Carb engine mishmash

Hi all,
got perplexing question.
I bought a used car years ago with a Chevy V8 small block gen 1.
(at least I think it's a gen 1)
I'm not able to find the engine code, so I' don't know what it's out of.

It's a weekend driver, it's always started and ran fine, but had that hot restart issue.
Been like that for years.

Fast forward to now, I dropped the car off with a shop to work on, (due to my own health)
The mechanic is telling me the carb and engine is not match properly. I know he's not wrong, cause previously when I took off the carb, I saw the intake manifold didn't look "right"

The carb is standard Holley, verified as 1850 carburetor



But my intake manifold, doesn't have the right bore sizes to match



This is the adaptor on there now, I had switched to plastic cause of the hot restart issue.
But it made the car worse, really hard to start now.



This is the adapter plate that was on the car when I bought it
(this is the one thats been on the car for years)



Mechanic says no way the car can run and drive as it's just dripping fuel in.

But I've been driving in on and off over the last few years when using the metal spacer.

I know it's not a good match tough, so we're trying to figure out a way to fix this.

He showed me a pic of an adaptor plate with the pattern to match the intake manifold



Also it should have some "groves"? (not sure how else to describe it) on the top surface of the spacer in order to match the vacuum ports on the bottom of the carb?


I'll bring him the old spacer to put back on, but he suggested I get a new one with the bores matching and with the grooves for the vacuum port (not sure if I'm describing it right)

 

It could be that you have more than one problem....and the carb adapter isn't really the problem at all. If the carb is dripping fuel, it might need to be overhauled. The Holley carbs have a lot of places they can leak.

Might put your location in your profile too, since it looks like you're somewhere that they drive on the other side of the road. This could affect our suggestions.

 

You need to use the original adapter to mount the "square bore" 1850 to the spreadbore manifold. The dripping fuel is an issue with the carburetor-float setting, pressure, dirt etc.

 

The carb spacer isn't going to cause the fuel to drip. It may not match up well with the intake manifold, or the carbs base but it will work as long as there is not a mechanical interference between the butterflies and the adapter. It sounds like you just need the carburetor overhauled or maybe buy a new one. You might just have a float sticking and its causing flooding, but if you start opening the carb to look inside, I'd have an overhaul kit handy. Also, does your mechanic of choice have experience with carburetors? Many younger mechanics have never worked on one...so I'd look for an older guy or someone from a local hot rod club.

 

Thanks guys
I'm based out of Hong Kong.
Not many mechanics will touch a carbureted car, never mind an old American V8 here.
In the past it was easier, but olders guys that knowledge of Detroit iron are now all retired...
(on last count, there's about ~3 dozen old carbureted American V8's here)
Even the Ford dealer in HK won't touch one.

Car is now with a shop that deals with "classics"
Their instagram is www.instagram.com/vintagevehiclemechanic/

However the mechanic assigned to work on my car, has some opinions I don't exactly agree with.
He's knowledgeable on carbureted German and Japanese cars.
But then I was never a professional mechanic.

I'll get on ordering an overhaul kit


Some more info in case it helps:
Originally the car had a dead head fuel setup and Facet solid state cube pump.
I changed the original fuel lines and made it a return system (was hoping this would help the hot restart problem, as many dead head system has the hot restart issue due to fuel boiling in line when underhood temps spike when the engine is shutoff)

When I did the fuel system, I swapped in the plastic spacer as well.
But I messed something up, and the header temps went real high. It caused the Cerakote ceramic coating on the headers to discolor. So the temps exceeded their 1800F temp rating.

The fuel pressure is set at 6psi.
carb is and 1850 and supposed to have #64 jets and a 6.5 power valve.
https://youtube.com/shorts/tMm6RCcD9sU?

regards

 

Cooking the headers is a sign of incorrect timing or running lean rather than running rich so you might have two problems. Did you miss a vacuum hose off when you put the new spacer in?

Like everyone else I’d suggest that new spacer whilst not good for flow won’t be causing any of the issues you described.

The cube facet fuel pumps can’t deliver the flow needed for a big capacity V8 at full throttle.

 

Mail order a rebuilt Q-Jet to HongKong and get rid of all the adaptors .
A Q-jet is a very "drivable" Carb which would be much more suitable to driving around HK

Holley also make a 650 spreadbore as a Q-Jet replacement
Spend the $$$ on compatible components instead of paying a "classic car expert" to hackjob mismatched parts together.

If you've converted from "Deadhead" to a return line to get rid of vapor lock, you need a relief valve in the return line [so the line holds pressured above vapor pressure]

The problem I've had with modern fuels is you need at least 14 psi to prevent vapor lock [too much for a carb]
so you need to get creative with the fuel system
On my V8 race car we used an EFI pump and 2 regulators [this cured the dreaded vapor lock if we stalled the engine]

 

Which one?

 

Headers.
So, the hot start issue is not related to the starter solenoid getting hot? That can happen with Chevs when the exhaust runs close to the starter, the solenoid in particular.

I would say 6psi is at least a psi too much. And I agree with Moriarity.

 

Thanks, it is very possible I missed a hose, or a hose(s) is leaking?

opps I meant include I also swapped out the pump, I'm now using a Summit brand pump, it's identical to the Holley Blue pump.

 

it's what the seller had in the description when I bought the car.
I see now, it should not be a gen 1

 

I had the starter changed out to one of the mini hi torque ones, but it didn't help

 

Interesting, I followed this diagram for my setup.

I have 2 filters and 1 Holley FRP, but no relief valve.
I had read a few posts from the internet where people converted to the return line system, but this is the first time I am hearing of a relief valve being needed.

You have any recommendations on a rebuilt Q Jet dealer?

thanks

 

Some of you guys might want to look at this older thread by the OP, just for reference.
https://www.jalopyjournal.com/forum/threads/sbc-gen1-350-shaking.1211933/page-2#post-14174009

 

The problem with modern fuels is they vaporize at about 180° which is the same as under hood temps.
This isn't a problem with EFI pressures.

You need about 15psi to prevent vapor lock [more is better] but this is too much pressure for a carb
With the bypass regulator shown in your schematic, any pressure above the setting is returned to the tank .so the whole line would be the same pressure [usually 6 psi]

What can be done [in a race situation or bad vapor lock situation] is to use two regulators inline, and an EFI pump. [set the regulator at 15-20psi]
Between the Bypass regulator and carb mount another dead-head regulator set at carb pressures [eg: 6psi]

All fuel before the dead-head regulator is at 15-20 psi [so it won't vaporize] after the dead-head regulator is at carb pressure. And the EFI pump flows enough volume to keep the fuel recirculating and cool.

On my race car I used a Bosch 044 external EFI fuel pump and only a dead head regulator mounted close to the carb.
Just prior to the dead head regulator a return line was T'eed off back to the tank and a 15 psi inline relief valve was mounted near the tank.
The whole fuel system including the return line was 15 psi

The inline relief valve serves the same purpose as a bypass regulator

 

Looking at the other thread I'd question whether the regulator you have is a bypass regulator or not. To run a deadhead regulator in a bypass system the regulator needs to be needs to be downstream of a fuel log, in the return line.

Chris

 

Holley blue is a 15 psi pressure pump , will need a regulator , Holley Red does not most of time 7 psi

I zoomed in on pic of carburetor, I see one of the base Philip screw middle one font butterfly's Is / looks lose , can case vacuum leak

Also put the original adapter back on , vacuum ports are not blocked .
Not the best choice for Performance but for stocker will be OK,

The fuel regulator does not look to be a bypass.
How is it marked ,is there a part # & brand on it ,
Is bottom marked " in ", left & Right out ,

If you are unable to work on your self ,,
The mechanic that is assigned to work on your car,
& has knowledge of import carburetors he should be able to pull up a video on a holly carburetor and watch they're really not that complex as they look.

Also you said hard start after hot ,, as in trying to start with key , engine turns Slow ,
If so Timing set to hight , just to narrow down whats going on , for start put 10-12 degrees of initial. Check ground & hot battery leads , from & to starter & ground .

Or turns Fast but hard to start , after starting cold & warms up lets say run 30-40 mints with hood down
Shut off engine , after a few mints does the carburetor smoke, if so flooding ,

Needle seat bad /dirty or float to hight or blown power valve , could also be metering block gaskets.

Just to sort out & getting Running /idling correct,
Try blocking off all the vacuum ports on carburetor,
Including not hooking up vacuum advance on the distributor, cap off Pvc plug on carburetor 3/8 port.

Turn in the idle mixture screws on both sides of the meter and block clockwise until they slight seat then back off one and a half ( to start with)
Back Big Screw on diver side the Idle speed screw off until butterfly's are closed , then turn screw clockwise until the butterflies open approximately .020-.030 thousands ,wants started
Cock wise will increase RPMs ,CounterClock will decrease RPMs,,

Op give feed back , others will try to help diagnose

 

Wait. If the guy is in Hong Kong, he's not necessarily dealing with "corn gas" like we have to. OP, what fuel are you running? And I agree, switch to a Q-jet.

 

"Dripping Gas" on a Holley 4 barrel usually indicates high float level or a blown power valve. Or that way more than you need fuel pump pushing too much pressure and pushing gas past the closed needle and seat.
Your "mechanic" is suggesting this style of adapter. That maintains individual runners rather than the open plenum That the spacer you have does. The individual runners being a bit better for Idle and low speed adjustments while the open style works for wide open throttle but can be a challenge to get the idle as smooth as one wants it. At highway speed running down the big roads you don't notice much difference.

 

First thing I would do is check the engines timing and do a vacuum check to see if its correct. Then given your circumstances, I would order a new Carb from Holley rather than pay the hourly rate that a shop is going to charge to fiddle with what you have. Look on their website and you will see that they have some newer design carbs that cost more but are easier to substitute parts for getting the correct tune. I'd spend the extra money for the better design.
Put it on and see if the engine runs correctly now.

Once the carb is functioning decently, I'd clear off a table and disassemble the old carb and place the parts in a manner that you can reassemble them. Then clean the carb and install the new parts. Once done, return it to service and see if it functions well now.

Then sell which ever carb you don't need. If you pay someone who doesn't work on those types of carbs normally, he probably won't do any better than you will and it will probably cost you more.

 

sorry late reply

We have pretty good gas here, no Ethanol in any gas.
98-octane standard.
They all get unloaded into on single terminal storage facility, which all the brands Shell/Esso/Caltex/Sinopec etc.. get from. Only differences between the brands is the so called "additives" from the different brands.

 

Thanks for the info, I'll let the shop know about the timing.

The regulator I have is setup for return.
Thats another rabbit hole of a story.
At the time when I ordered it, everything was on backorder due to supply chain issues. so the
"CARBURETED BYPASS FUEL PRESSURE REGULATOR" part number 12-803BP was not available,

However I was able to get the Holley 12-803

Some forum posts talked about modding the 12-803 (non bypass) into the by-pass version as both
I forgot which forum I found that thread on, but here's video that shows it:


Thunderhead289 also did the same,

and he also has the Holley Blue pump. He also had vaporlock issues
Until he converted to a return line setup.
So that what brought me down this path...

 

Sorry for being away. Here's some updates.
My car isn't a rush job, so work has been slow.

The mechanic took the carb out already and cleaned it. It was junked up.
I don't think the previous owner ever serviced it after being installed in the car.

Here is what it was like when taken out
https://youtube.com/shorts/BWoyCCSsXFY

here it is after being cleaned


Shop was supposed to call me back with an update this evening, guess they forgot.
I'll give them a ring tomorrow.

 

Thanks for that

 

The carb is being cleaned up already, but I'll keep this in mind, in case it's not running that great.
Thank you

 

Hello all
Just an update. carb is clean,
They shop tried to get the car running with the current parts, but it's not good.
Right now it requires fuel to be squirted into the carb to get started and keep running.
Mechanic doesn't like the intake manifold, and says it doesn't have the "molded runners" (I'm using my words as I don't know the correct term) to each bank to properly draw through air for the carb.

This the one on the car


He says I should be using one like this, I've circled the "molded in runners" (which the mechanic had pointed to)



My engine doesn't have any casting number anywhere. I guess the previous owner used a rebuilt/refurbished block.

The only number anywhere where by the front right of the car (when viewed from the driver's seat )
These number are not cast, looks like they were stamped in. It reads "VU370254461"
I've tried to decide this, with no luck.


Anyways, I was hoping to identify the block so I can buy a intake manifold like the one the mechanic suggested.
I guess a generic Small Block Chevy 350 carbureted intake manifold, will do?

Thanks

 

Nice to have "experts" working on your ride.... your original intake is likely fine, providing it was installed correctly, ie.. no vacuum leaks. I have used a spreadbore Holley on my big blocks for years and like them. That is probably what you need and a shop with more experience.

 

Here's a close up picture of the intake manifold in the car.
As you can see, right under the circular inlets, it's one big open space shared by all the banks.
Seems like thats a problem?

Tough I have driven the car before, however it's also never been reliable....
I've had serious hot restart issues and plug fouling.
If the new intake manifold helps, then I'd be happy to get it.