NEW PRODUCT – 351C Fast Water Pump Pulley

Comments welcome! ;-)

Scott, Sounds like a good idea to me. Most street cars spend most of their time at idle or at low RPM's. I am curious. Will the water pump over spin if the engine revs to say 6500 RPM? Curious.

Better cooling is the result of good airflow through the radiator and the coolant spending optimum time in the radiator.

Increasing coolant flow may not be the answer.

Just my experience . . .

quote:

Better cooling is the result of good airflow through the radiator and the coolant spending optimum time in the radiator.

Increasing coolant flow may not be the answer.

Just my experience . . .

Running the water pump at the intended speed of Ford Engineers is a good thing. Torinos and Mustangs of the era actually run the water pumps faster than the 11% increase that my water pump pulley will provide. Those cars had crank pulleys in the range of 7 inches.

I agree with your point that airflow is key. However, it is a proven fact that running the water pump faster at idle will help with low speed cooling. This will not correct a car with a cooling system problem. AGAIN, this is for low speed cooling. It's effect on cruise or performance driving will be minimal.

Tony,

11% at 6500 will spin the water pump at 7215rpm. Do you think that is too fast for the period of time your motor will see 6500?

Again, our water pumps are UNDER DRIVEN from the factory. Some of the other Ford cars of the era had 7 inch crank pulleys with 5.5 inch water pump pulleys. That is way more than the 11% my pulley will provide.

I am not reinventing the wheel here folks. I am simply driving the water pump at a closer speed to what the Ford engineers did on the other cars of the ERA.

Others have done a similar change with other pulleys with AMAZING positive results.

Scott

It is easy to throw out statements like "amazing " results. Or 11% faster than stock speed.

Also the Pantera's cooling system is nothing like a standard front engine design.

Where are actual temperature results? Without actual before and after temperture readings this is nothing more than hypothetical.

quote:

It is easy to throw out statements like "amazing "
results. Or 11% faster than stock speed.

Also the Pantera's cooling system is nothing like a standard front engine design.

Where are actual temperature results? Without actual before and after temperture readings this is nothing more than hypothetical.

This has been tested with very favorable results. Sure, this part may not be for everyone, but there are folks here having low speed cooling issues where this will certainly help. And 11% faster than stock speed isn't a number that is THROW out there. It is a fact! Do the math!!!

Actually, faster flow is generally better. The greater the difference in temp between the coolant temp and outside air, the better the rad transfers heat. Thus, keep introducing hot coolant rather than allowing cooler coolant to linger.

opposite for the block. Cooler coolant absorbs heat from surrounding metal better than hotter coolant. if you slow it in the rad, you slow it in the block also. Better to have cooler coolant entering the block rather than allowing hotter coolant to linger that is less efficient at absorbing heat energy.

Flow is the answer. I think Scott is on the right track with the pulley and am glad it is available to Pantera owners. If I needed additional cooling capability and had already invested in good fans, a smaller pulley would be a good approach.

Scott is offering something to the Pantera community that it has needed for 40 years. I shall offer facts & data to support this claim after the holiday, until then everyone have a safe & enjoyable labor day weekend.

Thank You JT and George!!!

Do you need to get a longer belt?

quote:

Do you need to get a longer belt?

Hi Paul,

There may be enough adjustment to use the same belt, BUT, if not, you would need a slightly smaller belt.

The stock pulley is 5.5 inches in diameter. The new pulley is 4.9 inches in diameter.

Take care, Scott

Scott, I know from experience that Ford Racing sells or used to sell an under drive pulley system for mustangs. I have a set on my 67 fastback. It states in the literature that it is only a track part meaning it doesn't circulate enough coolant at idle for street use. As a matter of fact when my fastback idles too long it tends to slowly begin getting hotter. If I hold the gas at a fast idle it tapers off a bit and then after a while it begins cooling. The convertible does not have this issue as it has a standard pulley system.

I too applaud you for continuing to bring affordable aftermarket parts to the pantera community that actually work and at much less cost than the other vendors.

I would be interested in conducting an actual experiment to see just what happens. I wonder what George has in mind?

quote:

I would be interested in conducting an actual experiment to see just what happens

Tony,

I would be happy to supply you with a pulley to evaluate!

Scott

I agree with John.
Nice job Scott!!



Ron McCall

Thanks for the efforts Scott. I had already gotten some info from George on what Ford racing had determined about pulley sizes, and this is one relatively simple area that those who've re-engineered cooling systems might've overlooked.

Since my belt needs adjustment anyway, I ordered both the pump and crank pulley. A little less weight and the chance to move more water can't be a bad thing.

Thanks for your work.

quote:

Originally posted by ZR1 Pantera:

quote:

It is easy to throw out statements like "amazing " results. Or 11% faster than stock speed.

Also the Pantera's cooling system is nothing like a standard front engine design.

Where are actual temperature results? Without actual before and after temperture readings this is nothing more than hypothetical.

This has been tested with very favorable results. Sure, this part may not be for everyone, but there are folks here having low speed cooling issues where this will certainly help. And 11% faster than stock speed isn't a number that is THROW out there. It is a fact! Do the math!!!

I applaud and appreciate anyone that develops products for our Panteras.

Just as performance products are dyno tested confirming HP improvements, so should this product.

You are stating that by increasing the water pump speed it in fact reduces the engine’s operating temperature. All I am asking is that you provide actual data from your testing.

Important data would be the “Cleveland’s” water pump as stock or aftermarket? An original radiator or after market? The fan type and their placement.

But most importantly temperature readings (preferably a calibrated aftermarket gauge and sending unit) at various engine speeds before and after the installation of your product.

Assuming you did run these tests on one or more “Cleveland” equipped Panteras supporting your claim of reduced operating temperatures should not be difficult.

quote:

I applaud and appreciate anyone that develops products for our Panteras.

Just as performance products are dyno tested confirming HP improvements, so should this product.

You are stating that by increasing the water pump speed it in fact reduces the engine’s operating temperature. All I am asking is that you provide actual data from your testing.

Important data would be the “Cleveland’s” water pump as stock or aftermarket? An original radiator or after market? The fan type and their placement.

But most importantly temperature readings (preferably a calibrated aftermarket gauge and sending unit) at various engine speeds before and after the installation of your product.

Assuming you did run these tests on one or more “Cleveland” equipped Panteras supporting your claim of reduced operating temperatures should not be difficult.

Thanks 4134. We will provide that data shortly. I actually have offered the pulley to a few owners to do there own evaluation and then report back in order to get a nice mix of different configurations.

My apologies to the members of this community for the written conflict that was made public in this thread. I've removed the posts and I expect those involved to refrain from any further public confrontation. A person only needs to comment they don't agree with the design of a product or request further data derived from testing once.

The mission of this collection of forums is to assist DeTomaso owners and enthusiasts, to make DeTomaso ownership an enjoyable thing. PERIOD. They are never to be used for confrontation or humiliation of another member.

Thankfully I don't have to do this very often, and for that everyone has my gratitude.

-G

Ordered mine, will install and report..........

well its Tuesday morning and we are still trying to cool our cars. with due respect to all sides of the arguments on what is the best approach I would tend to think that a faster pump speed would help but the variables are many. blades in the pump size of the pipes to the radiator flow characteristics of the different radiators the thermostat this cam vrs that cam the list goes on. I like the idea less weight and a little bling ( even though we can't see it) so enjoy the conversation as long as we don't get any more request for pictures of a mangusta engine compartment!

It was I that told Scott there was a market for the smaller pump pulley; when he asked me how small I told him 4.9" to 5” diameter, i.e. enough to overdrive the pump by 10%. 10% was not a number I pulled out of the air, it was based upon the amount Ford engineers over-drove the pumps installed in the 351C powered Fords and Mercurys. So as promised here’s the information I have to offer on the subject.

Historically speaking overheating during stop and go driving is the cooling system problem that plagued the Pantera, especially the Pre-L versions. The overheating problem was more or less resolved when DeTomaso/Ford replaced the vertical radiator tank baffle with the horizontal baffle in April 1973. The 1974 L model Panteras could idle all day long without overheating, with the air conditioning operating, on a warm day. Most owners would agree however the Pantera's cooling system performance during stop and go driving is perhaps best described as "fragile". I do not advocate extensive modification of the cooling system; I do however advocate a direct approach that identifies the cooling system’s primary deficiencies (if any) and corrects them.

I have come to believe there are 3 primary deficiencies in the Pantera’s cooling system:
•Coolant leakage around the OEM radiator’s vertical baffle allowed coolant to bypass the radiator.
• The Pantera’s cooling system has never had a functional vent system for automatically removing air trapped in the radiator. When air is trapped in the radiator it reduces the radiator’s effective surface area and in extreme cases impedes coolant flow.
•The coolant flow rate is insufficient at low rpm as a result of the coolant pump being under-driven and/or the coolant system plumbing being restrictive.

DeTomaso/Ford resolved the first deficiency in April 1973 by modifying the radiator, replacing the vertical baffle with a horizontal baffle. The second deficiency can be resolved by installing a drain cock at the top of one of the radiator tanks and manually bleeding air from time to time, or by performing the vent system modification I have detailed elsewhere.

What I intend to do is explain the factors that lead me to believe the third condition is a primary deficiency. Bear with me, as most of you already know I can be a bit verbose at times.

Fords and Mercurys powered by the 351C were not plagued by the same cooling system problems as the Pantera. The Fords and Mercurys which were contemporary with the Pantera were not equipped with modern high flow rate style cooling systems, their cooling systems have more in common with the Pantera’s cooling system than not. Examining the differences between the Ford/Mercury cooling systems and the Panteras cooling system may help identify the deficiencies in the Pantera’s cooling system.
_____________________________________________________________

One difference between the cooling system of the Pantera and other 351C powered vehicles is the diameter of the pulleys which rotate the coolant pump.

There were at least two different diameter crankshaft pulleys (basic part number 6312) used on 351C powered Fords and Mercurys for driving the coolant pump; one was 6-5/8” in diameter and the other was 6-3/4” in diameter. The variance in circumference is 20.81” to 21.20”.

Although there was several coolant pump pulleys (basic part number 8509) used on 351C powered Fords and Mercurys the pulleys can be lumped into two general categories: the smaller ones used for cars equipped with air conditioning and the larger ones for cars without air conditioning.

Most of the smaller coolant pump pulleys vary in diameter between 5-15/16” to 6-1/8”. The variance in circumference is 18.6” to 19.2”.

Most of the larger coolant pump pulleys vary in diameter between 6-7/8” to 7”. The variance in circumference is 21.6” to 22”.

In conclusion, the coolant pumps in air conditioned Fords and Mercurys powered by the 351C were over-driven by approximately 10% whereas the coolant pumps in 351C powered Fords and Mercurys without air conditioning were under-driven by approximately 4% or less.

The Pantera was equipped with a 5-1/2” diameter crankshaft pulley (17.3” in circumference) and a 6” diameter coolant pump pulley (18.8” in circumference). Therefore the Pantera’s coolant pump was under-driven by 8%. I am not sure if the coolant pump pulleys were the same diameter in all Panteras, the pulley I measured came off a 1974 Pantera-L.

The Flow Kooler coolant pump has a unique impeller design they claim improves the low rpm pumping rate of their pumps. Pantera owners who have installed the Flow Kooler pump report improved stop and go cooling system performance as a result. Does the improvement noted by owners indicate the Pantera’s coolant pump may be under-driven a bit too much? I thought so.

A quote from the DeTomaso Macchine da Corsa book, page 102, from an interview with former group 4 Pantera driver Marcel Schaub: “Bertocchi also installed a smaller pulley on the water pump, which helped increase the pump speed and lowered the water temperature. I raced chassis 2873 for ten years from 1974 to 1984. I won three Italian and one European championship.” Guarino Bertocchi believed the Pantera needed a smaller coolant pump pulley, at least for racing.
________________________________________________________

Another difference in the cooling system between the Pantera and other 351C powered vehicles is the diameter of the plumbing between the radiator and the engine. When a valve is partially closed on the inlet or outlet of a centrifugal water pump it reduces the pumping rate of the pump at any given speed, therefore significant restrictions in coolant system plumbing should have the same effect upon a centrifugal coolant pump. The Fords and Mercurys were equipped with a 1-1/2” hose between the coolant outlet and the radiator inlet; whereas the hose between the radiator outlet and the coolant pump inlet was 1-3/4”. The Pantera was equipped with 1-3/8” OD plumbing in both directions (roughly 1-1/4” ID).

The coolant exits each 351C cylinder head through a ¾” square hole; the coolant exits of both heads have a combined cross sectional area of 1.125 square inches. The cross sectional area inside the Pantera’s coolant pipes is about 1.96 square inches; so although the coolant pipe between the engine’s outlet and the radiator’s inlet is 1/8” smaller in diameter than it is in Fords and Mercurys, it seems as though it is still large enough.

The 351C coolant pump inlet has an inside diameter of about 1-1/2”, or a cross sectional area of 2.35 square inches. Fords and Mercurys connect the pump inlet to the radiator outlet via a 1-3/4” hose, whereas the Pantera uses tubing with an internal cross sectional area of 1.96 square inches. I suspect this is where a flow-rate reducing restriction occurs.

I have heard reports from a few original owners that the hose connecting the under-car plumbing to the coolant pump suction would collapse as the car sat idling. Does that corroborate my suspicion that the pump suction plumbing is too restrictive? It seemed that way to me.

John Taphorn has written of experiencing improved cooling system performance during stop and go driving after reducing the restrictions in his Pantera’s cooling system plumbing. See Pantera International magazine issue 116, POCA Profiles and elsewhere on the internet.
_____________________________________________________________

To summarize all that stuff, the Pantera’s coolant pump is under-driven by a greater amount than 351C powered Fords & Mercurys which had no air conditioning! Although the Pantera’s a/c condenser is not located in front of the radiator as it is in Fords and Mercurys, the a/c compressor does increase the load upon the motor when it’s operating. This would point to the need to under-drive the Pantera’s coolant pump less than non-a/c equipped Fords and Mercurys. The restriction in the coolant plumbing between the radiator outlet and the coolant pump inlet also points to the need to increase the diameter of that plumbing OR spin the coolant pump faster to compensate. That fairly well sums up all the factors and information that was on my mind when I made my recommendation to Scott.

Please note that even though the Pantera’s OEM coolant pump pulley is 6” in diameter; IPSCO chose to manufacture their standard coolant pump pulley 5-1/2” in diameter. They obviously believed there was a need to spin the pump a little faster.

If an owner has already installed a Flow Kooler or Stewart Components coolant pump I would hesitate to recommend the 4.9” pulley; for they have already accomplished the same thing accomplished by the smaller pulley.

I am curious about learning how well the Pantera’s cooling system performs during stop and go driving with the 4.9” pulley in combination with the OEM radiator fans. So if anyone goes that route I’d love to learn about your experiences.

I also plan to purchase a 4.9” pulley for 6018.

-G

George,
A great and very thorough analysis. And by your post this pulley could/should improve low speed cooling.

But what bothers me is that this product was stated as showing “AMAZING” results. Even with your extensive post there is no statistical data supporting this statement. Or what effect it may have at higher RPMs.

It would be honest and fair of the seller to state that his product in theory should reduce coolant temperatures, but is as yet untested. The buyer should be informed that they are in fact the beta testers.

This type of marketing is at best assumptive and at worst misleading and deceptive.

quote:

George,
A great and very thorough analysis. And by your post this pulley could/should improve low speed cooling.

But what bothers me is that this product was stated as showing “AMAZING” results. Even with your extensive post there is no statistical data supporting this statement. Or what effect it may have at higher RPMs.

It would be honest and fair of the seller to state that his product in theory should reduce coolant temperatures, but is as yet untested. The buyer should be informed that they are in fact the beta testers.

This type of marketing is at best assumptive and at worst misleading and deceptive.

The testing has been done prior to my statement. I have talked with several owners who have done this change on their own with very favorable results. I have myself, increased the water flow on my 351C (when I had it) and saw a 10 degree reduction in water temperatures.

The word amazing is a marketing term. Are you having low speed temperatures problems? If not, I wonder why you feel the need to police my advertizing.

I guess I need to run my ads by the Pantera community before I release a product to make sure I am not offending someone by a marketing term.

Geez... the computer is going off!!!!!!!!!!!!!!!!!!!!!!

Come on guys. I don't think it was Scott's intent to dupe anyone by using the work AMAZING. I found it kind of silly and funny. One of those advertising words that make us chuckle.

Scott, you've always been a pro in every correspondence and transaction. Though I have no 'real' low speed cooling issues on my 74 (FlowKooler also), it flirts with 210 w/AC on at idle sometimes. That's it, hasn't overheated in 5 years since.

Yet I'll measure my pulley vs. yours.

If only a bit smaller, will still install to give any results I can share, for low and high speed. If the same, I may do it anyway for the bling factor!

I concur with George and his research that the greater volume of FlowKooler basically eliminated my problem. (Also purchased on his recommendation.)

Since I don't drive my car at 145mph very much (!) I'm just going with the fact that more water flow can only be a good thing.

Again, thanks for your work, effort, and attitude in this rather minuscule market.

Sounds like a worthwhile product to me. I think I'll try one on my next build. Jim Coyne

Here are the results of my testing of Scott’s new reduced diameter (4.9”) water pump pulley.
Both tests were conducted with the engine at idle, radiator fans cycled on, and A/C on (cycling).
Deck lids were closed, trunk installed, engine bulkhead cover installed.

Test vehicle was a ’71 Pantera
Engine: ’71 351C, 127K miles (never rebuilt), original cam, 11:1 advertised C/R
Water Pump: Edelbrock High Volume
Thermostat: 180*F Robert Shaw 333-180
Temp sensor location: front of block
Temp gauge: mechanical, 270 deg sweep
Radiator: Fluidyne (4.3 yrs old), mounted in the stock position (vertical)
Fans: Dual Flex-A-Lite sucker, 2500 cfm (unverified)
Factory timing & idle specs: 6* BTDC, 800 rpm

Test #1
Pulley: 5.5” (stock)
Belt contact with pulley: 92*
Duration: 46 minutes
Ambient temp: Start: 91*F; End: 92*F
Relative humidity: Start: 54%; End: 54%
RPM: No load: 765; w/fans on: 728; w/fans & A/C on: 658
Max temp: 202*F

Test #2
Pulley: 4.9” (reduced diameter)
Belt contact with pulley: 87*
Duration: 47 minutes
Ambient temp: Start: 92*F; End: 93*F
Relative humidity: Start: 46%; End: 45%
RPM: No load: 766; w/fans on: 728; w/fans & A/C on: 657
Max temp: 197*F

Summary of this test: After continuous idling for approximately 45 minutes, with the cooling fans
running and the A/C cycling, the reduced diameter pulley showed a reduction of 5*F in the coolant
temp. Note that there is a 5* loss in belt to pulley contact with the smaller pulley, which should not
be a problem.

The belt that was used was a NAPA #7405 (13/32 x 41-1/8”). There was enough adjustment left
to reuse the existing belt. Approximately ¾” is required at the adjustment arm slot. If you don’t
have that much adjustment left, you will need a slightly smaller belt.

YMMV

John


Edit: I forgot to mention that prior to the test, the car was driven 10 miles (9 on the freeway). Upon returning, the car was left idling and the test time was started.

As a clarification, the initial ignition timing for a stock '71 351C is six degrees BTDC. In '72, the initial ignition timing for a stock 351C is sixteen degrees BTDC.

That's AMAZING!

sorry, I couldn't resist

George you are a bad boy. Tisk Tisk Tisk

jb1490 thanks for the review and careful testing. Although 5 degrees is not much its an inexpensive 5 degree improvement. Sounds like its worth the small effort to swap the pulley.

quote:

Although 5 degrees is not much its an inexpensive 5 degree improvement. Sounds like its worth the small effort to swap the pulley.

I agree, and some cars may gain more (or less), as there are many variables among our cars.

John

quote:

Originally posted by jb1490:
Here are the results of my testing of Scott’s new reduced diameter (4.9”) water pump pulley.
Both tests were conducted with the engine at idle, radiator fans cycled on, and A/C on (cycling).
Deck lids were closed, trunk installed, engine bulkhead cover installed.

Test vehicle was a ’71 Pantera
Engine: ’71 351C, 127K miles (never rebuilt), original cam, 11:1 advertised C/R
Water Pump: Edelbrock High Volume
Thermostat: 180*F Robert Shaw 333-180
Temp sensor location: front of block
Temp gauge: mechanical, 270 deg sweep
Radiator: Fluidyne (4.3 yrs old), mounted in the stock position (vertical)
Fans: Dual Flex-A-Lite sucker, 2500 cfm (unverified)
Factory timing & idle specs: 6* BTDC, 800 rpm

Test #1
Pulley: 5.5” (stock)
Belt contact with pulley: 92*
Duration: 46 minutes
Ambient temp: Start: 91*F; End: 92*F
Relative humidity: Start: 54%; End: 54%
RPM: No load: 765; w/fans on: 728; w/fans & A/C on: 658
Max temp: 202*F

Test #2
Pulley: 4.9” (reduced diameter)
Belt contact with pulley: 87*
Duration: 47 minutes
Ambient temp: Start: 92*F; End: 93*F
Relative humidity: Start: 46%; End: 45%
RPM: No load: 766; w/fans on: 728; w/fans & A/C on: 657
Max temp: 197*F

Summary of this test: After continuous idling for approximately 45 minutes, with the cooling fans
running and the A/C cycling, the reduced diameter pulley showed a reduction of 5*F in the coolant
temp. Note that there is a 5* loss in belt to pulley contact with the smaller pulley, which should not
be a problem.

The belt that was used was a NAPA #7405 (13/32 x 41-1/8”). There was enough adjustment left
to reuse the existing belt. Approximately ¾” is required at the adjustment arm slot. If you don’t
have that much adjustment left, you will need a slightly smaller belt.

YMMV

John


Edit: I forgot to mention that prior to the test, the car was driven 10 miles (9 on the freeway). Upon returning, the car was left idling and the test time was started.

As a clarification, the initial ignition timing for a stock '71 351C is six degrees BTDC. In '72, the initial ignition timing for a stock 351C is sixteen degrees BTDC.

that's the way a test should be done! Looks like very good results. Great job Scott.

Im surprised the temps got up to 195*/200* with a fluidyne rad, dual fans and the proper Robershaw stat with zero load on the motor.

quote:

Im surprised the temps got up to 195*/200* with a fluidyne rad, dual fans and the proper Robershaw stat with zero load on the motor.

Actually, there is a load on the engine. The alternator has to supply all of the necessary current for all of the electrical loads that are "on". There are the radiator fans (20 amps), A/C condenser fan (9.5 amps), A/C compressor clutch (2.8 amps), plus the gauges and the ignition. There is also the load of the A/C compressor. All of these items add load to the engine, and each reduces the idle speed of the engine (as noted in the test results), which slows the water pump.

John

quote:

Originally posted by jb1490:

quote:

Im surprised the temps got up to 195*/200* with a fluidyne rad, dual fans and the proper Robershaw stat with zero load on the motor.

Actually, there is a load on the engine. The alternator has to supply all of the necessary current for all of the electrical loads that are "on". There are the radiator fans (20 amps), A/C condenser fan (9.5 amps), A/C compressor clutch (2.8 amps), plus the gauges and the ignition. There is also the load of the A/C compressor. All of these items add load to the engine, and each reduces the idle speed of the engine (as noted in the test results), which slows the water pump.

John

What I meant was the car isnt being driven. I would think the upgraded cooling system would not have allowed the temps to get to 200* at idle.
What are the temps going to be cruising at 3000rpm?
Alot more heat generated at 3000 than at 700rpm, no?

Isn't the main overheat issue with our cars "low speed driving in traffic"?

Cruising at 3000 RPM at 40 of 50 mph is moving a lot of air through the radiator. This is not where the problem that Scott is trying to address lurks.

I believe that John's test is pretty representative of the environment that can cause problems, and he gave you a very clear baseline to evaluate from.

Anyway - I would say if you don't have any cooling problems - then good for you. If you do (at low speeds, in traffic, with low airflow), John has provided solid evidence of improved cooling performance with the SACC pulley.

You decide - just think how many people do things to their car to provide a small incremental gain in horsepower. They are probably spending a lot more on modifications that provides less benefit than the SACC pulley.

Rocky

PS> and OBTW - It also provides serious (some might say "amazing"?) "bling" after you install the clear plexiglass bulkhead cover bubble that SACC has in the works at their design bureau!

Sorry if it sounded like I was being negative towards the test or product. That wasnt what I was trying to say.
Test proves it works well.

Here are the results of my testing of Scott's new reduced diameter (4.9") water pump pulley.
Both tests were conducted with the engine at idle, radiator fans cycled on, and A/C off.
Front deck lid closed, rear deck lid open, trunk out, engine bulkhead cover removed.

Test vehicle was a '72 Pantera
Engine: '72 351C, 43920 miles (never rebuilt), original cam.
Water pump: rebuilt stock, installed late 80's (more on this later)
Thermostat: stock
Temp. sensor location: front of swirl tank (stock)
Temp. readings also (laser)taken at top water pump outlet pipe, indicated in photos below with red dots.
Temp. gauge:stock Veglia, pictured and marked below.
Radiator: stock '72 original, original position.
Fans: stock (650cfms?)
Factory timing and idle specs: 16*BTDC, 700rpm.

Test #1
Pulley: 5.5" (stock)
Belt contact w/pulley: unk
Duration: 30 minutes.
Ambient temp:Start: 78.8*F, End:79.8*F
Relative humidity:Start: 37%; End 37%
RPM: 700; w/fans on and A/C off: 700
Max Temp: 192*F

Test #2
Pulley: 4.9" (reduced diameter)
Belt contact with pulley: unk
Duration: 30 minutes.
Ambient temp: Start:80.1*F; End 85.1*F
Relative humidity: Start: 33%; End: 32%
RPM: no load: 700; with fans on and A/C off: 700
Max Temp: 185*F

Summary of these tests:
The start, with stock '72 everything.......



The red dot at top left is where the temps were laser read, and the miss aligned pulley it had been running with since the rebuilt pump was installed in the '80's



And sure enough, when first installed, the new pulley repeated the same miss alignment.



The fix?.......This .1350 thick fan spacer installed behind the pulley worked great to.....



Bring the pulley out to perfect alignment......ymmv



The Finish, and ready for the second test.
I used the slightly smaller (13/32"x 40-5/8OC)NAPA #7400 belt,and the different (closer) alternator position on it's bracket can be seen



The Gauge, in red is where the stock pulley was indicating when the max temp. was 192*F (Test #1) and in green was where the smaller pulley was indicating when the max temp was 185*F (Test #2)



Overall impression.........This pulley is a lot of bang for the bucks...... I'll take 7 degrees any day at idle, and tomorrow afternoon/evening I'm taking it out for a ride around the valley, ending at a car show and I will have lots of time to watch the temps under all conditions then.
Thanks Scott!.........

Ron

quote:

And sure enough, when first installed, the new pulley repeated the same miss alignment.

Ron,

Your misalignment of the alternator pulley with the water pump pulley could be the result of mounting the alternator bracket 'behind' the alternator which would push the top forward creating the misalignment. Try moving the bracket to the front of the alternator and see if it corrects the belt alignment.

I too do have the bracket behind the alternator, and no misalignment of any kind.

Top bracket's purpose is belt tension only, as the actual alternator position (more for- or backwards) is made by means of the bottom bracket.