Engine fan

[SirRobyn0]

I have the 700r4 and it shifts pretty sloppy and basically slides into gear lol. I used my dial back timing light and it was set at 40 initial, I revved it up from there and it went up but I wasnt too worried about how high the timing went because it didnt seem to ping and I knew i was going to fix it. All checks were done with the vacuum advance unhooked and plugged the hose from the carb. It did have a little valve or fitting on the line just before the dist but Idk what it is for yet. Anyway I moved the timing to 11 initial and revved it up to about 3k and the timing went up to about 40 so it seems good now. I only had to adjust the idle speed after that, it seems fairly responsive for a smog motor now and runs ok. I just picked up some true duals from lmc truck today for a change from the y pipe and single 2 inch, hopefully that will help out the power a little bit too.

Well you have the timing sorted out now and that's what really matters any way.

I'm still running single exhaust, I thought about going dual when I needed to do exhaust work but what prevented me is that my truck has a dump kit on the factory box and pump is mounted on the in board side of the passenger frame. I do not want to run hot exhaust right next to that, so I went to a high flow cat, larger mid pipe, I think it's 3" and a big 22" high flow low noise walker muffler with dual outlets. So I think it's a pretty free flowing exhaust system for what it is anyway.

 

[80BrownK10]

Hi I'm trying to get my new to me 82 k2500 suburban up to my standards and have looked everywhere but can't find the answer.
I can't find the proper clutch fan , I bought a new clutch at napa but no one seems to carry the fan or even list it even lmc truck. Does anyone have a part number that'll work? I have a 350, thanks!

You will need to search a junk yard, ebay, someone bhere or on CL or FB that has parts trucks.

 

[Kurnacopia]

Does anyone know if there is a more efficient blade design for a clutch fan? I was watching some YouTube about that and there is a definite HP draw on some of the old school fan designs. I have a 7 blade OEM I pulled out yesterday, cleaned up and will go with but before I do Id like to see what ya'll think.

MK

 

[SirRobyn0]

Does anyone know if there is a more efficient blade design for a clutch fan? I was watching some YouTube about that and there is a definite HP draw on some of the old school fan designs. I have a 7 blade OEM I pulled out yesterday, cleaned up and will go with but before I do Id like to see what ya'll think.

MK

I think you should stick with the factory 7 blade. Is there a HP draw sure, but most of that is going to be when the fan clutch is locked up and that thing is sucking tons of air though the radiator which is exactly what you want when it's hot out. When the fan clutch is disengaged there is little HP loss. My 2 cents run the 7 blade fan. Make sure your fan clutch operates properly and engages and disengages as it should. A severe duty fan clutch will pull the most air when locked up, heavy duty will be similar, possibly a little less and a standard duty will only pull about 65% of the air, a serve duty will. BUT when it's hot it'll have to stay engaged longer and more often to keep temps where they need to be. Thats what I've got. I'd run the 7 blade with severe duty clutch and not think twice about it.

 

[Matt69olds]

Get the TV cable on the trans sorted out before you drive it. You say it’s sloppy and slides into gear, it’s only going to get worse. Keep in mind, the linkage for the kickdown cable used on a 350 trans won’t work correctly for a 700.

I have run my Olds at the track both without the thermal fan clutch, and with it installed. These were back to back tests, there was no difference in mph or E.T. The ******** stories people have about mechanical fans taking lots of power is exactly what I said, pure ********.

A thermal fan clutch might pull some power when it’s engaged, but unless your cooling system is so marginal that the engine is close to overheating all the time you will hardly notice the fan.

 

[Bextreme04]

Get the TV cable on the trans sorted out before you drive it. You say it’s sloppy and slides into gear, it’s only going to get worse. Keep in mind, the linkage for the kickdown cable used on a 350 trans won’t work correctly for a 700.

I have run my Olds at the track both without the thermal fan clutch, and with it installed. These were back to back tests, there was no difference in mph or E.T. The ******** stories people have about mechanical fans taking lots of power is exactly what I said, pure ********.

A thermal fan clutch might pull some power when it’s engaged, but unless your cooling system is so marginal that the engine is close to overheating all the time you will hardly notice the fan.

Its not pure BS. It does take power to turn the fan. Empirical data from a dyno on engine masters showed that it can be as much as 40hp drag at full engagement(i.e. no clutch). In a racing instance or driving on the highway where you are moving enough air through the radiator without the clutch engaged, you are probably drawing next to nothing. The clutch spins at ~10-20% of engine RPM when not engaged, which is not a linear relationship to HP. 20% of 40hp is still only 8hp. I would bet that 10-20% rpm only requires maybe 2% of the same power to turn the fan as it does at high RPM, which works out to 1hp or less to turn the clutch fan when it isn't engaged. When it does engage, at high RPM, you are going to start to feel it pretty quick.

 

[Matt69olds]

I have seen that episode.

When engaged, they do draw some power. But most people don’t try to race with the engine hot enough to cause the clutch to engage.

As I said, I have run my car with and without the fan and clutch, back to back on the same day. There was no difference, maybe a couple hundredths of a second. There would be a huge increase in ET, and loss of mph if the fan really took 40 hp.

 

[gsuburban]

The eighth digit on your Vin number should either be an L or an M in 1982 for an L motor with air-conditioning It should be 14006712 it’s a seven blade fan .In 1982 if you have an M motor the blade number is 14009080. That is a five blade fan 19 1/2 inch diameter. This is right from my GM parts manual hope this helps you

Does this information apply to 1989 v1500 engines as well?