Opinions on engine upgrades

Hey folks, I'm looking to throw a little more $ at my problem and would like opinions and advice.

The intake will only save you some weight...it's not really a better design than the iron manifold.

If you do decide to buy that stock aluminum intake, be sure you look closely at the areas around the coolant crossover passages. The metal is thin and over the years the antifreeze can corrode it a hole in it. 

The stock heads on the GM 290 hp crate motor are worse than the 882 heads on your L82. They only have 1.94 / 1.5 diameter valves with pressed in studs and no guide plates while your L82 would have the 2.02 / 1.6 diameter valves and I believe screw in studs and guide plates. Both sets of heads have 76 cc chambers so no increase in compression either. Be careful adding more hp to a 38 year old engine too; previous owner of mine hopped up the top end on mine and this summer I took the bottom end out of it.

Thanks for the info and things to look out for.

I've been there with mine.  I was in a quandary for years about what I wanted to do and how far I wanted to go.  I'd go back and forth between doing what you're proposing to rebuilding everything to crate motor and then back to just bolt-ons.  My hand was forced when I was replacing harmonic balancer and I broke the hold down bolt off in the end of the crankshaft.  I had original block bored and other machine work done and pretty much replaced the top end with vortec heads and all other new stuff.  You're in a little better situation than most of us are/were since you're starting with an L-82 which has higher compression than us poor saps with L-48s.  Low compression motors don't seem to respond too well to cam upgrades and possibly even some of the other stuff like exhaust.  I put 2 1/2" true dual magnaflows on mine before I did anything to the engine.  It sounded better, but not much else.  It never seemed to run as good after I did that and it sure felt like it lost some low end grunt.  My advice is go big or do nothing.  Cam upgrade by itself may not be ideal and new heads can create other problems as Greg points out.  (I had the top end rebuilt on a Honda once and that part of it was great, but it started burning oil like crazy -- better compression sealing at the valves was causing oil to go past the worn rings.)  If it were me I'd keep the original block, freshen it up a bit with a bore or at least a hone, and then upgrade cam and rework or replace the heads.  Most likely you can keep the original crank and maybe rods.  Another benefit is you will be able to get new cam bearings when you do this.  

Dave has said what I meant to say. Take his advice and make sure the bottom end is strong enough before working on the top end. And he's right, not many green '75 L82 4-speeds out there so take good care of that block.

Your L82 probably has about the same power as that 290 GMP.  Your rating is net the engine is gross.  I have a 1980 L82.  I have appreciably more power, but I don't think it is because of any major internal changes.  The power drop from 1974 to 1975 was about 35HP.  I think most of it is due to changes in intake and exhaust.  Last month I loaned my car to Flowmaster.  They used it to design their new low back pressure exhaust from the exhaust manifolds back to the tips.  In return< I now have the first of the new exhaust system.   They will market the new system in about a month.  I seem to have about a 10% power gain from lowering the stock exhaust backpressure.  No dyno test but it gets going a lot faster.  Sounds good too.

Perhaps a lower back pressure cat converter would let your engine be more of what it wants to be.

Ray

There are a lot of great after market heads out there that can give you the upgrades you need, cam, heads,intake and carb will run you $2000.00 in parts,if you shop smart you can get them cheaper.Don't forget the ignition system,that can make all the difference in the world !