Thread: Project Sebring GT Spyder

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Next up, I welded up a section of curved fill pipe. I kind of goofed when I built the gas tank in that I installed fill hose connection on an angle. I thought then that it would be easier to hook up that way, but I really should have put it in straight up. I wasn't about to pull the tank and cut it up for that, so I just worked around it.

I also made a set of tubing bead dies for the bead roller and rolled a hose retention bead on the bottom of the fill pipe. I actually had to do this twice since I made the first internal die a little too big. The first time I used it, I managed to crimp the tubing perfectly around the die! Had to cut that one off and start over.

The last piece of this puzzle was a new aluminum plunger for the cap. The original part was designed to seal the cap when closed. It was spring loaded to apply pressure to the seal and keep cap pressed up against the lock bale. The cap wouldn't work without it, but the original wouldn't work with the internal secondary cap. It took a little fiddling to get the clearance just right.



After all the work, it turned out really well. There is even enough clearance for a locking cap. I had a flip cap on my T and found it open once after leaving it unattended for awhile so the locking option will be nice to keep curious folks from tampering with it. The hose is wire reinforced gas hose.

I like the way you solve puzzles!

Thanks 36. Most of the stuff on this car goes together like a Chinese puzzle! After this, I think I'm going to take up building ships in bottles. It couldn't be any harder!

Another change I made due to my back issues is a new transmission crossmember. Some of you may remember that I modified the trans tunnel to allow me to install a 4L60 automatic transmission if I ever needed to. With my back acting up like it has, I decided to build an adjustable trans mount that would allow me to install just about any transmission I wanted to, including a 4L80E. It adjusts down to 3 and 4-speed length, also. This will just make the swap process that much easier if the time comes and keep me from having to mess up the chassis paint. My intentions are to keep the T56 6-speed as long as I can deal with it, though.







I should also mention that the LT1 T56 went off to Texas to be converted to LS configuration. I had actually figured out a way to make the LT1 trans work on the LS (even though I was told it was impossible), but I was concerned that my makeshift conversion would give me issues down the road. By having it converted, I can source readily available replacement parts for repairs. I bought an LS style bell housing to go with the new configuration. The LS swap shifted the trans mount back about an inch, but that worked out fine with the new crossmember.

It's probably a good thing I decided to do it, too. While they were in the trans, they discovered that it had a failing reverse and second gear. The synchros weren't looking very good either. The car it came out of had been street raced, which was the reason it was in the salvage yard. It also got some Stage 2 upgrade parts, so I should be good to go for a long time.

I got a package deal on a lightened steel flywheel and a Stage 2 clutch with stock LS1 throw out bearing, too.

It occurred to me some time after I posted about the crossmember that I had used to wrong pictures. When I built the one in the pictures, I intended to run the exhaust over the top, but that proved to not be practical.

I had to remake it as a drop crossmember. The side brackets are the same, only the actual crossmember has been changed. Sorry for the confusion. This was all done months ago and I forgot to take pictures of the build at the time.

Here are some pictures as it is on the car now. Unfortunately, it's hard to see with the exhaust in place.

It's looking great. I really like the adjustable cross member. That T56 game can get expensive. That's why I stuck with the T10 in the camaro.

Well, as usual for me, this thread has been MIA for several months. Back when all the Corona Virus stuff hit, my company took no chances with the workers at my job. With little info to go on about how to protect us on the job, they decided to split all the workers up and went to a skeleton crew. Just enough people actually on site to keep things going. This meant that I had a lot of time off on my hands. Our governor also issued a stay at home order, so I decided to make the most of the time. I made up my mind to quit playing around and get the chassis to the powder coaters. To this end, I started spending long hours in the shop.

The bottom line is that, in July, I accomplished my goal and delivered the frame and most of the suspension parts to the coater! A couple of weeks later I had them back in my shop. I never took the time to post about this work since I was dead tired every night and pretty much just showered, ate supper and went to bed. During this time, we were having a heat wave that had the heat index hovering around 105 every day. This was a hard thrash with gallons of water drank, but it was worth the effort. Luckily, my back cooperated and didn’t protest very much about the long hours on my feet. It only complained during the last few days that were spent mostly bending and stooping for the final welding push. For a very short time at the end, I actually had a mostly complete car sitting on my lift! About the only things left to do were plumbing and wiring. It sure hurt my feelings to take it all apart again.

Going forward, there will be very little mocking up or fabrication. Everything that is assembled will be permanent and that feels extremely good! I have found a few minor items that will need a little fab work, but it won’t be major fab stuff.

Consider this a reset of this thread. There were many changes made to correct things that bugged me during the thrash. I got more work finished during this time than in most of last year. My intent is to make an honest attempt at documenting the final assembly. I will attempt to cover things that I built or changed to get to this point as well as stuff that has been built for a long time and never posted.

To get things started, here is a pic of the chassis loaded on the trailer when I picked it up at the powder coaters.

OK. I’m sitting here watching Hurricane Laura come ashore. The eye and major wind is predicted to go well west of us, but the big worry in our area is tornados that pop up with little warning from the bands as they track around the eye for a hundred miles or more. Looks like I’ll be keeping a late night vigil so that my wife can get some sleep, since she has to work tomorrow and I don’t. I figured that this would be a good time to kick this reset off with an update.

While I was eager to get started on the chassis, I decided to hold off on that and get the engine and rearend reassembled.

A little history on what’s going on. The aluminum LS1 that I originally bought for this car had to be replaced. I found out several months ago that some water had somehow gotten in three cylinders. This was a very early engine and these blocks were not recommended for boring. Only honing 4 or so thousandths. The rust in the cylinders was just bad enough to prevent clean up with honing. I might have taken a chance with it, but didn’t really feel comfortable with that. This engine was virtually new inside. The bearings and pistons looked like they had just came out of the box. The rods even still had the date codes on them like they were new, so all I really needed was a block. Unfortunately, I couldn’t locate a good LS1 block. I wound up with an iron 4.8 block that I had bored to fit the 5.7 pistons. Hard to believe that GM left enough metal in those blocks to be bored that far, but apparently, they did. The iron 4.8/5.3 to 5.7 build was pretty common back when 5.7’s were popular and still available in large numbers. I had to take the block to the Mississippi gulf coast to find someone that would use a torque plate. That’s a long drive, but I think that it’s worth it. The main downside to the iron block is weight. I don’t really like it, but that’s the way it goes sometimes. BTW- This was my first LS build. They are definitely a little different, but I had no real issues. It did take me about 3 times longer to build than a typical small block mostly because I had to verify that I was doing everything right.

I started the build up by mocking the crank, rods and pistons in the block with no rings so that I could see where the pistons were in relation to the deck. This block had to be decked a little to square it up and clean up some rust pitting around some water passages. I had read that LS pistons can be down in the hole or above the deck or anywhere in between. Mine were .005 above the deck on one end of the block and .006 above on the other end. I also plasti-gaged the main bearings just to make sure that the clearances were good in the new block. They all came up .0015.

Next I degreed the cam. It’s a Trick Flow brand part number 30602001. Intake center line was 110* on the money. Right where it was supposed to be. The specs on the cam are 216*/220* @.050 with .560 lift. This used to be called their Stage 1 cam, but I don’t think they call it that now. They started selling this grind several years ago.

I wrangled with cam selection for months. I looked at the LS6 stock cam, but it seemed to me to give up a lot on the bottom end for a few extra HP at the top. The TF cam gives up some on the bottom too, but no more than the LS6 and picks up a lot more on the top. The main thing I like about the TF cam is the “low intensity” lobes which should be easier on the valve springs. TF originally picked the “Stage” cam group that this cam was part of because they were not prone to valve float and were easy on the valvetrain.

The last thing I had to check was the head cc’s to see what head gasket I needed. I wanted a tight quench, but didn’t want a wild compression ratio since I wanted to run it on pump gas. Trick flow recommended at least 10.5 to 1 static for the cam I chose. My heads were some older CNC ported heads that I picked up at the local machine shop. They had belonged to a street racer and he was going to LS3 style heads. I’ve actually had them sitting around for over 2 years. I started to check the chambers and that’s when the wheels came off the train!

I knew the heads had been milled, but was very surprised to see the chambers coming in at 59-60 cc’s! They should have been around 66 in stock form. My heads must have been shaved a LOT. My CC’ing tools are pretty simple. Just a piece of Lexan with a hole in it and a large veterinary syringe marked in milliliters (same as cc’s). I thought my technique may be off so I pulled out the original LS1 heads and checked them. 66-67 cc’s just as they should be, so my measuring was most likely correct.

I knew before I fired up my compression ratio program that the numbers weren’t going to be good. I came up with a little over 11.7 to 1 with a .052 thick GM head gasket! Even worse, the dynamic compression ratio was over 8.5 to 1. I had hoped to keep that at 8 to 1 or lower for pump gas.

Now there are usually options, but in this case, none were very good. A thick head gasket was out of the question. The .052 was the thickest I really wanted to use. The early original LS1 heads I had were some of the worst stock heads GM made and I didn’t really want to use them. Which was why I got the CNC’d heads originally. I could have found better stock heads and had them rebuilt, but the only local shop that I trust is very busy with commercial customers and I literally would have to wait weeks to get them back. I also could have went to dished pistons but that would mean rebalancing the rotating assembly and there again, it would be the same shop doing the work. Weeks of waiting. My only real choice, it I wanted to solve this issue quickly, was to buy new aftermarket heads and that was money I really didn’t want to spend. But, it really was the only choice that kept me moving forward, so I bit the bullet and ordered new heads.

The heads I picked are Trick Flow Fast as Cast 220’s. They have 64 cc chambers that are CNC cut. The ports are as cast, but they are very, very smooth for castings. The short turn radius at the valve feels perfectly blended to the floor and bowl. I doubt you could gain enough with a grinder to make it worth the effort on a street engine. They also have a raised valve cover rail so that you don’t need a spacer to run roller rockers. It just so happens that I had picked up a set of Harland Sharp rocker arms months ago. Trick Flow also changed the valve inclination a few degrees to improve flow. Several years ago when these heads first came out, it was claimed that they were good for 15-20 HP more than similar heads.

With the new heads and a .045 head gasket, my static compression came out to 10.7 to 1 and the dynamic is around 7.7 to 1. I’m hoping that those numbers along with the .039-.040 quench will help this engine tolerate pump gas.

The engine assembly went pretty smooth even if it was slower than I would have liked. I felt like I was building my first engine! All the torque to angle bolts were a real pain to me. I like setting the torque wrench and getting on with business. It did get easier the more I did it, but I still didn’t really like it.

Then there was the whole oil pump alignment thing. What a pain! Disassemble the pump and scrape up enough shims to hold everything in alignment while you tighten the mounting bolts. It’s obvious that this engine was designed to be assembled by robots that can stab a part in perfect alignment with nothing other than what it’s camera sees.

I did get lucky a few months ago and scored a set of front and rear cover alignment tools. These the are Kent Moore tools that GM recommends for this job. They were laying on the shelf at a local pawn shop and I picked them up for chump change. This set of tools is stupid expensive for what it is. Something to the tune of $300-$400!!!!! The set is a cast brass(bronze?) part that does the actual alignment and a plate that bolts to the oil pan rail to keep that surface aligned.





The rear seal came with it’s own installation tool already in the seal. It’s a double lip seal and is marked which way is out. The trouble is. The writing is very tiny for my 62 year old eyes. I had to get it out in the sun to actually see the markings. I marked it to make sure I got it right in the shop.



I made one mod that the block didn’t come with. I added this LS2 timing chain damper. The boss was there on the block, but it wasn’t drilled. Getting this thing lined up for drilling was tricky. I made a tapping guide out of aluminum to hold the tap square to the block. Sorry no pics of that operation, but it turned out ok, I think.

Another thing I added was a better windage tray. I’m already using an LS2/LS3 Corvette oil pan. The Vette pan is pretty close in size to the LS Camaro (F body) pan, but has more baffling.



The windage tray is by Improved Racing. It comes with a very close fitting crank scraper and has extra baffling with trapdoors.


Crank scraper


New windage tray compared to the factory part.

I also intend to install an Accusump oil accumulator. The LS Vette engines with the low profile oil pan like mine were known to have oil starvation issues if cornered really hard. Bob Bondurant’s driving school was losing engines to this issue. The GM engineers recommended adding an extra quart of oil for tracking the car. That sounded like a bandaid solution that would cause a lot windage. The Accusump is like poor man’s dry sump system and should cure the starvation issue without all the windage. Here’s a video if you want to know about it. This is a moroso, but the principle is the same.

https://youtu.be/vyaGoj60A6s

Thanks for the update Mike, I've never had to open up a LS based motor, but I've heard they are a little bit different, and nice score on the oil pump alignment tool! It's going to be fun watching this get butt back together, hopefully for the last time for you!

Very nice progress and some more nice parts too! The score on those tools is awesome!

Thanks. Glad ya'll are still following along.

I did run into one unexpected issue with the new heads. This is hot rod building and I should have expected something to pop up to throw a monkey wrench in the plan.

The old CNC heads did have bigger ports than stock, but they were not that not much bigger. The TF heads are quite a bit larger. My original plan was to run LS6 exhaust manifolds and they matched up with the CNC heads pretty well. I liked the tri-y design and they offered stock reliability. While trial fitting them to build a custom dip stick, I realized that the ports in the manifolds were visibly smaller than the exhaust ports in the TF heads. I could have ported the manifolds where they mated to the heads, but they have fairly long individual runners (for stock manifolds) that I can’t get to to open up.

I do have a set of long tube headers that a friend gave me to see if they would fit the car. They are for a 69 Camaro and I did manage to get them on the car during the initial fab work, but they were very tight to the frame rails at the collectors and one tube on the passenger side was close to that frame rail. I also thought that they hung down a little more than I liked. I really wasn’t wanting to run headers on this car, but they do fit the exhaust ports and I already know that they kinda fit the frame. I don’t think anyone will have anything on the shelf for a kit car that hasn’t been made in 25 years and never even came with an LS engine. So, it’s either make these work, build custom headers or go with the LS6 manifolds and live with the small ports. Looks like I’ll be running headers! The big issue is that I already have a complete exhaust system in stainless, the 2nd actually, and it looks like I’ll be doing at least part of a 3rd. At the very least, I’ll have probably have to put some bends in the collectors and dent the tube next to the frame. I may just whack most of the collectors off and use V-bands to attach some offset collector extensions. The length issue might be solved with some skid protection. I’ll just have to wait until I get the engine back in to come up with a solid plan.

I can’t find a brand name on these headers which leads me to think that they are Chinese knock-off parts. They are stainless of some kind, probably ChiCom 409’ish. The upside is that they do have very thick flanges, fit the heads well and they were free. Of course, it goes without saying, that the long tubes will be a lot better for power.





Here’s my fitment issue. The pics are from the build.




I’m pretty sure I can put some offset bends in the collector and cure this. Might not be the best for power, but that’s the way it works out sometimes.

Where the collector gets close to the frame bracket would it work to cut the collector back 2" or 3", then weld on a reducer to the size of your exhaust tubing and put the V-band clamp flange on there? Hard to tell from the picture how much additional clearance it would garner, just a thought.