Warm L89

[Noel O.]

Very recently had my 68 L89 rebuilt. Seems to be running very warm. 215/225
this morning (about 70ish medium humidity) when driving 55/65 for aboutr half an hour. When I stop it, temp guage runs straight up to red, comes back down quickly when moving. no overflow, not boiling, no starting problems. Nonetheless, getting a bit nervous and gun shy at this point to drive it all. Might sound crazy, but I put a mechanical meat thermometer probe onto the sending unit (which is new) and it registered 220 def F. The guy who did the work I beleive to be quite reputable, good refs, built a number of big block cars etc. He had mentioned that he thought it was running a bit warm but thought that it might be guage ad he felt the sending unit was 20/30 deg cooler in addition to the coolant being significiantly cooler.

Thoughts?

[lyndon sharpton]

Re: Warm L89

make sure you cooling system is in real good working order. you said you just had it rebuilt the L89, did you go through and check your radiator?

[Bill Stephenson]

Re: Warm L89

-------Sounds simple but, perchance, did you forget the thermostat??? Also, a fresh engine still breaking in the pistons and cyl. wall crosshatch will run hot........Bill S

[Mark #28455]

Things to check

Make sure all your radiator to shroud and support seals are intact and sealing. Make sure the spoiler is intact under the nose of the car. Make sure your timing is correctly set. Make sure your fan clutch is working. Is your thermostat fully opening at the correct temp (put it into a pot of water on the stove and check)? As noted above, is your radiator clean? Is your radiator full? 50/50 antifreeze and water cools better than pure antifreeze.

Hope this helps,
Mark

[Duke W.]

Re: Warm L89

A new engine should not overheat, so there is probably a root cause that could either be in the cooling system or ignition map.

As built many SHP big blocks have a tendency to run hot or overheat if the radiator and fan are not functioning as new, and the root cause of this problem is "ported" vacuum advance.

Many SHP BB owners drive their cars a lot more relaxed now (aren't worrying as the temp gage relentlessly climbs in hot weather low speed traffic because the temp gage no longer climbs) after converting to full time vacuum advance and installing a suitable vacuum advance control. Any convenient source of full time manifold vacuum can be used, and teeing into the choke vacuum break hose on the center carb is easy to do with a 1/8" tee and a couple of feet of 1/8" vacuum tubing - just remove the OE hose and make a complete new harness.

The proper VAC (assuming you have the OE cam) is NAPA/Echlin VC1765 (stamped B22) or VC1808 (stamped B26) both of which provide 16 degrees crank advance at 12" Hg. manifold vacuun, and the OE cam should idle at 14"@900 so the VAC is "locked" at full advance at idle. Total idle timing should be the sum of initial plus full vacuum advance plus maybe a couple of degrees of centrifugal - in the range of mid-twenties to low thirties. The cooler EGT resulting from having proper total idle timing will reduce the thermal load on the cooling system, and this can be verified with an IR gun aimed at the exhaust manifolds. It must be a gun that measures up to 1500F as the manifold temperature with ported vacuum advance can exceed 1000F after extended idling, but with proper total idle timing will drop to as low as 500.

You can also cross reference these part numbers at other brand web sites. All should have the same stamped ID number regardless of brand or part number because the Standard Ignition Products is now the sole manufacturer of virtually all single point/TI dist. replacement parts.

Duke

[Noel O.]

Re: Warm L89

Guys,

Many thanks for the responses. First thing I will do is follow up with the engone builder to discuss some of the points mentioned here. Regarding the radiator, it has been replaced prior to the rebuild at which point the car did run a bit warm a times but not to extent that I can see now. Just for my own edifcation, what would be the best source for a new radiator and related kit and any tips for installation. BTW the car is Late Feb 68 build with the 842 heads

Duke - regarding the cam, I decided to go with a Crane #133841 so I dont know how this might alter your thoughts.

Thankyou all again

[Duke W.]

Re: Warm L89

Most aftermarket cams are a mistake, but guys keep doing it because the "engine builder" said it was best. It will never end. It probably has more overlap than the OE cam, and even the OE SHP cams have too much overlap. Increased overlap will be evident with a lower than OE cam manifold vacuum reading. If it only generates 10" - good luck. Put a decent cam in it or live with overheating, poor low end torque and throttle response, 8 MPG - whatever.

The basics on vacuum advance are the same for all cams. Run full manifold vacuum advance and select the vacuum can using the 2-inch rule with 25-30 degrees of total idle timing.

Run the test by binding up the centrifugal weights with a rubber band and disconnecting the installed VAC and installing a vacuum gage to a full manifold vacuum source. Advance the base timing to 25-30 degrees. Set the idle speed and mixture to get a stable idle.

The more overlap the cam has, the higher the idle speed necessary to get reasonable idle quality and stability, and it may want over 30 degrees total idle timing.

Once it's "optimized" take an idle vacuum reading. Reset the initial timing to spec and go get the right VAC.

Duke

[Rob M.]

Re: Warm L89

Noel,

Most on this board will recommend Tom DeWitt for a new radiator. I know I really like mine and would recommend him highly. Here is the link: www.dewitts.com

Good luck,
Rob

[Gary #41345]

Re: Warm L89

Make sure they have all the heater hoses connected properly, after getting my 66 completely done over the body guys switched the hoses and that led to very warm conditions.... took me a while to sort that one out.

[Noel O.]

Re: Warm L89

Rechecked the cam specs and if I have calculated correctly, the overlap of the Crane 133841 is identical (81) to the 3863143 cam

[Duke W.]

Re: Warm L89

I don't know how you calculated overlap, but timing numbers alone don't tell the whole story. If the cam you bought is sold as an exact reproduction of the 143 cam, then that's okay. If not, who knows.

Install one of the vacuum cans I recommended and convert to full time vacuum advance. If it still runs hot, and the fan clutch tightens when it gets hot, then the radiator is suspect.

Duke

[Noel O.]

Re: Warm L89

Couple of follow up questions: If gasse are getting into the cooling system, will you see the odd bubble here and there as the coolant flows through the radiator or will it prenounced in addition to foaming of the coolant? Is there a way to check the operation of the fan clutch?

Thanks again for all the comments and help