| The reason for the install was to provide added clearance for exhaust and to make changing the oil filter easier. Each engine swap is different. Some need more clearance than others do. There is more than one way to achieve the same result. PARTS: 
COST: - Adapter - $40
- Gaskets - $5
- Bolts/Washers - $2
- filter - $2
INSTALLATION: - Drain the oil.
- remove filter
- Wipe down any oil/dirt/etc.
- remove existing adapter and bolts
- clean again
- assemble new adapter with gaskets.
- install new adapter
- torque bolts to 14-19 ft-lbs
- install new filter
- check for leaks
Here is a picture of my install 
Here is a picture of the old parts and the new parts: 
Notice that the old bolts are special. They are a 5/16th bolt but the hex head is that of a smaller bolt. This is for clearance reasons. NOTE that my picture has standard grade 5 bolts with the 1/2 socket. In the first picture, top right there is a small picture of the interference between the bolt heads and the adapter. Thus you NEED cap head bolts if you want to torque it correctly OR you can buy the correct bolts from GM, but they are not cheap. Make sure to use grade 5 or higher bolts, as the 14-19 ft-lbs is higher than anything under grade 5. Stainless is out of the question too, unless you know the exact composition of it. Most stainless bolts are grade 2, although I have seen some that are grade 5. Be safe; get the grade 5 or higher. BEFORE AND AFTER: 
Here is the result. You can see much room is gained with the adapter install. Now I can replace that bad bend on the exhaust manifold with a freer flowing one. In my opinion that bend is restrictive. 
GENERAL NOTES: Make sure that your adapter fits correctly. Most V8 blocks should be machined for the same distances, but I suspect there were variances over the years. Thus if you have a 1969 block, it might not work. If you have a 1987-up, it should fit correctly since oil coolers were available from the factory and used the same idea. GM released a bulletin about oil leaks, see below for a synopsis. The fix is to install a washer under the bolt. I used Grade 8 washers as they are manufactured to tolerances, unlike the grade 1-5 you get. That's it. I hope this is useful to those that want to do this swap. BULLETIN
PRODUCT CAMPAIGN concerning OIL LEAK AT OIL FILTER
1992 CHEVROLET CORVETTE
Source: Chevrolet Product Campaign
Bulletin Number: 92C08 - (06/15/1992)*
General Motors has determined that certain 1992 Chevrolet Corvettes with LT1 engines may develop an oil leak at the oil filter area.
To correct this condition, install washers under the oil filter adapter bolts.
VEHICLES INVOLVED
Certain 1992 LT1 engines
PARTS INFORMATION
Parts required to complete this campaign are to be obtained from General Motors Service Parts Operations (GMSPO).
Part # Description Quantity
00120393 Washer 2
25010908 Oil Filter (PF51) 1
INSTRUCTIONS
Remove oil filter & forward adapter bolt.
Add washer (PIN 00120393) under bolt head.
Reinstall bolt with washer and tighten, but do not torque at this time.
Remove rearward adapter bolt.
Add washer (PIN 00120393) under bolt head.
Reinstall bolt with the washer and then tighten, torque both bolts to 14-19 lb. ft.
Now install new filter PF51 (PIN 25010908) and tighten 3/4 to 1 full turn after initial seal contact.
Add new (synthetic) oil as required.
Run the engine and check for leaks.
If leaks are found, then replace the gasket and seal. Original Bulletin Copyrighted by General Motors Corporation ©®. All Rights Reserved.
Related Forum: 1984-1996 Technical Discussion http://corvetteactioncenter.com/forums/forumdisplay.php?s=&forumid=4 Submitted by: Mark_ZZ3
Edited by: Dougofthenorth
Rev. 27AUG04
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