Inliners International Forums General Discussion Engines engine questons for a '67 camaro 230 ci

i have a 67 camaro with a 230 ci engine and a rochester monojet.

The carburator has 2 small connections.
one next the side of the mixture screw wich i think is the thermac, and one on the other side just below the gas valve.(manifold vacuum????)

Now the questions?

what is the idle speed of this engine?

where do i attach my ignition vacuum advance ? Does this engine use vacuum advance? If so how much does it advance at idle speed and what is the underpressure on the tube?

what is the ideal static (basic) ignition advance

and last but not least: does anyone know a good book for this kind of engine. i own a chilton camaro book, but that mostly covers the V8's

sorry for the bad english but my native tongue is dutch

Hello!
I think the best book on the Chevy 6 194, 215, 230, 250, 292 is
Leo Santucci
"Chevrolet Inline Six-Cylinder" Power Manual
Motorbooks International
2002

There is also a book on Rochester Carbs, 1-barrel, 2-barrel, 4-barrel, just saw it at a swap meet and shoulda bought it but I didnt. I dont know the reference but I know it's out there.

Try this site for Rochester Carb info:

http://www.tocmp.com/manuals/Carbs/

Good luck, how much is gasoline over there?

The vacuum advance should hook up right next to the idle mixture screw ( radiator side, at the base of the carburater). This is a full time vacuum port, about 18 to 20 inches of vacuum.

Depending on the octane of your fuel, set the timing at 6 to 8 degrees before TDC. Remember to not hook up the advance till after you set the timing.

The idle speed screw is on the firewall side of the carburater around the linkage. Most of the Mono-jets have the idle screw head towards the valve cover, down towards the base of the carburater, some have a electric solenoid that controls the idle speed but it adjusts the same way. Automatic transmissions set at 650 rpm and manuals around 750 rpm. Its mostly by feel and how it goes into gear.

While you are messing with the carburater, you should set the mixture screw. Start by shutting off engine, then turn the screw all the way in till it stops (GO EASY), then back it out two full turns. Start engine and let it settle down, then slowly turn the screw in till the rpm starts to drop or engine sounds bad. Turn it back out till it runs smooth and as fast as it can. You may have to go in and aout a few times till you get a feel for it. Eather way, in or out, shouldn't be but about 3/4 of turn from the 2 turn starting out point. With this set for max rpm, you can now reset your idle speed! You can also use a vacuum gauge when setting the mixture. Just use a "T" fitting and hook it in line with the vacuum advance, then set mixture for maximum vacuum. Both maximum vacuum and rpm should be at the same spot.

Joe

the carb you discribe isn't the same as i have...

i took some pics so you can see it for yourself:

www.kla.be/prive/carbu1.jpg
www.kla.be/prive/carbu2.jpg

BOTH tubes are BELOW the gas valve. so have max vacuum at idle and less vacuum at higher speeds...

i attached the ignition to the one on the side of the idle screw and got ignition at +-20 Before TDC at idle speed.

so again the same question... where is my vacuum advance tube??

a 2nd problem i have is:
when i put the car in drive, put on the hand brake and rev the engine it runs good.
when i let go off the gas the engine stops.
idle is set at 600 rpm

DeuceCoupe: gas in belgium is expensive.
95 octane is about 7.5 $ per gallon
98 octane is about 7.8 $ per gallon

Dear Lord B;

You have a major vaccum leak is the problem.

Connect the open port to the dashpot (that white thing) which will move the choke (cold).

Now adjust everything (hot) with the vaccum adv. line disconnected (port pluged). Then connect it & slow it back down with the speed screw only.

Good luck.

PS: Your "vacuum adv. tube" is the one you connected to the distributer correctly.

ok that was a misunderstanding...
in operation the lines are offcourse connected...

the connection on picture 1 was connected to the choke and vacuum advance.

the connection on picture 2 is connected to the the exhaust... (thermac)

when the engine is running at 500 RPM the vacuum advance advances the ignition to +-20 BTDC (should only be 6-7).
so i guess the vacuum advance connection is wrong but i don't know where to hook it up.

#1 goes to choke only.

#2 goes to Vaccume Adv.

The "thermac device" goes ?? Leave it off & see.
You can probably remove it totally.

I'll check vaccum diagrams if you need.

Good luck

i still have a verry rough idle...
i'll do a compression test and test for manifold leaks on thursday

What happens when you adjust the mixture screw??

This should clear it up. If not, do what you said.

An easy test is; place your hand over the top of the carb. restricting the airflow a little. If it gets smooth, there's still a leak or your Adj. to lean.

ok, i did a compression check and every cilinder is between 8.2 and 9...
so that is PERFECT:-)

i tried looking for an intake leak with break cleaner, but didn't find one.
when i put my hand on the carb the engine stops.

anyone have an idea. can't get a stable idle.

next i'm gonna do i change the spark plugs, wires and try someone elses coil

I have only had a couple Rochester Monojets and dont care much for them. One buddy of mine got so mad at his poor-running Monojet he punched out the windshield of his 3/4-ton truck with his fist (no kidding - bad idea).

I far prefer the Rochester BV carb, used around the early to mid-60s.

I'd find one of those, clean it (really easy) and put it on there, see if it behaves any better, then you can isolate the problem.

ALWAYS have a good-running spare carburetor, is a good plan

I was wondering what is a compression check of 8.2 - 9....?
You should be looking @ cranking compression??
Like 120 psi or so???
The distributor advance hose connects to the port/tube where there is no vacuum @ idle.
Do you have a port like that?
You do not want full timing/vacuum advance @ idle. If you do, it is incorrect.

Hank

They are metric over there, probably KiloPascals or some other useful(?) units.

More likely the gauge is measuring atmospheres @ 14.7 psi per. So readings between 8.2 and 9 is 120.5 - 132.3 psi. Nice thing about a gauge graduated in atmospheres is that it is neutral to English versus Metric . . .

By the way if the gauge were metric the numbers would have been really attention getting 810 - 912 kPa since one atmosphere equals 101+ kilo-Pascals
Pressure Units

actually it is in metric (sorry)
it is in BAR

1 bar = 100 000 pascals (Pa)
it is also equal to the compression ratio..., so 8.5 bar is a compression ratio of 8.5
sorry but metric system is a lot easier... :-)


HANK i don't have a port without vacuum at idle

actually it's not metric (sorry)

There are two scales for pressure in the metric system: small - pascals as Ed pointed out (newtons per square meter) and very small - dynes (centimeter gram seconds per square centimeter).

Bar and Torr are used in meteorology to measure barometric pressure. One bar is roughly equivalent to one atmosphere.

The slight differences we see in how the readings from these bar(g)/atm graduated gauges are interpretted have to do with the way users of the English System round off (14.6956 psi is called 14.7) versus the way Metric System users round off (101.325 kiloPascals is called 100).

In the end such 'bar-gauge' readings are basically measuring system neutral and represent the pressures 'above' one atmosphere at sea level - since the gauge reads 0 in the open air.

I agree that the metric system is alot easier for calcuations - but having grown up and used the English system all my life it's a more comfortable and familiar perspective for us yanks.

If what you are saying is that a 'bar' graduated gauge is 'rounded' for the benefit of a metric system user - whereas an 'atm' graduated gauge is 'rounded' for the benefit of an english system user then I agree. But this distinction just determines which 'tick' marks get a round number on the face of the dial. The basic scale is the pressure of the atmosphere at sea level which is neither english or metric - hence the easy translation to compression ratio.

true and not true...
The International System of Units aproves the USE of BAR, but doesn't include it in it's list of metric stuff


BAR uses mili, centi, kilo, hecto and so on like other metric units
bar and pascals are multiplied by a factor of 10.
* 1 bar = 100 000 pascals (Pa)
* 1 mbar = 0.001 bar
this makes it kinda metric.

as a footnote: square meter is also approved to USE by the IS, but is not metric :-(

btw weather forecast in belgium use hectopascal