Cranking cylinder pressure (in psi) will give me some "clues" on how much overlap is ground into that cam. (lobe seperation angle)

As the overlap increases, the low rpm cylinder pressure drops, that is what makes the "lumpy idle' that hot cams tend to have.

Textoad, Do you have the "cam card" that show this info?

One "trick" I have used to decide on cam advance is to set the engine up so you can take cranking compression readings (in psi) and then test different cam positions until you get the most cranking cylinder pressure.
DD

Now that's a neat trick...!

I measured the psi in cylinder number 2 (it was easy) and got 140 PSI cranking pressure with engine pretty cold. It's been sitting since Monday.

Cam card here it is.

Isky part number 152115 for a Slant Six 170-198-225.

Grind VA-160 ( whatever that means)

Type Solid (lifters of course)

Cam Lift: .298
Valve Lift: .448
Duration: 264 (not sure of the units) degrees maybe?
050 Duration: 228 (not sure what this is.)
Lobe center:109
Valve Lash Hot: .018 ( which valve? I assume the exhaust)

Intake Timing
Open BTDC: 24
Closed ABDC: 60

Exhaust Timing
Open BBDC: 60
Closed ATDC: 24

Intake Timing
Open BTDC: 6
Closed ABDC:42

Exhaust Timing
Open BBDC: 42
Closed ATDC: 6

Hope I got that right.

My wife found the Cam Tech info. She's trained well eh?

Thanks

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Sweet Emotion

140 psi is good cylinder pressure and it looks like the cam has 48 degrees overlap.
You should be able to get this to run better at idle.

1) Loosen the valve lash as much as possible without excessive noise, this will reduce the effective overlap event.
2) Rebuild the carb., set the float level low and look for anything that may let fuel "sneak" thru. Look to see if the "power valve is quantifiable and adjustable.
3) If the test does not look at the timing, advance it for max manifold vacuum. (be warned, this could increase the NOX output)
DD

Nice 'n' high.
Not outrageous.
Yep, that's 264 degrees.
"Duration at 0.050 inch". Means the degrees through which the valves are open at least 0.050". This is as opposed to "advertised duration", which is your 264° number and is the kind of duration Chrysler used.
If they give only one figure, it means they want 'em both at 0.018". This does tend to support the idea presented earlier that your intakes are set too tight for the cam, aggravating your running condition.

The first set of timing specs is for the 'advertised' duration, so let's discard the second set.
OK, figure it this way: There is exactly half a crankshaft revolution—180°—between top dead centre (TDC) and bottom dead centre (BDC). Each piston stroke up OR down corresponds to ½ of a crankshaft revolution, or 180°. So, if you look at that Intake Timing spec, you see that the intake valve opens 24° before top dead centre, and closes 60° after bottom dead centre. Add 24 + 60 + 180 and you get 264, which is a number you should recognise. OK, now you see where the 264 number comes from.

Now, look at the timing specs relative to one another: we've been talking about "overlap". That's the period during which both valves are open at the same time. It occurs between the exhaust and intake strokes. So, look at the exhaust timing events: The valve doesn't close until 24° after top dead centre. But the intake valve opens 24° before top dead centre. So 24 + 24 gives us 48° of overlap. That's a fair amount for a street engine, and can be expected to cause rough idle and make it very tricky to get the car to run acceptably, BUT not impossible.

Thanks for the info on the cam and everything else. Very very useful for me and my son.

About the air cleaner. When I called the tech line at the inspection station the guy told me they would look at everything. So I got a little creative and took the stock air cleaner and retrofitted it to the Holley. I cut a round piece of flat galvanized sheet metal and nibbled a hole the same pattern as the holley. Then inserted it into the stock air cleaner on the underside and riveted the two together. Then I cut away the stock cleaner to give clear air flow to the Holley because the stock 1920 hole size was too small. Then I drilled 2 holes for the Holley air cleaner hold down bolts and created a bracket with a bolt in the middle sticking up through the stock air cleaner lid and used a wingnut. Looks totally stock and uses the stock heated intake as I mentioned, although non functional right now. Buuttt they never looked under the hood. Oh well.

About, the pcv, the Pro Fuel style Weber adapter has a PCV tapped hole in the base so that's where I hooked it up.

About the purge line, that's exactly where I hooked it up.

The vac line right under the cleaner lip is likely the line that goes to the vacuum amplifier as the pulse signal. Seems like the right diameter but not sure the Pinto or Mustangs ever had a vac amplifier for the egr. BTW I always wondered what the vacuum amplifier does? How can you amplify vacuum? I'm an Electrical Engineer so I'm stumped on that one.

Tomorrow my son and I will be rebuilding the carb and loosening them valves. I'll uncork/plug the egr and then fire her up.

BTW the Holley 5200 is the clone of the Weber 32/36 DGEV so lovingly talked about here and on the .com site. Same carb as far as I can tell. I put one on a 74 German Opel Manta back in 1985 and it ran so flawlessly I was really impressed. The Opel was a 1.9 L 4 cylinder rebuilt stock so it was a bit less tempermental than my current Slant Six project.

I'll be posting pics of this car soon, I've been keeping a full log. You'll be impressed. It's a car for my 17 year old son and he has been there every step of the way watching and learning. He's going to be doing the carb rebuild. He torqued the mains and the head and has helped on everything. We completely rebuilt the car from ground up. Paint and all. Too much to explain here. Glad to hear you've been to Tucson Dan it's a great place to live. I love it. My daughter goes to U of A and lives near University and 4th Avenue.

Thanks

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Sweet Emotion

Ok guys, carburetor rebuild complete. I loosened the valves and fired her up. Better response on the air fuel mixture. I can get it to almost die when I screw the mixture screw all the way in. Backed it out until it smoothed out and left it about 1 to 1 1/4 turn out. Then I set the idle at about 700 and the timing to about 12 BTDC with idle readjusted to about 700. Seems much cleaner smelling for sure. Took it for a spin and seems about right. Maybe a little on the sluggish side but better, might have to bump the timing a little more. So we did a hot running valve adjust and set all the valves at about 18 to 20. I can slip a 20 in there while running and maybe even a 22 but haven't tried the 22. Does this seem about right? hard to get it while running. So we're gonna put the valve cover on drive it a bit. Oh also I am going to disconnect the vac to the egr for now. I'll post progress tomorrow night. Seems like the rebuild and valves did the trick.

Thanks.

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Sweet Emotion

It might've been easier just to use the air cleaner that was designed to go with the carburetor. When the guy said he was going to check the underhood equipment, he meant he was going to make sure that the thermostatic air cleaner *function* was in place. He wouldn't have been able to tell if you had a different air cleaner unit. (But it sounds like he didn't check at all).
OK, that's a good location for it. I asked because unlike Mopars with the PCV fitting on the carb's throttle body, Fords had a fitting on the intake manifold.
Probably not. Fords used an entirely different EGR system that did not make use of a vacuum amplifier.
The vacuum amplifier's job is to look at the carburetor venturi vacuum signal (which is a good indicator of when it is appropriate to have the EGR valve open, but is not strong enough to open the EGR valve) and, when it sees the appropriate level of venturi vacuum, apply *manifold* vacuum (which *is* strong enough to open the EGR valve) to the EGR valve. You're an EE, so you know how an electrical relay works. The "vacuum amplifier" is really just a vacuum relay. But, your Ford carburetor likely does not have a tap into *venturi* vacuum, which is what's needed to operate the Chrysler EGR system. No matter, just
Well, same *family*, yes, but remember that the '75 PintoStang you took it from was equipped with "strangulation" style emission controls and a very mild cam, and the carb was set up specifically to work with Ford's versions of those primitive emission controls. It may or may not be as tuneable/customizeable/adjustable as the aftermarket versions of the carb. Note the '75 PintoStang 5200 carb is almost certainly smaller (in CFM) than the 1bbl you removed...again, you may well eventually find you do better with a Carter BBD.

One other thing: Is your OSAC valve still hooked up? On most '74s it's installed in the sidewall of the air cleaner body, though early-production '74s still had it cut into the RH side of the firewall. Hose running to the carb, hose running to the distributor. These devices play hell with driveability, and since they're not testing for NOx in Tucson, no reason to leave it hooked up. The vacuum advance hose should go directly from the advance port (find the right one!) on the carb, to the distributor vacuum advance. It's easy to hide this mod when you take the car in for the smog check; just run a loop of hose from the one OSAC valve to the other OSAC port, and hide the fact it's a loop in all the rest of the engine bay "spaghetti".
So do I!

Excellent progress!
Depending on what distributor you're running, that may be a little too much initial timing. Per previous question: OSAC valve?
Much closer to where you want it!
Wise.

What does the OSAC valve do? The one on my Duster is still hooked up.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

The OSAC valve's job is to delay vacuum from the carb to the distributor by 17 seconds. In this manner, vacuum advance is effectively blocked until the car is at cruising speed. This was a desperation measure to try to get cars past the Federal Emission Certification Tests which at the time bore zero relation to any real-world driving conditions, and replaced more complicated '70-'72 setups which were interlinked with the speedometer cable and/or transmission to prevent vacuum advance below a certain speed (manual) or until the transmission had shifted into 3rd (automatic).

The OSAC valve is notorious for causing stumbles and slow acceleration. Five houses up from me is a '74 Valiant in unrusted condition, driven by the original math-teacher owner. This is a real rarity up here in salt country. He obviously takes care of it. I was chatting with him about the car one day and we were looking under the hood (clean enough to eat from!). He mentioned a persistent hesitation on acceleration.

I asked him "D'you mind if I make a simple, non-invasive, completely reversible modification consisting of moving one vacuum hose? If you don't like it, we can change it back." He agreed. I ran the distributor vacuum advance line directly to the carburetor port, and looped the OSAC hose back on itself.

The next day he knocked on my door. "WOW! I've been trying to solve that hesitation since I bought the car brand new! I finally gave up and just lived with it, but...WOW!"

I think the OSAC valve was only on certain cars. My stock air cleaner does not have it. Also in my Haynes manual there is a description and picture that says the timer is not fitted on all models. There apparently was a timer and solenoid relay as you described and mine never had those devices. So OSAC does not appear to have been fitted to my car.

Drove the car a few more miles after my post and it seems pretty peppy but not a tire burner yet.

As far as the carb it appears the original mains were 145's and the idle jet was a 100 which is pretty big. According to Chris at Proline Fuel the idle jets should be 50 or so and the mains should be about 175 but he wasn't specific to cam or timing. I have 55 in the secondary idle jet and 50 in the main idle jet. 165's in the main jets. BTW how can this carb have an idle jet in the secondary? I didn't think the secondary was active until the pedal was mashed. Anyways I would like to try a larger main idle jet and a bit larger main jets.

BTW this carb was bought on e-bay and never came with an original air cleaner. I did buy a small Weber VW style rectangular air cleaner with chrome top, which my son likes, but we are sticking with the retro fitted stock cleaner.

Dan you may be right about the carb being not the right one for this car but I'll tinker a little more before declaring failure at this point.

I looked into the Gunson Colourtune and they cost about 60 bucks from what I can tell. Does that seem about right? I like that idea for trouble shooting. Also since I am winding down on the other time consuming projects on this car I thought I might try an O2 sensor for fun. There is a DIY wide band project and Edelbrock sells a setup for determining gross A/F mixture. I'd like to have a self diagnosis before taking it into the test facility the next time. Also they have a one year one time waiver here in Az but next year would be a problem. Any suggestions on getting an accurate assessment at home before going to the inspection?

I can still smell Hc's but since the A/F screw has much more pronounced effect and the driveability is better I believe I am much better than I was. BTW the car belches a little bit of black exhaust at start up but nothing more after a second. Also I noticed quite a bit of moisture and even a trail of water on the ground as I pulled out of the garage. Any suggestions on this water? Could it be weather related? Also won't it cause some rust issues in that new exhaust system I have over time?

Also I plan to run it a few miles tomorrow and check gas mileage so I'll report back on that.

Thanks again for all the help.

BTW my son really enjoyed the carburetor rebuild project. Nice to work on an already clean caburetor. Took a few pics and he really enjoys this project. Set him loose to fill it up after all the tuning. Modern radio works great and we're dialing in all the details. Lights and such. Still having trouble finding the window seals where they seal to the front door windows (2 door car). It's a fair weather bird for now.

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Sweet Emotion

They were on ALL carbureted Mopars sold in the North American market starting in '73, except Lean Burn models starting in '76. It's possible someone swapped on a non-OSAC air cleaner assembly sometime in the past 3 decades, or yours is/was on the firewall. Remember, the Haynes Dart/Valiant book covers '67-'76, and the OSAC valve appeared starting in '73, so what you're looking at is Haynes' sloppy writing.

You're not seriously trying to use a Haynes manual to do anything but wipe after you use the toilet, are you? Those books are full of misinformation, and there are huge gaps in the information they do provide. Instructions for proper use of a Haynes manual are here: http://u225.torque.net/haynes_instructions.html

You really, really need to get a factory service manual. They are neither difficult nor expensive to find. The haynes book is about 3/4" thick and covers ten model years. EACH year's factory service manual consists of one or two 2" thick volumes. You do the math on what's missing in the Haynes book.
Not on '74s, there wasn't. Haynes strikes again. I recall one Haynes manual for a Chrysler product that gave pictures and a description of how to press the ball joints into and out of the control arms. Problem is, Chrysler products use ball joints that screw into the control arms. Using a press would destroy the arm and the ball joint. Do yourself a favor and get rid of the Haynes book before you hurt yourself and/or damage your car.
Errrr...larger? Why? Your problem was running rich; that's not fixed by putting in more fuel. It sounds like you're making progress towards getting the mixture set correctly, but it still sounds rich (since you still can't make the engine stall by closing down the idle mixture screws completely).
Smart choice. Those mini chrome-top air cleaners are no good.
I bought mine about 15 years ago and it was about $42, so yeah, that's probably about right by now.
If you do this, remember the best place for an O2S is at the collector portion of the exhaust manifold (assuming you're still running an exhaust manifold and haven't done something like put headers on.) There are exhaust manifolds for \6s that are already drilled and tapped to accept an O2S in a good location; you might want to swap one of these on. The 45 minutes' manifold swap time will still be less effort than welding in an O2S thread ring anywhere in the system.
Beyond making sure the flame is blue, no, not really.
Percolation. Search this forum for the term 30R9 and follow the instructions in any of the posts that come up as search results for reworking the fuel line.
It's supposed to be there. Don't worry about it. Combustion produces water vapor. It condenses and leaves the exhaust system as liquid water until the exhaust system is hot enough to keep it vaporized.
If you only ever take short trips and the exhaust system never gets up to temperature, then yes. If you drive it long enough for the exhaust system to get hot enough to drive off the moisture, then no.
http://www.danielsternlighting.com/prod ... ducts.html

No headers on this car.

About the O2 sensor. I spent a great deal of time putting on the intake/ehaust manifold and I'd hate to think about that task again. More than 45 minutes for me. Couldn't I weld a bung on the pipe right below where it attacjes to the ehaust manifold? I could get that pipe off easily sinces it's brand new.

Regarding the quarter window seals, Laysons and year One fall short. I've called them bothe on no dice. Year One has A Body seals for a 72 but not the '74. I may have to search for a parted out car and get the whole window for both sides or custom make something. This part has actually been the hardest part to find for this car.

Regarding the stock air cleaner, it's possible someone swapped it out because I have no history on this car.

Regarding the idle jet, I read that if the idle jet is too small then you have to engage the main circuit to get a good idle which is not the right setup. I could go smaller or bigger and maybe I should buy a few of them to try. As far as the A/F screw goes, shouldn't it almost die when screwed all the way in? Before I rebuilt the carb it did very little no matter where it was. I guess I don't know whether this screw shuts down fuel or air. I'll keep studying.

Thanks again Dan.

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Sweet Emotion

Another smart choice. If you ever feel like upgrading, get Dutra Duals.
You can do that. If you go this route, make sure you get a heated O2 sensor, since that location will have trouble keeping the O2S hot enough to give accurate readings at extended idle.
I would be genuinely surprised to learn there's actually a difference (or at least a difference that would prevent the use of the '72 seals on the '74 car.) I will see if I can find factory parts books and do some comparing.
Yeah, that actually makes sense.

You should be able to kill it (all the way dead).