I think you're right about that... maybe some standing wave cancellation hitting that bend right away. But the x-pipe for sure mellows it out too.
When I pulled the differential last year, I ran the car a little while with and without the x-pipe. (my neck down to 2.5 is near the mufflers after the x) It made a very substantial difference in idle... loudness I guess. Without the x it reminded me of a friends old race boat... just ridiculous for a street vehicle... works fine for a boat competing offshore though lol. The x calmed it down a lot at idle but... wide open was still too much. I got on it well over a mile from my friends house and got a text almost immediately asking if that was me followed by a never mind I figured it out when I turned down his block. I like it as much as the next guy but it was a little too... racey for me even at 25. That's why I abandoned the cutouts idea months ago. I'd never use them.

 

Just a quick update,

I struggled with idle tuning for what seemed like forever. I went through 10 gallons of fuel until I got it figured out. I don't know if that shows perseverance, stubbornness or some level of mental retardation. But either way I finally have it idling with an IAC the way she should. So this is what I had to do.

First I didn't want to spend the money but I bought a Nick Williams 102mm throttle body. The ebay throttle body was sticking a little and was also leaking vacuum. So I figured before I wasted time trying to tune for idle I wanted to put a good throttle body on it.

I was a little mad at first because with the new TB the idle quality didn't change. So I had to look at the tune. In my defense I have never tuned an engine with this big of a cam or intake or with this much compression. Holley used a base idle timing of 12 degrees. So I upped that to 18. Then I jumped the timing in the 600-700 range to 26 deg. This creates a "lip" so to speak on the timing map. Basically it helps the engine stay alive if it starts to stall. Then I smoothed out the rest of the timing curve. I have 25 deg up top at WOT and 18-19 at idle.

After that I messed with the IAC settings. I was able to get it to run better but it would still stall from time to time. Then I found out the big issue. Holley set the idle air fuel ratio to 13.8:1. With it this rich it's no wonder it kept stalling. So I leaned out the idle and cruse AFR to 14:1. I know this is still rich. Wow did that help. Now she idles very smoothly at 875 rpm.

If it would ever stop snowing or freezing rain I might get the hood bolted back on and take her out soon. Just waiting on the weather now.

There have been a lot of comments on my YouTube channel asking for a driving video. Or at least one of me talking about drivability with everything done. So when the weather breaks I think I'll steal my kids GoPro again and make one after I get the fuel map a little more dialed in.

 

Well, the weather was finally nice enough and I finally was able to get a friend to come over to help me put the hood back on. Honesty that seems so stupid. I mean these cars look so freaking cool without a hood. Why PA law says I have to have one is beond me. Anyway, it was good to see her outside. Even if I did get her muddy. I do love that semi-gloss black paint!




So, I still have a lot of work to do on the tune. I did a data log while driving. I only drove about 10 miles. I was having a little trouble with the IAC. It's getting stuck for some reason. So, I'm going to try either a new Delphi or ACDelco IAC. The one that's in it is a Holley. The pindle on the end had popped off at one point and I jammed it back on. I'm sure it's not right. That and my current fuel map is almost as lumpy as my driveway.



I'm also getting a lot of surging. I'm sure it's because the timing table isn't much better than the fuel table. But all in all, it seems to run pretty well. I will say that the big cam and the big stainless headers make a lot of noise. At first, I thought it was a tapping from the rockers. I pulled a valve cover to check the torque. Then I thought it was the injectors. Turns out this is a common LS issue. Big cam + big tube stainless headers = tapping that will drive you nuts! I found a bunch of posts about the subject on LSTech forum. It did get better with the hood on though.

So I think with a new IAC and a few more data logs in learn mode I should be able to have it dialed in. I will say though the throttle response with 11:1 compression is nuts. You have to be carful bumping the throttle. She gets a little jumpy!

 

For mine, the sewing machine noise is pretty noticeable even with the mild 220/224 cam, especially after it warms up.

 

This thread, and a few others have good referance material it getting my lq9 and t56 swap on track. I even found your rambletron on youtube. Very helpful.

 

Thank you. I've been meaning to post an update to this thread I just haven't gotten around to it. So I got a new job. That's relevant because of money. The new job pays double (not an exaggeration) what my old job paid. That and ebay sales have picked up so I decided to treat myself with a set of stage two T.E.A. heads. I know it's a waste of money. But this motor seemed to be lacking in power under 4500 rpm. It would still light the tires up but it didn't have the same low end punch as the old LS6. So after talking to some people who know way more than me the theory is that when I ported my own heads that I opened up the valve openings a little too much. It would be fine if the cam was bigger. So to see if they were right I pulled the 243 heads off my LS6 that was collecting dust on my engine stand and sent them in to Total Engine Airflow. I have them bolted down now I just need to finish the passenger side rockers/valve cover and put the intake back on.

I also drilled and tapped the intake for the nitrous nozzles. I don't have the nitrous parts yet. I told myself I had to stop buying stuff with Christmas so close. But shortly after New Years you better believe I will have nitrous parts and an M1 carbine I've had my eye on.

 

Dod you ever get your fast intake set up for nitrous yet?

 

I did. Well sort of. I got the holes drilled and tapped but no nozzles yet. I made a video showing how I did it without a machine shop.

 

You must have uploaded a new vid without me catching it.

 

looks like a fun car, nice work

you ever take it to a drag strip or put a dragy in it?

 

Not since I LS swapped it. Back when I had the small block I took it to the local flashlight drags at our local airport. But unfortunately those have been cancelled indefinitely. I know they do them at another airport about an hour away. I want to run there this summer if I get time.

 

Great info, thanks for posting. I will be referring to it when I mod my '86 sending unit for the Walbro 450.
Sorry to hear about the snag, I know it's after the fact but an old trick is to insert a portion of a length of rope thru the spark plug hole. Stops the piston and allows the balancer bolt to be removed and reinstalled.

 

Not sure if it has been said already, but for whatever shortcomings you may have, you make up for it with a great build story

 

Well thank you. I'm wrapping up my PLC controlled direct port nitrous now. I might make an update if I get some time.

 

Awesome build and story.

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