V-8 Swap Cooling

[ntsqd]

Simply pulling coolant out of the rear of each cylinder head has proven itself to me. Dropped overall temps about 10-12* and ended my over-heating on a grade problem. I did it in the intake manifold of a small block Ford. SBC's are a little tougher with the dizzy back there being close to the right cylinder head, but it can be done. I'm reserving that option if I have trouble with the TPI swap.

 

[Elbert]

Ok...on the "run rich" issue.

Have to admit the dumb stuff bit me in the @$$.. Allthough I did not spend anytime trying to figure out the issue as I just had the truck towed to the GM shop this AM to get my friend to check it out. They checked the fuel pressure and sensors etc... all the inputs.. I think they have teh tech 2 or 3 ..whatever the current GM $$ scan tool is.

So anyway turns out that I had a coupld of spark plug wire boots that were "cooked" and one or two plug wires that were toast. So plug wires were toast and then spark plugs got fouled from all the gas. I guess PCM goes crazy when stuff like that happens. I may change plug wire brands down the raod but installed NAPA belden wires for a 99 GM pickup with 454 becuase it has teh straight plug wire boots and mates with flat top dist cap. Got new A/C plugs, and new NAPA rotor button and dist cap. I don't pay for the GM shop price on parts as I've grown tired of profuse bleeding from certain orfices when I do go down that road.

So anyway..... Truck runs great...idles smooth and I can't believe it...so lesson learned...check the old school stuff if you have the time as it will save you some time and aggrivation. Also bught some heat sheild "socks" from NAPA that help protect the plug boots and part of the wire. We'll see how that works. The rams horn manifolds aparently did a good job of cooking the plug wires.

On the cooling...I hope to go back out to the local RV park tomorrow and give it hell to see what it does. I did cut off part of the top of the shroud maybe 1.5 inches in depth , all I could do right now without having to take the thing all teh way apart (fan, clutch, shroud, radiator...etc)...

I'll post back up on how the shroud mods turned out. It does feel as if more air is coming across the radiator now. We'll see.

 

[Elbert]

Oh..yea

Something came to mind about the accuracey of the gauges (mechanical).

When it cools off my truck will run righr at the thermostat value which is 180F (for now). So if I know that the thermostat is 180F and the gauge reads 180F ... I tend to believe the gauge is somewhat accurate.
I use the autometer brand and right now its one of the mechancial types, as I like the graduations on the gauge, and its fairly easy to read.

Just a thought...of course you don't see this until it cools down...later in the fall and winter. Right now just driving back from the shop and around town...gauge is showing 185 or so.

 

[Kurtis]

Do you have your vss setup hooked up on the truck yet? Or did you have your computer specially programmed to run without it? I know that has a lot to do with air fuel mixture, egr, and other assorted functions. I know incorrect fuel/air mixture ratios will cause higher temps as well.

 

[Elbert]

Yes VSS has been on the truck for some time now. I initally ran it a few weeks without VSS but that was a mistake. I bought one of the last VSS setups downy sold.

 

[chicago]

Ok...on the "run rich" issue.

Have to admit the dumb stuff bit me in the @$$.. Allthough I did not spend anytime trying to figure out the issue as I just had the truck towed to the GM shop this AM to get my friend to check it out. They checked the fuel pressure and sensors etc... all the inputs.. I think they have teh tech 2 or 3 ..whatever the current GM $$ scan tool is.

So anyway turns out that I had a coupld of spark plug wire boots that were "cooked" and one or two plug wires that were toast. So plug wires were toast and then spark plugs got fouled from all the gas. I guess PCM goes crazy when stuff like that happens. I may change plug wire brands down the raod but installed NAPA belden wires for a 99 GM pickup with 454 becuase it has teh straight plug wire boots and mates with flat top dist cap. Got new A/C plugs, and new NAPA rotor button and dist cap. I don't pay for the GM shop price on parts as I've grown tired of profuse bleeding from certain orfices when I do go down that road.

So anyway..... Truck runs great...idles smooth and I can't believe it...so lesson learned...check the old school stuff if you have the time as it will save you some time and aggrivation. Also bught some heat sheild "socks" from NAPA that help protect the plug boots and part of the wire. We'll see how that works. The rams horn manifolds aparently did a good job of cooking the plug wires.

On the cooling...I hope to go back out to the local RV park tomorrow and give it hell to see what it does. I did cut off part of the top of the shroud maybe 1.5 inches in depth , all I could do right now without having to take the thing all teh way apart (fan, clutch, shroud, radiator...etc)...

I'll post back up on how the shroud mods turned out. It does feel as if more air is coming across the radiator now. We'll see.

AAAAAH! That is great news that it was just the wires. Guess that'll do it.

 

[Elbert]

got out the scan tool. For baseline...drove the suburban around..given its factory gauge about all you can say is that it runs under 210 (has 195 thermostat). Looking at the temp through the scan gauge "just driving around"..without A/C runs very close to 195F, with A/C on around 200F to 205F. Factory temp gauge does not reflect this variation.

ON the LC, Still have not had time to make full mods to fan shroud, but decided to change thermostat to 195F to have everyting OEM, as I noticed the fan clutch did not cycle until around 195F- 200F. So went out drove around on pavement..according to gauge truck ran 200F to 205F... Was not able to check temp going dow the road with scan tool since I need to relocate my ALDL connector from under the hood, but at extneded idel truck shows to be at 197F at the scan tool. I'll locate the ALDL connector and check temps driving with the scan tool.
During this I noticed the gauge readings varied a good bit...so as some of you guys sugguested the gauage itself may be flawed, but I think its to be expected that there will exist some differences between the two based on the location of the sender on the engine. . Noticed the gauge read higher than the (ECT PCM temp gauge) every time I checked it. During the time I looked at this...I would say there is roughtly a 5 to 10F variation between the PCM temp reading and the mechancial gauge reading, with the gauge at the cylinder head being hotter and teh PCM reading at the intake being cooler. (FYI)

As time perimits I plan to space the shroud out from the radiator core which appears to me , would allow additional air flow over the full radiator core (better air flow).

 

[ntsqd]

I don't know that I call it "flawed." Gauges are a trickier thing than they seem. At one particular temperature they may be spot-on, but go in either direction from that point and they will differ from the 'true' temperature (slope); they may not read exactly the same temperature when arriving at the temperature from hotter vs. arriving at the temperature from colder (hysteresis).

Said differently; If you plotted the reading vs. the 'true' temperature over the whole temp. range you might see those two lines diverge and/or converge (slope), you might see one line run exactly parallel to the other, but offset up or down (scale), you might see one line has a bulge or a belly to it and that whether it is a bulge or a belly depends on if warming up or cooling down (hysteresis). If the gauge readings aren't the same at the same temps when approached from the same direction then you've got a repeatability error (the worst possible kind of error IMO).

If you can plot in Excel (or similar) several to many gauge reading points vs. a known to be highly accurate thermometer's readings, and then do a curve-fit you'll know where the gauge's reading is acceptably accurate and where it is not.

Pull up nearly any gauge offered by McMaster-Carr (McMaster-Carr) and they will specify what these errors are. Typically they'll say something like "3%FS" or "3%FS, 1.5%MS" or something. I've never seen such an error listing for the automotive jewelry type gauges. That is why I dismiss them as 'jewelry', not because I know that they aren't accurate - but because I don't know how accurate or inaccurate they are. An inaccurate gauge is worse than no gauge at all, but a mildly accurate gauge - so long as that accuracy is known and appropriate for the need - is perfectly fine.