Starting to understand why building engines may be best left to the professional

[My427stang]

Maybe jack the truck up a bit to let the axle hang to get more room for the pan?

Also, did you get the timing gear moved?  Remember, you really should check it with the degree wheel again, no assuming

As far as the PV, no need to beat a dead horse, but "going back to stock" with the PV will not cause the rich condition you had.  I feel like I keep saying the same thing over, but here is a different discussion.  The PV circuit does two things.  1 - Time when the PV enrichment adds fuel to the mains, and 2 - Controls how much fuel goes to the main jet circuit.

The PV itself only controls timing.  So your 3.5 gives the same amount of fuel, it just gives it later.  IF, you are getting TOO MUCH fuel from the PV, then there are restrictors behind it that can be changed.  Small jets (PVCR = power valve channel restrictors) that control the amount from the that is added to the main jet.  However, for a street vehicle, typically you have some room to jet down so that it burns clean until you add a load, then the PVCRs add fuel.  So, if you really believe there is a PV fuel issue (I am not sure there is, I think yours was blown from the backfiring) then I would start by looking behind the PV to see if someone left a restrictor out completely.

Now, why all this stink from me about the PV?   At higher throttle openings, the engine is running on main jet.  You want it to burn lean for mileage on a street vehicle, when you roll in, like climbing a hill or passing, you want the extra fuel to kick in.  With a 3.5 PV, you likely will never get that fuel.  If the engine doesn't need it, then you have too much main jet (but we know that isn't the case)

So I will eventually give up trying to talk you into setting the carb up correctly but, I am still with you, looking forward to hearing what you come up with this weekend.  The cam timing should get you some throttle response and make it easier to tune.

If you pull apart the carb, you will likely need float bowl gaskets, metering block gaskets, and the PV.  However, as a carb stays together a long time, things tend to stick.  So taking it apart to check on things inside will likely mean you have to replace all those gaskets even if you don't want to.  If it was me, I'd either leave it for now, or I'd just set it up correctly before you fire the motor.  I know it counters what I originally said, but there is no real reason to take it apaprt multiple times and risk stripping a float bowl thread or potentially warping a metering surface from overtightening. 

[Barry_R]

Listen to Ross.

He is telling you good things.
He is accurate.

You do not need a 3.5 power valve.

Put it back together with the cam advanced, the timing marker verified, and drive it before making huge alterations.

[Yellow Truck]

Ross, I thought I was following your advice. I'm not touching the carb at present but was going to drive it and report its behaviour post cam adjustment. I did hear you that I needed a bigger power valve and I thought I saw you or Drew say a 5.5 or 6 PV was needed, so when I saw a 5.5 I grabbed it. It was only $10 so cheaper than driving back to get it later. Based on your post I now regret deciding not to pick up a package of metering block and float body gaskets. I did pick up a couple of intake gaskets since they tend to perish each time I dismount the carb.

I did jack up the truck to get at the pan, it is still hanging with the wheels 2 inches off the ground. I'm off to the hospital - Fridays I help my brother with his therapy to give his wife a day off.

I do look forward to your tutelage on the carb as reading David Vizard's book is helpful but not a substitute for doing it. What would help is some direction about what parts I should plan to have on hand. I have a bit of time before I move to the carb, but do you think I should put the 5.5 PV in or go and try and find a 6.5 that it came with? In fact, are you urging me to go all the way back to bone stock? If so, won't it return to stinking rich and fouling plugs?

I think I'd have to order a 6.5, I didn't see one on the shelf.

[Yellow Truck]

Deleted duplicate.

[Drew Pojedinec]

Don't drag me into this

I'd be redoing everything like Tobbemec stated.
my recipe for this carb as a starting point is the same as his pretty much.  I wouldn't even decide a PV opening point until I drive the car/truck at cruise and roll into wot with a Vac gauge hooked up.

I'm too poor to have fancy tools like distributor machines, dynos, flow benches, etc so I just use a vehicle for testing.

[My427stang]

OK, so get her running and we'll go from there.  I think you'll end up with a 6.5, but, let's see what your vacuum is and how it behaves when you get it back together.

Just to clarify one more time, no such thing as a bigger power valve. That's my point, its an earlier (bigger number) or later (smaller number) opening, so trying to explain that there is no need to fear a number change.  Only a bad power valve or something else could cause the rich situation you saw before the PV swap

[Yellow Truck]

Ok, will do. BTW I did read your very good explanation and I really meant "bigger number".

[Yellow Truck]

Question about setting the cam to 4 degrees advanced. I have a Ford Racing timing set, and it has additional keyways marked A2, A4, A6, and A8 as well as R2, R4, R6, and R8. There are also corresponding marks (circles hammered into the gear) for each of the additional keyways.

Am I correct in thinking I need to find TDC on the crank, then make sure I know I'm on TDC at the start of the compression phase of the cam, and at that point I retard the crank by 4 degrees and slide the A4 keyway on the crank gear over the Woodruff key, and the cam dot and the crank A4 dot should be aligned?

Then after finding TDC on the crank again, check the cam events to confirm it comes in 4 degrees ahead of where the card calls for (0.050 open occurs at 13 BTDC instead of 9, and 0.050 closing occures at 41 degrees ADTC instead of 45).

I started on it this evening but was tired and making mistakes so thought I'd start fresh tomorrow.

[My427stang]

Question about setting the cam to 4 degrees advanced. I have a Ford Racing timing set, and it has additional keyways marked A2, A4, A6, and A8 as well as R2, R4, R6, and R8. There are also corresponding marks (circles hammered into the gear) for each of the additional keyways.

Am I correct in thinking I need to find TDC on the crank, then make sure I know I'm on TDC at the start of the compression phase of the cam, and at that point I retard the crank by 4 degrees and slide the A4 keyway on the crank gear over the Woodruff key, and the cam dot and the crank A4 dot should be aligned?

Then after finding TDC on the crank again, check the cam events to confirm it comes in 4 degrees ahead of where the card calls for (0.050 open occurs at 13 BTDC instead of 9, and 0.050 closing occures at 41 degrees ADTC instead of 45).

I started on it this evening but was tired and making mistakes so thought I'd start fresh tomorrow.

I think you are correct but overthinking it, just line up the marks that are there now before you take it apart.  If you already took it apart, start at step 3 below, there is no reason to find any compression stroke, when a pair of marks are lined up, the cam is phased correctly.

1 - Rotate the motor until the current timing marks line up. 
2 - Pull the crank gear (have to pull the cam gear too to allow it to move)
3 - Turn the lower gear to put the crank key in the A4 slot
4 - Install the upper gear temporarily and realign the marks.  Use the A4 mark and the dot on the upper gear
5 - Put the chain back on.  Loctite the cam bolt
6 - Check valve events just like you stated

[Yellow Truck]

Well I'll file this under "Learn something new everyday". A2, A4, A6, and A8 must refer to advancing the CRANK, which retards the cam. You can see in the picture that the crank is ahead of the cam. I think the whole idea was the other way around!

Back at it after lunch.
IMG_3406 by Fred Snoyd, on Flickr

[My427stang]

I do not think you are correct, but you can check when you degree it.

The 4A position should advance the cam timing.  In the end though, the degree wheel will tell you.

[Yellow Truck]

This is confusing me. Clearly the yellow dots show the cam gear came through advanced, but the dial indicator is showing the lifter reaches 0.050 opening at 7 degrees BTDC, and it reaches 0.050 closing at 49 degrees ATDC. It had been 8 BTDC and 45 ATDC, so I'm getting a slightly different duration than my last measurement, but the lift looks correct and it returns to the same positions on multiple rotations.

I also moved the dial indicator to make sure I had it set up correctly and it came back to the same values. I also rechecked TDC and had at most 1/2 a degree of difference.

[My427stang]

So you advanced it 4 degrees, but it retarded 2 degrees? 

Check the wheel again, make sure TDC is correct.  You are using a piston stop to determine TDC right?

Also, did you verify before you started, to include tweaking the wire that points to the wheel to make sure the wheel was exactly correlated to TDC?

If TDC is right and the wheel is on right with the wire adjusted exactly, try another notch LOL see what happens.  You could have a mis machined set, but that would have to have that groove 6 degrees off.  My hunch is you tweaked setup a little this time

[Yellow Truck]

Before you replied I went back and did it all over, tightening up my technique.

I am using a piston stop and it is very consistently giving me a 57 degree sweep (28.5 before and after TDC) so I'm pretty confident I that. I also will re-check TDC if I so much as brush the pointer. I have had a lot of practice with it.

Before I was doing the measurements without hammering the crank gear all the way on - just until the key was flush with the front of the gear, and partly tightening the can gear down.

I thought it was more likely I was doing it wrong by cheating than the parts were wrong, also I had doubts about using an extension on the dial indicator. I went back to the 6 degree advance keyway and hammered the gear all the way to the back of the crank, mounted the chain and cam gear dot to dot, and tightened it down snug. Then I changed the dial indicator to a short tip with a sharp conical tip on the end, and fitted it down into the pushrod sitting in the lifter.

My results were very similar to the cam installed dot to dot - 0.050 opening occurs at 8 degrees (compared to 9 on the card) and it closes 0.050 at 46 ABDC (I think I put the wrong value above), and it does it consistently.

The A4 keyway did not advance the cam compared to the straight up keyway. Time to do as you suggest and move it to A6, but I think I'll try straight up again first and see what it shows when I measure it the same way.

[blykins]

Well I'll file this under "Learn something new everyday". A2, A4, A6, and A8 must refer to advancing the CRANK, which retards the cam. You can see in the picture that the crank is ahead of the cam. I think the whole idea was the other way around!

Back at it after lunch.
IMG_3406 by Fred Snoyd, on Flickr

Do those yellow dots line up when the dot on the crank gear is in the 12:00 position? 

Using the "A" keyways will definitely advance the cam timing.  You should be putting the dot at 12:00, not the keyway.  You'll see then that when you move the crankshaft CCW to do that, the cam will indeed be ahead of the crank.