Make sure that he knows that all the valve stem heights need to be correct to give proper lifter preload on a non-adjustable Oldsmobile rocker arm setup to include the installation of a thicker head gasket. I doubt you'll find a stock thin steel shim head gasket. I went through a similar situation on my 330 when it blew a head gasket between #4 and #6 cylinders except it did not blow my radiator, just caused fluid out the overflow.

 

Thanks for mentioning that Eric. For clarification, if he takes .002" off of the valve face and valve seat he'll have to take .004" off of the valve stem height, correct? What about the thickness of the Fel-Pro head gasket vs. the stock gasket?

I asked him if he had done Oldsmobile engines with non-adjustable valve train and he assured me that he had done it many times. Actually, it's the same machine shop that rebuilt the 455 that I have on an engine stand right now. However, I did use the Comp Cams adjustable roller tip rocker arms kit on that engine.

 

I already picked up the heads from the machinist. $420 later. He didn't install new guides or seats but he cut new faces and seats. Plus he trued the heads, installed new freeze plugs and valve guide seals and; of course, hot tanked and magna fluxed them. Here's the obligatory pic.



I need to remove the valve covers from my engine that's on the stand. This weekend I might paint the heads using the old valve covers or maybe I'll clean the deck in preparation for the install. Lots more to come.

 

I notice that I last posted in this thread over 5 months ago. I suppose it took quite awhile to get my 71 started. I'm not going to beat myself up about it though. I've accomplished something every weekend between now and then.

So, I started my 71 today and ran it for about 10 minutes. At first, I had the distributor 180* out so all it did was belch and backfire out the carburetor. Once I re-stabbed the distributor it started and idled effortlessly. Started out with a little lifter tick that quickly subsided.

Unfortunately, the engine steamed like locomotive. Remind you of earlier posts (#s 15 & 23)? The headers already have a nice crispy brown patina on them...

Once the engine started I didn't adjust the timing or carburetor at all. I tried to pull it out of the garage but the transmission needed another quart of ATF. While the engine was idling the OE radiator that I reinstalled in it was steaming between the side tanks and core. After idling for 10 minutes there was quite a puddle on the floor. I shut it off and called Oldsguy.

Interestingly, I reused the same thermostat and the upper radiator hose was rock hard pretty quickly after starting it. I suppose the thermostat could be bad and it's causing the radiator to steam and pressure to build up in it. Or, maybe I didn't let it idle long enough for the thermostat to open? If the radiator is bad of course it will steam. Maybe a bad thermostat contributed to my original problem and caused the parts store cheapie radiator to fail?

Ultimately, another compression test is in order and I should probably get a coolant system tester and remove that thermostat to test it. I wouldn't think that Oldsguy and I were so careless as to make a grave error when installing the heads. The rest of the reassembly went pretty well without a hitch besides installing the distributor 180* out a first...🤔

Here's a pic of all the steam coming off of the radiator. The engine had only been idling for 10 minutes.



I had a sizable puddle of antifreeze that came from the radiator (seeping out from between the radiator core and end caps).

 

One vote for copper/brass if you can get it, but Aluminum may be better.

Was talking with a jag mechanic a while back. He told me that 2005 (Ford-era) Jags and many other makes went to plastic thermostat housings as a cost measure in the 90’s or so. He stocked thermostat housings as a replacement part, so you know what that means about frequency failure: plastic doesn’t endure all too many years getting constantly heated & cooled. I like plastic just fine, but not for radiators.

His quote that stuck in my mind was “Your Olds 455?, run that thermostat housing on a belt sander for a few seconds & it’ll work for another 50 years.”

You probably know lots more than me, but I switched over to a 70% distilled water / 30% antifreeze mix with water wetter and it made a difference in my 455’s. They’re running cooler than with the usual 50/50 mix.

 

70% water will run cooler than 50/50.
​​​​You could take it a step farther if you wish by adding an emulsifier such as RedLine Water Wetter.

Good luck!!

 

WOW not good

If you know the radiator is leaking, get it fixed. I found a local old school guy who recored my copper/brass 4 core OEM. I think more durable. Never a problem afterwards. Cost some $$$$.. Needed for originallity/show..

I had a water pump loose its impeller press fit on the shaft it drove me crazy.................................. chased ALL the wrong things..

Take off the raditator cap, get a flashlight and look down into the bottom, fire up engine look for a nice steady streams of coolant once the thermstat opens. This will also let you know if thermostat is stuck...Factory thermostat was usually 195F FYI. A temp gun will giev you an idea how hot you are running. Shut down immediately if you have to...

Yes a new compression test is needed first. I would also do the exhaust gas check in coolant... You could check radiator cap fr correct pressure and also pull Thermostat to see if it is opening.

Again, a loose impleller can drive you crazy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Also had bypass hose blow the cheapo one you get at autozone. Never again rated 50 lbs. not too old..

I now use Goodyear Hy-T heater hose rated at 200 lbs. now no probelm..

Have had probelms with Goodyear raditator hoses. Now use Gates, or Dayco seem to be doing better..

Good Luck! Keep us posted

Fred

 

Thanks for the comments gents. I might have to try the 70/30 antifreeze mix. It doesn't get cool enough in OK to need a 50/50 mix. FWIW, it turned out that the thermostat was bad. I replaced the radiator & thermostat and did a compression test. All is good!👍

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