Does the exhaust heat rider cause start up problems?

No. But it will cause drivability problems and or fuel consumption increase depending on position it is stuck in. The theory heat riser valve operates on is this; when engine is cold it directs exhaust gasses up to choke pocket and manifold under carburetor to speed heating of intake, and retraction of closed choke. The faster the intake heats to operating temperature the sooner air fuel ratio leans out to ideal mixture, and also prevents carburetor icing during cool ambient temperatures, a condition that causes fuel to drop out of suspension and puddle on walls & floor of intake manifold. Cold intake leans out mixture, and in case of icing causes drivability to degrade to a point where engine often won't idle, drivability while under way to be very poor, and fuel millage to drop into single digits.

If heat riser is stuck closed, or to say always directing hot gasses to bottom of manifold, fuel bowl boiling and hard restarts become a problem.

If you flapper is stuck, or its bimetal spring is broken, get it moving freely by using some "slip", PB Blaster or such for New Englanders, perhaps warming with torch to brake it loose. Stuck heat riser flapper could be contributing to your drivability problem.

It is not unusual for several little problems to add up making one larger problem that never seems to get fixed correctly. I never gave heat riser valve a thought frankly as my car has headers, and I haven't fiddled with one since the previously mentioned Dart some forty years ago.

Another old guy story to wade through:
You’re probably asking yourself how come Bill's car doesn't need a heat riser with headers. Well I went through the cold manifold, icing drill for a while one damp Maine fall in '08 when first got my Dart. I had to build a hydronic hot-spot under the carburetor that is supplied with hot coolant from heater loop, and installed an electric choke delaying thermistor that reads engine temperature and throttles choke open as needed.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

I knew the manifold heat riser was important. When I had the intake and exhaust manifold off I had it bead blasted so it was all cleaned out. It's not frozen I know. I did load it up with PB and/or some penetrating spray. It moves freely, but it's not loose, it's not stiff either, but it won't flap back and forth if you barely touch it. And I've got the little spring on the other side. I'll recheck it tomorrow and make sure it's still moving good. When you said it could lead to fuel boiling that brings to mind my 73 Charger 400. I redid the motor on that and had the manifold blasted and cleaned. The manifold valve spring was broken on it so I ordered an NOS kit and welded in a new butterfly and everything on. When I was done something didn't look right compared to the original. The flapper was too small, it didn't cover the entire diameter inside the manifold. It has an edelbrock 600 and when I drove it in the summer it was hot out, but the engine didn't over heat but it shut off with no warning in the middle of a busy intersection on Friday afternoon 5:30ish. It was hard to get started again. Wondering if that's part of that problem or just that junky carburetor? That's why I'm working on my Valiant for awhile, a whole lot less motor to work on.

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1965 Plymouth Valiant 200 4DR 2.8L 170CID
1973 Dodge Charger 6.6L 400CID
1986 Plymouth Reliant SE Wagon 2.2L 135CID

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An automobile engine of this vintage is just another engine no mater of displacement. A slant six works and uses the same basic designed bits and pieces as a big block. Cylinder count and carburetor bores differ, but they all utilize the same technology. Once one learns how it all works, and can systematically troubleshoot problems, these hunks of iron become old familiar friends.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

The heat riser is not likley to be causing the issues you have; but it should move freely. Just keep working it back and forth with a lot of lube and it outght to get more and more free. Sounds like you are paying a lot of attention to the little things so you ought to get this licked. The possibility of a poor carb is fairly great. Have you been able to check vacuum levels yet?

Where do I hook up the vacuum gauge? I know if I try to get the manifold fitting out the head will round off or threads will strip out. This is the 2nd reman carb in a year and it ran the same with both carbs. I did notice the fuel bowl was leaking on this new one so I tightened it. I will install the new choke today and see what happens. Maybe a mixture adjustment too.

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1965 Plymouth Valiant 200 4DR 2.8L 170CID
1973 Dodge Charger 6.6L 400CID
1986 Plymouth Reliant SE Wagon 2.2L 135CID

Vacuum gage has to be reading manifold vacuum, in other words most any place tapped into manifold below throttle plate. Generally there is an unused tap at base of carburetor that sees only manifold vacuum and or some intakes have a tap on side of intake just below carburetor. As long as the tap you use sees vacuum at idle you probably will be reading manifold vacuum.

The one tap you do not want to use is the tap which the vacuum advance is connected to, that would be "Ported Vacuum" and only sees vacuum when throttle plates are opened because it sees only what is happening above throttle plate.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

And there is a manifold vacuum port on the #6 runner of the intake manifold, or a pulg in the hole for one. If there is a vacuum line running from the #6 intake runner to the firewall, then you can tee into that line. If there is only the plug, then you can find an adapter at an auto store to install in place of the plug in the #6 runner and adapt down to a vacuum line.

You can see this plug locaiotn in the manifold pix here: http://www.rowand.net/Shop/Tech/SlantSixTBISwap.htm

Ok Saturday I went and installed the new choke thermostat and gooped up the exhaust flange to manifold leak again. It started up fairly easily and then shut right back off with the new choke installed. Then it started right back up and stayed running after that. I let it idle for about 10-15 mins before I did anything. Of course that exhaust flange gasket to manifold was still leaking. After it had run awhile I attempted to do a mixture procedure following what I read on the 65 Plymouth service manual under carburetors. I have the video I did, let me know if this is right. I haven't successfully adjusted many carburetors but seeing how this is just a 1bbl I figured it would be the best to learn on. Here's the video on youtube.
https://www.youtube.com/watch?v=V-UcAptLu4w
Even after this video I drove it around my small driveway a few times full throttle to see if it stayed running. After about 4 or 5 different times adjusting it over about 20-30 mins I got it to run full throttle without stalling. However, never could get it to stay running reliable when backing it up. As long as you backed it up slow it did ok but if you mashed the gas to back up quick it died. I checked again with some brake cleaner all around the intake gasket and carburetor base and vacuum hoses and couldn't find any vacuum leaks. How much fuel should you see in the fuel filter once it's been running that long with a half tank of gas. It looked like it was just dribbling out.

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1965 Plymouth Valiant 200 4DR 2.8L 170CID
1973 Dodge Charger 6.6L 400CID
1986 Plymouth Reliant SE Wagon 2.2L 135CID

Are you sure float level is correct. backing up fast will cause fuel to surge forward in fuel bowl, and if it is too low may expose idle and main jet circuits to air which will kill the engine; just a thought.

Please do not use chlorinated brake cleaner, that is the nasty old school brew not so called green brake cleaner to test for vacuum leaks. When brake cleaner is combusted it produces a substance closely related to chlorine gas the same stuff used in WWI to wipe out armies, and a small whiff of its combustion vapors will give you nerve damage. Use water from squirt bottle, or carburetor cleaner.

Fuel filter will never fill up, that's just the way it is. If it bugs you, get a metal filter then you wont see anything. LOL

It look as if you are making progress.

As for using #6 runner for vacuum gage you may find that the pulse produced when # 6 intake valve opens and closes will make vacuum gage needle wag back and forth a bit. When gage is connected to larger plenum area, say at base of carburetor, the pulses are more numerous because gage sees six of them, not one in every five. There are youtubes that show what different vacuum gage reactions indicate of engine condition; good stuff to know.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

I didn't check the float level because I figured being a remanufactured carb it should be set at the factory level. Which is what United Carburetor told me. Plus it did the same thing on the previous remanufactured carburetor I replaced this one with. I also didn't want to start tearing apart the fuel bowl on this because in order to get a new fuel bowl gasket the only way I can find it is a new $30 rebuild kit. I am happy that I was able to end up with the correct list number for this year and this engine. The previous remanufactured carb I took off was also from United Carburetor but the list number was from a 67 or later. Not that it matter much but it's always nice to have the right number on the carb. I also didn't use the chlorinated brake clean they don't sell it here as far as I've seen. Could I still be off on the mixture if it does ok in forward but stalls in reverse? Question also out of curiousity from this link
http://autohobbypage.com/specs/gen/ply60.html
How would the 170 from 60-66 be rated at 101hp and 155lbs-ft and then in 67-69 jump to 115hp? I see the only difference being the timing. I've got mine at 2.5 degrees and in 67 I see it changed to 5 degrees ATC cap. What does ATC cap mean?

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1965 Plymouth Valiant 200 4DR 2.8L 170CID
1973 Dodge Charger 6.6L 400CID
1986 Plymouth Reliant SE Wagon 2.2L 135CID

Well of course United will say they set the float level right..... no one can expcet them to say "Uuuuuh, well, sometimes we just don't do what we are supposed to do"....LOL. So that statement can be totally meaningless. The suggestions to chekc this are important, becasue the float level being off will thorw almost all of the carb functions out of whack.

You can do a float level check on that carb without removing the float bowl; it is called 'wet float' measurement. You remove the 'economizer valve' by removing the 3 screws from the small triangular cover on the horizontal surface on the driver's side of the carb just behind the bowl. Carefully separate the gasket with a sharp razor blade so you can reuse it. Pull out the economizer shaft and spring, and you can see the fuel right down there in the float chamber.

With the car idling, measure the level of the fuel down from the flat surface (where the economizer flange screws down) to the surface of the fuel in the bowl. I don't know the exact level for your year, but for my '62, it is 11/16".

If it the fuel level is indeed off, then you DO have to remove the float bowl to adjust the float.

I do remember that float level check in my 65 Plymouth service manual but didn't do it. I've never done it and was wondering if there is anything I need to watch out for when doing since the car will be idling. I don't what to expect when removing it while the engine is running. Will it splash up or it will be running rough when I remove it?

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1965 Plymouth Valiant 200 4DR 2.8L 170CID
1973 Dodge Charger 6.6L 400CID
1986 Plymouth Reliant SE Wagon 2.2L 135CID

Sometime around 1970 standard or method of measuring automobile engine output changed. I don’t have the exact changes off the top of my head at the moment, but in a nutshell earlier higher horsepower and torque values were achieved by testing engine with no accessories attached such as anything run by a belt, and revised method took into account all parasitic losses from accessories. Both your 60-66 170 and later engine are mostly the same…

Ooooops, pre-coffee reading comprehension malfunction of your question, sorry; you can still keep the above info under you hat when you discover a 225 went from 145 hp pre 1970 to about 115 hp post 1970…

To answer the power increase 66 to 67 I believe a camshaft change was made along with timing differences, and some combustion chamber revisions in head for better burn. Someone will chime in on this if I'm all wet.

All those theoretical output listings are moot, just pretty numbers; best way to evaluate real-world power is to test entire powertrain to determine rear wheel values. This method takes into account all rotational losses from fan up front, transmission & rear end inefficiencies’ to the rubber on the road.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

The fuel level will just be jiggling about in the float chamber and not splashing up or out. The engine will be idling fine; the 'economizer' valve (power valve) only operates when the vacuum drops below a certain level during heavy cruise or WOT conditions.

Wont splash, but there is a vacuum opening at the top of the economizer cover for the economizer actuator. When you remove the 3 screws in the cover with the engine running, the vacuum source will suck air, and the engine might stop running. I dont remember if I unplugged the vacuum source for the carb (best option, you're checking level while in idle, no need for vacuum) and plug it in the carb (you can put a screw in the vaccum hose end, or use a rubber cap in the carburator vacuum source), or if i carefully put something with rubber to seal the hole (careful, you dont want that piece falling inside the carb bowl, or you will need to open the bowl to remove it) (This is for a Holley 1920, which I understood you have)

By any chance have you noticed if your car sputters if you turn hard to the right (I think...) or in general in any direction? Also, can you take a picture of the lever connecting to the power valve, to see in which hole is it (I think there are 2 or 3 holes in the lever). Maybe you have it in the highest injection possible, and the 170 might not like it.

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/6 Dodge Charger 69
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