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232 Valiant Project
http://slantsix.org/forum/viewtopic.php?f=19&t=62972
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Author:  232Valiant [ Tue Nov 06, 2018 5:05 am ]
Post subject:  Re: 232 Valiant Project

I’m thinking that cylinder 1 may have a loose valve(s). It’s relieving to hear that the car doesn’t that insane amount of compression :mrgreen: A little disappointed that it’s not that much bigger than stock, but now the car hustles better than its ever been.

If a cylinder has low compression compared to the others, will that drag the motor down? Also, would that cause it to ping at higher rpm?

Author:  coconuteater64 [ Tue Nov 06, 2018 6:21 am ]
Post subject:  Re: 232 Valiant Project

232Valiant wrote:
If a cylinder has low compression compared to the others, will that drag the motor down? Also, would that cause it to ping at higher rpm?

Yes, and possibly.

Author:  SpaceFrank [ Tue Nov 06, 2018 8:29 am ]
Post subject:  Re: 232 Valiant Project

Still kind of a WAG since there's so much variation in starting head cc volume, but using generic numbers for 198 rods and 2.2 flat top pistons with a block and head that have only been cleaned up 0.005-0.010", I get SCR numbers in the 10.5:1 range.

What spark plugs are you running? If you still have issues with pinging under load, you might consider running a cooler plug. The extended tip plugs are probably a bad idea for this engine.

Author:  Dart270 [ Tue Nov 06, 2018 2:41 pm ]
Post subject:  Re: 232 Valiant Project

If your valve lash is too tight on that one cylinder, that could cause the low psi reading. Try re-lashing those valves (hot) and do your comp test again.

Lou

Author:  232Valiant [ Wed Nov 07, 2018 2:58 pm ]
Post subject:  Re: 232 Valiant Project

The spark plug part number is : NGK GR4GP
They are platinum plugs.

I still need to do the valves on the cyclinder and check the compression again.

Author:  slantzilla [ Wed Nov 07, 2018 3:09 pm ]
Post subject:  Re: 232 Valiant Project

I would suspect a tight exhaust valve. If the valves are good I still would not be overly concerned with the 160 number.

You could also get one of the usb bore cameras that work with your phone. I got one for less than $20, and it works pretty good.

Author:  232Valiant [ Thu Nov 08, 2018 12:10 pm ]
Post subject:  Re: 232 Valiant Project

The intake and exhaust were tight. Corrected the lash, and I still have the same 160 compression. Not super concerned at the moment. Cooler plugs will be coming in Friday.

I noticed something odd in the cars idle. When it’s in park/neutral, the idle is at 750 rpm. When it’s gear, it drops down to 400-500 rpm, and having trouble keeping it’s idle consistent. I have to keep my foot down slightly to correct the idle. Any ideas?

Author:  Dart270 [ Thu Nov 08, 2018 1:15 pm ]
Post subject:  Re: 232 Valiant Project

Not enough ignition advance at idle, valve lash too tight, or the springs in the mechanical advance in the dist are too light and the mechanism is fluctuating/bouncing. Sounds like it's not lash, so initial advance is my best guess. Could also be bad idle mixture adjustment.

Lou

Author:  232Valiant [ Sat Nov 10, 2018 6:17 pm ]
Post subject:  Re: 232 Valiant Project

Update!
With everything gone over to ensure everything is correct, the cars runs great! The timing is set at 12* with 18* mechanical, total of 30*. The vacuum can is plugged, which cured the over advancement. I went colder plugs. The pinging is gone at higher rpm :mrgreen: Valve lash is perfect (cylinder 1 has 170 compression now). It was done hot. The idle is much more stable now by changing out the springs. I spaced on getting the limiter plates. Ordering it Monday with the spring kit. Still have a little backfire/sput + lag? when accelerating hard then letting off, then getting back on it. Sitting at light, in gear, the idle is still low but constant. Could be a float level problem? Reason why I’m asking is because when I stop hard, the engine slows/ almost dies. The idea popped into my head after watching Motor Trend. Confused about that, but way too happy with the way it runs now.

Author:  Dart270 [ Sun Nov 11, 2018 3:55 am ]
Post subject:  Re: 232 Valiant Project

Sounds like great progress. Enjoy the ride and keep tuning...

Lou

Author:  SpaceFrank [ Wed Nov 14, 2018 11:31 am ]
Post subject:  Re: 232 Valiant Project

That sounds like a pretty large RPM drop from neutral to drive, but I'm not really sure what's normal. Your float level wouldn't give you problems at idle. I would connect a vacuum gauge to the intake manifold (port on the #6 runner is fine) and adjust your idle mixture screw(s) for max vacuum reading.

There may also be some work to do adjusting the jetting or accelerator pump to avoid the backfire/stumble, but get the idle straightened out first. Your idle mixture can have a bigger effect in the mid-RPM range than you'd expect, depending on the carb. Can you be more specific on what it's doing there?

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