AirborneZ

I have a couple questions and it will require a lot of background information so please bear with me here. To start, I am a 100% disabled veteran but was a mechanic before I was in the military and also worked part time as a mechanic while in the military. The only reason I included that is to say I have always done my own engine work and rebuilds. My first full rebuild was my 1968 AMC Javelin SST 290 V8 when I was 16 and it turned out great. Because of my disabilities many times I will start a project and throw out my back or something and it sits for weeks or months until I can get back up to full speed and get back on it so for the very first time in my life I put my engine in another mans hands. I think we all can see this one coming a mile away. I asked around to see if there were any good speed shops in the area and found one near my home that the owner/ head mechanic specialized in Corvettes, and gm and had a few nice corvettes of his own. To top it off he was in the middle of another 350 LT1 to 383 LT4 conversion on a 1994 Z at that time. I told him I had the motor pulled and tore down to the block already and I didn’t need to depend on the car for transportation so he could take his time as opposed to the one he was doing on the 1994 that was a 2 month job and almost done. Long story slightly shorter, 2 years later and 15k spent on separate machine shop, parts and labor I finally got the car back with a TON of problems and a last minute bill of 5k for additional labor. I was told the extremely poor drivability and 8mpg were only due to the extreme mods running with the factory tune, which I accepted as the reason as I knew it would not run well if at all until the pcm was retuned. He said I needed to take it to a guy he uses to do the dyno and tune but that since it would need to be dynode to tune it I needed to drive it as it was for the 1k miles break in. Many other things went wrong with this but I am touching on what I hope is the important information. I finally got through the break in and got it up to be dynode and tuned for another $750 and the guy that did the tune had a hard time getting it to run well and it fell short of the power he had expected to get as it only made 337 rwhp. He said the tranny was a bit weak and I had planned on swapping it out for a 750 hp street/ strip one anyway. Even on the ride home I had issues with it and called the guy. It was sputtering and missing on acceleration and it all but died sputtering from a take of sitting at a light. He agreed to retune the car for free after talking to the mechanic that did the rebuild but he wanted all the mechanical aspects of the engine checked out first. I had the car back to the guy several times and every time I got it back I still had the drivability issues and now only a whopping 9mpg. Finally I gave up and started checking it out myself. Immediately I found one plug wire dead (#5) from severe damage that was hidden under the heat shield/ boot protector and another damaged with higher than normal resistance but still firing. Then I found #8 cylinder was dead, 0 compression. So I started tearing it down myself. I found the #8 exhaust valve spring was shattered, causing the dead cylinder and three rockers that were so loose that they could be pulled up and turned right off the valve stem and in fact they had damaged the roller tip so badly they no longer rolled and the pushrods had jumped out of the seat in the rocker and chewed up the push rod cup where they should seat into the rocker. Several others were so tight I needed to loosen them more than 3 full turns before I could get the tension off when they were at the lowest part of the cam lobe. I believe the over tightening was what shattered the #8 exhaust. When I tried to get the engine at TDC #1 to set the lash on the new roller rockers (replaced the pushrods too) I found it was not at the right spot on the cam for some of the valves so I knew the timing must be off. I ended up pulling the front cover and sure enough the mark he had made on the damper hub to show TDC was off. Although the timing marks aligned between the cam and crank, when it was at TDC the mark he had made was way off. In case there is some confusion at this point the 1993 lt1 doesn’t have timing marks on the torsion damper with the fuel injected set up and is not located by a positioning key. It is pressed on the snout of the crank and the damper should be positioned so the hub arrow is at the 12-o’ clock position. However the key he used to keep the crank gear aligned was slightly too long and interfered with the positioning of the hub so to compensate he made a mark on the hub to align with the notch on the bottom of the front cover to show when the motor was at TDC. I only found this out after pulling the front cover. And of course his mark was off by about 16 degrees. I also found the new MSD billet optispark cap and rotor were shredded from putting the cap on without the cap gasket. You could see where the rotor cut into the cap and instead of telling me it had happened and replacing the cap and rotor he cleaned out the shavings and put the distributor back together with the gasket in place this time. I later found out upon questioning him about it at his shop that the new guy he had just hired when he was supposed to be addressing all the issues with my engine was the one that had done it. The owner denied it had been done but was kind of stuck when his “new guy” that happened to be standing there admitted he had made the mistake. Once I had all the problems fixed and the engine back together it ran much better and has had almost no issues but is still getting only about 9mpg and I can sometimes hear a miss under heavy load (wot acceleration) and a couple times I have noticed a slight stumble if I have been sitting at a light for awhile. It has not yet been retuned as it is just recently back on the road and I am trying to make sure everything checks out before taking it back to be tuned. The tranny is still an issue I believe as although it seems to shift and run just fine it will not shift with any real power between 1st and 2nd but it will smoke the tires quite easily from take off. I don’t notice any real problems with the tranny like slipping under load, it just doesn’t seem to have the power it should. Second I think I should be getting way more than the 9mpg I am getting because I have looked at several other builds comparable to mine and they get in the mid to upper teens at least. I know I will not get the 21mpg I got before but heck 13 – 15 would be great as opposed to 9. Now to give you the stats to make sense of what has been done to the engine and what I should be expecting. The block was clearanced and the cylinders bored to accommodate the Eagle street and strip 383 rotating assembly (part# ESP-B13054L030) Balanced rotating assembly, street/strip, cast steel crank, hypereutectic pistons, I-Beam rods, Chevy small block kit. Melling M-55HV high volume oil pump. Milodon 18316 pick up and Milodon 30909 6 quart street/strip oil pan. Crane Cams 109661 Grind Number HR-230/359-2S-12.90 IG cam with lift at valve being .574 intake and .595 exhaust with 1.6 rockers (which is the ratio I am using) intake duration 230 degrees and exhaust duration 238 degrees. Crane Cams 10535-16 Hydraulic Roller Lifters. Cloyes Gear 9-3151 true roller timing set. BBK Performance 1542 power plus throttle body 58mm. BBK15960 shorty headers, ceramic coated 1 5/8” Primary, 2.5” collector, deleted cat, flowmaster exaust (that was already on from cat back and I don’t honestly remember the series muffler but I don’t think that is a major piece of info for this. It had cat before but was deleted by mechanic). Accel 150826 fuel injectors, 26 lbs./hr advertised flow rate, 269.0cc/min advertised flow rate and 14.4 ohms impedance, Bosch/Amp-style. (only 26lb injectors so I really thought I would see better than 9mpg) Breathless Performance ? (that is on the box not sure if it is the maker) 100-208 LT1 Adjustable fuel regulator 92-96 (it was the fourth or fifth fuel regulator he tried and kept saying they were the wrong ones. Yet another of the countless delays on getting my car back). Bosch 12014 premium O2 sensors. LT4 intake and heads I purchased off a 1996 Corvette grand sport LT4. Heads completely stripped down, magnafluxed (checked for cracks, not sure if they still use magnaflux method but they were checked), machined and ported and polished. 2.08 intake and 1.60 exhaust valves. Intake machined to get max flow from 58mm throttle body. Full MSD ignition to include MSD 83811 pro-billet LT1 Distributor, MSD 8226 Blaster GM coil, MSD 32149 8.5mm Super Conductor wire set (second set as I replaced the whole set when I found some damaged from the first set) and MSD 6420 6AL CD ignition. AC Delco Rapidfire Performance Platinum plugs gapped at .050. TCI 243105 Streetfighter Torque Converter 10” diameter advertised at 3,000-3,500 rpm stall speed. The transmission is still stock 4L60E and rear end gears are stock. I upgraded the suspension with Hyper Flex Systems Complete Masters Set Energy Suspension bushings, mounts etc. New tie rod ends, shocks, struts, upper and lower ball joints, bearing plate strut mounts and slotted and drilled rotors. For wheel I have 20” x 9 ½ “ rear and 20” x 9” front (I am not a big fan of large rims on a sports car but was told when they were ordering my rims that the only way to get 9 ½” wide in the rear was to go up to the 20” rims. But they actually seem to work on my Camaro and I have gotten nothing but compliments on the wheels.) Feel free to check them out in my photos I have them on my public profile albums here on the site. I have Nitto NT555 Extreme ZR 255/35ZR20 97W treadwear 300 temp A tract A tires in rear and same but 245/35ZR20 95W in front.

AirborneZ

ok well it wouldn't all fit in one post so:
I believe I have covered all pertinent data but if there is something missing feel free to ask I will try to find out. Bottom line should I go back to the same guy that tuned it before since he is offering to do it for free now that all the other mechanics problems are fixed? (He is about a 2 hour ride away for me) Or should I go to another place near where I live that I have heard good things about from several Corvette and Camaro owners I have met at local shows and just bite the bullet and pay for a new tune and hope it turns out better? I don’t believe the problems were caused in any way by the first guy that tuned it I think there was just too much wrong with it for him to properly tune it. Should I expect a better gas mileage after a new tune now that everything has been hopefully fixed? I am still getting about 9mpg now even though it is running better but there is always a VERY strong gas smell in the exhaust smells way too rich to me. Should I expect more than 337 rwhp now? The 1994 Camaro that had essentially the same 383 LT4 conversion made about 450 rwhp according to the guy at the dyno shop and the only difference between mine and his was he had the AFR LT4 heads as they came in the box. The AFR heads do perform better than stock LT4 GM heads from what I have read but the larger valves and porting and polishing was supposed to make the GM LT4 heads very comparable to the AFR’s according to the speed shop mechanic. I hope this isn’t too much and hopefully someone like Injuneer will have some good info for me. All input and advice is welcome and valued I just have seen Injuneer tackling a lot of these tougher ones in the week I have been here so far.
Thanks so much,
Jerry

AirborneZ

ok I appologize, I just read through what I wrote and I know it is REALLY long and for some strange reason I kept typing Dynoed as Dynode (I don't think either are an actual word). Hopefully someone can read through it all and make sense enough to offer help. Thanks again in advance.

Revolutionary

Wow.
Two things really stand out. One, If you ordered a balanced rotating assembly, is it internally balanced and if so is the counterweight removed from the flexplate and the flexplate rebalanced? Otherwise you will be seeing bearings soon and that would give you some major driveability issues.
Two, with all the crap that was wrong with the engine there is no way the tuner could get the job done so I would at least give him the opportunity to try to tune the thing with it actually running on 8 cylinders. He should have spotted a problem and stopped and told you to take it home a fix it before tuning but either way, if he's willing to retune for free, go for it.

Airbornec507

Just me but due to the improper instal of those parts there is realy no telling how messed up other things are until the motor grenades itself later on down the road when they will claim no responsibility. I'd have them pay another shop to overhall and blue print your motor right away. I just wouldn't trust them to do it right. Also once that thing is up and running correctly those injectors are gonna be hurting. Some SVO #30 injectors would be the absolute minimum I'd go on that motor. To do it right I'd go with #36 injectors or higher and get it tuned.

I put #38 Delphi's in mine because my motor was maxing my SVO #30 red tops out at over 80% duty cycle at 5400 rpm on my motor and going lean.

Injuneer

Some helpful advice from the Moderator....

Nothing wrong with a long explanation, and a lot of details - but use paragraphs to organize your thoughts. Not many people are going to try and read through that.... trust me. We want to help.... but its going to be difficult. It was difficult to pin down that its an LT1.

Finally, this is a good topic for LT1 Based Engine Tech.... but I won't move it there until you have a chance to clean it up.

Again.... WE WANT TO HELP.

AirborneZ

Thanks for the comments so far and I did see after posting that it was really long and hard to read that was the reason for my follow up remarks. I appreciate the help and I will try to repost it. I was honestly afraid if I reposted it someone might yell at me for posting the same thing twice. As long as it is ok with the moderator, I will just let this thread die and repost it with some indentions for paragraphs and split it up into three posts instead of one huge one and a second large one.

But before I let this thread die I want to reply to the other two comments.

Trust me I have thought the same thing about what else could be wrong with this engine. After doing some investigating through his head mechanic who quit shortly before my car was done because of crap the boss was doing and all the customers complaining to him because the boss was always "unavailable at that time", the block was done before he quit.

(I keep saying boss because I do not want to say his name and take the chance of an issue with the shop)
Then the boss hired a new guy off the street and left him to finish everything like front cover, damper hub, adjusting the valves and all the rest that goes with installation. The internals were done, oil pan on and timing set on when the head mechanic left. I trust all that was correct as I frequently talked to the head mechanic and popped in to inspect the progress and take pictures. When the head mechanic left I was no longer able to pop in and take pictures etc. except just a few times when the boss was there and he had told me he was doing all the work himself. I never knew the new guy who was qualified to change oil and do brakes was doing the rest of the work until the third time I had to take the car back and he admitted to making the mistake with the distributor cap. In fact on a few occasions when I stopped by the shop and my car was just sitting and no one working on it he (the boss) told me it was because they were backed up because he only had himself and the new guy and the new guy couldn't do anything without being told how to do it and being followed around behind.

I have taken the engine back down to the heads and took off the timing cover to check the cam/ crank timing so I found all the problems there and have addressed them and I am fairly sure everything deeper than that was done right. Iknow there is a lot of the story that I couldn't include because it was too long already but I think I have gotten up to the pertinent stuff.

AirborneZ

I will wait until I hear from you Injuneer as to whether to re-post in a new thread or re-post here.

AirborneZ

Oh and I forgot Revolutionary's question, sorry. Yes the machine shop was a separate place and they did do the internal balancing and there was a new flexplate purchased to upgrade and go along with the balance rotating assembly. I guess I forgot to put the flexplate in there, it was late and a very long post. When the block came back to the speed shop it had the rotating assembly in it from the machinist. I paid quite a bit to have the block clearanced, blueprinted, balanced and head work done and as I said that was a separate shop and a reputable one. I think my machine shop bill was about $2,500 because of all the work but I would have to check to get the exact amount.

Expense95

You definitley need to get the car re-tuned. If your original tuner would do the job for free start there, otherwise try Ion @ Madtuner. He will help you get it figured out.

Injuneer

I actually copied your post to Word and started to reformat it. I think you need to:

Delete the superfluous info on why you ended up sending it to an outside shop. "Due to circumstances beyond my control, I took my engine project to a shop. Here's what went wrong:"

Separate it into engine items/problems, and put that post on "LT1 Based Engine Tech". .... tranny questions and post it on "Drivetrain"..... suspension questions and post it on "Suspension, Chassis and Brakes.

If I get a chance, I'll forward what I did in Word.

Fred

AirborneZ

Hey, Injuneer, thanks for the help. I will check my e-mail in a bit. Ok, point well taken on the superfluous info leading up to why it went to a shop, I was just trying to relay what my level of mechanical understanding and ability was and that unfortunately I had to send it to a shop. I will shorten that considerably or just go with what you e-mail me. I did think about where to post this and there were two reasons I thought it might be an advanced tech and not LT1 thread and that was:

1. I read through that section and it seemed like just basic stuff related to LT1 like figuring out what a noise was caused by or finding a loose wire or vacuum line and asking if anyone knew where it might go or diagnosing a problem on a stock LT1. Since this was a performance build and it was no longer a 350 LT1 but a 383 LT4, I thought LT1 chat may not be the best fit.

2. Since this was rather involved and had a lot of performance modifications instead of stock and it wasn't addressing a single thing like a driveshaft question or a timing question I thought it might fit here in advanced tech.

But, really it is not a problem where ever you think it needs to be I will be happy to post it there. I really didn't have a tranny question the info on the tranny was just related to the dyno and the low results. I tried to keep it to a minimum but I didn't want someone to think it was so bad it was slipping or not shifting or something like that. I just tried to give an accurate description of what the tranny was doing, I know it needs rebuilding or replacement and that is my next part of the project. Also I don't have a suspension question I just included the info on what all mods were done to give an idea of the overall car and what has been done. I can drop the trans stuff completely and just not mention the suspension upgrades or wheels and tires.

I always seem to see people that post a very short question and then it takes at least three different people asking what the particulars are before they can even start addressing the issue so I tried to give any info that was important or might be related. I appreciate the help and will look over what you send me and will post it in LT1 chat. Maybe I can have a link to this thread in it if anyone WANTS to see more information to help them better understand anything I miss in the condensed version. LOL I really didn't mean to make my first question here in the forums so much of a hassle and kind of why I waited this long to ask. I knew it was a screwed up situation and a long road to get from where it started to where I am today and trying to move forward. It has been almost 2 1/2 years since I pulled the engine and handed it over to the custom and performance shop and there has been legal issues involved and is the only reason I won't say the name of the shop or the owners name.

DirtyDaveW

Sounds almost verbatim what I ran into on mine. The fatal mistake is telling any shop "oh... take your time..." Mine took 2.x years and it was a piece of crap from day one. The shop ran into legal issues, the machinist and the shop had a falling out, the guys that took the car apart took short cuts, then quit so no one knew where my parts were or what belonged to who's car, etc. That was on my 383 solid roller motor. Shoulda been a killer but was a pure pain in the ***. Killed some valvesprings, just like yours, vibrated like hell as it climbed in RPM's etc. Lifters finally came apart and took the motor out. My current turbo motor, a 355, is a stone cold killer though

.... Definitely take it back to the tuner with the current setup and give him another chance!
Best of luck to you!

AirborneZ

Thanks DirtyDaveW, sorry to hear about your car woes as well. Yes you are definitely correct in the first mistake being telling the shop to "Take their time". I have addressed the valve spring issues by contacting the cam manufacturer for the recommended springs and then went a bit over that to be safe. I am as we speak (well about an hour ago) installing a new k-member and hope to be posting pics soon.

I went with Comp cams high performance bee hive springs 26918 and they are rated to a .60" of lift and my max lift is .595. Comp cams retainers 787 and 601 valve locks. I already replaced the Rocker arms with Summits fully roller rockers G6936 and pushrods SUM-1457200 so my valve train worries are a thing of the past hopefully.

The k-member I am installing is UMI's tubular k-member 2325 and the main reason I decided to replace that now was my starter died. With the stock k-member and BBK headers there is absolutely no way to get the starter out up or down. I took the bolts out of the headers and removed the y-pipe but the headers can't be taken fully out and the starter can't fit past them and the huge stock k-member. Plus I already wanted to replace the k-member because the y-pipe was crushed between the stock k-member and the oil pan, so the starter was the last straw for the stock k-member.

This is the second starter that has died on me just since I got it back from that shop, which by the way went under. I just saw the new signs on the place today. The first starter would drag and you would have to turn the key sometimes for 5 minutes to get click, click, click until it finally turned over the engine. He told me that starter was a high torque starter but I don't think it was. He did replace the starter and it worked well for about 2 1/2 - 3 months then one day, dead no click no nothing. I was told by a buddy at my local parts store that high torque starters are notorious for dying young but less than 3 months can't be right. He said his son has a race car and typically has to replace the high torque starter every year to year and a half.

Anyway thanks for the advice and sharing your horror story. Once I finally get everything fixed and running well I plan to take it back and give the tuner another shot at it. I have kept in contact with the tuner and he knows what I have run into and still stands by his promise to retune when all mechanical issues have been resolved. 2 1/2 years+ to get it back from the shop and so far almost three months of fixing bulls@#& mistakes and problems but I hope to have a dependable beast soon.