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Discussion Starter · #1 ·
The engine I've got is the 1968 327 210 HP with a 3-speed manual transmission. I know it was rebuilt once, but I don't have any reason to believe it was built to anything other than stock spec. I recently put an Edelbrock Performer on with a Quadrajet. I've been researching everything timing and generally see a recommendation of 8-12 degrees advance. However, the original specs for the engine look for 2 degrees of advance.

Why the difference and more importantly, where should I start? There will certainly be more fine-tuning later but I want to be sure I start off as best I can.
 

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Does / did the engine have a SMOG pump system"
David Ray,
I’m curious if you think the QJet regardless of size is too much for the 210hp version. My brothers 67 has the 210/2bbl carb and it runs great because the engineers designed it that way. I’m not poo pooing on the intake/4 bbl add on, just curious what you think.
 

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The initial advance depends on what mechanical advance you have in the distributor. If you find the numbers stamped on the body of the distributor to verify it is original and then look at the bottom of the advance plate to determine the mechanical advance. and example of the stamp would be 724 or 524 etc. The 24 indicates the distributor is limited to 24 degrees mechanical advance. Thus to get a 38 degree total mechanical advance, you could start with 14 degrees initial advance IF you don't get into spark knock and don't get hard starting problems when hot. To determine the best mechanical advance, you must determine the curve (when the advance comes in and when you reach maximum advance). I don't recommend just setting the initial at 12 degrees and hope it gives you the best performance, but 4 degrees or so above GM specifications generally does not hurt anything.
 

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Discussion Starter · #6 ·
David Ray,
I’m curious if you think the QJet regardless of size is too much for the 210hp version. My brothers 67 has the 210/2bbl carb and it runs great because the engineers designed it that way. I’m not poo pooing on the intake/4 bbl add on, just curious what you think.
I'm not David but while we wait for a response...

The engine specs for the 327/250 HP in the back of the chassis service manual are exactly the same as for the 210 HP, except for the carb. Same cam, same compression ratio which makes me think they're the same heads as well. The 327s up to 300 HP are all listed with the same cam.

Is anyone aware of what other differences between the 210 and the 250 would be?

The tuning specs for the 210 and 250 are nearly the same as well, with the 210 looking for AC44 spark plugs and the 250 looking for AC44S spark plugs. But more to my question, the initial timing for the 210 is listed at 2 degrees ATDC whereas the 250 is listed at 4 degrees BTDC. ?
 

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I'm not David but while we wait for a response...

The engine specs for the 327/250 HP in the back of the chassis service manual are exactly the same as for the 210 HP, except for the carb. Same cam, same compression ratio which makes me think they're the same heads as well. The 327s up to 300 HP are all listed with the same cam.

Is anyone aware of what other differences between the 210 and the 250 would be?

The tuning specs for the 210 and 250 are nearly the same as well, with the 210 looking for AC44 spark plugs and the 250 looking for AC44S spark plugs. But more to my question, the initial timing for the 210 is listed at 2 degrees ATDC whereas the 250 is listed at 4 degrees BTDC. ?
Roger that. So there is definitely hp and torque gains from just that. Bolt on hp lives.
 

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FWIW when I had a 327/210hp/2brl....I put on a Edelbrock Performer intake and a 600 cfm Eddy 4 brl and it made a big performance improvement.
My first car was a 69 327/210. Ran well but not very powerful. When my dad wasn’t looking, i put a Torker, Holley 780, and Accel dual point on it. I was surprised how little it gained. I credit most of what it did gain to the advance curve. Looked a lot better under the hood, though.
 

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'68 396 SS/RS, '97 SS, '02 SS
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My first car was a 69 327/210. Ran well but not very powerful. When my dad wasn’t looking, i put a Torker, Holley 780, and Accel dual point on it. I was surprised how little it gained. I credit most of what it did gain to the advance curve. Looked a lot better under the hood, though.
I was lucky. My first car was the former family car that my dad bought new. It was a Ford Galaxie 500 with a 390. One of my dad's longtime friends worked for Holman-Moody and had him rebuild the motor on my '65 at night. My dad would give him money for this and that and tell me "For God's sake don't tell your momma". It wasn't much off of the line but was pretty quick on a 30 roll.

As far as initial timing I'd would try it at 8° and work from there.
 

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650 cfm Q-Jet should be really good for the low horsepower engine.

The statement that initial is set by the mechanical degrees available is completely backwards. To do it right, INITIAL setting is needed, then, the correct amount of additional degrees makes up the TOTAL advance, initial + mechanical.

Case in point, last Pontiac 455 engines. High timing limit, 36 deg/BTDC. ONLY issue, the mechanical advance has 40 degrees ot timing. This gave MINUS 4 deg/ATDC at IDLE, not workable to anything but an emissions severely detuned engine. Earlier Pontiac 455 used 10 deg/BTDC INITIAL, and added 26 degrees of MECHANICAL advance, for a total of the 36 degrees.

THAT is the way it works, not the mechanical dictating initial timing degrees.
 

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67 327-210HP (A.I.R.) Man 2 Before TDC @700 rpm
67 327-210HP (A.I.R.) Auto 2 Before TDC @600 rpm
67 327-210HP Man 2 Before TDC @500 rpm w/ AC on
67 327-210HP Auto 2 Before TDC @600 rpm w/ AC on

68-69 327-210HP Man 2 After TDC @700 rpm
68-69 327-210HP Auto 2 Before TDC @600 rpm
 

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The OP needs to know what distributor he has in his engine. I believe the original for his 68 is 1111257 which had 28 degrees of mechanical advance at 4300 rpm in stock form. Thus, agreeing with David Ray, if you want 36 degrees total advance, one could run initial timing of 8 degrees, maybe a couple more.
However, if the distributor is a smog distributor 1112047 swapped in from a 1971 350, it only had 17 degrees mechanical advance built in and would require and initial advance of 19 degrees to obtain the same 36 degrees total advance. I would expect hot start issues may occur with 19 degrees initial advance.
Thus, it is important to know what you have before pushing the initial advance up. Of course to optimum determination can be obtained with an accurate tachometer and timing light to map the actual curve as it may have been modified with heavier weights, lighter springs, etc.
Kinda like don't jump into the water until you know how deep it is!!
 

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Discussion Starter · #16 ·
One might consider hooking up a timing light and testing it in action to see how much mechanical is coming in.

Just a thought.
It took me a little time, is all.

My copy of the chassis service manual has me spec'd out with a 1111440 dizzy (327, 2bbl (originally) and a manual transmission). It says that distributor should be good for 8 degrees of advance at 1400 rpm and 36 degrees at 3950 rpm. I just measured and that's pretty much spot on with my measurements.

Part of the reason for my question is when you read about this you get the impression that the engines are de-tuned at the factory spec. Coupling that with a slightly modified version of the engine it's not clear where the best place to start is or if the factory spec was really ever the best place to start.
 

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Discussion Starter · #17 ·
Reviewing the article "Timing and Vacuum Advance 101" from "Corvette Enthusiast" by John Hinckley that was referenced in this post:

Vacuum Advance Article

He writes:

"One of these crude, but effective systems was GM’s Air Injection Reactor (A.I.R.) system, which pumped fresh air into the exhaust ports to “afterburn” pollutants in the exhaust manifolds. The key to making this system work at maximum efficiency was retarded spark at idle; with retarded idle spark timing, the “burn” begins late, and is not complete when the exhaust valve opens, which does two things that were important for emissions. The incomplete burn reduced combustion chamber temperatures, which reduced the formation of oxides of nitrogen (NOX), and the significant increase in exhaust gas temperature ensured rapid “light-off” and combustion of the hydrocarbons in the exhaust gas stream when the fresh, oxygen-carrying air was introduced from the air pump. As a result, these engines ran poorly, and an enormous amount of wasted heat energy was transferred through the exhaust port walls into the coolant, causing them to “run hot” at idle; cylinder pressure fell off, engine temperatures went up, combustion efficiency went down the drain, and fuel economy went down with it."

Which explains the factory recommended initial timing of 2 degrees ATDC.

Looking at the advance curves of all the distributors noted in the back of the 1968 chassis manual, it's also clear that around 34 degrees of mechanical + initial was the goal for almost all 327s.

Looking elsewhere it seems like more than 38 degrees of initial + mechanical is asking for trouble.

For the interim, I'm going to start at 2 degrees BTDC which puts me right at 38 degrees of initial + mechanical. With the relatively low compression engine and the fact that I'm running at an altitude of 5,000 feet I think it's a reasonable place to start and I can tweak from there. Of course, moving to manifold vacuum will move my actual timing at idle up quite a bit. If I want to adjust the initial timing further it looks like changing the advance curve of the distributor is probably a good idea or perhaps just moving to a new distributor.
 
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