BB Cooling Problem

[Louis C.]

Re: I'll play the student......

Tom & Jerry:

Thanks for the information, however, I feel like I got caught in a game of CAT & MOUSE! Humor guys! Yesterday I found that my timing was at 25 degrees at idle and 55 degrees total. Think this can be a contributor? I read an article in the Spring 1999 Restorer titled; "Summer Overheating." In the article (page 14) it explains that advancing the timing two degrees can reduce coolant temperature by five degrees. Retarding the timing will increase your coolant temperature. I called Tom Douglas and he said this is correct. I always thought it was the other was around!

[Tom B.]

Re: I'll play the student......

Chip,

This is supposed to be fun. It still is. Sorry to create such a distraction for you.

Is your distributor original? I'm not familiar with what you are stating about your timing. It appears off the scale. That isn't your dwell, is it? I can't verify which way, advancing or retarding, the timing will do for over-heating but I will pass on the timing advice Joe Lucia gave me for my over-heating checks and adjustments. That was to set the timing at what the specs called for out of the book. In my case I have an original factory (68 L89) set up, even though I have a "correct" (but '66) TI distributor. Hope this can help. Tom #24014

[Tom B.]

Re: I'll play the student......

Chip,

This is supposed to be fun. It still is. Sorry to create such a distraction for you.

Is your distributor original? I'm not familiar with what you are stating about your timing. It appears off the scale. That isn't your dwell, is it? I can't verify which way, advancing or retarding, the timing will do for over-heating but I will pass on the timing advice Joe Lucia gave me for my over-heating checks and adjustments. That was to set the timing at what the specs called for out of the book. In my case I have an original factory (68 L89) set up, even though I have a "correct" (but '66) TI distributor. Hope this can help. Tom #24014

[Louis C.]

Re: I'll play the student......

I have a T.I. distributor of unknown origon. I understand there were some 23 variaties made. I hope to learn more about the advance curve and have mine redone in the near future. The car runs fine presently, just have to get it to run cooler. Regarding the timing figures I mentioned, 25 at idle and 55 total: A buddy of mine has a timing light which checks total advance by way of a calibrated potentiometer on the light. You point the light and vary the pot bringing the balancer mark to zero and then read the scale on the light. I beleive most people these days check total advance, 55 in my case. Most say 38-42 is right. Back to the theory of advance to cool, retarded heats. Is fifty five too much?

[Louis C.]

Re: I'll play the student......

I have a T.I. distributor of unknown origon. I understand there were some 23 variaties made. I hope to learn more about the advance curve and have mine redone in the near future. The car runs fine presently, just have to get it to run cooler. Regarding the timing figures I mentioned, 25 at idle and 55 total: A buddy of mine has a timing light which checks total advance by way of a calibrated potentiometer on the light. You point the light and vary the pot bringing the balancer mark to zero and then read the scale on the light. I beleive most people these days check total advance, 55 in my case. Most say 38-42 is right. Back to the theory of advance to cool, retarded heats. Is fifty five too much?

[G B.]

Yes, 25/55 is too much.

Uh...you did disconnect the hose to the distributor vacuum advance canister before you checked the timing, right?

[G B.]

Yes, 25/55 is too much.

Uh...you did disconnect the hose to the distributor vacuum advance canister before you checked the timing, right?

[Chuck G.]

Re: BB Cooling Problem

Hello Chip; Seems awfully advanced to me. Don't have a spec book handy, but I think that the initial advance with the vacuum disconnected should be about 4 to 8 degrees at about 600 to 800 RPM. The vacuum should add another 10 to 12 degrees. As I recall, total advance (initial + vacuum + centrifugal) should be somewhere in the high 30's. 55 degrees seem way too much.....burn a hole in the piston too much. Hope this helps. Check the spec. book for your BB. Also, how much do you "trust" your harmonic balancer? Some are known to shift around the perimeter and lead to incorrect timing readings. You might want to check it by finding TDC and seeing how the balancer TDC mark aligns with the timing tab. Chuck

[Chuck G.]

Re: BB Cooling Problem

Hello Chip; Seems awfully advanced to me. Don't have a spec book handy, but I think that the initial advance with the vacuum disconnected should be about 4 to 8 degrees at about 600 to 800 RPM. The vacuum should add another 10 to 12 degrees. As I recall, total advance (initial + vacuum + centrifugal) should be somewhere in the high 30's. 55 degrees seem way too much.....burn a hole in the piston too much. Hope this helps. Check the spec. book for your BB. Also, how much do you "trust" your harmonic balancer? Some are known to shift around the perimeter and lead to incorrect timing readings. You might want to check it by finding TDC and seeing how the balancer TDC mark aligns with the timing tab. Chuck

[Louis C.]

Re: Yes, 25/55 is too much.

No, I didn't disconect the hose or block it. Should I?

[Louis C.]

Re: Yes, 25/55 is too much.

No, I didn't disconect the hose or block it. Should I?

[John H.]

Re: Yes, 25/55 is too much.

Yes - disconnect the hose at the vacuum advance can and stick a golf tee in the hose - static timing is always checked with vacuum advance disconnected. Once you have set your timing by the book, re-connect the vacuum advance hose and observe the timing again to verify that the vacuum advance is working. I'd check the static timing both ways - with the dial-back on the timing light set to zero and read it on the balancer, and set the dial-back to the correct degrees and verify zero on the balancer; if they're not the same, the timing light has a problem. If your timing is actually 25 and 55 degrees, I'm surprised the engine even runs. Are you sure you've actually got the inductive pickup clamped around the #1 plug wire? Check that too before you start, and let us know how everything comes out.

[John H.]

Re: Yes, 25/55 is too much.

Yes - disconnect the hose at the vacuum advance can and stick a golf tee in the hose - static timing is always checked with vacuum advance disconnected. Once you have set your timing by the book, re-connect the vacuum advance hose and observe the timing again to verify that the vacuum advance is working. I'd check the static timing both ways - with the dial-back on the timing light set to zero and read it on the balancer, and set the dial-back to the correct degrees and verify zero on the balancer; if they're not the same, the timing light has a problem. If your timing is actually 25 and 55 degrees, I'm surprised the engine even runs. Are you sure you've actually got the inductive pickup clamped around the #1 plug wire? Check that too before you start, and let us know how everything comes out.

[Steve Moore - NCRS #35476]

Re: Can you scan in a shot of the damage?...Helpfu

Mike, Sorry it took so long to get the pictures posted. The pictures can be seen at:

http://hometown.aol.com/castoriva/79Corvette.html

Any advice or help would be appreciated!

Steve

http://hometown.aol.com/castoriva/79Corvette.html