Project C4, 85 Corvette

[D_Eclipse9916]

Good fix, I actually did the same thing (LS6 valley cover breather setup) on mine. Supposed to help the engine breathe better as well.

I have never seen someone cut out that section though, there is a block-off piece available from GM that pops in without cutting and is OEM. However, you look like you needed more space than even that! Nice job!

[Steve85]

solid fixes! glad to hear its getting put through its paces too, if you've already covered over 5k miles since the swap happened. doing it right

Making it a fun reliable driver again was the whole point of going this direction. I picked up the younger son from school in it to take him to soccer practice on Tuesday and when he walked out and saw it he screamed "race car! awesome!" and ran to get in it. :thumbup:

Good fix, I actually did the same thing (LS6 valley cover breather setup) on mine. Supposed to help the engine breathe better as well.

Thanks!

I saw that, your switch to the same breather had a lot to do with pushing me this way.


And I also switched back to the CCWs for a little while. I really want to do the centers gold. :wink:

[Goodspeed]

And I also switched back to the CCWs for a little while. I really want to do the centers gold. :wink:

[JPolen01]

Goodspeed coming through with the amazing gif again. CCWs are so choice.

[Jeff]

Goodspeed coming through with the amazing gif again. CCWs are so choice.

+1

[Steve85]

Holy shit time flies - can't believe it's been 19 months since the last post! Makes me very happy to have done the LS, ownership has been very easy since the swap.

I had a vibration in the drive-line that increased with speed so started with the easy stuff. The way the LS mounts, the drive shaft yoke gives up about an inch of spline engagement on the output shaft and wanted to check with some pros whether that mattered. Had a good conversation with a local off-road shop that has an in-house drive shaft business, had them do the u-joints and check the balance and vibration is gone.

I also had a bit of a shimmy in the steering wheel and a more general vibration that was fixed with a fresh wheel balance. When I took them off and looked real good, I noticed a few weights must have been knocked off at some point. Drives much better now with a couple annoying vibrations gone!

Desperately need seats, just have to decide whether to recover the existing or go with HPDE friendly seats. I have a hard time pulling the trigger on them since I'm still pretty salty about being ripped off by company that went out of business after I ordered brand new seats. It's only been 8 years...

Could also use a carpet refresh in the back area and cleaner stereo equipment install. Hopefully get to this stuff this summer since I don't have to dick around with the engine all the time now.

Have a few body issues I'd like to address too.

Or just sell it and pick up a ZHP...

[HAULN-SS]

Don't sell it without posting it here first

[Steve85]

BLUF - I got new tires which are great and discovered I was 20psi down on fuel pressure at WOT. The car feels better with the much better tires and has about another 50HP with a better fuel pump! The deets:

I decided to finally get new inner barrels for the front wheels since one was welded. 

The plan was to get get a diff't width and then swap the front / rear inners to go from a 12.5 / 10.0 setup to 11.5 / 11.0. I bought second hand and the barrels ended up being same size as rears so the fronts got bigger but the rear didn't get smaller. (weird because I had pics with a measurement, so not sure what happened) New tires were in order and I found some Yoko Advans on ebay that were brand new, just a couple years old and they mounted and balanced with minimal weight. The previous setup took a fruit roll up length of weights to balance and never felt right.

I was very excited until I got 100 yards from the house and couldn't accelerate. So pissed...

It seemed the problem was with #8 so I did all the usual swapping coils, plugs, wires, injector, fuel pressure was good even when it started to stumble. It was just a funny thing, no matter long it idled in the driveway or I revved it without load, it was good, take it on the road and 100 yards out, it would shit itself. I had to try something so I went with an O2 sensor for that bank, no change. Then I noticed this:


I decided on a 25% underdrive unit for mad HP gains. And to hopefully not kill the AC compressor I plan on installing that was originally designed for about a 4500 rpm redline.



The side hope was that the vibration was causing a false knock. The pull and install took a total of 4 hours, 3:45 of that was finding just the right mix of stuff to pull the balancer (borrowed a kit fro Advance but the LS crank has a stupidly deep snout). Got it done without having to pull the steering rack so that was a bonus. I heated the damper as instructed by the manufacturer and it went on smooth.

Unfortunatley, the car still ran like crap. Back to the basics, fuel spark compression. Which really means, the right amount of good fuel, hot enough spark at the right time and enough compression.

I decided to get into the tank and noticed a murky fluid settled on the bottom. Like, you could see stuff floating 3/4 of the way down a full tank. It was actually pretty cool, like a layered B52 shot. Here is a comparison of the fuel from the bottom of the tank and the top layer:


I hooked some fuel line to the pump outlet and pumped out 4 gallons from the bottom of the tank to gas cans. I timed it, it took 1:55 to pump out 1 gallon, which becomes very important... Reinstalled the pump and test drive was great! I had shitty water filled gas. I think it was actually the HEET I put in the night before that pulled all the shit to the bottom.

During the test drive I still had the FP gauge taped to the windshield. At full throttle, and not falling on its face anymore, it quickly dropped from 60 to 40, whoa! I always thought it was a bit flat up top but figured I needed a tune. It has a slight cam and Z06 intake on a standard LS1 tune.

So I pulled the Walbro 255 out of the drawer (I have no idea why it wasn't already in the car..) and installed it. The tank in a C4 is not in a great spot from an engineering perspective, but it sure is user friendly! WOT pull and it stayed at 60 psi, yay! And by yay I mean..

FUCK ME TO TEARS AGNUS - WHAT HAVE I BEEN MISSING!?! 

Probably 50 HP at WOT from 2500 rpm on up, that's what! It pulls hard all the way now. I'm not sure at this point I gave up anything to the previous 408.

I'm not sure if I got shitty gas after putting in the O2 sensor when I topped off the tank or it just built up water from sitting for a while. All I know, I've been missing out for years and this has been a great discovery!

[Goodspeed]

Yessss so glad to see this thing is still alive! Congrats on 50 horses after a simple job, I need to ride in this at the next MM show or whenever

[Senor_Taylor]

Wow, this sucks for sure, but you also knocked out a ton of maintenance and gained a ton of power so.... good thing?

[Steve85]

Yeah, it was a goodish thing, could have done without the balancer problem but glad it was bad fuel and not broken valve or worse. And it got me driving around with a FP gauge taped to the windshield where I discovered the fuel delivery problem!

Well, one too many fuel pump/sending unit removals on a 30yr old tank has ruined the mounting area. It was rusting out and I was kind of nursing it along but threads are finally gone from one of the holes. There is also good evidence that the bladder in the tank has given out and is allowing fuel/moisture behind it which then eats at the metal tank. Becoming more of a regular thing on these as they age.

I ordered a new tank and sending unit today and will be replacing the tank over the next few weeks. Should be fun, have to remove the rear bumper cover which is held on by 127 hidden 7mm nuts that are surely in perfect condition, easy to access, and eager to be removed. Might have it repainted while its off since there are some issues at the bottom and around the marker lights.

Oh, and might be a problem with the hydraulic throwout bearing, I keep losing fluid and no sign of leaks on the lines from the master cylnder to where they enter the bellhousing. Engine has been great, just need these other things to cooperate...

[Steve85]

I got the new tank and sending unit in and everything buttoned up.

I had to pump an almost full tank out so I set up my battery charger to power the pump directly and ran some fuel line into a few gas cans. I roughly measured the flow to compare to the other fuel pump that was leading to the fuel starvation at higher RPM. The old pump did something like 130 lph and the Walbro did 226 lph. It's rated at 255 but the charger was a low setting and probably only delivering 11 volts or so.

The actual tank replacement wasn't as bad as I thought, the worst part is really getting the tail lights out (and back in) which you have to do through the hole behind the license plate. I don't know what the original assembly procedure was for these cars, but I can only imaging they hired the fairest of folks in all of Bowling Green, KY to reach in there...



Once the tail lights are out, it's just feeling around for the 10mm nuts at the sides of the bumper and a few screws along the top. A couple more 10m along the side above the marker lights and the bumper just slides off backwards revealing the tank and impact bar.



4 bollts on each side to drop out the tank and impact bar as a unit.



And the impact bar was apparently put to good use at some point in the car's life. You can see the up right corner is bent in and the absorber is mangled. It's a big piece so shipping is killer. I'll try to find one locally and if not, ask one of the parts vendors for Corvettes at Carlisle to bring one on the truck.

New tank strapped in and ready to go. 



Fired it up and checked for leaks and so far all is good. Nice to have a working fuel gauge too. The old sender would just read down to about half tank and stay there. 


Next up is addressing the loss of fluid in the clutch system. I'm pretty sure at this point that the pedal is travelling a bit too far and overextending the throwout bearing. I don't think the seal is blown out since it doesn't leak unless it's being used. I've read that once the seal is blown out, fluid just keeps leaking via gravity. I'm working on an adjustable clutch pedal stop this week...

[ScottyB]

nice work, looks like a nice arm-slicer though!

feeling around for the 10mm nuts at the sides of the bumper and a few screws along the top

so how many times did you drop your socket/screwdriver and have to collect it and start the process all over again?  because that's something i'd do.

[Steve85]

nice work, looks like a nice arm-slicer though!

feeling around for the 10mm nuts at the sides of the bumper and a few screws along the top

so how many times did you drop your socket/screwdriver and have to collect it and start the process all over again?  because that's something i'd do.

I thought I was in for cuts but luckily the SMC is relatively think and pretty rounded off at the the edges. If this was stamped sheet metal, I'd have emo arms no doubt.

So many times when trying to get the tail lights out!   . Got lucky and had it drop through to the ground all but once. I felt like I was on the Price is Right playing Plinko.

[Steve85]

My hydraulic throwout bearing finally gave up the fluid for good. I had to fill the reservoir a couple times over the years and now it was just emptying out after a few presses of the pedal. This is the old one, a "stock" version from Speedway motors since I'm using a stock C5 clutch.



Turns out, using the threaded rod there as the stopper was eventually going to kill this thing anyway, it had rubbed a good indent in the bleeder outlet!

The new one is an updated heavy duty version from RAM, recommended for street car use. I made room in the garage, pulled the car in, put it up on jack stands, removed a bunch of bolts and this fell out:



I just looked on my phone and apparently I was NOT in a picture taking mood during this job. This is it. It makes sense though, I was on my back almost the entire time. There is a little area on the garage floor now where can see that I rubbed everything that fell off the bottom into the floor   Drained the old fluid (most by accident) and replaced with new gear oil. I had to take a few measurements to set up the bearing clearnace so I had to go back in and remove the clutch and flywheel. I measured about 15 times and felt pretty good I had the right number of shims in there.
This pic is from the original install of the old bearing, the gold rings are the shims to give an idea how it is set up. This new bearing has more travel and took less shims.
 

Had a delay in getting new lines, the old bearing used -4 lines and the new one -3 lines. I tried to source locally but all the hose makers around are more industrial focused and don't have anything that small.

I really thought it would be easier but forgot the LS sits farther back and only tilted a few degrees before it hit the firewall and made it difficult to clear the trans tunnel with bellhousing. There was jusssssst enough room, which meant going back in was going to suck. And it pretty much did, try this, try that, then another thing and finally it jumped right back in. Didn't help at all that I was trying to balance it on a regular jack. There is a C beam that bolts the trans tail shaft housing to the rear diff nose and it makes everything a real PIA. Put all the other parts back on, bled out the bearing and hoped like hell it didn't blow out right away, I've heard horror stories. It was a little soft at first with some tiny bubbles coming up into the reservoir but after a driving it a bit the pedal firmed up and has been good!

While I had it up in the garage I decided to tackle a couple other small things.

The power steering setup used the orginal reservoir with some molded hoses to the pump. It's like they were made to fit except belt clearance was minimal and I had a ziptie providing insurance. The hoses were also slightly different sizes so it never really seald at the reservoir. I went with easy button and ordered a kit from Summit that came with a factory C5 reservoir, bracket, correct hoses etc. Took about 5 minutes and it's much cleaner look and no leaks!

I also needed to finish my rear brake job and put new pads and rotor on the right side. And since it was up in the air I finally decided to tackle the parking brake which hasn;t worked I think ever. I broke out the manual, followed the adjustment procedure and got it working again. Until I put everything back together and pulled the car out... I pulled the brake handle and it wouldn't hold. I got out, kneeled next to the car, pulled the handle and...it worked. Got back in the car, pulled the handle, no worky.   

So, while in the car I pulled the handle up and pushed it a bit towards the outside at the same time and it worked. (When you are sitting in the driver seat, the parking brake handle is at your left knee. After it's pulled up and engaged it goes back down to get out of the way) It seems the ratcheting mechanism has become a bit finicky after 30 years and a million pulls and just the different angle made  the difference! This is one of those little things that is soooo nice to have working again.

It's been a good / bad few months with new inner barrel and fresh rubber up front, new leak free fuel tank, working fuel gauge, some new found power up top thanks to a proper pump, good rear brakes, good clutch and working parking brake. Some much needed stuff after a few years of overall neglect and it feels good to drive again! 

Plans ahead are to clean up the bottom and under the hood now that the leaks are fixed. And I have some cracks in panels I want to try my hand at fixing and prepping for paint.

[Steve85]

Some time ago at an autox (this was the first college solo I think)  i looked at on course pics and had a lot of positive camber in the rear around turns. First pic looks normal (driver rear) but second pic shows how positive it went when loaded up.






I got an alignment and used the VB&P specs for aggressive street which included going with offset bushings up front. (occasional casual autox) At rest, there is definite negative camber in the rear.

At my latest autox this weekend (MBCA at James Wood High School in Winchester), I decided it would be cool to get a shot of the rear suspension in action. Here it is below. I was very surprised to see the inboard mounts for the camber rods deflecting in/downward when turning. If you pause at the :32 mark, you can really see the deflection, the adjustment bolt is lower and more inward than the other side. That point on the course was a medium right hand turn after a straight, so it would load up the left pretty good.



It's hard to maintain camber when the mounting point is moving and the way it mounts there is no (or shouldn't be) pivot point. 

I tested the bolt tightness and it wasn't loose, but it wasn't as tight as it likely needs to be. I think this probably allowed just enough movement to make things worse over time. 

As suspected, the lower bolt hole has been worn and is now a bit slotted. You can see in the pic how much wider the bracket hole is than the hole the bolt goes through. It looks like it is offset, but as the photo was taken the left side of the bracket hole lined up properly with the diff mount such that the bolt could go through. 



I tightened the bolts and then went for a test drive to see if they would hold for now until I can get to a permanent solution. In the video, it looks like they holding for now. (And the rear definitely felt more stable)



I think the other contributing factor is that the bolts are not the factory original and while they are grade 8, they are "all thread". I believe this makes them just a bit skinnier than if they were a non-threaded shaft with threaded end (partial thread). Kind of what Dave was getting at and a great point! (I'll also look into the suggestion on the eccentric, these are actually VBP Smart Struts and you're right, really no need for the eccentric with the adjustable rod)

My solution will be to either get new brackets or have these welded to repair hole, order new flange headed partial thread bolts, and double check torque on installation. Then go back in after a few drives to make sure they aren't coming loose. 
Anywho, pretty cool to see the suspension in action (which was really the point of this shot to begin with ). It's amazing how much movement there is despite feeling so stiff.

[Senor_Taylor]

That's a super cool shot! Amazing to see how much everything flexes!

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[ScottyB]

wow, i did NOT expect that much movement. really great shot there. glad it worked out for now, at least you've figured out it was a simple bolt vs. throwing adjustable rods and alignment sessions at it!

[Steve85]

I don't drive this enough mostly because with a heavily raked windshield, glass top, and all glass rear hatch, it is a blistering hot greenhouse without AC. Basically a Jetsons car.



I've had a Holley bracket for a while now that allows the old GM R4 style radial compressor to be mounted on an LS. A few things had me putting it off - 

1. The area it sits in was already pretty crowded with heater lines and I wasn't sure the compressor bracket would fit with modifying the water pump to change the heater core outlets
   
2. I would need custom lines made 
   
3. The bracket did not fit my slightly older style R4 compressor (it's made for slightly updated versions of my compressor) 
   
4. I have very little AC experience.
   
5. And just being lazy about it...
   

Decided the other day though it was time to take this box of cold air and get it installed.

 

First issue was the compressor didn't quite fit the bracket so I needed to grind away a very small section. Not sure what the "boss" is there for, but it's not on the 91+ compressors.



With that out of the way I was able to install the compressor in the bracket and test fit to the car for belt alignment and see exactly what I had to do to the water lines. The green line I think is going to be OK, it fits under the bracket. I think I can make the red one work by shortening the hose piece that comes up from the water pump. It's funky because the inlet to the pipe points up but the hose is coming from below it. Just needs to be a "tighter" install.



I dropped it in for a test fit and it does look like I can squeeze the second water line underneath the bracket. This is a pretty big deal for the install since removing and modifying the pump was going to be a big PIA. Belt alignment also looks good so I think I'm good to go with this compressor. 

With it dropped in, I started planning for the lines I need to make. 

The large line from the accumulator to the evaporator will work so I only need to make two lines, the line from compressor to condenser (orange) and another from the accumulator to the compressor. For the comp to accum line, I have 3 possible paths, red, blue and yellow listed in order of preference. (long live MS Paint!)



I'm building out my shopping list through Vintage Air and Nostalgic AC. I'll end up ordering like $250 worth of fittings and only using about $50-75 worth. A lot like a home plumbing project but these stores aren't right up the road so a little overkill to hopefully not get stuck.

Hopefully get everything in this week / weekend then I'll need to figure out the wiring.

[Senor_Taylor]

Why does this need to be done? What's wrong with the stock system?

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