Good luck!!

 

Mike, any detail on the new radiator you installed? You said 'high efficiency' and so I am interested in the design, brand, cost etc. Thanks. You are cool now!

 

I do not know who manufactured the radiator but I'll look it up. I left the packaging at the shop but a phone call should yield an answer. It is supposed to have the same heat exchange capacity as the 19" 4 row in a 3 row design. Like one of you guys mentioned, the more rows, the less efficiency in the later (closer to fan) rows. I think this design relies upon fin design to yield higher capacity.

Now it may be a load of smack and it may plug after one dry day in wheat stubble- but we'll see.

I regret not having had more time- It would have been interesting to see how much difference just the timing advance diaphragm made- and how much difference the new (used) fan and clutch made. Because I changed out anything that looked or acted tired, I have no way of knowing which culprit was the most responsible.

In some ways I regret spending the $210 on the radiator rather than just dealing with the timing and fan.

But I spent the money because downtime when I need the truck it is a lot more expensive, the old radiator was tired (according to the radiator shop) and I wanted the truck cooling and on the road.

And the timing is good- I need to use gas compressor that is mounted in the service body in the central part of the state tomorrow. And for some reason, someone gave me an early 70’s Cadillac located in the same region last week. I am planning on bringing the Caddy back with the service truck- I try not to pull with this thing because after a Powerstroke, it is just painful to pull with a gas motor. And expensive!

Anyhow- it will be an interesting trip – It is a really clean rust-free 26 year old truck with good components like a 14 bolt rear, a Dana 60 front, a PTO winch, a compressor and crane on a good service body. I sometimes question the wisdom of spending money on it- But tomorrow will be good to test for the recent work.

By the way- why does the motor have a spark delay valve? The original looked cooked (hot) so I swapped in a new one when I replaced the vacuum lines. Does it simply delay the rate at which the spark is advanced by limiting the vacuum flow rate? If so, why bother delaying it? And why is there both a vacuum and what appears to be a mechanical advance? Did the later GM gas motors with electronic ignition do away with these advance mechanisms?

-Mike

 

Mike, the spark delay was part of the NOX emissions package, you could have simply thrown it away unless you are subject to emission inspections. All older engines (pre computer control) used a centrifugal advance and almost all except high performance engines used a vacuum advance. You have to go back to the basics on these. The advance is to compensate for the burn time of the air-fuel mixture. The centrifugal advance is set up for the maximum lead that the engine can handle under load. The vacuum advance makes up the difference between this and what the engine can tolerate at light load. One of the issues that came up with the advent of emission controls was very limp advance curves on the early systems leading to higher temperatures, abysimal fuel economy and no power.

The engineers found that the engine would run leaner, and therefor cleaner at idle with retarded timing. The first emission systems in 66 California models and 68 49 state simply retarded initial timing, added air injection in some cases, and jetted the carburetors lean. The side effect of this was inceased NOX emissions due to higher combustion chamber temperatures. The second round of "improvements" was the spark delay system, either a delay valve or a delay module.

The other item that took place was smaller carburetors allowing the leaner mixtures to at least run. The next phase was the EGR systems which diluted the mixture with burned exhaust gases to further weaken the mixture. The follow on to this was the catalytic converter. Catalytic converters, in order to do their best work, need a narrow range of air-fuel ratio....enter the O2 sensor and feedback carburetors. Finally the engineers realized the ultimate solution was going to be complete engine control by a computer, giving us our modern engines with no owner adjustments possible.

Each of the big 3 along with AMC used different concepts and the different GM divisions even had their own sytems. GM worked mostly with add ons such as air injection, Chrysler went with engine modifications and Ford split the difference, air injection on manual transmissions and engine modifications on automatics. AMC had to buy what they could from GM and Ford.

When the first catalytic converters came out, GM and Chrysler had a bed type that was extremely restrictive, Ford used a "monolythic" or grid style that was smaller and freer flowing than GM's design. Ford also used 2 on V8 engines for better fit and efficiency.

I hope this helps some, if not, then maybe you are still confused, just on a higher level

Bill "Old School Hot Rodder"

 

85labaron2:

Thanks for the education. I guess I could have saved the $12 on the delay valve... Oh well.

Since replacing the vac advance, I have some pinging at moderate load. Does this mean that the ignition is too advanced? Is there an adjustment to the vac advance or should I retard the distributor?

I ran that poor small block loaded at 18,000 lbs. 10 days ago. The truck burned significantly less fuel and did not heat at all. But at certain throttle settings I notice some pinging. I am guesssing that the new vac advance is working well enough that it may be advancing the ignition too much.

I should go back to step #1 and check the timing on this truck as I have not touched it since it came the utility company.

-Mike

 

Mike, is your EGR valve working? A non-funtional EGR will cause part throttle pinging. If everything is in order, check that your centrigal advance isn't too fast due to worn springs. You are welcome for the education, I have been doing it for years. I don't mind explaining things, but have bee accused of being long-winded. I have started a website for these things and will give you the link if you PM me. I can't find anyplace on my user CP to list it.
Bill " Old School Hot Rodder"

 

Bill:

Thanks

-Mike

 

Is the radiator the original radiator? How many miles? If the radiator has more than say 100K miles on it, the cooling tubes may be getting clogged up. This happens even in a properly cared for coolant system. The silicon in the old coolants made deposits that over time get thick enough to decrease coolant flow. Might need a new radiator or to have the core "rodded out" the old fashioned way.

Also your main coolant hoses may be collapsing. Squeeze the hoses while the engine is running and warmed up. They should be firm not squishy. Naturally watch for moving parts while your hands are in there, duh. Also sometimes you can see old hoses collapse while reving the engine and looking at them.

Good Luck,

Jim Henderson