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  #1  
Old 11-15-2001, 03:10 PM
Wheeler Wheeler is offline
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Default Solution for fixing cold weather running problems

Hey guys. Some weeks earlier, I posted a question asking help on solving cold weather running problems on a 318 V8. Thanks for all the help!
Some time ago, I went on the n2performance.com website and posted the same question for Jim McFarland. Jim is a legend in hot rod circles and used to work for Hot Rod magazine and Edelbrock. Jim has also written many tech articles for Hot Rod, Circle Track, etc.

Here is my question and Jim's response. Hope this is helpful...

Hi Jim. I hope you can assist me with a problem a have.

I own a 1985 Dodge truck with a stock 318 V8 and factory Holley 2bbl carb. When starting the truck in the morning, the engine idles very rough, wants to stall and rund extremley rich. This is a traditional Chrysler cold weather running problem, aggravated by the fact that I live in the cold Canadian north!

It seems that carb icing is causing the cold weather running problem. Chrysler small block intakes have a tendency to get plugged with carbon in the crossover passages, not allowing heat to reach the base of the carb. As a result, the throttle plate ices up. The truck won't run properly until the engine is TOTALLY warmed up.

My problem is also aggravated by the fact that I have Hedman headers. The headers have no heat riser valve, so no heat reaches into the intake crossovers.

What I would like to do is install a 4bbl intake (either a Chrysler factory unit or aluminum aftermarket piece) and Edelbrock carb 600 cfm for improved performance and drivability.

1. What would cause the intake manifold crossovers to get plugged up with carbon?
2. I have noticed that Chrysler products have a history of cold weather running problems, not so with Chevys or Fords. Can the problems be traced to poorly designed intakes or carbs for factory Mopars?
2. I have read that an aluminum intake conduct heat better than cast iron intakes. Should I go with the aluminum 4 bbl, or would a cleaned out, factory cast iron intake be sufficient in cold weather?
3. Do I absolutely need a heat riser valve for winter operation, or would a proper intake and good aftermarket carb be sufficient.
4. What other suggestions would you have for fixing carb icing problems?

Jim's Response:

Sir,

1. The "cross over" passages in an intake manifold communicate directly with the exhaust port of the cylinders joined in the cross over.
Thus, they are subjected to the same sort of carbon accumulation typical of exhaust pipes. In this case, however, there are much closer to the source than areas further down the exhaust path.
2. The amount of exhaust heat experience by an intake manifold's plenum floor includes a function of cross over passage design and the number of ports contributing to the cross over...sometimes two cylinders, sometimes four. as I recall, it's four in the case of MoPar V8 inlet manifolds...back around the '85 engine you cite. Included in the cross over "design" issue is now much plenum surface area is exposed to the exhaust gas. The less the area, the less the amount of heat applied to incoming air/fuel charges. In the range of engines you mention, I seem to recall less area was exposed than with GM and Ford counterparts. Of course, there are other factors, but these are among them.
3. Were I you, I'd choose using an aluminum intake manifold...for multiple reasons.
4. While a heat riser would help {depending upon the severity of cold weather conditions}, I suspect an aluminum intake would do the job.
5. Use the thinnest carburetor gasket possible...aside from the other suggestions made.

Jim McFarland
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Old 11-15-2001, 10:23 PM
5thAve 5thAve is offline
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If you take your intake off you'll probably find that the crossover is clogged. Cleaning it out will probably solve your problem for a few years until it clogs again. Mine wasn't clogged in the centre of the intake but more at each side where it meets the head.

Having a heat riser valve inplace definately would help, and when they don't work or aren't there quite often they are a big cause of the crossover clogging up, especially up here in Canada with cold winters.

There are 2 ports that lead into the intake, not 4. They come directly out of the heads of those 2 cylinders before even entering the passage to teh exhaust ports.

It took us a bit over 4 hours to put a 4bbl intake on my 360, that was from popping the hood to getting the carb seated on it.
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Old 11-15-2001, 10:41 PM
Wheeler Wheeler is offline
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Thanks for the feedback 5th Ave. It's nice to talk to a fellow Canadian!

I am pretty sure my intake is plugged with carbon. After the truck is running for 1/2 hour, the base of the carb still feels cold. The heat riser definitely helps, however I am running Hedman headers on my D150 so I have absolutely NO heat getting to the crossover passages.

I have always had this problem with 318 2bbl vehicles. On one car I owned (80 Mirada), I had the intake cleaned out by a mechanic, but it didn't help much. Didn't know if the mechanic did it properly or what. Also, the heat riser valve was cut off. I could take the 2bbl intake off my truck and get it cleaned, however I'm afraid it won't solve the problem.

I have often wondered if the traditional Chrysler cold weather running problem was caused by a poorly designed intake, or faulty carbs. I believe in McFarland's theory that the problem is caused by small plenum surface area in the Chrysler intake. As a result, not much warm air from the crossover gets under the carb. This is especially true in a 2bbl intake, and in my mind the 4bbl intake should be a big improvement. The aluminum should solve the problem, even with no heat riser valve. From my knowledge, the aluminum intake conducts heat better, and allows the carb to get the heat it needs for cold weather running. I would prefer the cast iron intake since it's cheaper, but I'm afaid it won't solve the problem.

Eventually I will get this problem fixed...Thanks again for your input!

Wheeler
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Old 11-15-2001, 11:33 PM
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2Sweet Neon 2Sweet Neon is offline
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Well i know how to fix the problem....move to where it doesnt get to cold in the winter ok so that might not be the most practical way to fix it
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Old 11-15-2001, 11:49 PM
5thAve 5thAve is offline
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I've never had a cold starting problem with my 318 until this year. The carb has needed a rebuild for a while and has problably gotten to the point that it can't get much worse and the throttle shaft is worn on it aswell. On the 360 I had no problems with it until last winter, then I changed the carb and with the new carb it was noticeable that there was something wrong- you'd set it and within a couple weeks it would need to be adjusted again because of how bad it would run. At times I wouldn't even use it because it was so out of whack.

I was meaning to go 4bbl but just couldn't be bothered to do the work, and was still collecting the odd parts for the change. I had the intake hot tanked and at the same time fluxed and glass beaded. During the change over I spent a good half hour chiseling all the carbon out of the heads and now that it's all togheter and with a rebuilt thermoquad it starts and runs a lot better. Right now it starts and runs fine, it's not 100% perfect, but the heat riser valve isn't in place either (that's going in next friday). When I got the 4bbl on there I got a new choke assembly, or whatever you want to call that spring and rod unit.. I'm sure that helped a bit aswell. I'm using a stock 79+ 4bbl intake. I've never cared for putting headers on my car and this is one of the reasons why!

Figured I'd throw my experience with this in when I read your post. And since I'm north of the border too where we get that nice -40 to 35+ temperature range I figured it may or may not help.. When it comes to climate it Canada isn't exactly the same as most of the US
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Old 11-16-2001, 01:05 AM
Wheeler Wheeler is offline
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Hey 5th Ave. Let me know how you made out. I am interested to see if installing that heat riser valve will fix the problem.

I should also mention that UAP/NAPA sells an electronic choke conversion kit for 2bbl equipped 318 and 360 engines. This device is a FULLY ELECTRONIC electric choke, and is different from the factory Chrysler choke. This choke looks a lot like the one found on a Rochester Q-Jet. This choke mounts in the factory location, and comes with a small sensor that you must mount on the intake manifold. You also must hook up two wires - one for constant power, one for switch power. It is manufactured by Echlin, and sells for around $60.00. Chrysler factory chokes tend to be tempermental, since they are activated by manifold heat. I have tried the electric choke conversion personally, and it seems to work OK - however, you must adjust it properly to prevent flooding.

In addition, the quality of rebuilt carbs can be iffy. To my knowledge, the only two brands of rebuilt carbs you can buy in Canada is Autoline (carried by UAP/NAPA, Bumper to Bumper, etc) and Holley (Canadian Tire, Partsource). I have heard lots of bad things about Autoline rebuilt carbs. A friend of mine had real bad luck with an Autoline rebuilt TQ - he wound up going to an Edelbrock Performer. I think the Holley rebuids may be better quality. If you have problems with rebuit carbs, I would consider buying a brand new carb (Carter AFB, Edelbrock, Holley), despite the huge price.

Of course, I am finding out the hard way about running headers in cold Canadian weather. Too late now!!! Even before the I installed the headers, the truck ran rough when first starting in the morning. Most likely was caused by a combination of plugged intake and bad heat riser valve.

If the new heat riser valve doesn't work, try an aluminum intake. I bet an aluminum intake would solve those cold weather running problems.

Good luck and keep in touch!

Wheeler
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Old 11-16-2001, 01:30 AM
Crank Crank is offline
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i have had this problem before it sounds like the choke either is not closing all the way or to much,check it when it;s cold most of the time it's the linkage to the cold idle adjustment .I don't use the heat risor either ,in fact sometimes it runs even better when it's cold .also use a vacume gage and adjust the idle screws on a cold day after you worm up the engine you will be surprised n how much it will vary from summer to winter.change your breather and pvc valve more often in the winter because it will gum up twice as fast because of thicker oil in cold air , Bottom line the choke is really hard to get it just write but when you do it will make the motor run 100% better ,no more chugging spitting hesitation out the hole stalling or power loss in cold weather.
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Old 11-16-2001, 01:52 AM
5thAve 5thAve is offline
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Hey Wheeler,

The carb I have is an AutoLine one. I had to send the 1st one back because it leaked gas out and wouldnt' start the next morning. The replacement seems to be OK so far but I haven't had a chance to test it fully yet (and been to damp out to know if problems are because of the carb anyway). I've been told that they're good quality rebuilt carbs but as usual with a rebuilt one there's no guarantee it's going to be perfect until you try it. The friend who helped with the swap got one for his earlier this year and has had no problems with it at all so hopefully this one will be OK too. The Holley rebuilds are crap. I got a rebuilt 2bbl for the 360 that was no good. I refused to take the 2nd one because it had mixed screws on it and even had home-made ports!! One of the ones that goes to the charcoal canister was actually longer then it should be and was kinked in the middle. The guy at the parts counter at Canadian Tire came right out and even agreed with me that he'd be leary too of the interior parts being messed up while the buddy who does the carb tuning for me (who's a mechanic) can't believe that they're from Holley. The 3rd one still didn't run right when I took it off and if it wasn't for paying almost $200 for it I would have kicked it into the nearest dumpster.

I know you can get electric chokes for the Thermoquads, but no-one could give me a straight answer for the others. It's a good thing to keep in mind if I have problems with the 318. Thanks! I'll let you know how it goes with the heatriser valve working right and when it gets worse out.
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Old 11-16-2001, 11:29 AM
Wheeler Wheeler is offline
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Hey 5th Ave.

Earlier this summer, I bought a Holley rebuilt Carter 2bbl for my 318 from Partsource. I heard lots of bad stuff about Autoline, so I wanted to try the Holley instead on in place of the factory Holley. The truck ran smoother, but didn't seem to start as good when cold or warm. Also, I think the carb was much leaner than the Holley - when I tried to accelerate when the engine was cold, the truck would hesitate. However, the cold weather running problems did not go away. I has thought that my cold weather running problems were due to a worn out carb. Turns out it didn't help.

The electronic choke conversion kit also didn't cure the cold weather running problem. The choke came off a lot quicker, so it helped my gas mileage. Sometimes when I left the truck for several hours and went to start it, it would flood and wouldn't start. I set the choke a little leaner, and it seemed to help.

One day, I was driving the truck on the freeway and I came upon bumper to bumper traffic for about 5km. It was an extremely hot day. After I got past the traffic, I nailed the gas and the truck would accelerate hard, then there would be a dead spot. It seemed like there was vapour lock. It did it to me two more times on the freeway. After that, I got leery of the carb and returned it to Partsource.

I should also mention that I actually ordered a rebuilt TQ from Partsource some time earlier - I was actually planning on doing the 4bbl swap earlier. When I got the carb, I notice that the throttle shaft had a lot of play in it. In addition, the carb was supposed to be for a 318 powered 78 Dodge Truck. The casting number corresponded to a 1977 400 powered Chrysler. I got leery about the carb and wound up sending it back. Later, I decided to try the rebuilt 2bbl.

I now believe you when you say Holley rebuilt carbs are junk!

I do not trust those Autoline or Holley rebuilt carbs anymore. Despite the cost, I think getting into a new Carter, Edelbrock or Holley carb would be the way to go.

After asking a lot of questions and doing some research, it seems that the only to fix the traditional Chrysler cold weather running problems is to install a new aluminum intake manifold and carb.

Good luck and keep in touch!

Wheeler
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Old 11-16-2001, 12:37 PM
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rumblefish360 rumblefish360 is offline
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Wheeler;

I believe it's Headman that sells some trick exhaust stuff. I purchased "stove" that gets straped on to the header. (1 tube)Theres a flexable pipe that is to run from the straped on stove to the stock aircleaner snorkel. Thus providing hot air right of one of the header tubes to the carb.
They also have a heat riser valve that bolts onto the collector of the header.
These additions should help you out if there needed.
I have seen them in a PAW catolog.
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Old 11-16-2001, 08:27 PM
5thAve 5thAve is offline
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Both of the problems you described in the last post are like what mine was doing. Since changing the intake the engine runs just about flawlessly when it's cold, I can very easily live with the way it's running right now but I'm sure that the heat riser valve will push it the rest of the way.

The stumbling you're talking about I've had aswell, but it went away with one of the rebuilt holleys and when I started tuning the timing and advance. Since I first started having constant carb problems I've had the shop deal with everything and especially when the rebuilt carbs seem to be iffy I'd rather have them find the problem and know it's the carb then me waste time dealing with it over and over again just to get more and more frustrated with it.

If you don't have to use the truck daily I'd consider pulling the intake just to see if it's clogged up at all or not. Won't take too long, especially if you don't have things like AC and such in the way. Who knows, it could well fix the problem.

I'll let you know how it runs with the heat riser, another thing I remember now is that the last time it was in before I got the 4bbl stuff on it actually ran better without the EGR setup so it was blocked off. When I put the 4bbl on I left the blockoff plate inplace to start with and will probably pull it off one of these days to see how it runs with the setup intact again.
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