Overheating question
- Thread starter DOMINIC
- Start date
Even though it is said to be 100% numbers matching, I like Jim's suggestion. The damper could very well be off 10dg. Easy to check though, set initial at 22 dg and run the cooling check again.
DOMINIC
Active Member
All good input and questions. Stock cam grind from lamaar Waden. Degreed in for sure. TDC was checked and marked at the balancer to assure "0" was right on. As you all know it has no vac advance. I played with timing all the way to 32 degrees adv at idle. This made it run a little longer before it overheats. It is the original waterpump,cast iron impeller that works without a flaw. I tried to slow the flow down with a smaller pulley. This had no effect. Original pulley is back on.
Yes I leaked it down (2 percent) so it's nice and tight. I even "smoke" tested it when it was hot (no leaks). Thought I had sky high compression, crank test is only 150psi. This is more than acceptable due to the cam profile. Not sure about that 348 head question but I do know for sure the heads match the block.
Is it possible my machinist missed something? Being that I no longer have HC's I am to believe there is no crack. But before I tear this back down again I am asking as many questions as possible. I assure you all common sense is being used. So far no one has said anything about my high compression (12+ to 1) and .060 over. Could this be my original problem? It is the only thing in this re-assembly that has not been changed. Thank you all for chimming in. I know we all can fix this together and many other 409 guys with similar issues. If someone would like to talk by phone, I am available. Dom
Yes I leaked it down (2 percent) so it's nice and tight. I even "smoke" tested it when it was hot (no leaks). Thought I had sky high compression, crank test is only 150psi. This is more than acceptable due to the cam profile. Not sure about that 348 head question but I do know for sure the heads match the block.
Is it possible my machinist missed something? Being that I no longer have HC's I am to believe there is no crack. But before I tear this back down again I am asking as many questions as possible. I assure you all common sense is being used. So far no one has said anything about my high compression (12+ to 1) and .060 over. Could this be my original problem? It is the only thing in this re-assembly that has not been changed. Thank you all for chimming in. I know we all can fix this together and many other 409 guys with similar issues. If someone would like to talk by phone, I am available. Dom
The only way to check for core shift is by sonic testing the cylinder wall thickness. I don't think this is the problem. are you taking your readings from the stock location at they intake manifold? I also have been battling heat issues for quite a while with my 409. I had an experience that I even I have a hard time digesting last year. After struggling most of the summer with overheating issues I inadvertently left the rad cap loose and took the car for a ride, after tightening the cap the engine did not overheat. The only thing I can think happened is I burped the system allowing the coolant to fully engage the cylinder walls. As you know if you allow the engine to overheat you get what's known as runaway overheating. Also keep the engine tipped toward the rear to help when burping the system and use a surface breaker such as water wetter. It may be a good idea to pop a few core plugs and peek inside the core, not much work and at least you could have that peace of mind. Lean issue at idle will also overheat. Are you running headers or stock manifolds?
DOMINIC
Active Member
Great input. At my shop we use a set-up called an 'air lift" . It's a set up that allows us to pull the cooling system into a vacuum when the system is empty. After it pulls it into a vacuum, a vaccum equipt guage will also tell us that the system is leak free and then allow the tech to draw coolant in from a 5 gal bucket. This process takes all and any air pockets out of the system. One of the best tools I have in my shop. I also need to mention that using a Raytec allows me to check for any hot spot around the engine. I have even temp all around. Radiator is transfering heat (20 degree heat exchange). I ruled out being lean. Original manifolds have about 400+ degrees at each exhaust oulet. This tells me carb adjustments are within range. As for the sonic test? This was in the machinists hands. I hope he was right. Next question?
Like I said, time to take a look inside via a core plug removal. No reason for these engines to overheat any more than say a small block! I suppose if you had less than .100" cylinder wall thickness you could end up with hot spots that would cause a runaway heat issue. Could be that there is still molding sand in the head or block? You sure got me thinking
. Pull the pump and make sure that the casting flash has been removed from the water inlets. I have seen some blocks that were 25/30 blocked.
. Pull the pump and make sure that the casting flash has been removed from the water inlets. I have seen some blocks that were 25/30 blocked.
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No real tips on the pics. Sometimes different sites are not set up to accept the"GIF" pics, opposed to the other "JPG" or whatever. Sometimes you can move your pic,tires to a folder and have some luck uploading them? We have some guys that are way better equipped to answer those type of questions than my tired ass!
My measured 12.5 compression stroker with a pretty aggressive cam had 195-205 for cranking compression. I have since dropped the compression to 12.0 but have not checked cranking compression. I will bet you are quite a bit lower than what you think, and 91-93 octane is all that is required. I run pump gas in mine. I think you are lean and possibly the cam is degreed incorrectally. How is the performance of the motor?
A few years ago my friend had a 427 Corvette come in with what sounds like the same symptoms. The temp would just climb with no end in sight. The engine had been rebuilt and every thing was new in the cooling system. Very puzzling. After a few of the normal checks like you have done it was decided that there had to some sort of internal engine problem. My friend is a very competent mechanic/dynoshop super stock racer, he knows how to build engines correctly and properly. He decided to do what could be referred to as a reverse blueprint, he measured every thing as he disassembled. Every thing was checking out. All the time he was suspicious that the cam timing was out but every thing was checking on spec. The only thing that was altered in this engine was it has Rhodes hydraulic lifters. While the cam measuered spot on and the installation was correct he changed the lifters to stock hydraulics and reassembled, The overheating issue was gone!
Ain't nuttin' wrong with the motor. The radiator on the run stand is too small . That's my story and I''m sticking to it.
Yeah Ronnie, sometimes it is the simplest things. The only othr thing I could possibly think of would be ring butting!
That is certainly possible. I wish we could see a picture of the engine installed on the stand. Specifically I would like to see the radiator, fan set up, and the placement of the radiator. I hope the radiator is the highest point of his coolant system. So many unanswered questions.
DOMINIC
Active Member
Sorry, I had to step away. I'm glad I have you all thinkn. Compression ratio was done via cc'n the combustion area assembled. Then I performed the proper calculated math entry. Cranking compression is acceptable with this cam profile. I even ran that past comp cam. Yes the radiator is mounted above the engine. Radiator is more efficient and has more capacity than a stock copper rad. Keep in mind the radiator is transferring 20degrees. That is not my problem. Bottom line, I still have the same problem I started with minus the HC's. I don't have a current pic of the engine on the stand but can take one next week. Ring butting is a no. Was the First thing I checked on disassembly and reassembly. Its easy to bark out conclusions but unless you are workn on it, the answers are not always so easy to come by. That's what forums are for. To sort it all out. Thank you DOM