I have a 78 351w in my daily driver car. I recently had a radiator leak and took it in to get it fixed but wasnt fixable. So I ended up upgrading to a brand new copper 3 core radiator over the copper 2 core the car came with (Advance wanted $3 more for the 2 core over the 3 core). Thing is though the water doesnt seem to flow through the cores as fast as it did with the two core. I figure this is from having those 1 extra row of cores but was wondering is there a water pump for heavy duty 3 core radiators?

I looked at summit and saw the flow kooler pump that puts out like 30% more coolant flow at city speeds but goes back to normal flow rates at highway speeds. I cant run that though cause it goes back to regular flow at 3500 rpm or higher and with this car that would be around 110 - 115 mph.

My other question pertains to an add on electric supplmental cooling fan. I am limited on which size I can run that I can mount infront of the evaporator but the main point is to add it on to help blow more air across the coil since its been converted to R134a. Would also have it set up to kick on when temps start to rise while sitting in traffic. My concern though is I want to keep the mechanical flex fan but I am concerned that the electric fan blowing more air into the mechanical fan will make noise. Simmilar to blowing air into a portable fan makes noise. Would this be a concern?

I found from the fan company flex-a-lite that I was looking at for electric they got a 6 blade steel clutch fan that I could replace the 5 blade flex fan with but I dont like the fact the clutch only spins at 70% engine speed where the setup I got now spins at 100% engine speed.

So in the end the two questions I have are as follows.

1. Is there a HD water pump offered in 78 351`s for use with the HD 3 core radiators?

2. Would installing a high cfm electric supplmental fan infront of the condenser while maintaining the mechanical fan cause any humming or buzzing noise as air is blown into the spinning fan?

 

Sooo I take it no one knows????

 

first off.. dump that 5 blade direct drive fan..they're worthless.. and go with a 7 blade clutch fan off of a 70's big block engine.. (usually in the 70's vans or trucks with the 460 and A/C)
I used to have a 78 motorhome with a 460 in it.. it had the 5 blade fan.. always ran hot.. dumped it and went with the 7 blade clutch fan.. made a HUGE difference..

 

Yes well no places locally has those type fans. I found one but the guy wanted more money for it than a 7 bladed flex fan brand new.

This fan worked great its just that I have a thicker radiator now since I had to get a replacement and now its not enough of blades to pull air through the thicker radiator.

I have been checking ebay lately and found a 7 bladed clutch fan but it came off a 93 ford enigne and it was a reverse rotation fan.

But what limits me is I have to go with a 18" diameter fan. Not to mention I dont even know if a small block clutch would bolt up to a big block fan.

On the other hand though flex a lite sells a 6 bladed steel clutch fan but theres a problem with that though. The cluch that goes with it spins at 60% speed of the engine so that means at 1000 engine rpm is 600 rpm fan speed. So roughly at 600 rpm engine speed in gear the clutch fan would be spinning a pitiful 360ish rpm. I just dont think a clutch fan honestly would move enough air at idle which is where my issues are at.

Electric fan would work but if I put an electric fan I want it to be a supplemental fan to bring the radiator temp down after engine is turned off or when idling for extended periods of time in traffic not a bandaid to fix a issue from lack of moving air at idle due to a thicker radiator core.

 

Forgot to add that Summit finally replyed to me after 1 week and the guy said he uses the 6 bladed nylon fan and it works great. I just dont think I could trust a nylon flex fan.

 

Well I dont want to start a whole new thread but I found out Autozone (the store i hate as much as napa) has a 6 bladed steel clutch fan and clutch listed for my vehicle.

So I am doing a clutch fan conversion from a flex fan. Quesiton though how long should the bolts be on the clutch to water pump pulley? Also what threads am I looking at for a 78 351w?

Hopefully someone sill see this an reply quickly since I am going to head over there in 30 mins or so to get the fan and clutch.

 

Are you using a fan shroud?Using an electric fan arrangement,or anything in front of the condenser/radiator will impede air flow over the cores.Standard fan arrangement should pull enough air for cooling.What are the condition of the hoses?You don't mention an overheating problem with this engine in your post.post back with more of your current fan/shroud arrangement.

 

Thats because this thread was orignally started asking about adding a supplmental cooling fan an electric one infront that would kick on when the AC is on or if the engine starts over heating while iding in traffic. Supplemental ones do not have fan shroulds its just a fan with bar brackets. Question was if the air from the fan being blown into the mechanical fan would make a noise. I since after posting it found out of people that run electric infront of mechanical and dont have any noise issues. The other question orignally of this thread was if there was a heavy duty water pump offered to 351`s in 1978 for use with the heavy duty radiators.

The cooling issue was discussed in the 289/302/351 section since this topic wasnt getting any action. It was basically the car pegging the temp gauge out to Hot every time the vehicle stop almost instantly. Come to find out it was a lack of air flow through the radiator because once I hit 20+ mph the temps shot down again. The 5 bladed flex fan that came stock on the car was designed for a standard cooling 2 core radiator. I installed a heavy duty 3 core radiator that was a good 1/2" thicker in the cores area than the 2 core radiator.

As far as the hoses the bottom one is brand new upper one looks new. The car has a factory fan shrould which the flex fan sits half in half out of. I already swaped that fan out as of sunday with a 6 bladed steel clutch fan which I probably need a spacer for since its about 1/2" - 3/4" gap between fan and the compressor pulley and the fan isnt really sticking in the shrould. But with the 1 extra blade on this fan though the engine doesnt do that anymore. It was just simply an air flow issue concerning a thicker radiator and a stock 5 bladed fan that couldnt pull the air through the thicker radiator fast enough at idle in gear.

 

Rusty,

Coming in late on those one, but here are my thoughts/opinions. First off, there was not a special water pump for the three-row radiator. With a properly operating thermostat, you will see less movement due to the extra row.

To 'see' more flow, just block off the air to the radiator, watch the gauge climb to about three-quarters and observe the flow at the filler neck-it should increase, then decrease when the blockage is removed.

The OEM five-blade fan was a flex-fan with fairly wide blades. The fan should fit about one-thirds in shroud, and two-thirds out, towards the engine.

A H.D. clutch is not a bad idea, since it free-wheels when not needed on the highway.

Again, sorry for being late.

 

Only HD clutch they offered for mine was thermal, I put one on a 302 E150 van and it sounds like a plane only thing though this fan is like 1/8 - 1/4 in the shrould the rest is out I dunno if I need a spacer to move it forwards or what. But the temp gauge never goes past the middle even idling it fluxuates back and forth between low and middle.

 

Rusty,

A good fan clutch, which is both thermal and rpm controlled, should NOT make a bunch of noise on the highway. The position in the shroud is critical.

 

well when the temps are hot the van makes alot of noise when you rev it up from the fan but when its winter here and the air is cold the fan slips and the van is quiet.

But I have to get a photo of mine but mine isnt positioned in the fan shrould alittle is in the shrould but most of the fan is out. I didnt get a spacer though because thats the clutch that is called for on my vehicle. I dont know if they had a different longer fan shrould for a clutch fan equipped engine over a flex fan or what in 78.