Thread: Rad Grill Question

Tweet

Well I have continued to search the Internet for an electric fan that will fit and found this site:

http://www.the-fan-man.com/shop/images/16.jpg

Maybe with these specific sizes I can get one that will work. Further suggestions are welcome.

Don Shillady
Retired Scientist/teen rodder

Originally Posted by Don Shillady

Brian Rupnow,

I have gone round and round on the fan installation for my roadster. The best suggestion so far is from Brookville which sells an electric fan rated at about 2000 CFM shich may be marginal. The tech guy at Brookville says they cut out part of the mesh screen bars at the bottom of the fan cage for the nose of the water pump and use a 16" fan. That might work but the fan is probably marginal since another tech guy at Walker Radiators says a SBC 350 needs at least 2500 CFM. I have also chatted with the Tech guy at Southern Parts who sell the Zip riser and he said the nose of the Chevy 6 cyl pump it uses will be at the same tight 1 1/4" clearance with the present short V8 pump. I tried three fans so far and they all had a "forward twist" on the blades that just hit the fittings for the transmission cooler on the bottom of the radiator. So far the clearance between the inner face of the radiator and the alternator pully face is just 4" and the alternator invades part of the center space behind the radiator which may interfere with an electric fan motor. Also I recall you saying your fan can draw up to 90 amps on startup and the Walker guy said theirs draws 70 amps on startup but only about 15 amps when running. In addition the Speedway fan relay is only rated at 40 amps. There is a lot of conflicting information out there so I wonder if you have a picture of your fan from the engine side? At this point the best setup (?) is probably the Zip riser but the guy at Southern

http://www.southernrods.com/categori...duct-1845.html

recommended moving the engine back for more clearance which is the last thing I want to do. It is not so bad buying and keeping/exchanging $35 fans but I can't afford to absorb $300 experiments unless there is a pretty good chance I can make it work. Maybe the Zip setup is best but then I may need another shroud so the idea of an electric fan with a built-in shroud for less than $200 is appealing if it will work. Can you send me any pictures of your setup? I would especially like to see the clearance of the nose of the water pump relative to the fan and the inner side of the radiator.


C9X, So far I have not found a fan that does not have the forward twist of the blades. Can you recall who might have such a fan in case I use the low fan/pump setup? I am still very surprised you can run a low fan with a big engine in the Southwest heat. I want to believe that would work for me if I can find a 15" fan without the forward twist but I am still researching possibilities.

Don Shillady
Retired Scientist/teen rodder

Hayden makes a fat blade stainless fan with six - very sharp edged - blades that has the blades sit back from the center of the hub.

I have a Hayden 17" six blader on the 32 and a 15" on the 31.
Later on I may go to a 17" on the 31.
That due to the 15" is all that would fit when I had the US Radiator in the 31 - which turned out to be too tall for a good hood flow line . . . speaking design-wise here.

I had a local shop that builds custom aluminum radiators make one for me and that should allow the 17" fan to fit.
The conflict is the lower hose bib.

Another way to think about the blade vs hub location is; if you lay the Hayden face down on the workbench the front edge of the blades and the hub will touch.

The Derale hub remains suspended off the bench.
Not a bad thing, Derale fans are ok, just that the blades are set different.

Here's a pic of the Hayden 15".
(Pep Boys carries Haydens last I saw and they usually have a good selection.)

Thanks C9X! Yes, that is what I need, just that 1/4" where the Deralle blade edge is out in front of the hub. I will look further for the "flat" type. I have been learning that quite a few folks don't understand electric fans. The tech guy at Brookville said they don't need a relay and just run off the ignition wire but then I found out it was a small motor that only draws 30 amps at surge and about 15 when running. The Brookville guy did not even know what I meant by a fan relay! Then I talked to a knowledgable guy at Vintage Air and he said, why of course if you want more than about 1700 CFM you have to go to heavy duty wiring and the fan may draw as much as 70 amps on startup. That must be what Brian has since he saw large surges that blew fuses at first. The lesson there is that if you want more than about 2000 CFM you need heavy duty wiring and can expect to draw a lot of amps on startup. I really wish I could get away with a low fan and I still don't know how you do it; maybe if you keep the speed up you can do it but what about city/town traffic?

Don Shillady
Retired Scientist/teen rodder

Originally Posted by Don Shillady

Thanks C9X! Yes, that is what I need, just that 1/4" where the Deralle blade edge is out in front of the hub. I will look further for the "flat" type. I have been learning that quite a few folks don't understand electric fans. The tech guy at Brookville said they don't need a relay and just run off the ignition wire but then I found out it was a small motor that only draws 30 amps at surge and about 15 when running. The Brookville guy did not even know what I meant by a fan relay! Then I talked to a knowledgable guy at Vintage Air and he said, why of course if you want more than about 1700 CFM you have to go to heavy duty wiring and the fan may draw as much as 70 amps on startup. That must be what Brian has since he saw large surges that blew fuses at first. The lesson there is that if you want more than about 2000 CFM you need heavy duty wiring and can expect to draw a lot of amps on startup. I really wish I could get away with a low fan and I still don't know how you do it; maybe if you keep the speed up you can do it but what about city/town traffic?

Don Shillady
Retired Scientist/teen rodder

Timing has a lot to do with how cool the engine runs in summer traffic on hot days.

You absolutely need a vacuum advance distributor with the vacuum selected to manifold vacuum.

Reason being, the idle air/fuel ratio is lean and it takes time to burn a lean mixture.

A lot of people don't believe that timing can have such a big effect on engine cooling, but it does.

Basics here are, GM started to utilize ported vacuum for the smog era engines prior to computers etc. so the engine would run hot at low rpms and have a tailpipe emission more favorable to the smog situation.

They did put a thermostatically controlled vacuum switch in most of the engines and that was supposed to switch over to manifold vacuum and once the engine cooled down it would switch to ported vacuum once again.

The 4-core Walker radiator in my 32 is circa 1985, the car was on the road in 1993 and no probs.

The 32 seldom runs over 200 degrees in summer traffic - 102 degrees here today.

In my opinion, electric fans should only be used if there's no other way out.
I went so far as to pull the center area crossmembers out, build new ones 2" further back just so I could run a mechanical fan.

If I had room in the 32, I'd run a clutch fan setup, but I don't.
Once the radiator is mounted in the 31 I may be able to do it.

Far as I'm concerned, electric cooling fans suck....

Thanks C9! I bit the bullet and ordered a Zip unit. I also found an aluminum heavy duty water pump for the Chevy 250 six-cyl as needed for the Zip. I will also try a 16" nylon fan blade because it is flat and does not have the forward twist on the blades; it is rated to 8000 rpm (Summit FLX-416). I talked to at least four mfgr. tech guys and they all said cooling a 350 with a Model A radiator is tricky at best. I agree with you on the preference for the belt driven fan but the Zip unit only has the belt on about 1/3 of the fan pulley. I chatted with the guy who invented the Zip pump riser and he reccomends a 160 degree thermostat and said the fan tensioning arrangement is tricky. He also thought that maybe with your big Buick block you are benefitting from a larger amount of water in the block? So I will go with the belt driven mechanical fan higher up in the radiator area. He has a Deuce coupe and a pickup with his unit so he knows how to set them up. I also made a number of calls to mfgrs. of electric fans and my conclusion is that the Brookville recommendation for a cheap fan working at 40 amps or less is marginal at best and probably not able to stand up to parade conditions. When you figure out how to get an electric fan capable of about 2500 CFM and add the need for about 70 amps surge which requires a high amp alternator you are in the same price range as the Zip unit so I will post a picture when I get it all together in about a week or so.

Don Shillady
Retired Scientist/teen rodder

Sounds good Don.

The big Buick may hold more coolant than an SBC, but it wouldn't be much and wouldn't make a lot of difference.

I do know that if the vacuum advance is connected to ported vacuum it overheats in 5-10 minutes in summertime slow traffic.
No probs with the vac advance connected to full time vacuum.


On the fan, are the blades real narrow?
If so, I'd opt for the wider stainless fan or better yet use the stock fan like Deuce Roadster runs if you have room.
I don't and do need the hub at the front of the blades on my Hayden fan so as to gain sufficient clearance from the radiator.

Reason I like the GM fan is the blades aren't as sharp as the stainless fat blade fans.
Got a couple good cuts off them when working on the engine when it was shut off.


I think the fan shown on Deuce Roadsters cars is the same fan that came up the winner in a big fan comparison that Steve Jacks did.
His article is floating around on the Internet somewhere.
Good info, the guy knows what he's doing.

You may be able to see how little V-belt wrap there is on my Buick engine in the 31 on 32 rails roadster.
It's the same in my 32, less than 1/4 and it works ok.
Slips once in a while if the belt has lost a little tension and I romp on the throttle.
That should stop with the dual belts on the 31.

Here's a pic I stumbled across.

29 Sedan with SBC.

Steering box is Saginaw, but not a Vega.
A touch larger, but it fits ok.

C9X, Thanks! That second picture answers a lot of questions since it sure looks like a Zip installation. It shows the belt tensioner over the top of the alternator. OK, now we know the secret about the vacuum advance from your valuable experience but I am a novice on the SBC so where should the vacuum tubing go on a Performer manifold with an Edelbrock 650 CFM 4-bbl? Another comment is that I chatted with the Tech guy at Flex-A-Lite and pinned him down three times about whether the nylon fan flows more than the wide blade and he swears the 400 series nylon fans do but not the 1000 series. Even so I have heard enough conflicting statements from Tech people that I still wonder, as you do, whether that nylon fan will pull as much air as a fat blade. At least the nylon fan is a "cheaper mistake" compared to some other choices, although so far I have been able to exchange three fans for other merchandise! Let's not get lost here, the main thing I need to know is:

Where do you recommend putting the vacuum tubing connection?

Don Shillady
Retired Scientist/teen rodder

Running a Carter/Edelbrock four bbl carb?

The vac advance line goes to the left front bib.
(USA drivers side.)

Or any other vacuum source in the intake manifold.

If you test the bib or other vacuum fitting with a vacuum gauge you should show 17"-19" at idle with a mild cam.
Big cams idle at 10"-12" or so.

Ported vacuum will show zero vacuum at idle with either cam.

As far as moving more air, think about WW2 prop driven fighter planes.
The P-47 had a big performance increase when they went to a fat blade prop.

Try to find Steve Jacks article on fans.
The info should be there.

I used a cool flex hose.

Yeah, I looked for a flex hose but could only find a 24" length for the top hose, no short versions. What was your source Arod? It looks like I have to redo the upper hose to a straight up thermostat housing and maybe trim the lower hose when I put in the Zip pump riser. For now I am just waiting for parts. 29arod, I would appreciate seeing any pictures you have of your engine compartment and interior.

Don Shillady
Retired Scientist/teen rodder

Well I am working on this but I am waiting for a 17" fan. The Zip unit is really neat and I got an aluminum high flow water pump for a 250 Chevy six and a "universal" alternator adjustable arm from Speedway. I also got a plastic shroud from Walker radiator. Walker does not make a shroud for a 29A radiator and you have to use the one for a '47 Ford radiator but it does not fit perfectly so you have to make some small fittings on the side to get it to fit snug. I am waiting for a Flex-A-lite 17" fan to trace out the circle to cut out from the shroud. I had to purchase my third thermostat housing to get the top hose around the alternator. I will eventually get this right and post a picture of the results, maybe in a few days. I think this is the fourth fan but I was able to exchange two of them. As IC2 said extra parts are the fuel of swap meets!

Don Shillady
Retired Scientist/teen rodder

Fwiw, if you're cutting a Walker plastic shroud with a saber saw cover the outside with masking tape.

Otherwise the saber saw will scratch a big circular pattern in the plastic where the saber saw shoe slides.

C9X, Thanks for that helpful hint! That is one more mistake I won't make.

Don Shillady
Retired Scientist/teen rodder

C9X, are you running a shroud? What if I do not add a shroud? I have the Zip unit on but the Walker shroud is not available for a '29. Instead the Walker Tech guy got me to buy a '46-'48 shroud which "almost" fits but I am reluctant to drill into the sides of the radiator even though there is a clear space before the tubes would be hit. I am not considering not using a shroud, comments?

Don Shillady
Retired Scientist/teen rodder