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Tapping it in, was what Howard's told me I could do, but it depended on the cam core, whether you can do it or not. I would've tried that last night, but learned about it, only this morning!
The Fel-Pro one piece oil pan gasket will not fit the L98 block. This is for both the Fel-Pro OS34500R spec'd for that year and the Fel-Pro Gasket Kit KS-2666, with both the stock L98 ('87-91 SBC with one piece rear seal) AND the Milodon '86 and up stock pan. I called Fel-Pro technical support and they told me that this is a common problem with this block and the ZZ4 crate motors. It should've mated up, right to the oil pan flange, but it didn't, thus the tech support call. Fel-Pro also told me, that Chevrolet Performance has the correct gasket for this application, PN 10108676.
are you certain your cast rear main seal carrier is correct?
I'm sure of it, I carefully reaearched this and corroborated with the Chevrolet Performance dealer, I've been working with. After the post above, I called Milodon and they flat out told me that the pan I had, won't work with the 89-93 TBI Fel-Pro Gasket and I could order their thinner 410001 gasket from them. I asked if this was a common problem and he admitted it was, so the final wotd on this, is that Fel-Pro doesn't really have a one piece gasket for the '87-93 L98 roller cam block. Finally, I did test fit the rear main seal casting and it lines up with not only the bolt holes on the back of the block, but also the locating dowel as well, and centers the rubber donut perfectly over the rear of the crank. So yes, I believe it is the right assembly. I just want to show what I've run into, both positive and negative as I go along. Those Fel-Pro gaskets are $40 each!
I finally got the got the oil pan gasket from GM Performance (PN 10108676) and it is thinner than the Fel-Pro, but you will find a gap will still exist when just placing it on top (though it's only half as much as the Fel-Pro gasket). It did cinch down well with two 5/16 bolts, but I'm still going to put a bead of gasket sealer, all the way around, just to be sure. Providing photos and PN's for those who may want to go this route, with the '86-'91 OE Roller Cam Block (638 Block).
Stock Pan L98 fit for rear main seal housing.
Milodon 31501 (Hobby Circle Track OR Street Performer, same PN). This pan has the advantage over Milodon's 30700 Stock Replacement Pan as there's a full length Windage Tray in the 31501 and NONE in the 30700 pan.
GM Performance Oil Pan Gasket 10108676 (tag on top) and associated GM Rear Main Seal Hardware (Rear Main Seal Housing, shown on next picture).
Rear Main Seal is the exact fit. Just a note on the Milodon oil pump pickup, PN 18307, it's a combination 'press fit' and a plate ties it to the bottom of the oil pump. Well, I could only get it in 90% of the way, after beating on top of the weld of the bung with an open end wrench (per their instructions) for a half hour, with the pump clamped in a vise. NO GO. Ended up, taking it to my local auto machine shop and they got it in, with something that looked like a cut down deep socket. I'll post pics of the oil pan fight, later on, had to trim the opening in the windage tray by 1/4" to get the pan, to go on the block. I wrestled with the pan, trying to put it over the oil pump pickup and it got locked up, trapped and wedged as tight as a penguins butt. I finally wrestled it off and then did the 1/4" hole trim. Thank God! It plopped right on! I called Milodon and they initially told me, I had to put the pan and twist it sideways first. I called them afterwards and suggested they trim it, just a wee bit more...
Rear of the Block
Front, Timing Chain Cover
Initial Oil Pan Fight (Oil Pan WINNING!, Me, LOSING!). Note the interference between the pickup and the windage tray. At this point, it wasn't coming down or up.
Oil Pan Before Trim Milodon PN 31501 (PS: Milodon, said, they'd fix this. Note the rough punch out and the 'peaks' in the circumference of the oil pump hole in the windage tray. Remove the bolts and then use a die grinder to grind it down. Finish with a file and sandpaper, rebolt on and boom! It just plops right on the block. Amazing! Tomorrow, lay out the goop, the gasket and put on the pan.
The new oil pan gasket did have some soft rubber on each end, but the sides are thin and they are not 'soft' and flexible like. They are a 1/3 of the thickness of your typical Fel-Pro blue one piece gasket. And because the oil pan is more or less a 'press fit' to the block, especially the *** end, where the nuts on the Rear Main Seal forced the pan down an 1/8 inch, I applied a bead of Permatex Ultra Black Gasket Sealer on the block, where the gasket would go and then, applied another thin bead on top. Per the instructions for the Permatex, you put the bolts in, but you do not fully tighten them, until the sealer has cured, for at least an hour. I did carefully tighten them, just a little bit, to get the pan at least seated against the gasket, all the way around.
The ARP engine accessory kit, specifically calls out a thin bead to be applied to the block. The bead on top, is for good measure.
Good thing the gaskets were still wet! Thanks, Jackson, saved my butt! I thought that shaft would've been a 'drop in' from the top. I've primed the pump in the past, with the drill, but have not installed the shaft.
I'll admit, my first rodeo with this. Been super careful, but always room for a lesson learned! That would've been a serious bummer at drop in...
I'm going to order Milodon's gasket on Monday and we will continue. They are in Simi Valley, only about 35 miles away. Meanwhile, I did get the intake off the old girl, this afternoon.
You're welcome.
Simi... have VERY old friends in Reseda... I me weathered the Feb 1971 quake in decrepit East LA building.
Don't know if you have int shaft yet … if not, suggest you get one with a steel collar in lieu of OE plastic retainer.
Also, recommend you seriously prime motor not long before you fire it … prime for a minute or two … rotate crank 1/4 turn ...prime … rotate another 1/4 and prime.... rotate another 1/4 and prime. Get the prime tool or take a junk 4.3V6 or sbc dist and grind its teeth off gear and weld and tack weld a socket etc to top of shaft to chuck drill to. Electric drill get a real workout, let em cool.
Thanks J Man! Reseda sure has changed in the last couple of decades! The whole SFV has changed... But seriously, I planned on a really good pre-lube, as you've described, before the first start. I do have the Melling drive shaft, with the steel collar. It's right there in the box!
It's a 355. The block was already done up, when I got it, that way. Secondly, tho' I really like the 383 (my Shop Bud next door had a bad-*** '74 Short and Wide with a 383 and a built 700R4, it got wrecked twice within two months! Pulled like a freight train and had a top end too!), I just didn't want to deal with the block mods and running a small cam base circle and all. With the compression, I'm running, you might recall from earlier in this thread, Howard Cams told me, 400 - 425 HP easy. And I'm happy with that!
Got the Milodon gasket today (it took one day UPS to my house!). First thing, I noticed is that unlike the GM gasket, it is softer rubber, including the sides. The GM gasket had stiff hard sides, but softer rubber on the ends and the Milodon gasket is thicker on the sides. The Milodon gasket is even softer than the Fel-Pro that wouldn't fit. So if you're gonna go with a Milodon pan, order the Milodon gasket. It looks like very good quality and it has the steel inserts around the bolt holes, so you don't overtighten it. There is still a small gap at the rear main seal, just sitting the pan on top, but this will compress all the way down.
And yes, the oil pump intermediate shaft is now in place!
01-04-2019, 12:09 PM
Thanks, Jackson, saved my butt! I thought that shaft would've been a 'drop in' from the top. I've primed the pump in the past, with the drill, but have not installed the shaft. 
