So after a couple of years I've realized that I just flat will never get one of those round-tuits and be able to do the work to the motor of my '80 to get it drivable again. I found a guy that does side work and based on talking & meeting with him, plus good word-of-mouth recommendations from 2 guys I think I've found someone that can get the heavy-lifting done for me. It's been a while since I was hip-deep into the motor stuff, so I'm hoping you guys can help me refresh my memory.

My '80 has the original L82(230hp in 80) with the TH350 trans. It's leaking from practically everywhere, so step one is going to be pull the motor, check everything to make sure the bottom end is in the shape a 52,000 mile motor should be and fix the leaks. Ditto on the trans. Once the leaks have been fix and the bottom end verified as being in good condition I'd like to just bring the smog motor out of it's head-induced slumber. I'm not looking to build a monster, just something respectable so that when you put your foot on the gas you know you're driving a Corvette.

I had asked Dart a few years back what they recommened head-wise, and their answer was the Summit-branded "fuelie" style iron heads. My reading from a while back suggested this was a pretty good plan and so that's still my thinking.

1980 introduced a new "low rise" hood, so my options on intakes may be limited, drop-base air cleaner included. I again recall reading the aluminum intake on the '80 wasn't bad and could just be used on the new heads to save some money & aggravation, but the guy who will be doing the work was thinking that a different intake to better match the ports on the heads would make sense.

The smog components were removed long before I got the car, cats included, and there are dual pipes welded onto the stock manifolds,. My thought was to get a set of Blackjack headers and connect those to the existing pipes and a decent pair of mufflers.

Lastly is the carb. The Q-Jet is a temperamental beast from what I read, but also from what I read tuned up right it will do the job more than adequately. But perhaps it makes more sense to put a new carb on vs rebuild the original?

Comments, suggestions, recommendations, accusations of insanity, etc are all welcomed. Just please keep in mind I am not looking to build a monster, pure-power motor here, just a nice solid runner. I also am not looking to lose what little is left of my mind and go with an LS swap - I have an LS2 in my '06 and when I want modern, refined power I drive that instead. My '06 is my weekend roadtrip car, the '80 will be for nights out and fun cruises.

I look forward (I think!) to your responses, thanks!

 

Just about any aftermarket heads will give you an improvement. Dart is good. I would try to clean up / rebuild the Q jet, small primaries and big secondaries make sense. I can't offer any advice on the exhaust because my views seem to twist other members panties too much.

 

The first question is budget; all decisions flow from there.

I recently used a set of the Summit S/R type heads - pretty decent castings in general with very good port shape...but the chambers really needed some cleanup (sharp edges, etc.) and they came with umbrella-style valve seals...not great IMHO. Overall a good value.

If you want to use all the stock '80 stuff including intake and exhaust manifolds there's no reason to go nuts here as you're somewhat limited. I suggest a good stock overhaul with upgraded springs and cam and call it good. Bigger valves and better heads frankly aren't going to make a huge difference in performance given the rest of the engine configuration. You'll spend about 70% of what you'd spend on a set of stock/replacement aftermarkets, but unless you're going to significantly invest in the rest of the engine you'll get a nice power bump for a reasonable investment.

Headers are a smart investment, but I'd spend a little more money here for a better header - Hooker, Hedman or DT Tri-Ys - and some good mufflers.

I'd keep the Q-Jet and intake for your application, and just have it overhauled/configured by a good shop and then spend the $$$ for a dyno tune.

I tend to be pretty conservative on these "stock/replacement" builds just because folks have tendency to "over head" and "over cam" these builds and then are disappointed with the results. A more conservative, better matched build that's correctly tuned will generally give the best results.

I may change these recommendations a bit based on your budget

 

Thanks for the input Bill, much appreciated, here's some more info, clarifications and questions for you.

As far as budget goes, I don't have a set number in my head but I also know how I will use the car so I don't want to go overboard. At $700 for the pair of assembled heads those Summit/Darts are a nice value but I wouldn't wince spending a few hundred more if it makes sense.

I do not necessarily want to use the stock stuff - the exhaust manifolds definitely go. The stock intake is an option simply because I know it can fit under the existing hood, and I really don't want to make a choice for a mild build that then has me buying a new hood and getting into the slippery slope of painting(not yet anyway!).

I will look into the other headers, that's the kind of advice I was looking for.

Everything I've read about smog motors indicates that the heads are
the culprit to the lower power. The bottom end of the L82 in my 80 is no different than when it developed 350hp in the early 70's - 4 bolt mains, forged pieces, etc. So I'm not sure why you think "the rest of the configuration" if I replace the exhaust, heads and intake is a problem, could you elaborate?

Again, I'm after a nice driver here, not a stop-light or dragstrip killer.

Thanks again!

 

Again, I'm a more conservative guy for these types of build - so I'd balance this with some other opinions on the board. There are a lot of smart engine guys here, hopefully they'll hop on this thread.

The budget helps - if you're willing to put maybe $1500 into the top then that opens some options. The more I learn about what you're looking for the more specific I can be in my thoughts/suggestions.

There's no question the heads aren't great - I don't have my references at work but I expect these are the '882 or similar "smog" heads. The "D-shaped" or "open" chambers on these heads will always make less power than more "heart shaped" or "closed" chamber heads. But given that we're probably shooting for around 275-300HP at the flywheel the difference isn't really going to be all that significant IMHO. A good overhaul of the stock heads with a little bowl cleanup will get you around 70-80% of what you'd see in an UNMODIFIED "stock/replacement" type-head. Figure $450 or so for a complete overhaul including guides, etc.

If you just want a new set of heads, the Summits or other S/R types are fine - go for a set of 64cc heads and pick up a point of compression while you're at it - if you're willing feed a steady diet of premium fuel.

The stock intake is somewhat of a limiting factor, but unless you really want to get into linkages, etc. I'd just stick. It's not a bad piece, and again for the power levels we're likely shooting for you'll find it more than sufficient.

The L-82 is a 4-bolt block (no real benefit at this power level) but to my knowledge was introduced in '73 @ 250HP and never rose above this number. Earlier engines had significantly higher compression - the L-46 350/350HP was 11:1 I don't have my references in front of me, but I'm not sure all the components are forged - someone else will need to chime in. Again, at this power level it wouldn't really matter.

When I say "the rest of the combination" I'm thinking about the trans, diff, carb, intake, compression, etc. Big heads made for 400HP along with a big cam just aren't going to make a "nice driver". A "nice driver" is generally an engine that is smooth and makes low-end torque, to some extent at the sacrifice of top-end HP.

Many factors, but my recommendation would be (based on your preferences):

- Stock intake and carb, with a carb overhaul and tune.
- Good set of tri-y headers and mufflers.
- Set of 64cc aftermarket S/R-type heads and an .028 head (GMPP) head gasket.
- New cam/lifters/timing set, something in a CompCams Xtreme Energy - XE262 would be my recommendation.
- Good dyno tune.

I'll run a DD Advanced on this tonight to see what we'd expect.

 

Before you make a decision on intake PM Motorhead he has a victor Jr
under his 80 hood.

 

I'll do that, thanks.

And thanks again billa, I appreciate all the info and look forward to what you see in DD.

 

I agree with billla. I have the XE262 cam installed. Here is a link to my 79 Top-End Rebuild that might help. Good Luck. http://www.corvetteactioncenter.com/...d.php?t=103334

 

I pulled the L82 out of my 80 and went with a ZZ4 to get the extra power and increase in fuel economy of the roller cam but there's no need to go that route.

If your motor only has 52K mikes you should have many more miles left in it. The motor will begine to use a significant amout of oil if it hasn't already becuase of the forged pistions and required clearance. My motor had 90K mikes before i pulled it.


The 80 L82 is low compression so I would go with an increase to 9.5 to 10 cr ration through a smaller chamber head. You can run at least a .5 higher ration with aluminum heads because of improved cooling.

A cheap but good set of performance heads is the late 80s early 90s L98 corvette heads. These are the same heads used on the ZZ4 and are cheap on the used market.

The L82 intake is OK and remember the stock dual snorkel cleaner will make more power because it draws cold air from the front. Do you still have all the plastic for the dual snorkel kit? If an intake is a bit too tall you can have it cut down by a local machine shop.

The Rochester is a great carb and should only need a good clean and rebuild. I run one on the ZZ4

The stock manifolds are OK but they are hurt by the 2 inch outlet. You can go with stock ones from an earlier vette that ran the 2.5 inch out lets and not have the header leaks or excessive heat build up from headers. The 2.5 do not have air injection if required. I went with Sanderson cast iron headers with air injection ports just in case they start testing here again.

I can't give you any cam advice as I'm sold on rollers but there should be enough info from others to help. I've always liked Crane quality. It's not the HP it's the torque that gets you moving.

I pulled the 350 trans and went with a Doug nash 5 speed. however prior to that i ran the 350. Do yourself a favor when you have it worked on a pull the lockup solenoid off the valve body. They can stick. If yours leaks I get a rebuilt 350 trans without the lockup feature and a new converter to go with it.

 

Your L-82 isn't that far from the 290 horse crate motor that GM sells. The reason your power is low is due to restriction in the intake and exhaust. Go to full headers and true duals, performer Intake and your probably around 300 horses, replace cam and your over. No need to go higher since even at 400 horses, someone is always faster.

 

If you have to spend any money on your heads get rid of them. 77
on up thin casting heads don't waste any of your money on them.

 

Running the configuration I suggested, the numbers were excellent: 345HP@5000 RPM, and > 400TQ from 2500 - 4000 RPM.

With '882 heads the numbers were 332HP@5000 and >380TQ from 2000 - 4500 RPM (-13HP & -20TQ). Contrary to popular belief these aren't bad heads; I wouldn't use them for anything where we're trying to make more than 1.2 HP per CID or in situations where Vortecs are a possible choice...but they don't suck.

This was all with 9:1 CR; moving to 10:1 showed about a 12 HP gain (a bit more than 3%; pretty consistent rule of thumb for engines making < 1.2 HP/CID).

Stock exhaust manifolds showed about 300HP for both heads, which was consistent with my expectations.

Overall, these are all pretty consistent with what I expected, other than better-than-expected power numbers from the XE262H cam. The gains from the better heads would be more significant with a larger cam, but you'd be sacrificing driveability for the sake of bigger numbers. This engine should pull pretty darn well with decent gears.

 

a few years ago i was in the same situation you are. after some research, i decided to go with my original qjet, a dual plane intake (went aluminum and did away with egr), a set of S/R dart heads 2.02/1.60 valves (with a bit of bowl work and port matching), old school LT1 springs, a 268 Comp cam (specs were real close to the factory L82 cam if i remember correctly), a set of stamped steel roller tip rockers (they will clear the factory covers, i went with a set of factory center bolt covers, off of an 89), with a set of run of the mill flat top pistons. i can not remember everything exact, but when it was all said and done, i was pushing 9.5:1 compression ratio. compression=HP, and a killer sound. i rapped it all up with a set of decent tubed headers(get a set with good thick flanges, large tubes, i had mine welded on the outside, where the tubes exit the flange, to strengthen them up), stainless exhaust (monza resonator tips/no mufflers) and the factory dual snorkel breather. i had it on a chassis dyno at FunFest a few months after it was all said and done, and it put 301hp on the ground. can't remember the torque or RPM limits. but i love it! it's no race car(at least not to me, but to more than you would think), but what a hoot to ride and drive. that was a 100k and about 10 years ago!
but, more than the engine, it's how you get what you have to the ground that is just as important.
without much work at all, any tranny guy can make a 350turbo a real superstar. 350turbos have a great intermediate clutch set up for an impressive 1-2 shift. make sure you get a hardened intermediate sprag. a bit of a higher stall converter will help you out also, in lots of ways. don't get outta hand, just enough to keep the car from pushing while in gear and enough to give you a bit of a sling shot when you flash it for a nice launch. also, gears. oh man, gears. a set of 3.70's will make any vette come to life. now, with the stall and a set of lower cogs, the only down side is you will be spinnin some rpms at road speed. 2700 or so at 60mph, or so.
the only reason i mention all of this, is because so many people think it is all about the motor. and hp. BS. it is not only what you have, but how easy it can do it, and how it gets to the ground.
also, watch your base vs. total distributor advance and when your qjet dumps the secondarys. little things like that can add up to decent hp/tq in the long run.
i am sure there are tons of options out there, just don't try to reinvent the wheel. see what works for others and apply it to what you are wanting to achieve. there are some killer heads out there available cheap any more. and i think that considering a roller cam set up might be worth looking into. you could upgrade to a later model 5.7 block, would already have roller provisions, and you would also gain the advantage of a 1 piece rear main seal.
also, things like an electric fan, and other options to conserve HP can add up quick. the list goes on and on. options are endless.
used to, the only boundaries a gear head had was his imagination, any more, it's just the depth of his pockets. (or his line of credit)
gook luck.

 

Thanks to everyone for the advice. Time to re-read, re-read and re-read, then go back and read again... then discuss it with the guys that will be doing the work.

I think I have a pretty good idea of how to approach things now though, so thanks again!

 

about a year-ago, a buddy was in the same situation with his '80 L-48..... he opted for vortec heads & an RPM Air Gap intake (both in kit-form from Scoggin-Dickey for < $1100), 670 Street Avenger carb, and a 270H CompCams bump-stick:
intake cleared low-profile '80 hood by using the Holley carb (I believe Q-Jet would've required a spacer/adaptor plate), and he is happy with the results.

http://forums.corvetteforum.com/show....php?t=1745688

I think billa estimated 350 HP/ 350 TQ in one thread.

I have considered using the 58cc L98 heads on my low-mile L83, but it is already 9.2:1, and with the much smaller chambers, I'd be scared of what the compression might-be (approaching 11:1? ), and the quality of today's elephant urine that passes for 'gasoline'

 

If you are not going to rebuild the bottom-end of your motor, just refresh the heads (new valves, springs, seals...add valve guides if you want), put in a little better cam, new lifters and call it "good". The engine will perform decently and run well for many years to come. Replacing the heads might make sense if you were changing pistons and boosting HP significantly....but not if you aren't.