Let's talk a little theory...
 

So, I'm about 3/4 done with porting my Vic Jr. Through my own testing with the elbow, and all the propaganda on the net, I have found the back 2 cylinders to be slightly lean. So here's my approach. I am doind a "full hog out" of the front 6 ports, and slight port/polish on the rear 2.

In thinking about this, this should allow more flow through the front 6 and correct my lean condition, right? Now this was with an elbow. My new setup is going to be with a 4150 TB with a direct port and carb plate. Is the problem with the rear cylinders a result of the elbow? If so, I guess I should port them all the same?

Any thoughts???

On my SS I did not have a lean issue on the back runners with a elbow. I have also tuned many cars using the elbow and not seen a lean issue. Is it something many people are reporting I am not aware of?

Since the velocity of the air is obviously going to be running down the back of the elbow maybe some do.

I know the edelbrock cast elbow I have in here right now has a devider made in that seperates the front from the back. Kind of interesting.
Dave

Jeremy,

based on your future plans of going with a carb plate and DP. i wouldnt do that. I havent seen any lean condition in the rear cylinders and i know we run the same elbow. I know the elbows dont flow a wet plate all that well and your most likely correct that the flaw is in the elbow.

I would rather see you do the full port job as evenly as possible. Once we get your DP done and the final setup complete, you can make the changes then. It will be much easier to correct a lean condition with a jet change then trying to correct it with a port job. I dont think you will have the same problem with your future setup, but the DP will allow you to change your A/F per cyclinder either way.

I agree with mike. You should not port the intake runners differently.

If you remove the elbow and the lean condition goes away great. If not you are going to have to tune the plate in either alittle richer or run colder plugs in those cylinders. As far as the directport stage you can adjust airfuel by jetting.

Dave

Without a flow bench I wouldn't even attempt that.

Alright, I'll hog the whole thing out. Maybe I was just over thinking the whole deal.

BTW If you've ever really looked in the ports, Edlebrock really turned out a real piece of shit off the shelf product. The seams are huge, and I've been finding a bunch af air pockets in the casting. This is a never ending project.

i think you just got lazy and didnt feel like finishing it up :engarde: thats the theory im going with

You son of a ................

Don't make fun of it too much when it gets there. Let me know if I went too far and ruined it.

That elbow didnt run lean on the back 2 cylinders on my car. For what its worth the 4150 accufab was a big step forward on my car. It just didnt make good power with the elbow.

If you really do think you have a lean condition on the back .rather than mess with cutting down air. i would get your injectors flowed and put the heavys on the back. also i think burning up the back comes more from how the heads flow coolant than lean conditions.

I felt a definate improvement going from the LS6 to the vic and elbow, but had 2 backfires in a row with the rear 2 plugs showing lean. I was going to fight through it this year, but I sold the setup for enough to get the accufab so I'm happy.

The top mount is definatly the way to go. is it a DP or plate?

I'm going to be doing both for this year.

Did it backfire going down track?

Yeah. Right about 5K in 3rd gear. I immediatly shut the car down, coasted to the turnoff and got pulled back to the pits. The plugs were fresh TR8's and I was hitting 200.

You said you had 2, what happened on the other one?

Same thing, exact same spot on the track. Talk about pissed..

What do you think is causing it?

Does it do it on less nitrous?

Well here's the full story of my weekend. Get the new setup, work out all the bugs, ops check good, head to the track.

2 Kits--1 wet HSW plate 2 dual nozzle firing down into the intake from the elbow

I made 4 total runs over the course of the weekend.

First run-- 100 in each kit. Plate off the line bringing the nozzle in 1.5 sec later. Car pulls harder than ever, I get nervous and short shift 1-2 and 2-3. Runs 3rd out the back door with no problems. Car runs 10.1

Second run-- I bring the second kit in at .75. Same early shifting problems 10.03-- personal best ET

Third run-- I bring the second kit in at .5 sec, ring out first and second. Shift into 3rd and about a second later she pops.

I spent all night thrashing--new plugs, check jetting, scrub tune, compression check, score a new MAF, and repair my lid.

4th run-- Same exact thing at the same exact spot on the track. Pack my shit up and go home. Season done.



I think the culprit was the 2 nozzles firing down into the intake. It's about all I can think of, or the inabality of the elbow to flow a wet plate. That's why I'm going to a 4150

How old are the springs?

Ever have any valve float issues?