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C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Project '85 Corvette w/ Currently Stock L98

 
Old 02-03-2019, 01:25 AM
  #1  
jonbonez
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Default Project '85 Corvette w/ Currently Stock L98

Hello to you guys if you read this, first post on here and hoping to just narrow down everything in my Vette here. My grandfather bought the Corvette back in the '90s, drove it but over time it sat and aged because it sat. Fuel tank went bad and rusted, car wouldn't want to ever start. Shady mechanics tried fixing things that they didn't know how to fix. Family members who didn't have the time tried to fix it but never could. Then my dumb spoiled college kid self fixes it in four months, which I must say, I didn't a darn thing about cars when I said I wanted to fix her. I will always be grateful for the time I took and how I first got excited when she did a slight pop meaning fuel reached a cylinder and a spark plug had lit the said fuel. Heads up to many of you who are fixing up an L98, btw, a huge bane to my labor was looking for vacuum leaks. ALWAYS check the cold start valve, the metal can and will bend sometimes while trying to move things and tear off fuel rails. If it bends, it causes a major vacuum leak that blows all the air straight out of your intake. Check your IAC, and never underestimate the reliability of a Factory Service Manual, a simple test drive to let the EPROM learn, and a simple reset of the idle tune by switching on the engine and then immediately turning it off. Now, I've been driving the girl a whole lot, and I can't help but say I will be so fond of this car and it will be my favorite car for the rest of my life. But, with how much I've driven it, I see its flaws. Down to it:
The car has the Z51 suspension, the forged pistons and rods that came in the '85 year (almost exclusively I think, which I feel damn lucky to have inherited this year the more and more I see the things it got), 3.07 rear diff performance package (haven't checked if it's the Dana 44, but it's probably that ole' glass body Dana 36), no mods to the engine except ease of life things like a fuel pressure regulator dial that allows you to change the fuel pressure up to a max of 60 lbs. The engine runs, feels, and sounds great (probably cause it's a vette) and doesn't miss whatsoever. Here are my problems and my to do list:

Problems:
-Starter has a point that is very rare and every now and then where it misses the flywheel and just spins and grinds itself on the flywheel (very loud metal grinding sound that makes your hair stand on your skin). I believe I needs shims, or I am experiencing something else maybe like just needing a new starter.
-A ticking noise of some kind in the engine (bare in mind I also freak out over the littlest sounds in the engine bay if it's not normal, love this car to death and will overthink anything that doesn't sound normal). Could be the crazy signature loud volume injectors firing off, or maybe my valve train clicking or the cam ticking. All I know is, with how much I've driven, if it was something bad, it would have done something to the engine already.
-There is a chipping sound in the driver's side front wheel that clicks and chips when you go from stopped to moving, it doesn't keep on doing it, but when you stop and then start moving, it clicks a few times and then you never hear it again until you get going from a stop again.
-There's a vibrating rattle from the engine bay at 20% throttle only when you're in between 20 - 40 miles per hour. The vibrating rattle definitely is nothing in the engine I believe because it's not heavy sounding and you don't feel it if you know what I'm saying. I do studio music production on the side and I know that certain frequencies cause certain things to vibrate, like my loud guitar when I hit a certain chord it vibrates the house. So in theory the engine reaches that certain 1100 - 1200 rpm and because of how loud and vibrating my exhaust is, it causes a vibration that rattles something. It's gotta be something like a loose heat shield, exhaust, or something metal in the engine bay. Or god forbid, the dang flywheel is messed up or something which I hope not, but I would figure it would be present at all speeds.
-Full throttle is not true full throttle. I have to perfectly slam the throttle and it may actually make the transmission down shift, this isn't reliable if you're in a roll and slam the throttle.Sometimes at 80% it will actually downshift.

Present Diagnostic Codes:
-32 EGR System Failure, my EGR Temp sensor is currently faulty and needs replaced. I know because when I disconnect it, the code goes away.
-33 Mass Air Flow Sensor High Voltage, this is a very intermittent code that doesn't effect driveability so far. Had it in the past and it did prevent the car from running and made it miss and surge, but that was fixed with a brand new MAF Relay behind the bread box.
-45 Rich Exhaust, it's slightly rich but not really noticeable. Wideband 02 Sensor gauge is on the to do list for tuning in the future.
-52 Fuel Calpak Missing, my dad tells me that when he swapped the whole computer he did move the chips he believes so it might not be reading or it's actually not in the chip.

To-Do List:
I don't want this car to be stupid fast, I want it a street car. Something I can have a lot of fun with and still give a punk kid in his new mustang a run for it's money. I have a great understanding that the L98's downfall is in how it is asthmatic like Darth Vader. Can't breathe and suffocates itself because of the lack of air flow.
-Thinking AFR 180 heads but I want a great air flowing head that also allows for the EGR just because I rather have the comfort that my cylinder temps won't be so hot and a little bit respective of mother earth.
-Longtube Headers are a must for me and probably the first mod I would make as it would definitely boost the air flow out of the engine with the heavily restrictive pipes.
-First TPI intake. Two words: HUGE RUNNERS. I love the look of the TPI intake, it's amazing, it's classic and looks muscular. Plus, the huge runners allow so much air flow compared to stock, and I can still keep that awesome torque with the air velocity and long tube runners. But I also think that switching to a TPI Mini-Ram would be cool but I would have to change the whole build of the engine to match a high rpm screamer instead of my currently low to mid boomer that demands attention with it's lion roar.
-Dana 44 Differential
-Stronger UJoints and Shafts
-Transmission beefed up or swapped to a 4L60/80, or even a 6L80.
-And a cam to match the FIRST TPI intake and average 180CC heads of some kind.
-An upgrade to the ECU and possibly a reposition of it that allows me to be able to tune on the fly and to access the chip fast and easy.
-With the above statement, I want a tuning setup that allows me to tune the car real easily and almost in a modern fashion, preferably real time instead of flashing a chip, but beggars can't be choosers.
-17x9.5 wheels.
-New Polybushings
-High Flow Catalytic Converter


If you got through all of this, I sincerely appreciate that, even if you don't reply. Cheers and good luck to all of you with your Vettes and drive on!

I'll attach a couple pics of the car.
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Old 02-03-2019, 01:38 PM
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Miket440
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-There is a chipping sound in the driver's side front wheel that clicks and chips when you go from stopped to moving, it doesn't keep on doing it, but when you stop and then start moving, it clicks a few times and then you never hear it again until you get going from a stop again

Sounds like a wheel hub issue to me.
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Old 02-03-2019, 02:06 PM
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KyleF
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First, welcome aboard and good luck. I like how you have taken stock of everything and know where you are starting and where you want to go. This is a big first step a lot of people overlook and waste time, money, and get frustrated. My word of advice is to really start with all the repairs and maintenance items before you start modifying. Get the car to a clean bill of health first. This will help a lot when there are issues because you won't have to worry about what the modifications are doing. Do it one step at a time knocking the list down.
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Old 02-03-2019, 03:20 PM
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Originally Posted by Miket440 View Post
-There is a chipping sound in the driver's side front wheel that clicks and chips when you go from stopped to moving, it doesn't keep on doing it, but when you stop and then start moving, it clicks a few times and then you never hear it again until you get going from a stop again

Sounds like a wheel hub issue to me.
Thanks for the suggestion, got the car off all fours right now on jack stands, and going to check the build of the wheel in question.
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Old 02-03-2019, 03:21 PM
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Originally Posted by KyleF View Post
First, welcome aboard and good luck. I like how you have taken stock of everything and know where you are starting and where you want to go. This is a big first step a lot of people overlook and waste time, money, and get frustrated. My word of advice is to really start with all the repairs and maintenance items before you start modifying. Get the car to a clean bill of health first. This will help a lot when there are issues because you won't have to worry about what the modifications are doing. Do it one step at a time knocking the list down.
Thanks for the kind words, and definitely a priority to make it spotless and perfect in function and feel.
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Old 02-04-2019, 12:10 PM
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vader86
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First code to fix is the Code 33, always fix codes in order from front of the engine to the back. Once you fix and clear that one out, see if others come back. Its likely they will not. EGR will be a separate issue and can be ignored for now.

Fuel injectors tick, sometimes loudly. That is probably the ticking sound. You can get a stethoscope and put it around the engine bay to convince yourself, its a good tool to have any way.

If the starter needs replacing, go with an 88-91 starter, which is smaller than the 84-87 behemoth. Its a worthwhile upgrade to make unless you want things perfectly original, especially if youre doing headers.

Chirping from the front sounds like front wheel bearings, grab the wheels at 12-6 and see what play is there, and replace both if one is bad. They are sealed units, and get an SKF bearing. When you do the rears, also make sure you get Spicer cold forged U-joints with no zerk fittings. Denny's sells halfshaft assemblies already put together if you want to just swap them out.

If it is 4+3 its D44, if A4 its D36. So you have a Dana 36. Your automatic already has the preferable 2000rpm TC, it may just need beefing up for your power goals. It does not need to be swapped out for the later electronic versions.

AFR 180 heads are fine if you're keeping it as a 350 engine. You dont need EGR, its not doing that much for your cylinder head temps unless youre spending a lot of time on the highway. EGR only operates on extended part-throttle cruising over 170F coolant temp. If you change the cam to something slightly more lopey, it will accomplish the same effect, which is what they did with the LT4 engines in 96.

Last edited by vader86; 02-04-2019 at 12:11 PM.
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Old 02-04-2019, 03:17 PM
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jonbonez
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Originally Posted by vader86 View Post
First code to fix is the Code 33, always fix codes in order from front of the engine to the back. Once you fix and clear that one out, see if others come back. Its likely they will not. EGR will be a separate issue and can be ignored for now.

Fuel injectors tick, sometimes loudly. That is probably the ticking sound. You can get a stethoscope and put it around the engine bay to convince yourself, its a good tool to have any way.

If the starter needs replacing, go with an 88-91 starter, which is smaller than the 84-87 behemoth. Its a worthwhile upgrade to make unless you want things perfectly original, especially if youre doing headers.

Chirping from the front sounds like front wheel bearings, grab the wheels at 12-6 and see what play is there, and replace both if one is bad. They are sealed units, and get an SKF bearing. When you do the rears, also make sure you get Spicer cold forged U-joints with no zerk fittings. Denny's sells halfshaft assemblies already put together if you want to just swap them out.

If it is 4+3 its D44, if A4 its D36. So you have a Dana 36. Your automatic already has the preferable 2000rpm TC, it may just need beefing up for your power goals. It does not need to be swapped out for the later electronic versions.

AFR 180 heads are fine if you're keeping it as a 350 engine. You dont need EGR, its not doing that much for your cylinder head temps unless youre spending a lot of time on the highway. EGR only operates on extended part-throttle cruising over 170F coolant temp. If you change the cam to something slightly more lopey, it will accomplish the same effect, which is what they did with the LT4 engines in 96.
Sounds like a good roadmap to follow, thank you. I do plan on keeping it a 350 because I just don't think any stroking to 383 is in my book of things I want to do. I just don't feel right about the durability of a shorter rod compared to a rod made for that exact block. If I go up, I'll just go big and get a LSx 427 like I always wanted, or just save my time and money and get a C6 Z06.
As for the wheel bearing; grabbed the wheel assembly with your 12-6 position and there wasn't any play in it except for the rotor itself which I imagine is okay because the its compressed by the tire. Might just disassemble it to find anything needing updated. Rear end I will get to in the future because there's no issues with it currently, it's all front end. But I will remember those cold forged ujoints and half shafts.
I'll definitely look into those later 80s model starters sounds like a good deal for clearance on headers. Spot on with the injectors too, got my stethoscope on the things and those things are pretty rowdy, even ran the engine with valve covers off for a second to listen to the valve train.
Lastly for that code, I will go through the FSM flowchart on the code over again until I find the solution that makes it happy.
Thank you, usually when I refer to this forum for ideas on things to check or help on what to look for, I do see your name pop up occasionally with suggestions for the thread starter that are usually spot on and very knowledgeably placed, please keep on doing the C4 community/owners good, sir!
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Old 02-08-2019, 08:40 AM
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cadmaniac
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Before you replace the starter, remove the old one and inspect the entire flywheel. You might have teeth that are ground down, and that would require a flywheel replacement. That is more likely than the starter itself.

Last edited by cadmaniac; 02-08-2019 at 08:41 AM.
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Old 02-10-2019, 01:03 AM
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Originally Posted by cadmaniac View Post
Before you replace the starter, remove the old one and inspect the entire flywheel. You might have teeth that are ground down, and that would require a flywheel replacement. That is more likely than the starter itself.
I'll check that out, got the car up on jacks so I guess why not do that.
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Old 02-10-2019, 05:17 AM
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Hello,

I am also rebuilding an 1985 4 plus 3. Your car looks really good. I am on Guam. Getting parts is a challenge. Good luck with the car..
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Old 02-12-2019, 12:33 PM
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What @cadmaniac said WRT starter. How does it normally engage once it does finally start, ie do you have to do anything to get it to work? Next time it does it, before getting it to start, take off the starter and peek in there, any damaged teeth (if present) should be evident.
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