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Old 05-22-2012, 10:35 AM
1969Wagon 1969Wagon is offline
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Buick 350 overheating solved?

So I had the Buick 350 rebuilt and boy does it run hot and even overheats. I tried every thing. The thermostat was new with the rebuild. I put in a new radiator, fan shroud, hoses, coolant and it had no effect. It was getting so hot that it cooked the new engine enamel off some spots of the Intake. Some suggested the timing was set too high. I got the original manual for this engine, a timing light and dwell meter and went to work. The timing was set between 12 and 14 TDC. That is all well and good if you have a Chevy 350, but the manual on this Buick said it is to be timed at 0 TDC. I got looking around and all the spark plugs are advanced one position clockwise on the distributor. The engine runs smooth and seems to have a good amount of power. A Mechanic friend of mine said that the guy who rebuilt it set may have set it up as a Chevy 350 and not a Buick 350. He said that it will run smooth, but the valves may be different enough on the Buick vs the Chevy that it is not allowing the exhaust gasses to escape at the right time and will tend to build up heat. I pointed this out to the manager of the shop that rebuilt it and he said to bring it in along with the original manual and he will have the mechanic take a look at it. The rear main seal is leaking and he said he will get that replaced under warranty so he may as well address this issue as well. What do you guys think? could that be the problem? My friend said that the would have to "re stab the cam" I am not sure what that means or what it involves, but I would like all of you with more experience than I to donate your 2 cents.
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Old 05-22-2012, 11:07 AM
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Timing can effect heat for sure.
I always vacume timed mine but as I recall it usually came in around 8-10* BTDC when I would check it with a light.
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  #3  
Old 05-22-2012, 02:10 PM
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Comancheap Comancheap is offline
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Not to ruin your day but after decades of owning Buicks the other thing a Chevy guy will do is set the mains at Chevy specs which is too sloppy for a Buick.

This is allot to digest but will copy you on a Buick post that goes into "Power timing" a Buick.Allot of this pertains to the big block 455's but has allot of other good common information.

"I see alot of questions about what initial timing to run on a modified BBB, without regard to what the timing is as the RPM's increase. Everyone should know exactly what their total advance is, and at what RPM it's all in at. The right timing, at all RPM's can make a huge difference in the way your engine runs, and makes power.

There are 3 components to total timing. Initial advance, mechanical or centrifugal advance, and vacuum advance. Since vacuum will be at or near 0 at wide open throttle (WOT), initial advance + mechanical advance are most important to how your engine runs under race conditions.

Initial timing is simply how you have your distributor installed, and adjusted, in the engine. You simply attach a timing light, and with the engine running,(vacuum advance plugged), you turn the distributor until the timing mark lines up with the desired number on the timing tab. As you increase the engine RPM's, you'll notice the timing mark move upwards, and out of sight. This is the mechanical advance in operation. There are weights inside the distributor, that pivot against spring tension, and move the base plate so that the spark occurs earlier(advance).

The springs determine how quickly the mechanical advance increases with rising RPM. There is a pin that moves in a slot under the weight plate. This is what determines how much mechanical advance is built into the distributor. Aftermarket advance curve kits generally provide a bronze bushing that goes on that pin, and limits the movement of the pin in the slot, thus limiting total mechanical advance.

The only other way to modify the amount of mechanical advance in the distributor, is to disassemble the distributor, weld the slot, and file it until you have the desired amount of advance you need. This is why you can't simply buy a junkyard HEI or other distributor, and put it in the engine, and run whatever initial timing you like. If there is too much mechanical advance in that distributor(this is typical for all factory spec'ed distributors), you'll overadvance at higher RPM. If you need higher initial timing, you need to reduce the mechanical advance in the distributor to avoid over-advance.

Most Buick V8's run best at WOT, with a total timing of 30-36*, all in at 2500 RPM, or less. The easiest way to determine your total advance is to use a dialback timing light. You simply connect the light, plug your vacuum advance, and have a second person slowly rev the engine. With the dial back feature, you adjust the light to keep the timing mark in sight as it rises. When the timing mark stops moving, you hold the RPM's steady, adjust the dial until the balancer mark lines up with the 0 on the timing tab, and read your total advance off the dial.

To do this with a conventional timing light, you need to make a 30* mark on your balancer. The Buick 350, and 455 balancers are 6 3/4" in diameter. Circumference (360*) of a circle is pi(3.14) X diameter. 6.75 X 3.14 = 21.195"/12 = 1.76" (30*). Looking at the engine from the front, measure exactly 1 3/4" clockwise around the balancer, and make a second mark. This is your 30* mark. Connect up your timing light, and watch your 30* mark as you increase the RPM's. At some point, your 30* mark will stop rising, and move no higher. This is the RPM, where all of your mechanical advance is in.

At this same RPM, with the distributor loose, adjust it so that your 30* mark lines up with the 0 on the timing tab. You now have 30* of total timing. Line it up with the 2, 32* total, ect.

Keep in mind that a stock distributor usually has stiff springs in it, that don't allow full advance in until 4000 RPM or more. For best performance, you want your advance in at 2500 RPM, or before. The easiest way to do this is to purchase a Crane adjustable vacuum advance kit. It comes with 3 sets of springs to allow your advance in as early as 1600 RPM, or as late as 3200 RPM, or anything in between. For points distributors (Jegs part # 270-99601-1, GM HEI, 270-99600-1). What I did was purchase the kit, and install the lightest springs(2 yellow). I used these springs to adjust my total timing, that way, I didn't have to rev the motor very high to see my total. Afterward, I installed the springs that brought my advance in at 2200 (2 silver)

One important note is to make sure the timing is returning to the initial setting, when the engine is idling. So when setting your timing, pay attention to when the advance starts, as well as when it is fully in. Having the distributor in the advance curve, at idle speeds, can cause excessive rpm drop with an automatic trans, with some camshaft/converter combinations. Generally, the more agressive a camshaft you use, the more important this will be. Advance curves should generally start at around 1000-1200 rpm, when your idle speed is around 800 in Park.



Now for vacuum advance. Some people prefer not to run vacuum advance at all. Under race conditions it is totally irrelevant, because it won't function at WOT. BUT, on a street car, it can be used to enhance throttle response, increase gas mileage, and let the engine run cooler at idle and low speed.

The problem occurs when there is too much vacuum advance coupled with a modified mechanical advance. As mentioned before, stock distributors didn't allow total mechanical advance in until upwards of 4000 RPM. At your typical cruising speed of 3000 RPM, only part of your mechanical advance was in. The vacuum advance would supply an additional 14-18* for a total of around 40* or more. At light loads (cruising), an engine can easily tolerate this much advance. The result is better gas mileage.

With a modified mechanical advance, all your mechanical advance is in at cruising speeds. Add the 14-18* of vacuum advance, and the engine pings when you punch the throttle, and the advance from the vaccum cannister doesn't/can't go away quick enough. The answer is to modify the vaccum cannister to allow only 8-10*of additional vacuum advance. With 30-34* timing + your vacuum advance, you'll be at 38-44* which should be optimal.

As far as running your vaccum advance off manifold or ported vacuum, everyone has a different opinion. In most cases, OEM used ported. I use manifold vacuum. With a wild cam, you can use manifold vacuum advance to give extra advance for a smoother idle, and better low end response. Everyone's engine will be different, so you need to experiment with your combination. With the Crane adjustable advance cannister, there is a better way to limit the degrees, than what Crane suggests. I'll post some pictures to detail this. With the stock cannister, you'll need to fashion a block off plate. You basically restrict the pull pin travel to .086" for 8*, or .104" for 10*. "
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1977 FSJ, Autumn Red 360 roached gas tank to match exterior!

1972 Buick GS 455 Stage 1.Total basket

1960 Electra 225 convertible 401 Nailhead 445 ft lbs of torque.

1970 455 MF'in Muncie 4 speed Buick GSX rusty yet satisfying! Drive it sideways!

1986 Chevy Silverado Dads first nice truck, claimed by the woods : (
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  #4  
Old 05-22-2012, 11:33 PM
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jdaniel83 jdaniel83 is offline
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^^^^ Great info Comancheap
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  #5  
Old 05-23-2012, 07:07 AM
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Comancheap Comancheap is offline
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And here is how one should run ha ha

2 wheelin on pavement http://www.youtube.com/watch?v=ui8jMXTJeOU

Some reason can't get to the link but referring to the one that says "GSX BURNOUTMP4" after the video link here on twin turbo 350 wagon

ah here it is !http://www.youtube.com/watch?v=U9F9X...eature=related
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John

1977 FSJ, Autumn Red 360 roached gas tank to match exterior!

1972 Buick GS 455 Stage 1.Total basket

1960 Electra 225 convertible 401 Nailhead 445 ft lbs of torque.

1970 455 MF'in Muncie 4 speed Buick GSX rusty yet satisfying! Drive it sideways!

1986 Chevy Silverado Dads first nice truck, claimed by the woods : (

Last edited by Comancheap : 05-23-2012 at 07:24 AM.
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  #6  
Old 05-23-2012, 10:26 AM
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Herk Herk is offline
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Cooking the enamel off the center of the intake is normal. That's where the exhaust crossover is.

I sure hope that 42 year old temp gauge is accurate. You did replace the sender on the intake, right?

The reason the base timing was specified at 0 degrees (TDC) was for emissions and smooth idle reasons. The engine will run far better and cooler with 10+ degrees BTDC initial. Whoever set it at 12-14 BTDC probably knew what they were doing. This assumes the mark on your timing damper corresponds somewhat to actual crank position. After 40 years the chance that the outer ring has migrated is pretty good (mine had). Try advancing the distributor to give the highest smooth idle. I run 15 degrees base timing, which seems like the best compromise between idle, and ease of starting. Depending on your actual compression ratio, you may need more advance, but more on that later.

Your friend who said it "may be set up as a Chevy 350" and the valves may be different not letting the exhaust gasses escape at the right time doesn't know much about engines. Don't listen to him anymore. "Re-stab the cam"?!? Is that porno speak? What cam is in there, stock? Was it degreed or did they just "line up the dots".

What pistons did your rebuilder use? Most of the engine "kits" for the Buick engines use later (231 V6) pistons. This will give you about a 7.5:1 compression ratio. You'll need more advance if you have these. I rebuilt mine with the "High Compression 10:1" pistons, which gave me an actual 9.5:1 static compression ratio, and I run 87 octane no problem.

What degree is the thermostat? (should be 195) What does the temp gauge indicate when it opens? (when the top hose gets hot) My truck runs with the needle in on the "M" on the temp gauge.

What water pump are you using? Is it new? What about the fan? FAN CLUTCH? Does it cool down when you are moving? Going down hill? Does it actually boil over? What is your radiator cap rated at?

Where did you get the new radiator? All my overheating problems went away when I replaced the aluminum cross-flow POS in my truck with an original radiator out of a junkyard.

You should educate yourself about these engines. They're really not all that cosmic, but there's a lot of total BS out there. Start here: http://www.v8buick.com/forumdisplay....all-block-tech the "Search" button is your friend.
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  #7  
Old 05-23-2012, 12:53 PM
1969Wagon 1969Wagon is offline
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The thermostat was replaced by the mechanic, but I have a 185* to put in it if that would help. The temp sending unit was not replaced and it could be original for all I know. The water pump is new, radiator cap is a 16lb I think. the radiator is a copper brass unit that is out of one of the AMC 360 wagons. The inlet/outlets had to be switched to work for the 350. It only had 4,000 miles on it when I got it and not a sign of buildup (very clean 4 row). I don't need a racing machine, just a good all around driver that can do some towing when needed. so if it is running smooth and the timing is fine, then why don't the spark wires from the distributor to the plugs match up as shown in the original manual? The fan is not a clutch fan if that makes any difference.
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Old 05-23-2012, 01:50 PM
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Herk Herk is offline
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4 row? Are you sure? That may be your problem. They are typically too dense to flow enough air.

A lower temp thermostat will make no difference. All that controls is the point at which water begins to circulate through the radiator. If the engine is actually overheating with a 195, it will still overheat with a 180 or even a 160.

If the gauge continues to climb past the point the thermostat opens (upper hose/top tank get hot) the thermostat isn't the problem, it is operating correctly. If the engine runs hot at idle, but cools down and stabilizes once the vehicle is moving, your fan is inadequate (driving 35 MPH will push a lot more air through the radiator than the fan can). If the gauge continues to climb when moving at a steady speed the radiator is inadequate. Turning the heater on full blast, should make a difference, an FSJ heater core can reject all the heat the engine makes at 35MPH or at idle for that matter.

The above assumes the gauge itself is accurate. More than once hundreds have been spent replacing perfectly functioning components because a $10 sending unit was wrong. Personally, until you know how hot the engine is actually getting (in degrees) I wouldn't recommend doing anything else. That is, if nothing you have done has solved the problem, make sure you actually have a problem.

Why are the wires one terminal off? My guess is the distributor was installed a tooth or two off and the wired were migrated around the cap to compensate. Not the best way to do it, but it can work.

Now, to recap, the best ways to make an otherwise properly functioning engine overheat would be retarded timing, too lean mixture, or plugged exhaust system.
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Old 05-23-2012, 05:58 PM
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Rich88 Rich88 is offline
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Quote:
Originally Posted by Herk
The above assumes the gauge itself is accurate. More than once hundreds have been spent replacing perfectly functioning components because a $10 sending unit was wrong. Personally, until you know how hot the engine is actually getting (in degrees) I wouldn't recommend doing anything else. That is, if nothing you have done has solved the problem, make sure you actually have a problem.

Yeah that too. Duct tape the stem of a candy or meat thermometer to the upper radiator hose just where it leave the thermostat. Drive until gage sez 240*. Pull over, pop the hood and confirm what the thermometer says. Should be close.

Also, putting in a lower temp thermostat does not fix anything. If its designed to have a 195* t'stat and a 185* improves something you still have a problem that will eventually rear up and bite you somewhere.

You may have multiple issues all contributing to overheating. In addition to other things mentioned, if you have an EGR engine make sure its installed & working. Non-working EGR on an engine designed to run EGR will make 'em run hotter.
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Old 05-25-2012, 08:26 PM
1969Wagon 1969Wagon is offline
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EGR

If you are talking about the little hole coming off the passenger side valve cover that is supposed to hook to the air cleaner then, yes it is gone and has some sort of chrome breather cap on it. So will adding a valve and hooking it to the air cleaner help the issue?
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Old 05-25-2012, 08:32 PM
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Quote:
Originally Posted by 1969Wagon
If you are talking about the little hole coming off the passenger side valve cover that is supposed to hook to the air cleaner then, yes it is gone and has some sort of chrome breather cap on it. So will adding a valve and hooking it to the air cleaner help the issue?

I did say if you have an EGR engine. You may not. I'm not smart on non-360's so someone else may clarify this for you.
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88 GW 360-.030 over/2150/727/229/Posi, e-pump, AC (broke), tow package, Monroe Air Shocks, TFI, CTO-Free, AIR-free, oil & tranny coolers, dried knuckle blood all over, GM 350 TBI in a box, waiting...
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Old 05-25-2012, 09:58 PM
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No EGR in 69, nor did any Buick 350 have EGR prior to 73.
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Old 05-30-2012, 10:01 AM
1969Wagon 1969Wagon is offline
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OK, I am thinking of the PCV valve. Will that make a difference? There is some sort of heat valve on the passenger side exhaust manifold that is frozen in place. Is this valve necessary?
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Old 05-30-2012, 10:34 PM
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So that's NOT a PCV it's a heat riser diverter valve. If it's frozen closed your engine will run like rancid hippo scat. If it's frozen open, your engine might take a tad longer to warm up. What this valve does is divert a portion of the hot exhaust through a passage under the intake to heat the area under the carb. This aids warm-up and cold weather operation. But keep in mind that the "valve" in the manifold was spring loaded, so when the engine was under load (more exhaust) the will blow open allowing the right bank to flow the same amount of exhaust as the left. If it were stuck closed it would be like having a potato stuffed in one pipe of a dual exhaust system. In reality, the valve only had to create a slight restriction on the right side to cause a portion of the hot exhaust to cross over to the left. The flat coil spring itself was bi-metalic so as the engine warmed up the tension on the valve would relax, causing less exhaust to cross over. Once the exhaust manifold was up to temperature (5 minutes or so) the spring had relaxed and the valve would pretty much blow open even at idle. You need to free this thing up!!! Do your best to get it working right. PB and vise grips. If you can't free it, then remove it and replace the shaft with a bolt. It WILL work fine this way (I ran this way for years). A Heat riser valve frozen in the closed position COULD be a factor in your overheating issue.

The PCV is located at the rear of the intake manifold and plumbed via a 3/8 hose to the carb base. This is a good thing and you'll only shorten engine life if you remove it. A plugged or absent PCV system won't cause an overheat, but carries it's own set of drawbacks.
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Old 05-31-2012, 10:17 AM
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lkmarsh lkmarsh is offline
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Good advice here. X2 on the heat riser and the V8 Buick web site. I'm guessing you have no fan shroud. Forget about finding one or making an AMC shroud fit. Waste of time. I found a sheet metal shroud that was close and cut it to fit. Add a real temp gauge too. You might want to look into hood venting and cold air duct work. A 4bbl conversion is a good idea, too. The TH400 really wants an oil cooler.
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Seemed like a good idea at the time...
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Old 06-06-2012, 11:02 PM
1969Wagon 1969Wagon is offline
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Several good things to think about! That valve on the Passenger side exhaust manifold could be a contributor to all of this. I will pass all this info along to the shop. I dropped the beast off there this morning. I will let all of you know the results.
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Old 09-12-2016, 09:44 AM
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And the answer was?
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Old 03-27-2017, 10:24 AM
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Just one more time?
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