600 for something decent.

 

that is quite the dilemma. Maybe I’ll be greedy and keep both. Swap them out from time to time and have a different driving experience. New carbs are quite expensive, I got a good deal on the ultra street avenger.

 

Just for something to do, check out a used carb web site that rebuilds Holleys and sells them reasonably. On the right side of the page is listed "rebuilt performance".
I have not dealt with them, so have no referral judgement.
I believe it was called AllState carbs? AlState carbs? Allstar?
Only bad thing is they want a rebuildable core exchange. Which I would not be willing to do.

 

Where do you want me to send that 1/2 a PBJ sandwich? I'll pay for shipping, too.

 

hahahahhaha. Better be made with JIF.