My 1st. Street 383 Build

[bytor]

Well, today was the big day. I finished my last to-do’s and fired up the build for the first time. It started immediately. No knocks, smoke or leaks so I consider it a success. Got it to idle on it’s own and set the idle AFR with my LM2 before the rain set in for the day. There is no way I would have had success if I hadn’t found this forum and all of the knowledge it contains.

Few pictures of the exhaust installed. Very impressed with the kit from Pypes. Very good quality and great tech support. I couldn't find anyone locally that could do a mandrel bent setup.

 

[mathd]

yay , taste of success here is it once again.

 

[grumpyvette]

glad we could help out! more pictures would be great!

BTW NOW THAT THE ENGINE RUNS...
HAVE you tuned it up and taken the car out for a drive?
hows the car drive and run?

 

[Indycars]

Love it when a plan comes together !!! [A-Team Quote]

Yes more pics would be great when you get the time.

 

[bytor]

A buddy of mine took this picture at a local Walmart.



(It's a little hard to make out but it's a guy with a trans AM that has no hood and using a tarp to cover the engine in a rain storm.)

It resonated with me as I don't have a hood on my vette at this time ether but I don't think I would drive it in the rain.



Not much to update on the build. Had a fuel leak to deal with, shifter and clutch adjustments and getting my LM-2 hooked back up for some tuning. In the process of connecting my home made HEI tach interface circuit I smoked it by hooking the power up backwards. So, spent last night fixing it. I'll get some more pics up this weekend. I'll get some info up on the HEI tach/LM-2 interface as well.

 

[bytor]

Got the shifter issue all straightened out. I could not get it to go into gear consistently after I got the motor back in the car. I got panicked thinking I could have a clutch/pilot bearing issue. I readjusted the shifter and something didn't feel right. Popped the boot in the console to get a good look at the shifter and holy crap, the two bolts that mount the shifter to the cross member bracket were backed out about half way.
The pic below is not mine but it shows the two bolts I’m talking about.



I went ahead and yanked it out and gave it a good cleaning and lube. It’s in great shape now and feels tight and new. Shifts as smooth as butter now.

My shifter


Started tuning the carb focusing on idle, off-idle and cruse using my LM-2. In the past I have found myself kind of chasing my tail when it comes to carb tuning and never considered myself having a structured plan of attack. I recently found this write up and it made a lot of since to me.

http://thefactoryfiveforum.com/showthread.php?2216-Carb-Tuning-101

Start with idle then, transition slot, primary jet/power valve then WOT. I’ll get some LM2 charts up soon of my tuning steps after I spend some more time on it. I decided to make thing a bit more convenient using my LM2 this time by using a remote control app on my Ipad to see and control the LM2 Logworks app. Made it a lot easier to view than having to look into the car at the PC screen from the outside.



But now it’s time to re-torque the heads.
Step 7 in the instructions for my head gasket spell out how to do it clearly.



So because the roller rockers are fat and make access to some of the head bolts impossible, I’ll have to remove the rockers to re-torque the heads. The re-install the rockers and perform the static valve adjustment procedure. I assume this is standard practice correct?

 

[Indycars]

I went back and looked to see what rockers you used, along with the head bolts. Since they are 12 point bolts, I would think you could get in there, but obviously not. I have the same rockers and 12 point bolts, so I may have the same problem.

I know your instruction said to loosen the bolts some and then re-torque them, but first I would check them for final torque value to see if they had backed out at all. Then proceed per the instructions. It's just that I would want to know if they were coming loose.

Nice work and pictures as usual !!!

 

[Indycars]

Any updates on the tuning process ???

 

[bytor]

Any updates on the tuning process ???

Yep, work and the weather have not been playing nice lately so not enough time spent tuning.

I have done some basic baselining on the carb getting it close. After I spend some more time with it I’ll post the results with LM-2 logs. I’m re-familiarizing myself with the transition slot to primary circuit timing and pump shot calibrating. Adding a TPS to the carb is helping a lot to see this on the LM-2. I want to do some testing by disabling the primary and running on the transition slot, (parked) to clearly see the fuel curve without the mains interfering. Also discovered the engine doesn't like vacuum advance. I have a 10* can on now so I disconnected it for some testing. I’m seeing improvements from the first time out to now. It’s got a nice ‘seat of the paints’ feel not but not at “like a raped ape” level yet..

 

[bytor]

Finally had some time to tune recently. Planed on getting some additional time with it today but is snowed, go figure.
Here's a few screen shots of my LM-2 during a few recent tuning sessions. Don't pay to much attention to the AFR in these graphs. I was focused more on the AFR curve.

You can see in the first graph, the AFR (pink line) is up and down all over the place. The BG 650 DP Speed Demon is set up out of the box stock. In the highlighted area of the 1st run, the 8.5" power valve is not open yet and primary is opened about 1/2 way or so. My TPS is off a bit as well in these.

(The pink line is AFR, red is vacuum, black is rpm and green is throttle position)


In the graph below, I reduced the high speed air bleed from .041 to .029 and the middle emulsion hold from .031 to .018 and things look much better.


The little bump just as the mains start is what I'm working on next. I played around with the transfer slot first trying to make it active longer by changing the idle air bleed and IFR with no success. I raised the float attempting to make the mains come in a bit sooner, no luck. Next, I reduced the size of the upper emulsion hole thinking it would help start the mains sooner. It actually made it worse/leaner. After some reading, it seems that a larger upper emulsion hole can help the mains come on earlier and richer. Kinda not what you would think, we shall see.

Below is a test I did to determine when the transition slots and IFR ran out of steam. I covered the main boosters with rubber glove finger tips and tied them off with wire to disable them, I then started the car in neutral and very slowly opened the throttle. As you can see, it's flat for a bit then gets progressively lean as it shuts off. The TPS calibration is off in this graph but now I know where my transition circuits shuts off and mains start.


As far as how the car is running now, I did my first rolling start burnout, just a little one . I was cruising in 1st. gear about 10mph and stomped it, the rear started fishtailing. Nice, I'm getting close on the tune.

 

[bytor]

Sharing more carb tuning results. The larger upper emulsion hole did the trick. The AFR curve has flattened out nicely.


I enlarged the upper emulsion hole to a .033 and that helped the mains when start be richer compared to before. Probably try a .032 next upper e-hole next. Moved from an 8.5 to 9.5 power valve as well. It seemed my primary jet was running out of steam just before the 8.5 opened causing it to lean out a bit. My PVCR is a tad too big making my AFR after the power valve opens slightly rich for my liking. Reducing the PVCR and verifying WOT AFR is my next step.

 

[grumpyvette]

this thread is becoming more useful with each post, as its pointing out the fairly new use for computer/sensor info usage, and how it can be used, vs the older spark plug reading and IR TEMP gun use I grew up using back in the stone age

 

[Indycars]

Could you post a larger graph???

I don't know enough to even figure out what the horizontal coordinates are. I'm
thinking the vertical is A/F Ratio with some other things also, but I just can't
make out enough info to try and understand.

 

[bytor]

this thread is becoming more useful with each post, as its pointing out the fairly new use for computer/sensor info usage, and how it can be used, vs the older spark plug reading and IR TEMP gun use I grew up using back in the stone age

I have been using the LM-2 now for 3 years or so off and on. I found it a challenge when I first got it to find on-line AFR tuning graph examples to help me understand what I was looking at. AFR measuring tools are very powerful tuning tools but if you don't know what your looking at, you can send yourself in circles making changes to the carb getting way of base. Innovate Morotsports, the makers of the LM-2 had a great tuners forum with all kinds of user examples of tunes and problems but the forum is no longer up. They have a few tuning articles up on their site though. Check them out, good stuff. The first one 'Wideband Tuning for Carbureted Drag Racing' is a good walk through using the LM-2. http://www.innovatemotorsports.com/resources/carb-central.php

I am by no means an expert at carb tuning, just enjoy learning about how they work and behave. You can drive yourself crazy with these things for sure. These is a lot of science involved but black magic plays a big part as well

Could you post a larger graph???

I don't know enough to even figure out what the horizontal coordinates are. I'm
thinking the vertical is A/F Ratio with some other things also, but I just can't
make out enough info to try and understand.

The legend on the far left goes like this. The left most column is the throttle position sensor % open (green), the next is manifold vacuum Hg (red), the next is RPM (black) and the last one is Air Fuel Ratio AFR (pink). Here's a larger graph from Logworks with some annotations to help understand the layout. Logworks is the PC application that connects to the LM-2 for data logging and setup.

What does the graph below represent? This is a session I recorded starting out cruising at about 2500 RPM in 4th gear. Just after 6:55 on the time scale at the bottom, I begin 'slowly' opening the throttle to the point of the power valve opens up (9.5Hg). This gives a clear picture of the transition from idle to the primary jet starting up then transitioning into the power valve opening up. In this session, the secondary is closed. My secondary doesn't begin open until the TPS is at 44%. Based on this info, I can conclude that I'm running at around 13.8-14.0 AFR before the power valve opens and 12.3 AFR once it opens. Now that I have a flat AFR curve compared to the out of the box setup, I can simply change the primary jet to adjust the 13.8-14.0 AFR and PVCR to adjust the 12.3 AFR if needed. In this case. I'm going to reduce the PVCR in order to get closer to a 12.8 AFR once the power valve opens.
If you go back to post #159 and look at the first chart, you can see how up and down the AFR was with the out of the box BG setup compared to this one.




Here's my current carb setup compared to stock.

 

[Indycars]

Now that's one graph with alot of data on it......thanks for posting a larger one!

I assume you are using the vacuum reading to determine when the PV opens. I wonder just how accurate those ratings are. The AF curve is trending richer, but there is not a sudden change around that area at 9.5Hg. It looks like the PV is not just Open/Shut, but does have some intermediate flow values.

Thanks again for posting a larger graph and explanation!

 

[bytor]

Long time since my last post. Work, weather, vacations and honey do’s have put a damper on the wrench turning time this summer.
Finally getting back to wrapping up the tune.

Quick build update,
- Replaced the 10% higher volume oil pump with a stock volume/pressure and very pleased with the oil pressure.

- Replaced the HEI distributor with a new Mallory Promaster distributor and Hyfire AL ignition box.

- Found the build likes a lot of initial advance. http://forum.grumpysperformance.com/viewtopic.php?f=70&t=4683

- Got the old demonic Demon close to where I want it. Nice flat AFR curve now and revisiting the idle, off-idle transition, pump cam and squirters now.

- I added a throttle position sensor to my Innovate LM-2 setup a while back. It really helped me figure out what I was looking at when reviewing the LM-2 logs. I could now see exactly when my secondarys crack open for example.

I recently added a fuel pressure sensor to the LM-2 as well. Thought it would be interesting to see what my fuel pressure was doing under different driving conditions. I’m running a stock GM mechanical fuel pump like this one with a functioning return line.


Below is a sample log showing a lightly loaded, slow throttle opening. The blue line at the top of the graph is the fuel pressure. It’s between 8.25 and 9.5 psi. I not experiencing any flooding or overly rich issues but 9.5 seems high.




Demon recommends 6-7.5psi MAX. At WOT the fuel pressure drops to 5.5-6 psi and at idle it at 5.5-7psi. I noticed on Summit that most of these types of pumps are rated at 5.5-6.5 psi. http://www.summitracing.com/parts/crt-m6101/overview/make/chevrolet

Do you guys think I need to consider replacing this pump? I honestly don’t remember where I got the pump from but it was replaced 5 years ago or so and it’s supposed to be a Delco.

Here are a few pics of my current Innovate LM-2 AFR meter setup.

The LM-2 hookup schematic


Here’s a screen shot of it in action on my PC.

 

[87vette81big]

There are higher volume mechanical fuel pumps made Bytor.
Edelbrock has offerings.
CV Racing Products Catalog .
Dirt track racers use mechanical fuel pumps also.
1/2 " feed line size recommended.
5/8" even better.

 

[87vette81big]

At work now but can't get real detailed.
Check CV Racing products online.
Electric fuel pumps work best with a return style system.

 

[Indycars]

Looks like to me that the carb needle & seat are sealing just fine or the
AFR would show too rich.

As long as the pump can keep up under WOT, then I don't know why you
want to change it. But I'm sure someone is going to change my mind!

What do you have invested in the Innovate system at this point? Sure looks
to be fun to work with.

 

[mathd]

Looks like to me that the carb needle & seat are sealing just fine or the
AFR would show too rich.

As long as the pump can keep up under WOT, then I don't know why you
want to change it. But I'm sure someone is going to change my mind!

What do you have invested in the Innovate system at this point? Sure looks
to be fun to work with.

Yeah, if the float level stay the same, should not have any problem.
Or, i dont know the price of the pump but a fuel regulator could be a sure way to have the pressure you desire.
I have the innovate lm-2 me too, love it alot.
Got a question about it.
Your using the logworks while running the car, is there a special precedure for that?
i tryed it with mine, dont know what am doing wrong but as soon as the car is runing or after i plug the cigaret lighter(Cant really remember) the logworks no longer see/connect to the lm-2.

So do you plug usb before the cigaret lighter or the other way around? and do you plug into the cigaret lighter before you start the car or after?