PN 3830711 is a production steel shim gasket for 4-inch-bore Gen I engines. It is 0.026-inch thick when compressed and should only be used with cast-iron cylinder heads.
PN 10105117 is a composition head gasket with stainless steel surfaces. This gasket is used on 4-inch-bore Gen I motors and has a 0.028-inch compressed thickness. It can be used with cast-iron or aluminum heads and is recommended for marine engine use.
PN 12557236 was used on the ZZ4 crate engine and other 350 HO engines. This composition gasket has a compressed thickness of 0.051 inch and can be used with other cast-iron or aluminum heads and 4-inch bores.
PN 10185054 is a heavy-duty, competition composition gasket that is Teflon coated with solid wire fire rings. Compressed thickness is 0.040 inch and it should be used with 4.0- to 4.165-inch-bore Gen I blocks. This gasket does not have any steam holes for use on street-driven siamesed bore 400 blocks. If used on the street, drill the steam holes in the gasket and use heads with steam holes.
PN 14096405 composition gasket has a stainless steel face on one side and graphite coating on the other. Compressed thickness is 0.028 inch and it is for 4-inch-bore Gen I blocks.
PN 10168457 is a composite head gasket for the 1992–2001 aluminum headed LT1 engine. It has a compressed thickness of 0.050-inch.
If you are building a siamesed 400 production block and you intend to use the motor on the street, you need to use a 400-style head gasket with extra steam holes and be sure there are matching steam holes in the heads you use. If the heads you intend to use do not have the required steam holes in their deck, you can use a 400 head gasket as a template to locate and drill the six extra steam holes in each head. If you are going to race a 400 small-block full-time, there is no need to drill the matching steam holes in the heads. Coolant flow at engine speeds above 3,500 rpm is sufficient to keep things cooled down.
Chevrolet Performance offers a Cylinder Head Installation Kit for the 5.7L L31 engine (1986 and newer Gen I engines). PN 12499223 is supplied with two head gaskets (PN 10105117), two center-bolt valve cover gaskets (PN 10046089), and intake (PN 89017465) and exhaust gaskets (PN 12550033).
When overhauling an engine, it’s best to go with a complete gasket set. Chevy Performance offers two kits that are supplied with gaskets for the following surfaces: heads, oil pan, intake, rear main seal housing, water outlet, front cover, fuel pump adapter, water pump, valve covers, distributor, and rear main seal. Kit PN 19201171 is for the 350 HO, HT383, and Circle Track crate engines (PN 88958602 and PN 88869602). Gasket Kit PN 19201172 is designed for the Fast Burn 385, ZZ5, SP383/350, and ZZ6.
Valve Cover Gaskets
For decades, the Gen I small-block was notorious for valve cover oil leaks. When the new center-bolt valve covers were introduced in 1987, valve cover leaks were prevented by using a new mating surface and gasket on the covers and a machined gasket surface on the rails on the cylinder heads. If you have the old-style valve covers, you can use a bar retainer (plain steel PN 14082321 or chrome PN 14044820) to help the bolts hold down the cover by distributing the clamping force over a greater area. There is also a torx stud (PN 14082320) and nut (PN 14051876) for the older type of flange bolted cover, which makes mounting the valve cover gaskets easier.
The old-style cork valve cover gasket, used from 1955 to 1986, is PN 3933964. The gasket for center-bolt valve covers is PN 10046089. Each bolt on the center bolt valve covers has a small O-ring gasket under the bolt head which is available new as a kit with PN 12497980.
| Clearances | |
| Main Bearings | 0.002 to 0.003 inch |
| Crank End Thrust | 0.005 to 0.007 inch |
| Rod Bearings | 0.002 to 0.0025 inch |
| Rod Side Clearance | 0.010 to 0.020 inch |
| Piston to Bore | Follow recommendations of piston maker |
| Valve Lash | Follow recommendations of cam maker |
| Minimum Piston Ring End Gap | Follow recommendations of ring maker |
| Minimum Piston Deck to Head Deck | 0.035 to 0.040 inch with steel rods, more may be needed with aluminum rods |
| Open Valve to Piston Deck | Minimum of 0.045 inch on a stock engine, 0.100 inch on a high-performance or race engine |
| Spark Plug Gap | |
| 0.035 inch with GM point ignition | |
| 0.045 inch with GM HEI ignition | |
| 0.035 to 0.060 inch with GM/MSD ignition | |
| Cam End Play with Cam Button | 0.004 to 0.006 inch |
This is a traditional oil pan gasket set for a Gen I engine with a two-piece rear main seal. You need to get the pan gaskets that match the dipstick bulge location on your block and pan. Then determine whether your pan needs either the thin or thick front pan gasket. The 1955 to 1975 blocks and pans used the thin, 1/4-inch rubber seals, while the 1976 to 1985 engines used thicker 3/8-inch seals.
Bowtie splayed valve heads (PN 10185040) use valve cover gasket PN 10185043.
Oil Pan Gaskets
Determine which side of the engine is set up for the oil dipstick location. You’ll want an oil pan that matches the block’s dipstick position. Oil pan gaskets are made to match whichever side the dipstick fits, and the block, pan, and the oil pan gaskets all must match. Some replacement and Bowtie blocks were made with provisions to put the dipstick on either side.
Gen I engines from 1955 through 1985 with two-piece rear main seals used four separate gaskets to seal the oil pan to the bottom of the block. Check the seal thickness used to seal the front of the oil pan to the bottom sealing surface of the timing chain cover. Two different thicknesses have been used over the years, and you may also have an oil pan that came from a different year engine than the block you are using. It’s no problem; most gasket sets come with both gasket sizes.
Here’s how to tell which front pan gasket to use: On engines from 1955 to 1974, a 1/4-inch-thick gasket was used, and from 1975 to 1985, a 3/8-inch-thick gasket was used. Take the oil pan you are going to use and place a straightedge across the pan rails and over the front gasket half-moon opening. Now measure the distance from the seal surface to the bottom of the straightedge. If the distance is 21/4 inches, use the 1/4-inch-thick seal. If the distance is 23/8 inches, use the 3/8-inch-thick seal.
Oil pans and oil pan gaskets for 1986-on one-piece rear main seal engines are different from those found on pre-1986 two-piece rear seal blocks. The one-piece seal blocks use a one-piece neoprene gasket (PN 10108676) to fit the redesigned oil pan found on Gen I one-piece seal engines. Use metal oil pan rail reinforcements (PN 12553058 LH and 12553059 RH) with one-piece-style oil pans. Gen II L99, LT1, and LT4 pans can use oil pan gasket PN 10108676.
Gasket Sealants
Since the head bolts go through the water jackets on production blocks, it is necessary to use thread sealant on these bolts to prevent water from seeping up the bolt columns. Sealants are used elsewhere in the motor, but use these sealants sparingly.
Excessive sealants are pushed out as bolts are torqued down and pieces can begin to circulate in the motor. They can wind up clogging the oil pickup screen and cutting off the oil supply. Blobs of sealant can move into small passages and prevent oil circulation in other parts of the motor. Gasket cements hold a gasket where you need it, and there