Thread: Zips riser

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Well I installed my Zips riser today but the oil fill tube/breather was in the way of where the altenator goes. I made a bracket to mount the alternator on the other side.. but lo and behold the fan belt hit the water pump. I finally modified the oil fill tube to miss the alt. Now I need to get a 1/2" fan spacer and I'll be cooking.

Summit racing has them Summit Racing

Even though this is not a recent thread it is still from 2012 and there are few good discussions of the Zip Riser on this site. I found more information on the Zip Riser on the Technical section of H.A.M.B. but I would be very interested in a description of your whole cooling setup, fan shroud, percent antifreeze, fan type and size and the engine as well as the radiator specs and the thermostat. I am wringing out a situation where a SBC overheats with a new Walker Cobra radiator and yet there are many examples of setups which do cool well with a SBC 350 in a Model A with a '29 radiator. I am getting close. 34-40 says my flex fan may be a problem, what fan type and size did you use?

Don Shillady
Retired Scientist/teen rodder

Don,
Regarding the percentage of antifreeze, you can analyze the characteristics of ethylene glycol with data from the Engineering Toolbox - Ethylene Glycol Heat-Transfer Fluid to see why the label on the Prestone bottle says "Minimum 50% Prestone/50% Water" (for corrosion protection, etc); and "Maximum 70% Prestone/30% Water" for cases where you need extreme winter cold weather protection. The 50/50 mix provides the "happy medium" that is good for about 90% of the people. As you look at the tables in the Engineering Toolbox note how fast the dynamic viscosity increases with increased percentages of anti-freeze in the mix. The best heat transfer will be achieved with 100% water, but you will have no protection for dissimilar metals (galvanic corrosion), no lubrication for seals, and lowered boiling point with your pressurized system.
I predict that the shroud you installed, plus adding water to your 100% antifreeze fill, will solve your problems.

Roger, Thanks for your reply. My guess at 55/45 comes from salvaging the Prestone I drained out while working on the shroud. I screen-filtered the liquid into two 1 gallon jugs at about half filled and then added water to the neck so I may have 50/50? Anyway I plan to add bona fide 50/50 Prestone and then use the diluted salvaged liquid as fill-to-the-top and later add spare Prestone. Heeding a caution by 34-40 I just ordered an aluminum blade NON-FLEX fan from Speedway. I chose the flex fan I have now for it's 10,000 rpm rating but the new fan is only rated at 6000 but enough for cruising even with low gear in the 700R4. For what it is worth I found that the thermoplastic shroud from Walker had to be trimmed quite a bit but wiping it with acetone on a rag made fabrication scratches glossy again so it still looks pretty good!

I ended up not needing the fan spacer. The radiator I used is an aluminum 2 row designed for a chopped 32. $170 on ebay. I mounted digital guages, speedometer and tach in the space between the top of the radiator and the grill shell. The fan is a 16 inch flex fan and I made a shroud from sheet metal although I don't think I need it. I use a 75/25 water to antifreeze. The truck runs very cool even in 110 degree temps. The guage will go up to 220 sitting ideling for awhile. I discarded the t-stat as it didn't seem to do anything. Everything is working great now. Fingers crossed.

Originally Posted by TomJ

I ended up not needing the fan spacer. The radiator I used is an aluminum 2 row designed for a chopped 32. $170 on ebay. I mounted digital guages, speedometer and tach in the space between the top of the radiator and the grill shell. The fan is a 16 inch flex fan and I made a shroud from sheet metal although I don't think I need it. I use a 75/25 water to antifreeze. The truck runs very cool even in 110 degree temps. The guage will go up to 220 sitting ideling for awhile. I discarded the t-stat as it didn't seem to do anything. Everything is working great now. Fingers crossed.

Hey Tom,
Glad you got it done. You may be fine without the t-stat, but when I moved from the midwest (no t-stat) to the gulf coast (Corpus) years back my old Chevy started running hot. An old mechanic down there told me I needed to either put in a t-stat or a flow restrictor (big washer) to slow down the flow and give the system time to lose heat to the air. With no restriction the water pump runs out on it's curve to or near maximum flow, and that may well be too fast for the radiator to dissipate heat - it goes in hot, screams through and leaves hot, and gets hotter on the next trip. Time will tell, but keep it in mind for the future if you start having problems in the summer heat.

Thanks for the data. I am bogged down fitting my shroud and I have ordered a non-flex six blade fan to replace the present flex fan and I will switch to 50/50 Prestone so we will see what happens in a week or so.

Don Shillady
Retired Scientist/Teen Rodder

Thanks for the advice.
I will play it by ear. I've run it for a couple months in 100+ weather with no overheating but things change sometimes. One thing with the 265 there is no place on the head to hook up a bypass line and with the zips riser you have to make some provsion for that. I had a t-stat in it that I drilled three small holes in but it stuck so I took it out and didn't replace it.

Originally Posted by TomJ

Thanks for the advice.
I will play it by ear. I've run it for a couple months in 100+ weather with no overheating but things change sometimes. One thing with the 265 there is no place on the head to hook up a bypass line and with the zips riser you have to make some provsion for that. I had a t-stat in it that I drilled three small holes in but it stuck so I took it out and didn't replace it.

Tom,
Dallas is much lower humidity than Corpus so you may do just fine without the t-stat. That heavy, moist coastal air doesn't pick up heat nearly as well as the dryer air up closer to the panhandle. I always just drill one nominal 1/8" hole to bleed the air out during fill, but to leave the t-stat fully functional to help speed warmups. Or you can always use a restrictor - Water Outlet Restrictor Kit - Speedway Motors, America's Oldest Speed Shop Once you have the right one in there it will be pretty consistent on temperature, but no help on warmup time which might not be an issue for you.

TomJ, I would really like to see a photo of your metal shroud if you can show it here.

Don Shillady
Retired Scientist/Teen Rodder

Hello Again,

Over at H.A.M.B. there is a special site in the "Technical" category on the Zips riser and some excellent installations of shrouds on '32 Ford radiators but I have not been able to find any on Club Hot Rod. I am about to make my SECOND try at installing a Walker "WS-70" shroud on my '29 radiator and I would like to get it right this time. For whatever reason my engine sets higher than most so that a 17" fan was very close to the bottom of the top tank of the radiator. Thus I have now switched to the less efficient 16" fan but of course the previous shroud hole is too large for this fan so I am starting over with a new blank shroud but I sure would like to see a shroud installed on a '29 radiator. Anybody out there have a picture of a radiator shroud on a '29 radiator since this thread is the Zips thread on CHR?

Don Shillady
Retired Scientist/Teen Rodder

Here is my latest Zips report.

It has taken about three weeks of waiting for parts and some fabrication but yesterday I was able to get another test of my 350 SBC heating problem. After setting up the Walker shroud (WS-70) for a '28-'29 Model A radiator (Walker Cobra with a bottom section for a trans cooler) I found the 17" fan tips were less than 1/2" from the bottom of the overhanging tank on the top of the radiator which worried me that motor vibration might lead to the fan hitting the bottom of that tank overhang. Thus after the usual shipping delays I purchased a 16" heavy duty flex fan and another blank shroud since the hole of the previous shroud is too large for the smaller fan. After a few days of messing around with the shroud I got it on and filled the radiator with 50/50 Prestone/water. I also drilled a 3/16" hole in the 160 degree thermostat and that was useful because I could hear the bubbles coming through that hole as the fluid filled the block so that eliminated a potential bubble-block. Then I released the bubble in the Zip pump with the usual amount of spilled coolant and topped off the coolant. I also added a full small bottle of "water wetter" which is supposed to lower the radiator boiling point by about 10 degrees F. I then fired up the engine and let it run at the 1500 rpm setting we used for the break-in run and timed the temperature response. The starting temperature of the garage was 62 F and with the garage door open and a small window fan blowing air through the garage the engine temp eventually boiled again at about 205 F. Pure water boils at 212 F but the temp gauge is not very precise. I shut the engine off when it reached 200 F but since the fan stiopped, the temp went a little higher to blow out coolant. It took about 21 minutes running at a steady 1500 rpm with the timing set at a constant 8 degrees advance to reach the 205 F temp. Along the way the temp seemed to hang around 180 for a while but then continued on up to 205 F blowout of coolant through the overflow tube. Note this is with the hood off. This morning consultation with my experienced engine builder just up the street at Progressive Performance indicated that he did not think this was a serious heating problem running at 1500 rpm standing still. Thus I would appreciate comments whether this is serious or not and whether the car is streetble allowing for brief stoplight pauses? A further test will try to time the inevitable boilover at a lower idle rpm of about 800 rpm. The advice is to try and run this way for a while. I see only two other options. One is an expensive electrical fan installation which I do not prefer. The second is to use the present shroud with my previous 17" fan because with the existing smaller hole I can measure from the blade tips and mark the exact 1/2" clearance to the 17" blade tips and get an optimum fit of the fan hole as tight as is safe for clearance. My friend at Progressive favors leaving off the vacuum advance on my 327 distributor with the Pertronix Ignitor magnetic points conversion. Comments, suggestions?

Don Shillady
Retired Scientist/Teen Rodder

Don,
I'm assuming that you had the pressure cap in place for this test, right? What is the pressure rating of the cap? Regardless your answer, 205F is not hot enough to boil pure water with a 212F boiling point (you're very near sea level), and with a 50/50 mix your boiling point is up around 265F at atmospheric pressure. With elevated pressure (the cap) that boiling point increases. If you're seeing water blowing out of your coolant overflow tube at anything below a coolant temperature of 275F to 290F you have a pressure problem. I suspect you've got a blown head gasket. If not, then it may be worse, because somehow cylinder pressure is getting into your coolant passages, causing your radiator to over-pressure at near normal operating temperatures. Maybe you can do a cylinder leakdown test to see if one or two adjacent holes are losing pressure, and watch for bubbles in your radiator while doing the test.

Thanks Roger, That is worth a check! Ethylene Glycol boils at about 225 F at 1 atm for a 50/50 wt. % mixture. My cap is not a pressure cap, I chose it for a second temp reading right at the radiator so it is just a simple cap with a thermometer in it. The first thing I can try is to use a real pressure cap and then try a pressure measurement on the cylinders. If the problem can be solved just by changing the cap that would be great. On the advice of my short block builder I torqued the head bolts 5 ft. lb. over the GMC specs so I am hoping I sealed the head gaskets pretty good, but of course a gasket problem is possible. If a head gasket is blown I might have water in a cylinder? I recall that one of the common maladies of the Ford flathead was a block crack that would allow water loss without water in a cylinder so I guess that is possible here. I will try a pressure cap first! Ironically I teach the Clausius-Clapeyron equation treatment of boiling point elevation over and over in my summer P. Chem. course but then I use pure compounds so now I have a new applied problem for a mixture. As is often the case in these equations it might be easier to just measure the boiling point elevation with pressure than to try to calculate it for a mixture so I have checked suitable tables.

Don Shillady
Retired Scientist/Teen Rodder