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Old 08-05-2010, 05:50 AM
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SBC Running HOt

I have a '67 El Camino, rebuilt 350/TH350 with about 3000 miles. Runs a bit on the hot side according to the aftermarket gauges...cruzing temp is 190-200. Idling temp is 200-230+. It has a brand new 3 row radiator (not sure how to tell how many cores) from Napa, brand new 180F thermostat (Napa), brand new shroud, brand new Flex lite fan. It also has aftermarket A/C which is not currently hooked up and the condenser is of course smack in front of the radiator. Timing is set at 10 btdc (has a cam with either 214 or 224 duration?). I have been told by some the timing should be more like 14-16 btdc, others say 10 btdc. The weather were I live varies from 70-95 in the summer time (summer only being two months!). It's only been running like this since the weather got hot. It was running at a constant 180F in 60-65F weather with a 160F thermostat, old radiator and no shroud. Sorry for the long post but any help/advice anyone has would be greatly appreciated.

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Old 08-05-2010, 06:52 AM
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The fact that it runs cooler when you are moving tends to suggest your fan is not doing the job. How far is the fan set into the shroud and how big is the fan.
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Old 08-05-2010, 07:12 AM
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FWIW, you can use more than 10 of initial timing- try 14-16- but do not exceed the maximum of ~36 total (this can vary depending on the heads you're using).

What you may be able to do, is bring the mechanical advance in quicker, i.e. at a lower RPM. Shoot for the mechanical to be all in by 2500-3000 RPM, sooner the better, as far as performance and possibly allowing the engine to run cooler goes. You would use lighter advance springs to do this.

Are you using a vacuum advance?

Just remember to not go too high on your total timing.
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Old 08-06-2010, 07:15 AM
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The fan is "18 6 blade and about 2 1/2 inches away from the radiator (well inside the shroud). The heads are '69. The carb is an Edelbrock 1406 and i have the the vacuum from the distributor hooked to the timed port. I've heard if you hook it to the manifold port it's possible to run cooler but your motor won't run as good. I'm not sure tho.
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Old 08-06-2010, 07:31 AM
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Quote:
Originally Posted by Fiasco
The fan is "18 6 blade and about 2 1/2 inches away from the radiator (well inside the shroud). The heads are '69. The carb is an Edelbrock 1406 and i have the the vacuum from the distributor hooked to the timed port. I've heard if you hook it to the manifold port it's possible to run cooler but your motor won't run as good. I'm not sure tho.
Manifold vacuum for the vacuum advance would only help temp at idle. As for making the engine run worse, I'll just leave that for now, this isn't the problem w/the temp.

The fan should be about 1/2 in 1/2 out of the shroud. The fan should not fit more than the blade width up inside the shroud in any case. You should have about 3/4" clearance between the fan tip and the shroud.

The water pump's drive ratio is often overlooked when a cooling issue arises. I'd suggest you go to at least a 1:1 W/P to crank drive ratio, to as much as 1.3:1 (W/P overdriven). You use the crank pulley diameter and the WP pulley dia. to figure the ratio- ignore any other pulleys in the system.
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Old 08-07-2010, 05:12 AM
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Didn't even think about the pulley ratio. Took a tape measure and checked...looks like the crank pulley is "6 and the water pump pulley is "8. So I'm not even 1 to 1, that probably doesn't help matters. Also I checked my pod on my distributor and I don't think it's working properly. I will check the timing and advance in the morning with my dial back timing light to see what I have. Drove home tonight in mid 50's temp outside and barely broke 190 on the temp gauge. I really wanna figure this out 'cause it's buggin the hell outa me!! I appreciate the replies I've gotten. If there's anything else anyone can think of I'm all ears. Oh, I heard my area has been getting some really crappy fuel delivered to the stations lately and lots of people have been overheating due to it. Never would have thought of that.
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Old 08-07-2010, 12:43 PM
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Not a big fan of the flex fan, But have seen a few good ones and just how far into the shroud is the fan sitting anyway? The fan should be like 1/2 in and 1/2 out.

Edit: Sorry Mark just seen where you told the OP about how the fan should set in the shroud.

Cole
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Old 08-07-2010, 01:23 PM
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Quote:
Originally Posted by eloc431962
Not a big fan of the flex fan, But have seen a few good ones and just how far into the shroud is the fan sitting anyway? The fan should be like 1/2 in and 1/2 out.

Edit: Sorry Mark just seen where you told the OP about how the fan should set in the shroud.

Cole
No prob, Cole- I've read where guys will run as much as the whole fan inside the shroud, but I believe that having some portion outside seems to work well.

But the point is that the entire fan should not be well up inside the shroud, and 1/2 and 1/2 works.
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Old 08-07-2010, 05:04 PM
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As a side note you will notice that with factory original mechanical fans w/shrouds, they are always 1/2 in -1/2 out, from every manufacturer. A lot of the air pulled is coming off of the blade tips radially(maybe centrifugally is a better word), if it is too far in the shroud the shroud outlet becomes a choke point.

You only want the fans close to the radiator if there is no shroud, otherwise the fan needs to be at the back of the shroud. Either move the fan back or trim the shroud outlet shorter to achieve the 1/2 rule
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Old 08-09-2010, 05:04 PM
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I'll try moving the fan back 1". My stock shroud isn't that deep so 1" will put the fan just a tad inside the opening. Wish me luck.
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