Ignition timing & Engine Temps

[slant6billy]

I happened onto something yesterday. My budy runs a caddy 429 in an 81 Pontiac Safari G body wagon. He runs the same 750 Edelbrock with the E choke as me. He noticed at cruising speed the engine starts to heat climb. Similar to what I see, grant it I'm running a mopar small block. We both run a stout gear and pretty tall tire 28 inch. his is a 4:11 in a Ford explorer 8.8. My 4:30 in and 8 1/4. So 55 mph is a scream for both of us.

So, my budy is getting the carb kit with different metering rods (smaller ones and then taller ones). He believes the secondaries are "leaning out" at cruising speed and needs to rich them up.

I'm going to see how he makes out with results. I'm going with a different direction. Engine timing! I believe my engine timing needs to be addressed since passing the emissions test. I see that there are 2 schools of thought on the effect of engine timing on engine temperature.

Does advancing the engine timing drive the engine temp up? Newer engines, like my 97 5.9 Magnum are set advanced and can't really get the "death rattle" pinging adjusted unless you move the crank position sensor. Grant it, my SS/T does not have this ping, due to computer mods. I hear 5.2 Dodges all the time with this ping. I understand the need to keep the engine advanced for emissions, but does it truly drive up the temps? I'm thinking to backing off timing by 3 to 5 ° to see if the temps drop at cruising or at least stave off from the climb to 220/230 °F

Any thoughts?

 

[slant6billy]

Just had to post because it is a work of art.... I know it ain't mopar, but I'm checking a woody wagon M body today and this Pontiac is edging me on "TO BUILD A MOPAR WOODY WAGON MONSTER"

 

[Aspen500]

Just a suggestion to anyone with a modified car. A wide band A/F ratio gauge is money well spent. Before I got one, screwed around with jets, idle air bleeds, timing, etc until it "felt" OK. Turns out it wasn't even close. Way too rich at idle and cruise, lean on hard accel. Using the A/F gauge got it all dialed in within a couple days.

Yeah they aren't cheap but without one, you will never know for sure. Actually, it will pay for itself after a while in fuel cost not to mention all the trial and error time. The engine runs perfect, more than enough power (and then some, lol) but the mpg went from a previous 6-8 mpg and is now about 12 avg.

Too much advance will cause spark knock (thank you Mr. Obvious, lol) but not so much effect on engine temp. Retarded timing will make it run hotter though. In all honesty, 220-230 isn't really much too hot but I know what you mean, gets a guy nervous.

If it gets hot at cruise, one thing that can help is by building baffles to go between the grille and radiator so all the air is forced through the rad instead of only some of it. Also, a small air dam (like new cars have) on the bottom of the core support a couple inches tall helps a ton by directing the air up into the rad instead of just going under the car. Some cars will overheat (3rd gen Camaro/Firebird for example were notorious for it) if the factory air dam gets broken off. Also a fan shroud is mandatory. Just a few ideas anyways.

I bought this one and have no complaints.

http://www.summitracing.com/parts/avm-30-4110/overview/

 

[Aspen500]

Forgot to say, sure is nice to see that Pontiac with something other than the typical small block Chevy under the hood! A 455 Pontiac would be better but the Caddy engine is a nice change from the usual.

 

[9secRR]

even though it's not a mopar, the woody wagon does look good.

I should have a wideband on my car. for $200, it's a no brainer. I just slapped myself for not buying one.

 

[Aspen500]

Yeah, I slapped and kicked myself for not buying one sooner. I had it in the plans and already had an O2 bung in place. Kept putting it off, especially after spending who knows how much money building the car, then building the engine again after 100 miles, replacing the new B&M converter that broke right away with a Hughes, replacing the stock twisted axle shafts with the wobbly flanges after trying out a buddies new drag radials (they hooked REALLY good, lol) and other miscellaneous "bugs", etc... (don't know the total, don't want to know). Those gauges are invaluable. Some of the best money I ever spent.

 

[kkritsilas]

Not trying to be a wise ass here, and this only pertains to your buddies Safari wagon,

What engine was in the Safari before the swap? When he swapped out the engine, did he bring the radiator from the donor Caddy to the Safari, or get a higher capacity radiator? The bigger Caddy engine probably generates more heat than the original small block or V6, so if he didn't get the Caddy's/aftermarket radiator put into the Safari, it will eventually start heating up as the radiator's ability to dissipate heat falls further and further behind the Caddy's engine heat output. Same thing happens when you drop a Mopar big block into our cars; you need to consider that the engine will be putting out more heat.

This is only based on your description of the overheating over time as the car moves down the highway. At highway speeds, there should be plenty of air flow though the front grille of that car (its not a snorkle breather like the 3rd Gen Camaro/Firebird), and as has been stated before, a good radiator shroud is very important.

 

[slant6billy]

Not trying to be a wise ass here, and this only pertains to your buddies Safari wagon,

What engine was in the Safari before the swap? When he swapped out the engine, did he bring the radiator from the donor Caddy to the Safari, or get a higher capacity radiator? The bigger Caddy engine probably generates more heat than the original small block or V6, so if he didn't get the Caddy's/aftermarket radiator put into the Safari, it will eventually start heating up as the radiator's ability to dissipate heat falls further and further behind the Caddy's engine heat output. Same thing happens when you drop a Mopar big block into our cars; you need to consider that the engine will be putting out more heat.

This is only based on your description of the overheating over time as the car moves down the highway. At highway speeds, there should be plenty of air flow though the front grille of that car (its not a snorkle breather like the 3rd Gen Camaro/Firebird), and as has been stated before, a good radiator shroud is very important.

He has a huge Champion Radiator 3 or 4 core, not sure but it is not the stock one for sure. Mark8 electric fan, volvo 2 speed controller, and a custom temp sensor (BMW- I believe)
My radiator is out of the AHB. did a flow check on it and seems fine

 

[greymouser7]

I did not read all of the responses- in his case, I think it is possible that he is running lean. In airplanes, you can thin out the fuel, more and more -besides detonation, which you cannot hear initially, the heat goes way up.

My heat went up in my Road Runner with it's tiny 22 inch radiator in this 90 + degree heat with a 650 carb when I ran the rpm's up=past the capacity of the cooling system-it expanded the rings (improperly gapped) until the cast piston fragmented all over creation in that particular cylinder.

I do not know enough about enriching the mix, but I believe that enriching the fuel with the carburetor, enough radiator cooling capacity, and the correct thermostat (190? or higher) would resolve any issues.

I might be wrong-this is my first suspect from what you said.

 

[Aspen500]

Kind of off your original question BUT, with my 500" stroker BB I had the local radiator shop (you may have heard of them: Glen-Ray Radiator. They reproduce the correct BB radiators and P.S. coolers for B-bodies) build me a 3 core using the largest stock tanks and side rails that came in an F-body. I'm assuming something like a 360 with A/C or Police(?). Even in 90 degree heat, with the A/C cranked, in city traffic, it never goes above 1/2 on the gauge. I checked and that's an actual 210 degrees. Using a 16 psi cap and 195 t-stat, RedLine water wetter, 7 blade fan with a thermal clutch and fan shroud. I was worried it might not be enough but turned out it is, just like I planned, lol. Or, just got lucky?

 

[kkritsilas]

Thermostat temperature point really doesn't have an effect on cooling if the engine has been running a while. After it hits the temperature that is its fully open position, it effectively ceases to have any effect. If the thermostat is not going fully open, it can raise temperatures by restricting coolant flow, but that is a defective thermostat, not really related to whether the thermostat is a 160 Degree or 190 degree.Checking the water pump for flow, and that the electric fans (what does the 2 speed controller actually do? Normally, you want the fans on fully when the temperature trigger point is reached at the temp sensor (S)), are actually coming on (as well as the temperature set point of the temperature sensor) would be other ideas.

 

[greymouser7]

Thermostat temperature point really doesn't have an effect on cooling if the engine has been running a while. After it hits the temperature that is its fully open position, it effectively ceases to have any effect. If the thermostat is not going fully open, it can raise temperatures by restricting coolant flow, but that is a defective thermostat, not really related to whether the thermostat is a 160 Degree or 190 degree.Checking the water pump for flow, and that the electric fans (what does the 2 speed controller actually do? Normally, you want the fans on fully when the temperature trigger point is reached at the temp sensor (S)), are actually coming on (as well as the temperature set point of the temperature sensor) would be other ideas.

What about running a 180 (or 160) degree thermostat (always NOT recommended) in regards to what you just said? There are tons of posts thru out the web telling people to stay away from the low temp thermostats in regards to keeping the vehicle cool (my guess is at idle, or sitting in traffic).

 

[greymouser7]

Just a suggestion to anyone with a modified car. A wide band A/F ratio gauge is money well spent. Before I got one, screwed around with jets, idle air bleeds, timing, etc until it "felt" OK. Turns out it wasn't even close. Way too rich at idle and cruise, lean on hard accel. Using the A/F gauge got it all dialed in within a couple days.

Yeah they aren't cheap but without one, you will never know for sure. Actually, it will pay for itself after a while in fuel cost not to mention all the trial and error time. The engine runs perfect, more than enough power (and then some, lol) but the mpg went from a previous 6-8 mpg and is now about 12 avg.

Too much advance will cause spark knock (thank you Mr. Obvious, lol) but not so much effect on engine temp. Retarded timing will make it run hotter though. In all honesty, 220-230 isn't really much too hot but I know what you mean, gets a guy nervous.

If it gets hot at cruise, one thing that can help is by building baffles to go between the grille and radiator so all the air is forced through the rad instead of only some of it. Also, a small air dam (like new cars have) on the bottom of the core support a couple inches tall helps a ton by directing the air up into the rad instead of just going under the car. Some cars will overheat (3rd gen Camaro/Firebird for example were notorious for it) if the factory air dam gets broken off. Also a fan shroud is mandatory. Just a few ideas anyways.

I bought this one and have no complaints.

http://www.summitracing.com/parts/avm-30-4110/overview/

This is just awesome! I have heard of this before, but thought it was part of a very expensive set up or expensive fuel injection.

 

[kkritsilas]

Thermostat temperature point only determines what temperature the thermostat opens at. It has an effect on the warming up of the engine, but as soon as the coolant reaches that temperature, the thermostat opens up. It cannot do any cooling itself. The thermostat temperature can have an effect on running before it opens up, and indirectly, things like the choke coming off or not, or the carb heat, cold running, cat;alytic converter light off, and things like that.

When, say a 180 degree thermostat sees coolant at 180 degrees, it opens up. When the temperature goes above that, it is still fully open; can't get any more open than it already is. It also cannot do anything to cool the car off; that is determined the water pump, radiator, air flow, and coolant type and flow rate, and coolant pressurization. If the heat generated by the engine is below that which the cooling system can dissipate/get rid of, then the car will run fine. If the engine generates more heat than the coolant system can dissipate, then the car will overheat at some point, how fast is determined by how much heat the engine generates vs. the capacity of the coolant to get rid of the heat. If the engine generates a lot more heat then the coolant system can get rid of, then the car will overheat fairly quickly; if the engine generates a little more heat than the cooling system can get rid of, then it will take longer to overheat. If the cooling system can get rid of more heat than the engine can generate, then the car will not overheat.

I think there is a lot of misunderstanding of the function of a car's thermostat vs. a house thermostat, probably because they are both called thermostats. House thermostats absolutely set the temperature inside a house; car thermostats only open or close based on coolant temperature that they see. The house thermostat is actually controlling an active system (furnace or air conditioner) that can actually raise or lower temperatures; car thermostats are a temperature sensiitve bi-metallic strip that can only open or close to allow coolant flow.

 

[BHA43]

I put a pair of knock sensors on my motorhome (pulled them off cars @ Boot Hill) and got a kit off the web with a led light with an adjustable reciever. Don't remember the Co. but they tell you what sensors too look for. Jap cars if I remember. I think it was around $50????? The sensors go on intake bolts.

 

[Monkeyed]

I didn't see any mention of what water pumps are on the either. I can't imagine running a massive $600 aluminum radiator with a $20 stock replacement water pump, but people do it all the time. First most obivious step once you determine that the thermostat is good would be a cheapy water pump, but if that didn't solve it, a good high flowing replacement comes before aa radiator change. People would be shocked to see how muchc of a difference just 20-30% increase of coolant flow looks like and how much of a difference it can make. If that didn't take care of it, and the larger radiator wasn't enough you'd have to start looking for obstructions to flow, blocked passages etc, if THAT doesn't do it, then you want to look for design choke points to flow, such as removing the thermostat entirely, or switching to a higher flowing one if you plan on starting it in cold weather and need it to warm up quicker. after that, maybe larger hoses, and dual radiators, I mean, where there's a will lol :toothy5:

 

[Monkeyed]

speaking of dual radiators... If you have A/C that functions properly, you might want to try running that with the windows down and the heat knob cranked to hot. then you're essentially blowing frigid air on a tiny radiator (the heater core) I know a guy in Phoenix that got his C4 "bottom feeder" vette to stop over heating that way..

personally both my 3rd gen camaro, and my own C4 fixed overheating with a high flow water pump.. I ran 160 thermostats in both and they both would hover around the 170-175 mark.

 

[Aspen500]

Oh yeah, good point (Monkeyed), running a 440 Source pass side outlet aluminum w.p. housing with a Milodon high flow pump.

 

[compubert]

I didn't see any mention of what water pumps are on the either. I can't imagine running a massive $600 aluminum radiator with a $20 stock replacement water pump, but people do it all the time. First most obivious step once you determine that the thermostat is good would be a cheapy water pump, but if that didn't solve it, a good high flowing replacement comes before aa radiator change. People would be shocked to see how muchc of a difference just 20-30% increase of coolant flow looks like and how much of a difference it can make. If that didn't take care of it, and the larger radiator wasn't enough you'd have to start looking for obstructions to flow, blocked passages etc, if THAT doesn't do it, then you want to look for design choke points to flow, such as removing the thermostat entirely, or switching to a higher flowing one if you plan on starting it in cold weather and need it to warm up quicker. after that, maybe larger hoses, and dual radiators, I mean, where there's a will lol :toothy5:

The old man used to race dirt track and they had to gut the thermostat and leave the ring in as a restrictor to prevent too much coolant from traversing the radiator too fast as it wouldn't pull the heat off the heads flowing too fast. . . my 2c. they also cut every other impeller blade off the pump to cut down on cavitation...

 

[Mcfly68]

Well it is nice to see someone actually understands what an automotive tstat does..kkritsilas you wouldnt believe how many times people have argued with me when I tell them the tstat controls warm up and flow not temperature!! ( even open it partially restricts flow to control the speed of the coolant through the rad...to fast and the rad cant dissipate the heat from the system). I run and have always run 195 stats. When I first started in the trade an old guy ( I guess I am the old guy now...lol) told me if you need to run a "cold" thermostat to make power, you have other issues. a fully warmed up engine is efficient. An efficient engine is a powerful engine and a cold stat is a crutch not a fix. The biggest problem I see in modified vehicles is "air" control...the air coming through the front of the vehicle will take the path of least resistance. it will go over, under and around the rad instead of through it, if it can. If the vehicle has no frontal area or grill then an air dam is required ( think mid 80's trans am with the pointy nose and no grill or a late 80's daytona..same no grill and pointy nose)to direct the air from under the vehicle in to the rad. So...make sure the sides of the rad are sealed to the rad saddle, the hood is sealed to the rad saddle( I have seen a missing hood seal cause running hot at highway speeds), and the space from the bottom of the front bumper to the bottom of the rad saddle is closed off..so ALL the air goes through the rad..a shroud will make the fan efficient in low speed operation ( think city driving, idle etc) as the fan shouldn't run when cruising...50mph air is more air than the fan can pull