Guys have a question I Have a fresh built French Block Flathead in my 34 ford hot rod I am Using the Aluminum Griffin Radiator That fits the 34 Ford I have Read some of the older posts on here from 2007 So would like to Re visit. I had a problem with this after I drove the car a few times The radiator did not come with a cap or a recommendation for one either any way the engine was broke in on a Dyno and engine ran fine put it in the car drove it a couple times short runs It had a 15 lb cap on it everything seemed fine. took the car to get alignment done on it sat overnight at the shop. anyway, next morning water all over the floor dripping out of right-side exhaust pipe Make a long story short number 4 cylinder had water in it also but when water seeked a level just below the head no more water leaked out drained the rest of water out of block got water out of cylinder there was plenty of water still left in the block. The Car never ran hot either. Any way pulled that head and after pressure checking the head and the Block they held pressure fine on looking at the head gasket could see where over pressure had killed the gasket blew up like a tick in areas. So believe this was the water leak and the problem so Questions I cannot find a 4 Lb cap that's fits that aftermarket Radiator I found a 7 lb that does fit I also got some 160 Degree Thermostats for it also did not have any in the first time So two new head gaskets the cap and thermostats. IN your guy's Opinion should these changes Fix this and was the cap high pressure what created this problem. I value your Opinions and suggestions you Have on this Subject Thank You Clyde28075
For whatever reason I ran a 7 lb cap in all my flat Motors 4 cylinder and V8s and every other customer car also and 160° thermostats but I've got to say in the winter it barely gets up to 160
I wouldn’t lower the cap pressure. I’d change your head gasket manufacturer. I’d also have the heads checked for flatness along with the block at the head seat.
That problem is caused by your head gasket not sealing. 15 pounds of pressure in the cooling system would not be the culprit....unless...as Petejoe alludes to your sealing surfaces are not flat.
I run 160 thermostats and a 4 lb cap on my flattie. The radiator I had came with a 1 1/2 lb cap. Not sure why that low but as speed went up it started pushing coolant out the overflow. Went looking for a 4 lb cap but could only find a 7 lb. Now running that with an expansion tank and so far it is not pushing coolant into the overflow tank when I get up over 60.
The Head and the Block have been machined they are Flat I used copper gaskets not composites. I do apricate your Input. and Ideas Thank you Clyde
Thank you for your reply as I told him the Deck is flat machined and head also was checked the other issue, I'm not sure the cap ever released pressure at 15 pounds it also may be Faulty. And pressure may have got higher than that
I'd probably run 180 degree thermostats as running the engine cooler than that has adverse effects on engine life, fuel economy, condensation in the oil, etc.. A 180 degree thermostat just allows the heat to build up before the water is released to pull heat out of it (in the radiator). Make sure you have high-quality thermostats and if they don't have a small 'bypass hole' drilled in them, then it is a good idea to add a small hole to allow air to escape and to circulate a bit of water before the thermostat fully opens.
Has nothing to do with a 5 lb cap vs a 15lb cap, as mentioned before. Did you re-torque the head bolts a few times after heat cycles? If coolant finds its way to the cylinder, it’s not due to a 15 lb cap. The tanks on original FH couldn’t withstand high pressure and could balloon. (The thought was) it had nothing to do with getting coolant into cylinders.
Iron block, aluminum heads and copper head gaskets were not a good combo for me. The head gaskets started leaking coolant when I would work the flatty going up hills at highway type speeds. I went to Best brand "Graph Tite" head gaskets and solved the issue. I had 180 degree thermostats and a 7lb. rad cap.
Thank you for your Input everything your saying sounds good to me And you must have been around a while to remember drilling the small bypass hole in the Thermostats Thank you again very good Information Got a ton of graet Info from everybody
This also is Really good Information and I have heard before about the metal combination not being the best combination Thanks again for your Help Much Apricated
If you don't Mind what is your water temp run at with what you have in it ???? Avarage summer time temps hoe warm does yours run Thank you clyde
Mine ran slightly below the thermostat temp around 175 on the gauge...but I chalk that up to poor gauge calibration. Always ran cool...outside air temps typically in mid to low 80's. Occasionally low to mid 90's. Flatty temp never changed. I ran no hood side panels and a mechanical fan .
Thank you for your reply Very good info Beautiful car also Great job on it. One Question did you run a electric Fan on your radiator or did you run no fan at all I have a couple pusher fans on mine don't have room to put sucker fan on it .was wondering if the pusher fans do more harm than good because they would restrict air going threw the Radiator just by being there .Your Thoughts ????? Thanks again for your Input Much apricated Clyde
When I restored my 34 Ford years back it came with aluminum heads from the factory and hose mounted thermostats...I used NOS Ford gaskets and they were always a composite gasket and had no pressure cap....Just a little info...
My tip of the day would be to reread anothercarguys post again. Some on here are going to disagree but in my book the composite gaskets are the way to go with the 7lb cap and as other have said before make sure you re-tension the heads after a number of heating and cooling cycles. As for the copper head gaskets the racing guys like them because they can be reused when they pull their engines down at regular intervals (but you aren't doing that on a street motor) also gasket cleanup is faster than composite so if you are racing then that time might be critical to you and you might damage your aluminium heads whilst doing the cleanup also you can get the copper gaskets in different thicknesses which might help in certain circumstances.
All good info. I’m contemplating rebuilding an old 49’ 8BA I’ve had under my work bench for 20+ years. Probably three times as expensive to rebuild than an overhead valve, but… cool has a price.
I'm running an 8BA flathead with Offenhauser aluminum heads and copper gaskets, I go by the old wives tale of painting the gaskets with aluminum paint to stop the corrosion between the different metals. I prefer the copper head gaskets since I've had fewer problems with them than the composite head gaskets. Brassworks radiator, 160 degree thermostat, 7 lb radiator cap and an expansion tank. Doesn't get over 180 degrees and takes a while to get to 160 in cool weather.
No pressure cap….down 1” in the upper tank for expansion. 7# cap and a recovery bottle/can. Amazon sell a great recovery kit for $30. Aluminum coated black with hose. I just put one on myLSR roadster..
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