shouldn't it help my mid range bog though? If i hammer it at 50 it falls flat for what seems like 2 whole seconds. And keep in mind I can't even feather the brakes a little to get the tires to start spinning. It just bogs down.
No, all your problems are a mismatch of parts. Gears and converter first. Then try playing with the AVS again. If you can't make it work, get the DP carburetor.
What if I switched to a stage 1 intake? Gears, and stall and possiblya carb...I'm looking at another $1500 and how much of a difference would it have made if my machinist would actually degreed my cam 4 degrees advanced?
The intake might help a bit, but not enough IMO. Gears and converter are what you need. I understand you have all these theories running around in your head. I would not touch the cam. Your problems are really a basic mismatch of parts.
Okay. Thanks for all your help. It will be months possibly years before I get this all sorted out. Sucks bad that I have such a rare rearend but from what I've read it's a good one.
Yeah, it's a good rear. It's the parts availability is terrible right now. You should call Fabcraft and put your name on the waiting list. The more guys that do that, the more likely it is that they will make parts. The 3.64 ratio would be sweet. https://fabcraftmetalworks.com/product/rear-axlerab4-08364/ I swapped my original 8.2 10 bolt 3.42 rear way back when I started going down the track. I didn't want to break it going into the 12's, and now the 11's. I went to an 8.5 10 bolt out of a 71 GS350. Put 30 spline Moser axles with matching Eaton Posi and Yukon 3.73 gears. Topped it off with a TA girdle cover. You should look around for a 71-72 Skylark or Cutlass rear. That will be the 8.5 10 bolt. Parts availability is excellent for them. The swap is easy too. Both your 8.2 and the 8.5 are bolt in axle. All you do is pull the axles, unbolt the backing plates and brakes, and swap out the rears, then bolt in the axles, backing plates/brakes. That saves the trouble of dealing with the brakes/Emergency Brake cables. One hydraulic brake line connection and 4 bolts, and that's it.
If I understand this right does that mean I can actually retain my current axle housing? Just axles and guts get swapped?
You keep saying ta told you the single plane intake works low end( which is true on the big block) Here’s some reading . https://www.hotrod.com/articles/intake-manifold-single-double-plane/ I do believe the dual plane and a converter will help some.
No, normally when you swap the entire rear end, you have to assemble your brakes onto the new rear end and hook up the emergency brake cables. Sometimes the rear you buy doesn't even include working brakes, it depends. Your existing rear uses bolt in axles, so the axles bolt in and out, as opposed to c clip axles where you need take the cover off, pull the c clips to get the axles out. The advantage to pulling the axles is you can unbolt the backing plates with the brakes and all and just wire them up to hold them. The 71-2 8.5 is the same bolt in axles. You pull the axles out, and unbolt the backing plates. Then you swap in your entire 8.5 rear, and bolt up your original backing plates brakes and all, and axles. It makes the swap easier.
The Chevelle rear is a Chevy 8.2 (actually 8.125). It's a c clip rear, and weaker than what you have now. You can get parts for it though. http://jdrace.com/content/diff_id/10b82chevy.php
I read the article and understand a lot of this from years ago when I switched from a single plane to a dual-plane on my 355 Chevy motor. But please re-read the whole description on this screen shot. Their studies were done on the 350 motor and they describe this as being a hybrid intake where you don't lose low end like you normally would with a single plane. One thing your article did mention is the tedious task fine tuning a carburetor to run properly with a single plane. I think the double pumper is going to help me out immediately. But maybe not.
I'll be honest with you guys I'm pretty discouraged right now. I just spent about five grand on a motor that won't even do a burnout. Yeah it's kick a*s when i to get to the power band but otherwise sucks. I'll film a video of me driving it here in a bit. Get it up on YouTube.
All those comments by TA ONLY apply if everything else is right. That is not the case here. Like I said, you have mismatched parts. I understand you are discouraged. It's a shame you made all these decisions before coming here. It happens all the time. Basic mistakes. Guys think their performance should be the sum of the parts they choose, but that is not the case. That cam and intake just need supporting mods to work. I suggest you take a break from this.
I agree nothing is going to help unless this is done also. Your also equating what you have done to the car compared to when you had a 2bbl and expect it to do a burnout with this new equipment. I bet what you have now would beat the old in a 1/4 mile.
I understand now that you have knowledge that ta performance doesn't have because you have real-world results. But I picked a mild cam honestly very mild cam as far as specs. I picked an intake that was supposed to be street-friendly. This is literally part of their selling point if you read their description. Both of these including the cam supposedly good with stock gears and stock converter. My brother even told me repeatedly to buy a stall converter. But dropping another 5 to 600 wasn't going to happen. I get in a GO MODE when I'm on a project. I should have been more patient...you guys warned me early on but I kept thinking the combo would be "good enough" based off the info provided by TA.
You changed the cam also and this takes out some of the bottom end You have everything there the DMN 256 REAR IS NOT GOING TO CUT IT. The cam is rated at 2500 rpm so you need to get the engine up into this area before it will move the car. TA is being wrong here telling you this intake will work on a basically stock engine. I don't know why it is marketed that way and yes it will work but the engine needs to spin to 6500 rpm. For one thing the crossover is now blocked and there is no heat to help atomize the gas That means the engine usually needs a little more gas to make up for this. MAYBE. I don't care how you cut this damn pie this is the way it is. I would take that carb back to its original carb setting for the jets and start over to get the off idle cruise right and then jet up the secondary system 1 step higher. You may need a nice Long pump shot when you mash it to keep away from the bog. You have to go back and forth with this until you get it just right along with a bigger or smaller shooters. You have to do this same darn thing with a Holley so don't think you are going to stab this on and it is going to boil the tires to the ground because as soon as you buy it you will be yelling at us for it not doing what you thought it would. You will just have to work with it until you get the rear and the convertor. I would get the convertor first at least it will come out of the hole on the cam at 2500 rpm it will spin then.
"Mild cam" is a relative term. People misunderstand what a cam does. They think you just add a cam and add x amount of HP. That's why the most common mistake made by far is over camming an engine. The limiting factor with any engine is air flow, an engine is an air pump. A bigger cam just holds the valves open longer so that the engine can breathe at HIGHER RPM where it can make more power. The stock cam makes power from 800 RPM - 4500 RPM before it's tongue starts wagging. Hold the valves open longer and you bump everything up. You lose low RPM response and power to get a bigger gain up top. Engine size plays into this as well. The bigger the engine, the less you notice the low end loss with the same cam. In any case, the TA 284-88H has a power range of 2000-5000. The stock converter stalls at 14-1600 RPM. The TA SP3 likes higher RPM even though it is good at low RPM, it still needs the motor to get up there faster. I feel like a broken record.
Don't be discouraged you did the right thing and these parts are good you just have 2 things screwing up your whole system and is easily worked out. I went from 2bbl to 4bbl but I still had stock intake. The Comp Cam 268 totally killed the bottom end but as soon as I hit that magic 2500rpm it was off to the races I had the same 256 rear as you. I beat a Wildcat that had a Nailhead in it and he got me out of the hole by a whole intersection but the moment I hit 2nd gear I went by him like a freight train He had to pay all my friends for that race. I beat his butt twice. Stock engine headers with the 268 cam and shift kit in the 350 trans 8.5 comp 256 gear. 650 Dbl pump Holley
