The Thermostat Housing On A Corvette LS1 Shark Engine - The Construction Zone

A Small But Vital Modification On The C5 Shark's LS1, And A Look At Two Other LS1-Powered Sharks

Bob Wallace Jun 1, 2002 0 Comment(s)
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This month we're going to step back from some of the "big stuff" that's going into the construction of the C5 Shark and take a breather of sorts. That's not to say nothing is happening on the project. Instead we're going to focus on one relatively small, but absolutely necessary, bit of work on the GM Performance Parts LS1, then take a gander at two readers' LS1-powered Sharks-one completed and the other still in its own "Construction Zone."

As I mentioned last month, we've heard from several readers regarding the "backwards" positioning of the LS1's thermostat housing in four of the photos in the March installment. I also mentioned last month that we had a fix for this problem, which will be the main thrust this month.

The thermostat housing on an LS1 mounts on the front of the water pump and, in stock configuration, points outward at roughly a 45-degree angle, on a horizontal plane. That works fine in C5s and late F-bodies (Camaros and Firebirds), and not at all in the narrow confines of a '63-82 Corvette frame, at least when the LS1 is situated in the original positioning for the stock, original drivetrain. (I went into some detail last month about why we opted to replicate factory engineering rather than set the engine where it fit best-or easiest.)

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The thermostat (arrow) is supposed to aim outward. The crew at Bow Tie Overdrives flipped the one on the C5 Shark's LS1 180 degrees just to get it out of the way. To make it work in this application, the housing will need to be cut and the outlet aimed straight forward.

The talented crew at Bow Tie Overdrives has done a great job thus far on the C5 Shark project. But, while it may seem like a minor task, the revisions to the thermostat housing fall a little out of their realm, and once again fall right into street rod territory. Ergo, we took the thermostat and its housing, an aluminum casting, to a street rod fabricator, Barry White's Street Rod Repair Company.

The best known car to roll out of the SRRC shop is Richard Berg's "Impact," an entirely hand-formed, all-steel, '33 Ford roadster-with an F-body LS1 and 4L60E for propulsion. Among the honors this street rod has been accorded is one of the most exalted-America's Most Beautiful Roadster at the 2001 Grand National (nee Oakland) Roadster Show. Yeah, the car is that good. Anyway, to make the LS1 fit under the hood sides of the '33 roadster its thermostat had to be modified, and ended up being pointed straight ahead. You may be thinking that a show car doesn't need to be truly functional, and in some instances you'd be correct. But Mr. Berg is a firm believer in driving his toy, to the tune of nearly 3,600 miles, in between shows in the past year and he has experienced absolutely ZERO problems with the roadster.

If it works on Impact, it certainly oughta work on the C5 Shark.

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Chad Vogele, a fabricator at Barry White's Street Rod Repair Company (just down the street from VETTE's palatial editorial offices) has modified several LS1 thermostats for use in street rods, and knew exactly what to do. First, he disassembled the unit, removing the thermostat and the rubber O-ring seal from the housing.

What has to be done is to take the thermostat itself out of the housing, cut the housing apart (where you cut is critical!), reposition the radiator hose-end of the housing, and TIG weld the thing back together with the hose-end pointing straight forward. The housing is an aluminum casting, with a nice finish to it. It is, however, an inexpensive casting, and is fairly porous. Aluminum is not the easiest metal to weld under the best circumstances, to weld a porous and fairly thin aluminum casting requires a high level of skill, and TIG welding, while not the simplest process, gives a very high measure of control.

On a recent Saturday morning we headed over to SRRC with one LS1 thermostat assembly, as well as cameras and film to record the procedure while fabricator Chad Vogele did the deed. Rather than blather on and on, we'll let the photos tell the story. And while this may seem like a fairly minor task, it's an important step ahead on the C5 Shark's road to completion.

Our Way Ain't The Only Way
This whole thing about swapping the Gen III (LS1/LS6) into early Corvettes is in its infancy. The engine has been in production for just 5 years, appearing for the first time in the '97 C5 and a year later (and in very slightly revised form) in Camaros and Firebirds. We're not exactly talking huge volumes of vehicles or across-the-board applications.

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Because the housing is a critical part of the cooling system, and any sort of minute leak is a major no-no, Chad carefully grinds a taper (for maximum weld penetration) onto the housing body and neck.

The traditional Chevy small-block was widely used in internal combustion vehicles of all descriptions, and was in production for well-over four decades. Literally tens-of-millions of the classic small-block have been built over the years; they're commonplace and inexpensive to buy and/or build up. By comparison, the relatively new and decidedly limited application Gen III is not exactly run-of-the-mill and fairly expensive to come by, whether it's C5 or F-body spec, new in a crate or "salvaged" from a totaled Corvette, Camaro, or Firebird.

The street rod guys are doing more and more with the LS1 (and LS6s), as are professional constructors like Paul Newman's Car Creations (Dick and Barbara Lagasse's '62 in the March '02 issue). Then there are guys like yours truly who, for whatever reason, go charging off, blindly, into unexplored terrain, game (or dumb) enough to try out something new and different. Thus I was very happy to hear from a couple readers who have succumbed to the same sort of madness (Gen III engine in a Shark) that I seem to be afflicted with. One's car is on the road, the other's is apparently at a similar stage of completion to the C5 Shark, and both cars are older than mine.

Colorado resident Joe Kring is in the process of fitting a "sort of" '97 C5 LS1, linked to a late C4 ('94-96-spec) 4L60E, into his '69 roadster. The LS1 is something of a hybrid-a new block and reciprocating assembly (replacing a "hydraulicd," unit that was covered by insurance after ingesting water) with ported '97 heads and a LS6 intake manifold. Joe is using the C5 oil pan and exhaust manifolds in his installation. He is utilizing adapter plates and 350-style motor mount cushions from Street & Performance.

There's enough difference in Joe's installation and what's being done on the C5 Shark that his power steering ram or slave cylinder clears the C5 oil pan (which is deeper at the front than the F-body spec one on the C5 Shark's LS1). On the other hand, while our GMPP 4L60E (a Tahoe police-specification unit) fits within the '76 floor pan and tunnel with no clearance problems, Joe tells us that he's had to cut and rework a 4-inch area on the passenger-side floorboard, near the tunnel and toeboard (where the floor goes upward to the firewall) because the trans servo hit the floor in that area. As of the second week in January, Joe was still working out the details on his transmission crossmember modifications.

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Next, Chad cleans up the cut surface of both the housing body and neck on a belt sander. This also gives him a chance to fine tune the angle at which the two pieces will be rejoined.

The second reader's LS1 Shark is a '73 roadster. Known to us as "Vette0617," he is from Ohio and has a big jump on both the author and Mr. Kring, having completed his install on June 5, 2000! Interestingly, this particular LS1 swap was to replace an L98 that was pulled from the '73 for installation in an early Camaro.

Vette0617 used homemade .625-inch aluminum adapter plates and 350-style motor mounts to locate his Camaro Z28-sourced LS1, which is hooked up to a matching F-body 4L60E. He also reports that he was able to reuse the fresh, stock C3 radiator with the LS1, and utilized a standard '73 small-block lower radiator hose after trimming off about 2 inches from "the straight portion of the hose." He reports that Mark Campbell of Street & Performance provided valuable technical help.

Vette0617 and his '73 have amassed about 6,000 miles since the swap was completed, "without any problems." You can bet that we're going to give him a call the next time we're in the Cincinnati area!

Actually, we're anxious to check out both of these unique Sharks, to photograph them, look over and discuss other people's approaches and solutions to this rather formidable swap, and maybe see how they drive. As we learn more about these other LS1 Sharks, we'll pass along the data.


Chevrolet Performance Parts
Detroit, MI 48232
Bow Tie Overdrives
Hesperia, CA 92345
Barry White's Street Rod Repair Company
Placentia, CA 92870


How To
Check out the thermostat housing on a Corvette LS1 Shark engine as we provide the tips to correct it!
Bob Wallace Jun 1, 2002


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