AirborneZ28

Hi, I have a 93 Camaro Z28 originally a 350 LT1. I have rebuilt the bottom end starting with the block being blueprinted and clearanced for 383 internals, ARP reinforced main studs, Eagle Specialties 383 balanced rotating assembly Part #ESP-B13054L030, high volume melling oil pump and pick up tube and larger capacity oil pan. Upper engine started with the intake and heads from a 96 Corvette LT4, the heads were ported and polished and intake done to match, larger valves in the heads and larger ports in the intake for 58mm throttle body, new roller lifters, new pushrods and 1.6 roller rockers. The tranny is still stock at this time but has a TCI high stall torque converter. BBK headers and magnaflow exhaust and I converted the '93 single wire O2s to the '94 four wire heated O2s.
I included that info as a condensed background of what has been done but my question is concerning the cam and if I HAVE to change my rear gears and what would be the best choice.
I read through the camshaft and valve train sticky topic and the closest cam I could find to mine was the GM847. Mine is a Crane Cams 109661 grind #HR-230/359-2s-12.90 IG with cam timing @ .050 of 230 intake / 238 exhaust 112 LSA and lift of .574 int and .595 exh. with 1.6 rockers. I know that is not exactly the same as the GM847 but seems close to me and that cam says gear change is REQUIRED.
My stock rear end gears are 3.23 and the car seems to lack power especially in the low rpm range. The tune is not yet complete so I know that can be a huge part of it but so far I have the VE tables fairly well straightened out and have done some work on the spark adv. tables and it runs fairly well with the exception of the low rpm bog. I have considered changing the gears to 3.73 or 4.10 but I do not want to lose my high end or highway speed capability. Is it most likely the 3.23 gears that are causing low rpm bog and if so what would be the best choice for the new gears. If it is more likely to be the incomplete tune vs. the rear gears causing the issue that's fine too I will keep working on it. This is my first higher HP (non stock) rebuild and my very first attempt to tune. I just want to make sure I am not beating my head against a wall trying to tune out the low rpm bog only to find it is because of the gears and I will never be able to "tune" it out.
I apologize if I have included too much info but normally when someone asks a short question of this nature the first thing that is asked is to provide more information about the rest of the engine, tranny etc. If there is anything I left out that is relevant please let me know I will be glad to fill in any gaps. Any help is greatly appreciated.

96TransAmboosted

iTrader: (8)

CALL Advanced inductions or Lloyed Elliot of elliotportworks and give them all the info and they will set you up with a great set-up. they do it everyday and have helped us all out

AirborneZ28

Thanks for the info. I just looked them up online and it looks like they only do work on the heads and intake, is there another area on their site I should be looking at than the LT1/LT4 area? Also while I do appreciate the steer in the right direction and will be more than happy to follow up on it, I was more hoping that some of the guys here would have run into this and already had a good idea of what needed to be done.
Again as I said this is my first time doing this kind of work and I have tried to do alot of research on my own. Unfortunately I have already gone the route of a preformance garage locally and lost more than 2 years and 20k and got back a mess that I have had to rebuild myself from the block up so I am a bit wary of going that route again.

myltwon

iTrader: (1)

that cam should be pretty decent given that the LT4s were ported by a decent head shop. 3.73s, different convertor, and long tubes would be what I would look into next.

if you are looking into a different cam, both AI and LE have great reputations on this site. myself personally, with an LE camshaft, am very happy and Lloyd will do nothing but go out of his way to ensure that you are satisfied.

95mysticta

iTrader: (4)

What rpm stall is it? You will definetly gain alot changing the gears but it depends how high you want to spin on the hwy. My dads lt1 with a hotcam and 3.42s works very well. Was a night and day difference going from 2.73 to 3.42. It usually spins about 2300-2500 from 65-70mph and gets about 26mpg trying to keep it around 2000 or under. As for the headers i dont see it being an issue with your bogging its in your tune. You will see a good gain stepping up to long tubes but i would consentrate on getting the tune done first.

96TransAmboosted

iTrader: (8)

I just dont think anyone should pick a camshaft cause of what someone online said worked for them. I think you should ask someone who has seen and built a varity and see what they suggest for you combo. Both companys have been doing these enignes for some time now and know what does and does not work. They can suggest and you can ponder over it , you dont even have to buy the cam from them.

jester1614

iTrader: (13)

to me it doesnt look like he wants to change the cam, he just wants to know what to do to make it perform better, if so I would go with a 3200-3600 stall and also a set of 3.73s.

I have a 3200 stall and love it, as well as i had a set of 4.10 gears, they were great for acceleration but sucked for gas mileage, as the speed limit on alot of highways were i live are 75mph so doing 80+ causes some high rpms.

my current build is a high rpm 350 (242 242 572 572 112 solid roller cam) and i am planning on going with 3.73's.

lt1-xjs

I would switch to a Yank SS 3600 first and if that doesn't cure the problem, add the 3:73's.

AirborneZ28

Thanks for all the help and I will try to answer all the questions if I can. First the torque converter is TCI's Street Fighter 243105 and the stall speed is listed as 1200-1400 over stock. I believe that puts it in the 3600 rpm range or higher. The tc and cam as well as most the other parts were chosen and installed by the local performance shop I had taken the car to. I am not looking to replace the cam at this point as I have already been bilked out of 20k and about 2 1/2 years of not having the car and have had to replace a lot of expensive stuff already. So at this point I am just trying to get everything to work together.

I started by having to replace broken valve springs and then eventually had to replace all of the valve springs, retainers, keepers, roller rockers and pushrods. The valve springs that the shop put in were apparently the LT4 hot cam springs. The same guy that ordered the springs also ordered the Crane cam and 1.6 roller rockers so you would think he would know they were not sufficient for the lift being made. The starter died and when I pulled it out I found it was a remanufactured stock even though I was charged for a brand new high torque starter. Then I noticed I had an oil leak at the front of the engine when the car was up on stands after being towed home for the third time with broken valve springs. While waiting for the springs, rocker arms and pushrods to come in I started taking the front of the engine apart to find the leak and in the process I found the MSD billit opti spark was installed without the O rings on the shaft and the cap was chewed up on the inside by the rotor as the cap was installed without its gasket and all three seals in the timing cover were leaking. At that point I decided to tear the engine down to the block as there was no telling what else was done wrong. The injectors that the shop ordered and installed were the ACCEL 150826 26 lb injectors and I was told they were way too small for the set up I have so I installed the red (or orange?) ford 36 lb injectors. The headers I have, again chosen by the performance shop, are the BBK peformance 15960 shorty headers and I have them wrapped and I upgraded to the 4 wire heated O2 sensors.

After the mechanical work was done the car still ran bad as it stumbled and nearly stalled about 50% of the time when trying to take off from an idle and would frequently stumble and misfire when trying to accelerate from a steady cruise speed and I was only getting about 7 mpg. I had already been charged $750 by the shop that did the work to send it to a dyno shop to be tuned and as I said it never ran well so I started looking into what I needed to be able to tune it myself. I got the equipment I needed from Craig Moates at Moates.net and I met a guy named Soloman who has helped me tremendously with learning how to tune it myself.

Soloman had me read the custom chip the dyno shop had put in and send him the .bin file and he said the tune was terrible and was most likely the cause of most of the problems. He suggested starting with the VE tables as they were mostly stock and way too rich for my set up. So I started by adjusting the VE tables with VEMaster and sorted out about 80% of the drivability issues. Then I started working on the spark advance tables and so far I have gotten it to run fairly well except the low rpm bog and still only getting about 10 mpg. I know I have a long way still to go on the tune but as I said it's my first time and also being a 100% disabled vet I only am able to work on it here and there as I am frequently "laid up" with health issues (which was the only reason I ever took it to a shop to begin with).

I was told by a few people that given the cam that I had in there I should change the rear end gears or it wouldn't run very well in the low rpm range which is what led me to posting this topic. If I NEED to change gears to say the 3.73, then that is what I will do and if alot of it is still just the tune I will keep working on that. I just do not want to miss something important because I am focused on something else if you know what I mean. I hope I did not ramble on too much and that I answered any questions.

In case it is important the parts I replaced in the valve train are as follows: Crane Cams 10535 Hydraulic Roller Lifters, Summit Racing 1457200 chromemoly street and strip push rods, Summit Racing G6936 Full Roller 1.6 aluminum roller rocker arms, Comp Cams 26918 Valve Springs with Comp Cams 787 retainers and 601 locks. Those were the parts suggested by Summit when I called them.

AirborneZ28

LT1-xjs is the TCI Street Fighter tc I have about the same as what you are talking about? Also I am rebuilding the 4L60 with the 5 pinion planetaries, hardened input drum, "the beast" sun shell, Alto red eagle clutches, kolene steels etc. and when I do TCI said they will dissasemble my tc and rebuild it to tweek it for my exact application for $250 versus shelling out another $600-$700 for a new stronger tc.

4K+Converter

IMO, this might be a solution to you gear dilemma.

I ran a CC306 with LE2 heads on it for years, and ran 3.73's. Due to the cam, the engine didn't really want to operate under 1800 rpm. So ultra low rpm highway cruising with 2.73's and the converter locked up was out of the question. I got the transmission to perform how I wanted to do it with tricky shift and lock up tables.

I had it programmed to hold 3rd for a long time. It would lock up around 33 mph (1600ish rpm) in 3rd, and held it locked up all the way to 53 mph (2600ish rpm). When it hit 53 mph it shifted into 4th while locked up for highway cruising (which was back down to 1800ish rpm). Then it held around 2400 rpm at 70 mph in 4th.

You could do something similar with 3.23's. Just for the sake of an example, lets say the cam you are going to choose won't like to operate under 1800 either. Have it hold 3rd for a long time, then have it shift into 4th when the motor will rebound at 1800 rpm, or around 60 mph then you'll cruise nicely too.

If your worried about the hit in performance, you probably will lose out a little, but I've seen cars go bottom 11's and faster with 2.73's. Not optimal, but it'll get the job done.

96TransAmboosted

iTrader: (8)

I would get a circle d converter over 3k. they are sick as **** converters and work very well. Yank converters are nice as well. Stay away from the cheap TCI converters they suck and dont perform very well at all

myltwon

iTrader: (1)

sounds like you have a 2600-/+ TCI convertor, not a good stall speed or brand IMO

Rob

iTrader: (6)

Yep, I'd get a converter first then gears if you need them. But I'd recommend a Vigilante. I had a 3200 in my TTA and my Mom has a 2800 in her Comp TA. No problem with either. Both cars have 3.27 and 3.23 gears, respectively. Very good manners on the street and were great at the track.

MICHZ28

That converter is a big part of your problem. Yank ss3600 at a MINIMUM. 3.73 gears for an auto, you don't really spin that high on the freeway.

96TransAmboosted

iTrader: (8)

if your going to do 3.73 just dive into 4.10 the rpm diffrenc is like 300 or so and the 4.10 are just better all around. with a 2800 stall and 4.10 i average a 1.88 60 ft on shitty 255/50zr16 street tires, and launching at 2200 rpm

lt1-xjs

The TCI is nowhere near the same as a Yank SS 3600. The Yank is far more superior in all aspects and by far the best LT1 converter. Do a little research and you'll see. I'm still running the original trans and installed my Yank 6 years ago. I would also recommend installing the modified Transgo kit from Probuilt Automatics, plus they have the most complete rebuild kit with all the goodies. A trans cooler is also recommended, I used a Hayden 24k from Pepboys.

AirborneZ28

Thanks to everyone for the help and suggestions. I will definately look into all the suggestions made. It is great to have a group of people you can brain storm and throw around ideas with because everyones experience and ideas are different. There was a couple things I did want to touch on and maybe clairify though. First thanks for the info on the trans tuning in the shift tables but unfortunately I don't have the electronic version (4L60E) trans, mine is the 4L60 and still has the TV cable for adjusting shift points (short of changing internal tranny parts). Also I believe the TCI converter I have is at least 3600 as the target range for the cam is 3800 stall and TCI says that this converter will work for that range and my set up. I do not know off the top of my head what the stock stall speed is but I thought it was around 2400 and the converter I have is 1200-1400 OVER stock. That would be like 3600-3800 if I am at least close on the stock stall speed. I know there are way better converters out there but mine is mainly for street and show and the $580 for the TCI converter was to me alot since I am 100% disabled vet and have a fixed inclome. This car is pretty much my only toy and project but also my transportation vehicle and has been about 6 years in the making due to buget and it's not done yet. I don't do too much at one time so I don't over extend myself financially. If the TCI converter is really that bad and causing more problems due to it's quality than what it is fixing with the higher stall speed then I may have to just live with it for awhile. I was just trying to find out if a gear change in the rear end was the solution or at least would be a big help. I do appreciate all the help and I will definately take all suggestions into account and do a bit more research, you guys have given me lots to think about. Thanks again.