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Timing for 350 Chevy SB

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Robert

Robert

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Hi, just bought a '24 T bucket (kit car) and noticed upon getting it transported back home when I took it for a 15 minute cruise drive it got really hot, radiator overflow into the expansion tank, and then about 2 ounces lost out of expansion overflow tube.

This drive was mostly cruising about 40 mph.

It's got a turbohydromatic 400, 350 Chevy SB, braided lines going to standard model T radiator (17" x 19" x 2.5" thick radiator).

Got a new spiral electric fan works fine , no shroud yet - - purchasing the aluminum sheet tommorrow to make a custom shroud.

Double Edelbrock carbs.

Considering adding a tranny cooler since they are cheap and new radiators are really high.

Going to replace the hex chrome radiator cap with a 15 psi model, flush my cooling system, add a pound of citric acid to dissolve any scale or minerals for a hour "hold time" then flush again, add the redline water wetter stuff with new coolant.

I got a long list of things to try, one of them was to check/adjust the engine timing.

It's been 30 years since I got out my timing light, trying to recall, seems you need to plug the vacuum line on the distributor ?

Do I have to connect the timing light clip sensor to plug #1 ?

Any idea what I should set timing at to get best cooling of the engine ?

S Plugs are tan on one side and carbonish on other side.
 
Welcome to the forum.

Careful with the radiator cap. Some radiators can't handle 15 pounds. I've seen some that the manufacturer recommended no more than 7 psi ( I had one). Check with the manufacturer of the rad if you can.

Disconnect and plug the vacuum line. Connect light to #1. 10 degrees before TDC is a good starting point. This is assuming that the balancer and pointer are in the right place. You might want to pull #1 plug and verify TDC on the balancer.

Mike
 
Really hot to me and a lot of others means boiling the coolant. This means you are over 212F or 100C coolant temp, to be practical. If the coolant vaporises (boils) it will blow out the overflow. Another thing to make the coolant blow out the overflow is gas leaks from the head gaskets or cracks. Bad gas leaks you can see bubbling up the top hose into the radiator tank with the cap off. A radiator shop will have a sniffer to detect exhaust gas in the radiator as well.
What you describe could be normal expansion of the coolant as it heats. A happy engine runs at around 180F, 80C which is quite "hot" to those unused to an open un-cowled engine. If the water loss slows and stops after heat up, start thinking things might be normal after all.
BTW I'd be very leery of a dose of citric acid in there, especially if you had an older ally radiator. Use a commercial radiator flush, it's not so aggressive.
 
You'll need a temp gauge to know if it's really overheating. The previous owner might have filled the system just before shipping. I would call and ask before spending money.

Jack
 
Hotrod46 said:
Welcome to the forum.

Careful with the radiator cap. Some radiators can't handle 15 pounds. I've seen some that the manufacturer recommended no more than 7 psi ( I had one). Check with the manufacturer of the rad if you can.

Disconnect and plug the vacuum line. Connect light to #1. 10 degrees before TDC is a good starting point. This is assuming that the balancer and pointer are in the right place. You might want to pull #1 plug and verify TDC on the balancer.

Mike
Click to expand...



Thanks, it appears to be a really old radiator, I'm considering having it taken apart by a radiator shop and the cores cleaned. I'll ask the guy if he can guarantee 15 psi on the rebuild.
 
If its an old radiator its possible that its partially clogged which will cause it to overheat. If its so clogged that it will overheat after only 15 minutes, a re-core may be on order.

New aluminum radiators are available on eBay for less than $200. It may be easier and cheaper just to go that route...
 
Maxed out @240????? {[Whistle]} Yes in deed, I'd say she's warm. Was sitting on the fence until I saw that....I'd clean the radiator, replace the thermo....check out the belt. Since things are full of corrosion, I'd yank that pump off the front also and open it up. That will give you a indication of how the cooling system was treated.

Get everything good and clean. If it were me, and the waterpumps are not that expensive, I'd check out getting a new one that hasn't been trying to pump brownwater.

Once everything has been returned to a good clean base state, you can troubleshoot from there if needed. A dirty radiator will heat things up fast.

Seeping headgaskets and cracks WILL develop if you continue to hit 240....

I agree with Mango, the orange juice is too rough, a simple flush ought to do nicely. Bringing things to spec. will do wonders for a dirty overheating cooling system....

But lets not do the scatter gun thing, get things clean, and the old thermo with new one....then try her out

I would even go as far as to look at the waterpump and refresh it with a new one, one that hasn't been trying to pump brownwater....

Rust, scale and crap are hell on the waterpump seal and gaskets. All that churning by the impellar, especially when the thermo is closed has a abrasive effect on those items....when trying to pump contaminants, rust, scale. Remember to change out your coolant system's coolant every 4 years or so....
 
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Sorry for the repeats in my postso_O, but the posting trys to screw up occassionally:confused:, I don't know if things took or things just disappeared.....:eek::coffee:
 
Mike! You Da Man! Thank You!
 
Thanks Mike! You Da Man!
 
I will start at 10 BTDC.


What disadvantages might I see as I go past 10 BTDC towards 20 BTDC (if any) ????
 
Total timing is what you should be mainly concerned with. That would be initial advance combined with mechanical (distributor) advance. Generally, 36 degrees BTDC (all in by 2500-3000 rpm +-) is a good number to shoot for. This does not include vacuum advance. With the vacuum advance hooked up you should be around 50+ degrees BTDC.

But there are a lot of factors involved. As mentioned, detonation is a bad thing. Rule of thumb if you don't have a timing light is, advance it until it pings (detonates), then retard it until it stops.
 
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What Bob said! Depends on the motor. You can get 2 identical motors, 1 can make 5 to 15 horses more than the other, timing and all will be different. I've seen some want only 32 to 33, and others 45+....
I always tune to what makes the motor happy.
 
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