Ok-decided to go shroud route verses electric fan But....help!

[ubtripn]

I listened to what all had to say and decided to go with a fan shroud to cover overheating while in heavy traffic. But my fan is 19 inches and I believe the LMC shroud is 18 inches. (Which I now have.) I can buy another fan (not flex) but the 18 inch says for use only up to 250 cid. Even LMC does not sell an 18 inch fan which makes no sense because the truck came stock with a 327 and now has a crate 350 so shouldn't 18 inch be right?

I am clearly missing something and need some advice, thanks everybidy.

[Trevor]

My '71 has (from factory) a 7-blade thermostatic 18" fan in the factory shroud which measure 19-1/4" (5/8" clearance blades to shroud).

Has a 350 in it, 2-core rad and has never once gotten hot even pulling trailers through the mountains ...

[fwayne]

A little misleading that LMC page. Usually the 250 six got a fixed blade fan and the clutch fans were for v8. an 18" 6 blade on a clutch is plenty adequate because it will move a ton of air. be sure to get the thermally operated clutch which will move a lot more air when the temp is up, and release the clutch when you don't need the air moving. This is how all modern engine driven fans work.

I'd give LMC a call and verify the dimensions. Ideally you want a fan to be 1" or less from the inside edge shroud for best performance. Also you want to shroud to be the right depth. The blades should be at the edge or even better is they are partially exposed and not all the way inside the shroud. Thats the difference between an AC and non AC versions.

[ubtripn]

Well I just received the shroud but have not had time to take it out of the box, been moving so fast. I found an 18 inch fixed blade fan locally and can probably use the clutch off my current 19 inch fan I am hoping since it is thermal.

[ubtripn]

Thank you for confirming what I needed to know. I was really stressing out.

[Stocker]

Originally Posted by ubtripn

I found an 18 inch fixed blade fan locally and can probably use the clutch off my current 19 inch fan I am hoping since it is thermal.

1) Make sure that it is a thermal clutch. If not -- get one that is.

2) I hope your 18" fixed-blade fan is one that is designed to be used with a clutch -- not one that was intended to be bolted directly on, with no clutch. Make sure you have the right type.

3) How many blades does your fan have? The OEM fan on my '72 K20 (350, factory A/C) is same as Trevor's (post #2, above) -- that is, 7-blade, 18", on a thermal clutch. Truck does not overheat.