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232 Is back
https://www.slantsix.org/forum/viewtopic.php?f=19&t=64117		 Page 1 of 2
Author:  232Valiant [ Sat Oct 05, 2019 1:05 pm ]
Post subject:  232 Is back
Finally have everything together with this car. However, it's still not quite right.
I have 1968 Plymouth Valiant 225 that has had work done to the motor that it became 232. The build was called the "Long-Rod 225." Using 340 springs, 198 connecting rods, etc. The valves are over-sized (valves are nearly touching each other). The block was bored out, and the head and block were machined. Bigger pistons were installed. For the ignition system, I am using the FBO HRR688 Mopar Computerized Ignition System, Part number HRR686. It was set up to be on constant manifold vacuum. Timing is suppose to be set at 14* initial and it has 16* worth in advancement. From the machinist specs, the lash must be set at .012 for both intake and exhaust.The car has a compression of 10:1. All cylinders have a compression of 180 psi. I am running 91 octane for gas.
The car has a 390 cfm Holley 4-barrel. Aussie short-runner intake. Clifford headers. Manga Flow Exhaust. 904 transmission with a TransCo shift kit. 7 1/4 rear end .I have a AFR and a vacuum gauge set up.
I need help understanding why the car is pinging around 2700-3000 rpm and having a hard time getting off the line. At a stop it idles fair, and as I accelerate about half way (~1500 rpm), it will go fall (bog?) and then pick up. City drive is great. No problem cruising. Getting on the highway feels slow or sluggish. At high rpm, it wants to ping. The AFR says its leaning out (16-17) and if i try to go past that, it flat lines on the read out. I have posted once before and I did not have my act together with information. Is there a better way to upload photos on here? Apparently the file size is too large.
Author:  Dart270 [ Sat Oct 05, 2019 1:51 pm ]
Post subject:  Re: 232 Is back
Lots of info there. Sounds like a fun car. Here are some more questions:

What cam are you using and where did you set the centerline (degrees)?

What rear axle ratio and what is the stall of the torque converter?

Is it possible your timing is set further advanced than you think? 180 psi on pump premium should be OK, if the mixture is right and the timing is no more than 30 deg total (no vac advance).

Happy to try to help improve your slanted experience!

Lou
Author:  Rick Covalt [ Sat Oct 05, 2019 2:29 pm ]
Post subject:  Re: 232 Is back
Quote:
It was set up to be on constant manifold vacuum.


Why is it not on ported vacuum instead of constant?
Author:  SlantSixDan [ Sat Oct 05, 2019 2:33 pm ]
Post subject:  Re: 232 Is back
Rick Covalt wrote:
Why is it not on ported vacuum instead of constant?


Because the FBO "performance" ignition people are full of beans.

Used beans, to be more specific.
Author:  232Valiant [ Sat Oct 05, 2019 3:00 pm ]
Post subject:  Re: 232 Is back
The cam is a Custom Delta- High Performance Camshaft. I do not have the part number, but I do have the specs:

Intake and Exhaust:
Lobe center sep = 111.4 cam deg
Valve overlap = 6.3 crank deg

Intake:
Valve opening = 3.2 (4*) BTDC (exactly)
Lobe center = 110.4 (107*) ATDC
Vavle closure = 45.2 ABDC
Duration = 228.4 crank deg
Max cam lift = .29311 in (.291)
Net valve lift = .43967 in
Lobe “area” = 24.41 in * deg
Lash = .012

Exhaust:
Valve opening = 46.5 BBDC
Lobe center = 112.5 BTDC
Valve closure = 3.2 ATDC
Duration = 229.7 crank deg
Max cam lift = .29272 in
Net valve lift= .43907 in
Lobe “area” = 24.49 in * deg
Lash = .012

I believe it is 2.76:1 for the gear ratio. What do you mean by "stall" in the torque converter?

It could be. I have not thought of that. Is there a chance when the shop rebuilt the motor, it changed its "center"?. Meaning that the timing marking plate that is over the crank pulley is no longer accurate?

I have done a test where I have the car on jack stands and having the rear end supported by a floor jack to check that curve. It instead lead me to a fix where the needle barrings in the u-joints were broken, causing slop in the drive shaft. I have not yet done that since the fix.

Timing (ported) is for emissions. The set is made for constant manifold vacuum.
Author:  GregCon [ Sat Oct 05, 2019 3:17 pm ]
Post subject:  Re: 232 Is back
I assume by 'constant vacuum' you mean it is connected un-ported. Few engines produce constant vacuum, or rather, the vacuum varies.

If your AFR is going in 16-17 range that is your problem way before timing. Especially under load, a 17:1 AF ratio will lead to reduced compression once the holes in your pistons appear.
Author:  232Valiant [ Sat Oct 05, 2019 3:32 pm ]
Post subject:  Re: 232 Is back
There is the timed port near the top of the carb and the manifold port near the bottom. The set up is specially set to run constant manifold vacuum. I have tried it the other way and when I called the tech that did the build, he got real annoyed at I did not follow instructions. I would blown up the motor if I had done it with ported vacuum.
Author:  SlantSixDan [ Sat Oct 05, 2019 3:33 pm ]
Post subject:  Re: 232 Is back
232Valiant wrote:
I would blown up the motor if I had done it with ported vacuum.


Oh, brother.

No, your motor wouldn't blow up if the distributor vacuum line were connected to ported vacuum. That's not a thing.

This what you're struggling with is what happens when neither the customer nor the builder knows much of anything about Slant-6 engines.
Author:  GregCon [ Sat Oct 05, 2019 4:01 pm ]
Post subject:  Re: 232 Is back
I have to wonder about any cam maker who issues data to the 2nd decimal place....

But again...you're like someone who says "I have a flat tire and the car is shaking horribly at 60MPH. Should I look at the harmonic damper?"

You're running way too lean. That has zero to do with timing on a carbureted car. Figure out why you're running so lean.
Author:  Rick Covalt [ Sat Oct 05, 2019 5:20 pm ]
Post subject:  Re: 232 Is back
Quote:
having a hard time getting off the line.

Quote:
Getting on the highway feels slow or sluggish.


Even after fixing the other issues you are still going to be slow off the line and getting up to speed with those gears. Should cruise at 70 -75 real nice. :D :D 0-60 mph, not so much!
Author:  GregCon [ Sat Oct 05, 2019 5:25 pm ]
Post subject:  Re: 232 Is back
Yeah, I gotta wonder how tall your rear tires are but I'm guessing they are not stock 13" rubber any more. So those 2.76's are especially tall.
Author:  232Valiant [ Sun Oct 06, 2019 9:27 am ]
Post subject:  Re: 232 Is back
15” tires for the rear. Stock stall at 1800 rpm.
Author:  hyper_pak [ Sun Oct 06, 2019 11:16 am ]
Post subject:  Re: 232 Is back
I know you are trying to work through this, just take it slow and fix one thing at a time, you don't need any body busting your chops.
On the posting pictures thing, I use the snipping tool on the original image and save the snip. It will make a lower resolution image that will post here.
I agree that the AF ratio is a problem and make sure you know what your timing really is.
Author:  Dart270 [ Mon Oct 07, 2019 3:19 am ]
Post subject:  Re: 232 Is back
I agree with Stan. Let's be patient and try some experiments.

Do you have some holley jets that you can use to change mixture on the carb? I would first try going up 3 jet sizes on the primaries of the carb and see what that does.

I am not familiar with that ignition system, but it looks like it has nothing to do with the distributor and whether you are using ported vacuum or not for the advance. What distributor are you using??

Thanks and all the best,

Lou
Author:  Greg Ondayko [ Mon Oct 07, 2019 5:52 am ]
Post subject:  Re: 232 Is back
Experiments are good.

Can't argue with science.

Take your time and adjust one thing at a time, you'll get there.

Greg
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