finding true top dead center

The power valve is just visible in your pic, the cover held on with 3 screws on the top of the main body casting.
One thought, check and make sure there is vacuum to it, take the (power valve) cover and valve off the carb and run the engine, you should have vacuum coming up thru a little hole to the top of the carb. It comes from a drilling from the carb base, if you don't have vacuum than the power valve will be "on" all the time, and when you set the jet for cruise, it can't richen when higher power selected. The wrong base gasket or if the adaptor for the turbo doesn't have the drilling for the passage, no vacuum would get to the valve.
IIRC it doesn't tie into the main opening, thinking back to my engines with the Holley, there was a small hole next to the main opening on the manifold that went into the main plenum to supply the vacuum signal, and the base gasket had a small (1/8") hole off to one side, if you put the gasket on backwards it would plug off the hole.
I'm reaching back about 30 years for my info, so I could be wrong, but I think I remember having a problem with vacuum on a Dodge 225 and it was the base gasket.

BTW when I was looking into building a turbo Slant 6, all I read and was told, 7-8 psi boost is all you could reliably expect with 7:1 pistons and no water injection on pump gas. I would guess that 10 lbs is pushing it a bit. You might be able to do a little better with an EGR system to prevent knock but not much. 5-8 lbs is where I would stay until I was sure I had the other problems sorted out.
I wasn't prepared to fit water injection, and never got the engine built, the A bodys were becoming hard to find in good enough condition and I gave up the project.

I will check the PV for vacuum tonight. this is the carb CHV universal. https://daytonaparts.com/universal-repl ... retor.html the picture dosent show a hole in the bottom, maybe its in the bore. I've been reading some on the internet, maybe I need to route the PV to the manifold after the turbo? would boost going to the PV damage it?

thanks jason

Don't hook the PV to boost, it would likely blow it out.

Here is pic of a Holley from a 282. You can see the large hole drilled at an angle up to the PV, this one also has a small port into the throttle body below the throttle plate, the 1920 on the 225 didn't have this port and relied on the base drilling.
Not sure why this one has both, the bottom is not plugged so it looks as if it could get vacuum either way, but a stronger signal would be supplied by the larger drilling in the base and not the small hole into the throttle body itself.
edit: It may have to do with the fact that this engine had a governor, mounted below the carb, with a 2nd throttle plate.

I just spoke with the tech at Daytona parts company, he said I do need to reference boost and told me I can just modify the cap of the PV. probably be clear when I take it off. I plug the hole that goes down to the bore (where the vacuum signal comes from on this carb), drill out the port in the cap and install a tube, then connect to manifold. he told me it will handle the boost. we'll see.....

thanks again!

I looked, and the airtex mechanical pump (it's new) on the motor puts out 20gph at 1800. should be enough? it runs and drives great, I just have to stay off the boost after 2500rpm till I figure it out. I brought down the boost from 10 to 5 for now. seemed to help a little.

Speaking of Airtex fuel pumps . . . I just got a complete refund including postage from Chev's of the 40's for an Airtex glass bowl pump for my '53 Chev. What a disgraceful piece of after market crap it was. If you want to see the photo essay on everything wrong with it, The thread where I posted it on the Yesterday's Tractors, Ford 9N, 2N, 8N Discussion Forum is titled,
The Case For OEM.
Here it is on page 4
Airtex Pump

Meanwhile, I picked up a great U.S. made fuel pump kit for my collection of good old ACDelco pumps from "Automotive Then and Now" . . . a work of art by comparison to the Airtex which, as I told the company, I'd be ashamed to disgrace my engine with.

One of the tractor guys who is a mechanic said he had two Airtex pumps that pumped way over pressure.

Anyway, that's my heads up.
I've got an electric pump on my R160 Cornbinder but I'm thinking of a rebuild kit for the mechanical pump on that '54 that now that I've found a good source for kits.

Terry

I can 2nd the quality of workmanship from Then and Now, I do my own Cummins PT pumps and am not afraid to tackle much of anything, but Then and Now do my mechanical pumps, I would buy their kits anyway, so let them do the work and have never been disappointed.

I just spoke with the tech at Daytona parts company, he said I do need to reference boost and told me I can just modify the cap of the PV. probably be clear when I take it off. I plug the hole that goes down to the bore (where the vacuum signal comes from on this carb), drill out the port in the cap and install a tube, then connect to manifold. he told me it will handle the boost. we'll see.....

thanks again!

I am very suprised they would recomend that, I know the diaphram on the Holley is thin, and I wouldn't expect it to stand up to 8 psi.
Vacuum goes to the top of the cover, to draw up the diaphram at light load. If you think about it, it isn't necessary for the PV to see manifold pressure, rather just that it dumps vacuum when the manifold is pressurized. I'm thinking a pressure tap on the manifold, thru a small restrictor, then into the passage that leads to the PV. At low power both the manifold and carb throat will have vacuum and the valve will be closed. Once the turbo spools, a small amount of bleed air can pass the restriction and overcome the small amount of vacuum from the throttle body, the PV wouldn't see manifold pressure as most would escape thru the throttle body port and go back thru the turbo, but would give the desired effect of opening the power valve whenever there is boost.
The size of the restriction and the size of the port in the throttle body will determine when the valve opens. On a draw thru, this "air" will be air and fuel, but as it is never vented outside the intake stream should pose no problem.
I can only see this being necessary, if there is sufficient vacuum below the throttle plate at high power to prevent the PV from opening. I'd 1st want to know that the fuel level in the float chamber is not dropping on high power, and that the PV system is working with vacuum up to the cover.
I think I would start by putting a vacuum tap under the carb, so you can see what is happening at that point and compare to what vacuum the PV is supposed to open.
I'd still do a quick check to see that you have a vacuum signal to the power valve itself, a passage that wasn't drilled all the way thru is not beyond possible and you don't want to end up chasing your own tail.

[/quote]
I am very suprised they would recomend that, I know the diaphram on the Holley is thin, and I wouldn't expect it to stand up to 8 psi.
Vacuum goes to the top of the cover, to draw up the diaphram at light load. If you think about it, it isn't necessary for the PV to see manifold pressure, rather just that it dumps vacuum when the manifold is pressurized. I'm thinking a pressure tap on the manifold, thru a small restrictor, then into the passage that leads to the PV. At low power both the manifold and carb throat will have vacuum and the valve will be closed. Once the turbo spools, a small amount of bleed air can pass the restriction and overcome the small amount of vacuum from the throttle body, the PV wouldn't see manifold pressure as most would escape thru the throttle body port and go back thru the turbo, but would give the desired effect of opening the power valve whenever there is boost.
The size of the restriction and the size of the port in the throttle body will determine when the valve opens. On a draw thru, this "air" will be air and fuel, but as it is never vented outside the intake stream should pose no problem.
I can only see this being necessary, if there is sufficient vacuum below the throttle plate at high power to prevent the PV from opening. I'd 1st want to know that the fuel level in the float chamber is not dropping on high power, and that the PV system is working with vacuum up to the cover.
I think I would start by putting a vacuum tap under the carb, so you can see what is happening at that point and compare to what vacuum the PV is supposed to open.
I'd still do a quick check to see that you have a vacuum signal to the power valve itself, a passage that wasn't drilled all the way thru is not beyond possible and you don't want to end up chasing your own tail.[/quote]

very interesting idea, I think i'll try that. it's gonna be a while, momma has some honey dues first. its driveable now, if I just keep out of it