Thread: 348 Running warm

Tweet

Originally Posted by 36 sedan

Great info! However, it appears he is installing the stat upside down???

Yep, the "pill" goes toward the motor.

.

I. Like using straight manifold vacume the ports on the carburetor that are intended for timing limit the vacume at idle so being more retarded burns more fuel and is a little better for pollution but a retarded idle makes engine run hotter. If you don't have an adjustable vacuum advance pull cap off and make a stop so to limit advance to 40 degrees at idle or cruising
There is a good thread on this but I am on the road try searching vacuum advance.
It explains it better than I can.

Not aware of any decent reverse flow waterpumps for 348-409-----------did you just change the impeller????? If so, that won't work as the impellar must not only fit the housing but inlet and exits must be arranged compatible to the impeller flow direction.

How many amps does your electric fan pull???????

See Post #2 in your earlier thread - 348/409 reverse flow water pump help

Originally Posted by 36 sedan

I do know to disconnect and plug the port for the advance for base timing.
Great!

but one thing I never understood is I think that the port vacuum is the factory spot.
Pre 70’s cars used manifold vacuum advance (all of the muscle car years), the 70’s brought us the SMOG motors (de-tuned) and the vacuum advance was moved to port or timed vacuum source (above throttle, no vacuum at idle) to raise idle temperatures and burn hydrocarbons.

so I always wondered what the advance weights in the dist are for.
Mechanical advance, allows the motor to start easier and helps in tuning the power curve for street use, race motors are locked out (no mechanical advance).

To add to that , then I never am quite sure if total advance should checked with the vacuum hooked up or not.
Vacuum disconnected.

From what I understand now, use the weights for total advance and plug the dist to constant vacuum after its all timed.
Correct! There are times with some motors that using the ported vacuum is advantageous. Some motors use no vacuum advance as it has nothing to do with horse power but rather economy.

Thanks, I feel like I just left vacuum advance college. I will double check everything this weekend.

Originally Posted by rspears

See Post #2 in your earlier thread - 348/409 reverse flow water pump help

I am going to check the timing and carb more and then check the flow of the pump. I'm not going to go through to much more work with buying $400 dollar pumps or changing everything to a v belt setup if the pump isn't flowing good enough. I have a reversed impeller in it right now, I was in to this thing so deep that was about my only option at the time. Tonight I drove it when it was about 75-80 deg and the temp never broke 200, I might just limp it along this summer and drop a 5.3 in for a winter project. I wish I could go back in time and talk to the young man who thought this whole 348 setup was too cool to pass up

Originally Posted by 53 Chevy5

Thanks, I feel like I just left vacuum advance college. I will double check everything this weekend.

Sorry, didn't mean it to be a lecture.

Originally Posted by 36 sedan

Sorry, didn't mean it to be a lecture.

No really, I wasn't be sarcastic, I really do understand better. Thanks

Originally Posted by 36 sedan

Sorry, didn't mean it to be a lecture.

Originally Posted by 53 Chevy5

No really, I wasn't be sarcastic, I really do understand better. Thanks

I thought that you did great too, 36 sedan! Clear, concise answers with no drama. Nicely done.

It’s a little difficult to see from your pictures, but it doesn't look like you're using a bypass hose with your current setup. I know there are folks that say the bypass hose isn’t necessary, but I can tell you from personal experience overheating problems can occur without the little rascal installed.

Hopefully your issue may be simpler to fix than you think … it may be worth a try.

4 C notes is a lot for a water pump, but it's a lot less than a new motor.

Do you have visible flow in the radiator with the engine hot? Beyond a gross timing issue, I think it's the culprit, having read the thread.

The previously mentioned oil cooler is cheap, and you can relocate the oil filter at the same time.

You've come so far, it seems a shame to give up now.

WOW! Nice catch Dan J.

Yes, that was a good catch!

Originally Posted by Dan J

It’s a little difficult to see from your pictures, but it doesn't look like you're using a bypass hose with your current setup. I know there are folks that say the bypass hose isn’t necessary, but I can tell you from personal experience overheating problems can occur without the little rascal installed.

Hopefully your issue may be simpler to fix than you think … it may be worth a try.

I am just about afraid to ask this because of embarrassment, but is that necessary? I found a fitting and some hose this morning and I am going to put one on right away. I need to drive it about 100 miles today for some exhaust and run some errands.

No need to be embarrassed, we all missed this except Dan J! Stuff happens, fortunately with enough people looking at problems from different view points we sometimes find the overlooked. From my research on this, the bypass was added by Chevrolet to correct the overheating, it lessons the cavitation at the impeller and increases system pressure.
This may well fix it.