265 Blown Head Gasket

[bvilletrack]

I recently swapped out a 230 for a newly rebuilt 265.  Only have about 100 miles on the engine and it blew a head gasket.  So I'm in the process of figuring out what happen and thought I would start by asking if the engine was running too hot.  Here's a little data:  The 265 has the internal by-pass coolant system while the 230 had the external by-pass.  The installation was a lot easier to use the old 230 thermostat housing and heater lines, etc.  I believe I read on the forum that it was okay to use the external components on an engine with an internal set-up.  If this is not the case I assume that the internal "holes" in the block could be plugged.  The thermostat that I'm using is a NAPA no. 155 (180 deg).  Engine warms up to 180 deg and idles just fine without any increase in temp.  However, at cruising speeds the temp increase to about 200F or slightly higher.   What should be the normal coolant temperature for the engine?  As far as I know the coolant distribution tube in the block was not replaced.  How often do these disintegrate?  Any suggestions are greatly appreciated.  DW

[Adam H P15 D30]

First, did you retorque the head bolts after the initial run in?

Second, my personal preference is to run a 160 thermostat unless you have a pressurized cooling system but 200 is not too hot just getting close.

 

Adam

[bvilletrack]

No i did not re-torque the head, which may be a significant error on my part.  I have a Stant TR-101 radiator cap (4 lb), so I don't think I have a lot of pressure.  Additional info, looking at the spark plug tips they have a nice chocolate color so I don't think the engine is running lean.

[Adam H P15 D30]

Check your block and head for flatness and chase all the bolt holes.  I know it was just rebuilt but check anyway, they will probably be fine.  Replace the head gasket, run it through a single heat cycle, then retorque (very important).  Run through another heat cycle or 2 and retorque again.  Shouldn't have an issue after.

Make sure you advance the timing a little from specification, it will make it run cooler.  Factory spec is ok if you are using 1950's fuel, fuel now days is different so give it a few degrees of initial advance.

A 180 thermostat is fine since you have a little pressure in the system raising the boiling point.

 

Adam

Edited October 25, 2018 by Adam H P15 D30

[bvilletrack]

Block is flat, but head is out 0.007" (at the machine shop now).  As far as a heat cycle goes... what I've done in the past is to run the engine at 1000-1200 rpm for about 30 minutes.  Is there a better method?  I'm using Landon's HEI distributor with full port vacuum.  I have the initial timing set at 4BTDC (vacuum disconnected).  Although Landon's spec sheet indicated 10-12 BTDC I am a little hesitant to go that much, but I can experiment a little.  Thanks, Dale

[Adam H P15 D30]

Dale,

 

Running it for 30 minutes and retorquing should work well.  I'm using a slant 6 distributor with a GM HEI module, I advanced mine until it pinged under high load, backed off until the ping was gone and went 2 degrees further retarded ending up at about 10 degrees initial, so Langdon isn't too far off.  He knows his stuff so I would try it and load it down in high gear and see if it pings...  His electronic distributor is top-notch.  Just curious, what coil are you running or is it built into the distributor?

When you say "full port" do you mean you have the vacuum advance attached to manifold vacuum?

 

Adam

[bvilletrack]

Adam,

I wanted to look a little more period correct so I ended up using the "round coil" instead of the one built into the distributor cap.  I purchased the coil from Landon when I got the distributor, its a Standard Ignition Coil (40kv I think) and seems to work well with the HEI distributor.  Yes, I have the vacuum advanced plumbed directly to intake manifold.  Dale

[Adam H P15 D30]

I agree on the round coil, I used a Pertronix 40kv coil I had from one of the many failed Pertronix modules I swapped out for someone, works good.  I use manifold vacuum on my Hemi because I had to retard the timing a lot for pump gas and it gives back the advance at idle.  I am thinking of switching my flathead to manifold vacuum also for more timing at idle.  Anything above idle it works the same as ported vacuum.  

 

Adam

[bvilletrack]

Adam,

You must have one of those high compression Hemis.  11:1?  I've started to hear bad stuff about Pertronix.  I have one on a 1943 White Superpower, but am not quite ready to start the engine up.  Let me ask you a rebuild question.  VPW recommended using plumbers pipe dope on head bolt threads on flathead engines to seal the water jacket, which I used.  But when I took the bolts out to remove the head, it seems that the pipe dope deteriorated quite a bit even to the point where a couple of them started to seep.  At the moment I'm thinking No.2 Permatex or Aviation Permatex might be a better option.  Do you have a preference?  Dale

[Adam H P15 D30]

Yes it is an 11:1 Hemi, difficult to run on pump gas but not impossible. 

This is what I use on all the bolt holes that are not blind. 

 

Edited October 27, 2018 by Adam H P15 D30

[James_Douglas]

There is no way I would run a flathead without taking out and inspecting (replacing if necessary) the heat distribution tube. 

[bvilletrack]

Inspecting the heat distribution tube sounds like a good idea to me.  Is there an easy way to remove the tube from the block?

[Jerry Roberts]

12 hours ago, bvilletrack said:

Inspecting the heat distribution tube sounds like a good idea to me.  Is there an easy way to remove the tube from the block?

Um , NO . Not usually . There is a write up on the project . Go to Technical ( along the top headings for the main page )  . Then go to Tech Tips . Also do a search as the topic has been covered many times covering all aspects . 

[bvilletrack]

Thanks for pointing me in the right direction!

[Adam H P15 D30]

If it's been recently rebuilt, it would stand to reason the tube was replaced then.  An easy way to tell is to check the temp at the rear of the head verses the front of the head.  There will be a difference but it shouldn't be extreme.  Mine is about ~10 degrees.

 

Adam

[bvilletrack]

Pulled the water distribution tube out yesterday.  It came out easy with two pulls on the slide hammer.  It's a brass tube with no corrosion or pitting, but I did find two pieces of what appear to be old water pump impeller constricting flow to the no. 6 cylinder.  I'll get it cleaned up and reinstalled.  No doubt that has contributed to the problem.  Dale

[Ricky Luke]

A trap I recently fell for...

 

My dad has a torque wrench similar to the photo. He tightened the head of his rebuilt 29 Plymouth as above to 40 ft/lb. It kept blowing head gaskets. When we checked the tension for the 3rd time I noticed the silver handle had unwound from the black nut, meaning the head was only tightened to about 15. Going strong since we fixed that little issue...

 

Sometimes you can blame your tools - until you figure out you're the goose that should have looked a bit further into the issue.

 

Rick

 

[Dan Hiebert]

How long you run the engine for the heat cycles is not as important as getting it to operating temperature and ensuring the engine is hot through and through.   Thirty minutes should indeed be OK (except in the dead of winter up here ), but you should still ensure the engine is thoroughly hot.