Ok, here's the story. I have a 1991 Formula L98 that has 155,000 miles on it.

The motor still runs well, good oil pressure, etc, and no oil consumption, but I am seeing signs that the rings are starting to go. It has started to seem a little more sluggish than it used to, and it seems to have enough blowby where having the dipstick pop out when running nitrous is becoming fairly common.

Aside from one bad valve seal, the heads are still solid. I was planning to replace the entire after this season, but now I am leaning towards building a new bottom end now and sicking with the stock heads and cam until next season, or maybe permanently. This is a street car first and formost, and it just depends on what situation my track car is in, and where I decide to go from there.

Wow, this post got long quick, eh?

My question is, I know a guy with a 1986 350 block, non roller, offered at a great price. I would like to run the stock L98 roller cam in it, out of my current motor.

I understand it needs some drilling and tapping in the lifter valley for the lifter retainers? Forgive me, I've never been inside a roller cam chevy motor. He says it has the pedestals for the retainers, they just haven't been drilled.

Also, is there any work needed to be done on the timing chain side? Will the stock pieces (or stock replacement pieces) transfer over from my current L98 to this block as far as that goes?

I am correct in thinking that the 91 heads will bolt on, right? Anything else I need to consider?

 

You may not want to hear this, but I have to strongly recommend that you do not waste your time with that stock L98 cam..... It is basically worthless and you can put a much better one in without having to go the whole 9 yards with head work and such. There are some that will even run respectably without PROM tuning (although, I would have to recommend getting into PROM tuning regardless of your engine plans, as you will be absolutely amazed at the mileage and increased power you can achieve with a PROM that you make for your car even if it is still stock internally).

I also would recommend getting some retrofit roller lifters and using a cam button with the roller cam of your choice on that older block. The factory roller setup for the 87 and up blocks is somewhat of an abortion in the first place and definately is not worth swapping over into another engine. With that many miles on the engine, a new set of lifters is really must with a rebuild anyways. Retrofit rollers are not that much more than OEM rollers to justify all of that F-in around with the factory setup and block work.

Hope that helps some...
Matt

 

I'm aware the factory cam is pretty much dog****. But, budget is a concern here, so most likely a stock cam will be going back in, or perhaps an LT1 cam, simply because you can get them for dirt cheap. Provided the lifters look ok, they'll go back in too.

later on down the road I will be pulling the heads off, so I'm not too concerned about performance, especially when with a new beefy bottom end, if I want to play, I'll just slap in the 200 shot jets. Right now, the concern is that I have a bottom end that is getting worn out, and I want/need to get it fixed, for as modest a cost as I can.

Why do you say that the factory roller setup is an abortion?Whats the difference between that and an aftermarkeet setup?

 

i am pretty sure you can't swap the 87 up factory lifter b/c of the lifter bore height.

 

You're right. You can't.

If you have an earlier non-roller block you will be LIGHTYEARS ahead in performance and cost getting a decent (and cheap) flat tappet cam vs. converting it over to a roller cam setup and stabbing in an L-98 or LT-1 cam.

 

I call it an abortion as it is just a bunch of unecessary junk that GM decided to go with.... The regular roller lifters (now referred to as 'retrofit' ones) were used for years in high performance and aviaton type applications and work great and keep the amount of components and machine work needed to run a roller cam to a minimal... The GM OEM setup is just.... well...... a very good example of over-engineering, IMO.

Somebody referred to it as an engineering intern's 'Junior Project' ..... rofl....