No the slits are not why, there are thousands of big blocks out there running head gaskets like that.

Can anyone confirm the comment about 340 26 inch Radiator lower inlet being smaller than would be on a big block 26 inch radiator? I am using a 340 rad and the lower hose is same diameter from water pump to the lower inlet.

I am working thru a 440 running too warm according to my gages which I am trying to confirm their accuracy. Mine is doing 220 highway and 230 idling.

Mike

Well it's good to see you John (its been awhile) & we've missed you! (ahem). what I was saying which you can see if you reread it is that the minimal flow is an obvious clue. John I am disheartened to see that you have not let this go after all these years.

Also check the WPHousing.. A lot of the aluminum WPH s look OEM but some of the ports narrow down quite considerably (like too a 1/2 inch) on the inside. I put back an old iron OEM WPH and my 383 and it runs cool as a cucumber......

[quote=shaker340]Can anyone confirm the comment about 340 26 inch Radiator lower inlet being smaller than would be on a big block 26 inch radiator? I am using a 340 rad and the lower hose is same diameter from water pump to the lower inlet.

I am working thru a 440 running too warm according to my gages which I am trying to confirm their accuracy. Mine is doing 220 highway and 230 idling.

Inlet outlet are same size 26" 340-440 rad 70 and up. I measured a 2998949, 3673925 both smallblocks, and 2998956,3443959,3443960,bigblock all 1.5 top 1.75 lower only thing changes is hose location. Those temps sound like radiator or gauge to me. I drove 900 miles with no fan, clutch failed so I removed it, home from mopar nats august, hot out, air on, and my 440 ran 180. But my block was is standard bore, original radiator.

4406bbl thanks for checking on the radiator inlet and outlet port sizes.

I did confirm the gage is accurate with a second gage and laser temp gun. So I am going to try less timing, going from 15 initial to 8 initial and a step richer jetting, to see if temp drops. Motor is stock bore motor home, at 8:1 comp so it probably doesn't need all that ignition. If this does nothing, then rad will get pulled and tested, its a used unit I have had for near 20 years hanging around in my parts collection.

Mike

Unless you changed temp sensors, swapping clusters only confirmed your dash gauge is consistent. If the sensor is FUBAR, the gauge only knows what the sensor tells it.

You can get an IR temp gun at any auto parts store if Harbor Freight isn't handy.

My buddy's MaxWedge was doing the run warmer than it should deal. Apparently not all water pumps are created equal because they replaced the new pump they installed when they built the engine with a different new pump and it behaves now.

Years ago my brother had a Sears rebuilt 318 that always ran warm. Drove it that way for years until a frost plug started leaking. Went to replace them all and discovered all the old ones had just been driven thru when the engine was "rebuilt". He fished them all out along with all the crud that had gathered around them and no more warm 318.

Kevin

Tree'd

Where in Eastern Ontario are you?

Kevin

Smiths Falls

I didn't change clusters, I have aftermarket gage cluster in the truck, and used a B&M temp gage to confirm gage cluster reading along with and IR temp gun.

That is correct. My 69 “053” big block radiator has 1.5” inch upper and 1.75” inch lower inlets. Later today I can measure the small block radiators I have.

So if the radiator inlets are right, I’d make sure the pulley ratio is correct for the number of water pump impellers. Also there was a comment about aftermarket aluminum water pump housings. If you have one of those I try going back to the factory cast iron to eleminate that question.

I read it fine, you are claiming his diminished flow is because of the slits in the gasket is how it reads.

There is minimal flow thru those slits , his dimished flow has little to do with the size of those slits, someone a lot smarter than you, or I, redesigned that head gasket. Why ???

Sorry, I thought you were the OP.

We're practically neighbors. I'm down by Spencerville.

If you do the cruise nite on Thursdays we've likely crossed paths. Haven't been this summer but we show up in a 65 Polara wagon.

Kevin

Update: I’ve got a radiator out of a 1968 Dodge Charger with 318 and air conditioning. It is a 26” inch two-core. Part number #2898041. Both upper and lower inlets are 1.5” inch.

Don’t know what the other small block radiator applications had but one would probably want to be aware of potential differences between big block and small block radiators.

Mike I would strongly suggest staying at 15 & not retarding it. Not sure what your total/springs are but 15 is fine & not the problem

Robert it made no difference backing the timing to 5 degrees, and will put it back to 15. Spark plugs looked great too, so mixture is about right.

What happened last nite the gage showed 240 idling but I was able to put my hand on valve cover, I know the gasket can reduce the temp. But the IR temp gun showed heads at 200, water pump was 180, rad top tank was 200, upper hose was 165, lower was 135. So I am not convinced yet I have a heat issue.

I am starting to suspect the temp sender, and have another new one to swap in to see if any change.

Mike

Sounds like your gauge is not reading correctly , what type/brand
is it ?

seeing those temps you posted, i wouldn't be concerned in the least ! just my opinion.

JohnRR I am using the Intellitronix brand of gages and also using a B&M temp gage that reads same number as an alternate. So I will try swap the sender to see if any change in readings.

Moparx I am agreeing with you and hoping its just the sender.


What was interesting that I forgot to post was that the IR temp gun pointed directly at the nut of the sender was reading 240. And the cast area around it was around 200.

I will say it again, first thing I like to do is put a thermometer in the radiator, then I know. 9 times out of 10 there is nothing wrong, other than the gauge.

I have an overflow bottle set up, so I will be getting a thermometer to check that out too.