Slant Six Forum

232 Is back
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Author:  69val6 [ Mon Oct 07, 2019 11:46 am ]
Post subject:  Re: 232 Is back

232, since you have the a/f meter hooked up, you should be able to tune all of your issues out. First though you need to verify your timing. The timing advance at idle only tells you a little bit. If you have 14 degrees of timing at idle, that's quite a bit. 225's were originally set up to run around 0 degrees initial timing at idle(without the vacuum line hooked up). Your distributor should have mechanical advance built in it that when combined with your initial timing should end up with around 30-34 degrees at 3000 rpm. Your timing doesn't need to advance under medium to heavy load past that rpm. You need to disconnect and plug the vacuum advance line at the carb to check this. The only purpose your vacuum advance serves is to increase fuel economy under cruise and light load conditions. The vacuum advance adds another 10-20 degrees of timing advance in these conditions. The vacuum advance cannister on the distributor has a spring in it that allows more advance with higher vacuum. How much you get and at what vacuum reading is determined by the spring tension inside that advance unit. Anyone who tells you that you will blow your engine up by not having the vacuum advance hooked up has no idea what they are talking about. If you have too much timing advance, your engine has a tendency to ping under light and heavy load as yours appears to be doing(too lean of an a/f mixture will also do this). Too much timing advance also raises your exhaust temperature and will wear out your exhaust valves and valve seats in the head prematurely. It also causes poor emissions such as oxides of nitrogen which is why all manufacturers backed off on the timing advance in the 70's. This is what lowered the power output of engines at that time. Too little timing advance causes low power but isn't as damaging(unless it's way low) because it doesn't raise the exhaust temperatures up like too much advance does. If your timing advance isn't correct it can also cause your a/f gauge to give inaccurate readings because it will allow unburned fuel to exit the engine and trick the gauge to think your running richer than you actually are.

I just put a wideband a/f gauge on my 225 and have learned a lot about what it likes and what it doesn't like. Look in the engine forum under Carter 9504 and wideband 02 sensor.

Here's what you need to check on the timing. You'll need a dial back timing light to check this or have degree marking tape or marks on your balancer. Disconnect the vacuum advance for this. Also, make sure that you checked true top dead center on your engine and verified your timing marks are correct. They are off by a couple of degrees a lot of the time.

Initial timing can start anywhere from 0 to 15 degrees advanced. Its not that important. It will idle smoother the higher it is though.

The timing should start to advance by 1000 rpm. It should continue to advance as the rpm goes up. It should be at full advance by 3000 rpm. Most performance distributors have lightweight advance springs and have full mechanical advance by 2000 rpm. If your engine doesn't have at least 25 degrees of timing advance by 2000 rpm, it will be very low on power. So somewhere between 2000 and 3000 rpm you should be at full mechanical advance between 30 and 34 degrees. If your timing advance is still climbing after 3000 rpm, your distributor is not set up properly for a performance application. If you write down your maximum mechanical advance number, then subtract your timing setting at idle, you will know how much mechanical advance your distributor provides which is usually 20-25 degrees.

Hook the vacuum advance back up to PORTED vacuum on the carburetor. If it's hooked up to manifold vacuum you'll likely have trouble setting your carb up properly. Rev the engine off idle until the vacuum advance kicks in and check to see how much advance it's giving you. It should provide another 10-20 degrees of advance. I've had a lot of trouble with these newer vacuum advance units blowing out and causing a vacuum leak so be weary of that.

Once this is set properly you can start adjusting the a/f ratio on your carburetor.

Here's what you should see for a/f ratios: You can hook the vacuum advance back up for this.

14.0-14.5:1 at idle. Set this first. If it's wrong it will affect your a/f ratio at cruise speeds.

14.0-16.0:1 at steady cruise speed which will be from 2000-3500 rpm holding the accelerator steady. The higher the a/f ratio is the better the fuel economy. The safest range is 14.0-15.0. Change your main metering jets to adjust this if it's off.

12.5-13.0:1 under load, but not enough to get into the secondaries. This is where you need your vacuum gauge. Watch your a/f ratio gauge and vacuum gauge to see where your power valve in the carb is opening. It will be around 6" of vacuum, check your carb specs to be sure. When your vacuum drops below whatever it's set at, you should see your a/f ratio drop from the 14-15:1 range to the 12-13:1 range. If it stays lean(above 14:1) you can get pinging or surging. If it goes too rich(below 12.5:1) you'll get low power or a bog.

12.5-13:.01 at wide open throttle(wot). If it's too lean you'll need to increase the secondary jet size, too rich you'll need to decrease the secondary jet size. Please note that some of the Holley carbs have fixed secondary jets so you'll need to review the spec's on yours before trying to adjust. Now, here's where your cam specs come into the equation.

When you put in an aftermarket cam with high duration and lift, it doesn't make power below 3000 rpm. If you have a low numerical gear ratio in the rear axle(3.23 or lower), your engine will normally run in the 1500-3000 rpm range. With the big cam, you're not making any power below 3000 rpm. If you have an automatic, the stock torque converter is pretty much locked up at 1800 rpm. When you mash the throttle, the engine revs to 1800 rpm(max stall speed) and it feels like a dog until it gets to over 3000 rpm. By that time, you're already going well over 50 mph and it's time to let off the gas if you're on a public road. The engine feels like a dog even if the carb is tuned right. If the carb or timing is off, it gets even worse. If you have high numerical rear gears(3.55 to 4:10:1) your engine will already be running near 3000 rpm so it feels like it's got a lot more power. If you have a high stall speed converter(2500 rpm or up) when you stomp the throttle it lets the engine rev up to a higher rpm which puts the engine in it's power range so it eliminates the bog or dogginess that you would feel otherwise.

Sorry so long winded.

Hope this helps.


Author:  DadTruck [ Mon Oct 07, 2019 6:48 pm ]
Post subject:  Re: 232 Is back

Joel, a lot of good information except,
It is late ignition timing that raises exhaust temperature.
When running a cam with a lot of overlap, adding ignition advance at idle can help to improve idle quality. With a large overlap, there is a significant amount of reversion and exhaust gases moving back into to intake charge at low engine rpm levels. That exhaust-gas mixture lights and burns slower than
a clean air - fuel mix. So addition advance at idle will get the EGR mix to burn in time.
That is why some folks run manifold vacuum instead of ported vacuum to the advance pod. It activates
ignition advance at idle. Ignition advance at idle can really help idle quality and off idle performance on engines that have larger than stock camshaft overlap.
I believe you are correct on the torque converter assessment.

Author:  GregCon [ Mon Oct 07, 2019 6:52 pm ]
Post subject:  Re: 232 Is back

Amen, DadTruck.

Author:  Dave M [ Mon Oct 07, 2019 9:12 pm ]
Post subject:  Re: 232 Is back

Do you know what the list number of your Holley is ?

Author:  69val6 [ Mon Oct 07, 2019 9:26 pm ]
Post subject:  Re: 232 Is back

Dadtruck, I don't disagree with you. The differences you mentioned are determined by the operating conditions. Too much timing advance at wide open throttle will increase exhaust temperature as well as way to little at moderate load. I should have been more specific but was trying to keep it short.
Running manifold vacuum to the distributor is just a bandaid to make it idle better. I don't like it but it will help under certain condition's. It's hard to condense all that info but I tried to give a solid plan that will get 232 on the right track without overloading with details.


Author:  232Valiant [ Tue Oct 15, 2019 6:36 pm ]
Post subject:  Re: 232 Is back

So let's start with some information:
I am running Holley 390 CFM 4-Barrel, Model 4160. Primary jets 51, Secondaries (conversion kit from metering block to jets) 59. Pump nozzle 25, pump cam red position 1. Power valve 6.5 (stock). Timing is at 3 degrees and idles fine. Running Champion Double Platinum Spark Plug CHP 7322. I had tried to run the car on timed ported, shook like a leaf. Put it on manifold, flat even idle. On the af gauge, I sit at 12.5 fluctuating (+-.2) in park. In gear, brake on, it is at 13.2 (same flux). From 1000-2000, depending on how hard I push the throttle: light: 13-14.7 med: 14.8-15.7 heavy: 16-18 + From 2000-3000, based off of the previous scale: (l) 14.7-15.8, (m)15.7- lean out, (h)lean out. In relation to the af gauge, the vacuum gauge read out is a little confusing to me. In park, I have 19-20 vacuum. In gear, it sits at 14 +-1(wiggling furiously). Accelerating: (l)6.0, (m)4.0-5.0, (h)5.0-0.0

Now I have some questions:
On the secondaries (the stop screw), I am wondering on how to set that properly. I messed with it a while back and it feels odd. Odd by the fact that it feels late when the kick on.

On the distributor plate where it mounts to the block, is the position of the distributor that bolts on to the plate critical? With the dist. out, the plate that is on there, is there a particular position it needs to be in on the arc or is it just a mounting point?

Author:  DadTruck [ Tue Oct 15, 2019 7:10 pm ]
Post subject:  Re: 232 Is back

Timing is at 3 degrees and idles fine

when you say timing is at 3 degrees and it idles fine,,
are you checking the timing with the hose attached to the distributor advance can and the manifold?
If so the vacuum advance is activated and you should be seeing 20 + degrees of advance.
The 20 degrees would be your initial advance of 5 to 10 degrees plus the vacuum advance of 10 to 15 degrees.
If you are only seeing 3, either the advance can is not working or your initial timing is set way retarded.

To find out where your timing is, disconnect the vacuum hose at the distributor and plug it, use a pencil or golf T.
Start the motor and check the timing. Record what the ignition timing is. I would be looking for 5 to 10 degrees.
Reattach the vacuum hose and with manifold vacuum, at idle you should see the initial timing + the vacuum advance.
Subtract what you have as timing with the vacuum can attached from the initial timing obtained and that is the addition advance that the vacuum advance is adding. 20 to 30 degrees ( initial + vacuum) degrees of timing at idle could be fine. You will need to determine what runs best, I do subscribe to the theory that says for a slant,, 30 to 35 degrees total, ( initial + vacuum + mechanical) is a good target.

Concerning the distributor position, it will 'clock' anywhere, but if it is too far out of position radially, the vacuum can will bump the
block and limit the initial timing setting. I set the can so it is about 4 or 5 o'clock.

Author:  232Valiant [ Tue Oct 15, 2019 7:47 pm ]
Post subject:  Re: 232 Is back

I had done it in the fashion that you have mentioned. That is where I got the 3 degrees from. However, I have not "seen" whether or not it is at 20 +. The can is pointing about the same as well.

Author:  DusterIdiot [ Tue Oct 15, 2019 8:30 pm ]
Post subject:  Re: 232 Is back

I am running Holley 390 CFM 4-Barrel, Model 4160. Primary jets 51, Secondaries (conversion kit from metering block to jets) 59. Pump nozzle 25, pump cam red position 1. Power valve 6.5 (stock).

Jeez that's all out of whack for that kind of build....

I'd bench it here:

Primaries #52 Jets
Secondaries #54 jets
Pump Nozzle (aka Shooter) #28
Acc Cam = Red is too short and stops giving a shot too soon when the plates are open... go to Orange #1
Power Valve on a slant six should be an 8.5...
Secondary Spring = Purple

Looks like you need to determine your timing curve and make sure that the static timing is set accordingly...

When you say 3 degrees at idle... are you saying that it is 3 marks BTDC on the timing tab from 0/TDC... or
does your dial back timing light adjusted to 3 and the timing mark is on 0? (Just making sure everyone is
referencing the same marks...)

Author:  232Valiant [ Tue Oct 15, 2019 8:38 pm ]
Post subject:  Re: 232 Is back

When I had the capped the distributor and shot the timing, it was set for 3 degrees advanced (3 marks BTDC)

Well that's comforting :lol: Fortunately, I have most of those parts, except the spring.

Author:  DusterIdiot [ Wed Oct 16, 2019 6:07 am ]
Post subject:  Re: 232 Is back

3 marks BTDC

Typically on the timing tab each mark is 2 degrees and depending on year the marks end on 10-12 deg...(more if it's the 1979+ tab)

So if you are 3 marks on the tab, you are actually 6 degrees advanced...

Author:  232Valiant [ Wed Oct 16, 2019 3:54 pm ]
Post subject:  Re: 232 Is back

Correct. I was using the timing light and marks to make sure that read the same. I said that it is 3 marks BTDC, but saying it was 3 marks (which makes 6) is not true. It’s at 1 1/2 “marks.” Thanks for looking out though.

Author:  wjajr [ Thu Oct 17, 2019 12:19 pm ]
Post subject:  Re: 232 Is back

Holley float level adjustment: ... aJ2K2wCw26

Author:  232Valiant [ Mon Nov 11, 2019 12:30 pm ]
Post subject:  Re: 232 Is back

Back again after some fixes and results. @DusterIdiot, the bench build you gave me has been a major improvement on the performance on the car.

Here are the new results since the upgrade:
Primaries #52 Jets
Secondaries #54 jets
Pump Nozzle #28
Acc Cam = Orange #1
Power Valve on a slant six is 8.5
Secondary Spring = Purple

I have disconnected the vacuum hose and reconnected it to note the difference between them. When the hose is off and capped I was getting 6 degrees (3 marks) initial timing. When I reconnected it, I got 18 degrees. If I followed DadTrucks (and the timing light instructions) correctly, I have 12 degrees worth of vacuum. I also did a centrifugal test as well.

At 6 degrees on initial with the cap plugged:
At 2500 rpm, advancement is at 16
At 3000 rpm, advancement is at 20
At 3500 rpm, advancement is at 24
That test was done in park obviously.

Now onto AF:

When in park at 800 rpm, the AF is about (+-.2) 11.2
In first gear, from 800-1500, AF is about 12.5-13.7
1500-2500, AF is about 14.1-15.6
2500-3000, AF is about 15.9-17.5

In second gear, from 1000-1500, AF is about 12.8-13.6
1500-2500, AF is about 14.1-15.5
2500-3000, AF is about 15.6-17.6

In third gear, from 1200-1500, AF 13.5-14.2
1500-2500, AF is about 14.5-15.9
2500-3000, AF is about 16.1-17.9+

Just after 3000 rpm in all gears, in wants to ping..... Other than that, its great. I believe the choke is out a little, seeing that its colder now in Cali. Harder start, takes the choke a minute come off.

Author:  69val6 [ Thu Nov 21, 2019 12:31 am ]
Post subject:  Re: 232 Is back

232, have you made any more changes since your last post? Kind of looks like you need to go up to a little bigger primary jet if you haven't already. That will lower the a/f ratio at part throttle below 3000 RPM. It will also lower the w.o.t. a/f ratio at the same time which it also looks like you need. I suggest getting your part throttle tuning fixed before trying to change the w.o.t. settings. Also, when you read your a/f ratio gauge,. Be sure to let the car run at a steady RPM for several seconds before writing down the reading. Every time you speed up the accelerator pump squirts extra fuel in to richen it up. It takes several seconds for that shot of fuel to clear out. Thats why the longer you stay in the throttle, the leaner it gets until it levels off, then it should stay pretty steady. I would also suggest you plumb a vacuum gauge in temporarily so you can see when the power valve opens up.

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