I just googled this and it seems off but EHOW states....

In 1979, Chevy gave the L82 larger valves, a 10.2-to-1 compression ratio and new cam to push horsepower to 225, and then 230 horsepower in 1980.

Read more: http://www.ehow.com/info_12185069_di...#ixzz2paSWedj2

I thought I was running more of a 9 or 9.5.1 compression ratio.

 

Hi Daltman,

Ok..so if you're going to go through this... here is my question..

1) is this your daily driver?

2) To get this perfect...we need to know if your motor is stock 1979 L82 for sure?

3) How many miles are on the bottom end?

4) If not daily driver we can get closer to perfect... pull the intake and heads.. lets find out exactly the pistons you have.. and cc (with cc kit) the valve reliefs in the pistons..

5) with this info.. you can determine heads (combustion chamber size) best...and best thickness of head gasket... with good quench (0.040 to 0.050 ) and determine your static and cam it for correct dynamic compression...

so, if this is not your only car..you can dial it in much better...

Otherwise.. we guess its a factory L82..and look up L82 pistons from 1979..(people here will know... i'm not a vette expert per se)..

But... to back up and do this right...

1) Have you taken it in for a simple leak down test...

2) Possibly have someone pull the oil pan and take a look , including scoring of bores...

3) Do you know how many miles on motor? When was it last apart? Can you talk to the guy that took the motor apart and repaired or rebuilt?

GET ALL THE INFO YOU CAN...it can save you thousands...in the future

 

This baby has never been taken apart from what I can see. I am the 3rd owner and the 2nd owner did not drive it much at all. He bought it in 2003 and never drove it. The receipts from 2004 show 83000 miles on it. I bought it in April of 2013 and put 1000 miles on it. Odometer reads a little over 85000 miles. The receipts show the normal stuff as being replaced. Water pump, master cylinder...etc.. I do see a leak at the rear of the motor so I will need to replace the rear main and oil pan gasket. The previous owner replaced the interior. My goal is motor then paint. My wife home schools the kids so I have a car to take to work plus I can work from home when needed. So this car basically sits in the garage for a sunny day and then I take it to work or if my wife has an appointment. So I drive it a couples times a week right now. The carb was rebuilt in 2003 and works fine so I will use it for now. I had a Holley 750CFM with dual inlet and vacuum secondaries in the past and was thinking of buying another for this car since I would be changing the CAM.

 

Before you do anything you will want to do a compression and leakdown test. You want more low end and midrange torque. Email Lars @ V8FastCars@msn.com and ask him for his updated timing curve paper. Updating to a performance timing curve will increase the bottom end throttle response big time for under $20. If you have $1000 headers and true dual exhaust is all you can do. You do not want a single plane intake. It will further reduce your bottom end power. To get what you want in power you really need heads. Power potential is in the heads. A set of Dart SHP 180 or Patriot 185 heads with 64 CC chambers, 1094 head gaskets and the headers/exhaust with a performer intake will get you what your looking for but your not getting it done for $1000. Your L82 cam is actually a pretty good cam especially if you bump your compression up with the heads. Your L82 measured actual compression is about 9 to 1. Your Qjet carb is a 750 and is capable of supporting 450 HP and a great street carb. If it needs rebuilding have Lars set it up for you at the above email address instead of buying a new one. Spend the money where it will do the most good, new carb isn't it.

 

ok...thats good info..

1) when they pull the oil pan..have an experienced mechanic..(that you will have do the cam and heads)... check out bottom end..best he can..full inspection of bores, looking for anything..

2) skip the carb... you'll make as much or more power with a standard 650 to 670 carb... it can make it run worse..

3) When mechanic has pan off..he can tell you if 2 or 4 bold main block..(as i said..im not a corvette expert )..

4) If he gives the go ahead from what he sees below.. then begin asking around here and searching the net for "builds"... somewhere...some magazine..has done what you want to do.. or very close to it.. and they test various cylinder heads, cams, headers, etc...like the link i sent you..

Then duplicate that motor...dont try to re-invent the wheel.. just copy what the article does... BUT..look at the date on the article.. if say 10 years old or so.. you will want to look at cam grind improvements...and can usually squeeze another 20 hp from that...

look for articles...like this..

http://www.carcraft.com/techarticles...e_tpis_zz_450/


NOW..when looking at articles... there are some connections you have to be looking for...

1) there may not be qjet carbs tested... thats ok.. look for a combo that performed with a 650 cfm

2) Look at manifold.. single or dual plane... you're going to want to concentrate more on single plane manifolds ..if you want that upper rpm scream..

3) If you see articles with miniram, super ram, LT1 intake...on old style 350's..which is what you have.. thats similar to a good carb on a SINGLE PLANE...

4) If you see a TPI engine build..(the old style..TPI that has the banana type long runners which are like 15 inches...) well a TPI intake build is more like a dual plane...

5) you'll see a common theme.. that the good carb on single plane (3.5 inch long runner), MiniRam, super ram...will all be upper rpm..higher horse power...and bigger cam type engines...

6) The dual plane, and TPI (banana style..with 15 " intake length.. will run low rpm and have more torque)...

So find the articles..and copy..for best result..

http://www.carcraft.com/techarticles...d/viewall.html

http://www.classictrucks.com/tech/10...d/viewall.html

http://www.superchevy.com/technical/...d/viewall.html

 

Hi Mako..i respectfully agree with almost all you've said..
but with his 4 speed and 3.70's... with more compression..dont you think the single plane would be fine on the street?

i just hate the way a dual plane falls down at 5500..

 

Edlebrock Performer RPM 7104 fits Qjet, Operating range 1500-6500. It says it will not fit under stock hood but there are many here running one with a drop base air cleaner. Search. The L82 cam is the same cam Chevy used with the L-46 in 1969-70. 350 HP 11 to 1 compression 224 duration @ .050. Good cam with the head and exhaust upgrade. 400 HP and good bottom end, midrange. Will pull to 6000 RPM. Actually with 3.70 gears and a 4 speed the L82 should roast the tires. Timing curve, ignition issue, possibly centrifugal advance plate not working correctly or vacuum advance not properly functioning. Problem with a single plane is it will give up bottom end power he is already lacking and can't get one that fits under the hood.

 

Pulled from another thread

 

didnt know that single plane manifolds would not fit under stock hood..

but if the L82 cam is what i've searched and seen...450/.460 lifts, 222/222 duration, 114 LSA.. and just hydro lifter...

this may have been ok back in the day... but is prolly 50 horse down from what can be had with decent heads... that cam needs a dual plane...to perform..it would fall on its face with a single plane for sure... but a correct grind with single plane... will make it fun to drive..not just a mid rpm thumper... in my opinion...

 

Edelbrock Torker manifold will fit under the stock hood but best used on boat engines I was advised. It was quite common to use the Torker manifold on Vettes back in the day because it was one of the few after market manifolds that would fit under the stock hood. I have taken one off my engine and replaced with a Performer 2701. I had to shave 9mm from the bottom of the drop base air cleaner to be able to get the hood closed though. I couldn't use the fancy nut on top of the air cleaner either but found a small brass wing nut that does the job perfectly. My car rarely see's the high side of 4000 rpm though (its an auto) the dual plane manifold made a marked improvement to the bottom end. FWIW I wouldn't want to be revving the bejesus out of a stock untouched bottom end that has 85k on it anyway:-) Mid range thumper suits me fine I guess!

 

Hi Haggis,

if you drive idle to 4k all the time... for sure..a dual plane ... is best

if proper air/fuel is monitored ...and with some maintenance, a little 350 is one tough cookie..even with keith black or cast pistons..

http://www.carcraft.com/techarticles...y/viewall.html

 

The problem is a bigger cam and single plane movers the powerband up. The op's main problem is he does not have sufficient bottom end power to "roast" the tires. If you go bigger on the cam you move the operating range up and sacrifice even more bottom end for upper rpm power. Great on a strip car that launches @ 4000 RPM shifts @ 7000 and runs WOT 1/4 mile at a time. not so great if your need is low end throttle response. You have to look at what RPM you use. Most street cars spend 90% of their time under 3000 RPM and 95% of there time under 4000 RPM. Yes a modern big fast ramp cam grind will make more power. A solid lifter flat tappet will pull more RPM. But that L82 cam has a flat torque curve that pulled 350 HP @ 5600 RPM with poor flowing heads and actual 2" outlet ramhorns in an L46. Add modern heads, headers and free flowing exhaust with an intake that will let it breath he will see his 400 HP easy, power from off idle to 6000 rpm shifts and have the old school gentle ramps for reliability. Hundreds of ways to build these but to make the best of what he has as cost effectively as possible this is what I would do. BTW that L82 has 4 bolt mains, forged crank, rods and pistons. If it is solid it is a great base for a performance engine but I would be leery of exceeding 6000 RPM with 85,000 miles on it even if it tests good.

 

• Keep your q-jet; tune for performance. It is already capable of 750-800cfm properly set up. Have one of the guru's on the forum blueprint it for your combo.
• Keep your intake; it is same as Edelbrock 3701 and already aluminum
• Rebuild/recurve distributor and pick up 40hp (yes, a performance curve does increase power off the line). I am "all in" at 36 degrees at 2500rpm. I also have the Accell Performance Replacement distributor with the adjustable vacuum advance can (I don't think stock adv can is adjustable).
• Step up to better flowing aluminum heads. I would go with DART Pro 1's as they are about $1,200 @ Summit now: 180cc intake/65cc chambers with 2.02/1.60 valves
• Crane Energizer cam grind 272H10... OR, keep your L-82 cam as it has same lift. Your cam just has longer duration and looser lobe separation
• 1 5/8" headers with 3" collectors
• True duals and h-pipe
• super turbo mufflers
• Keep your pistons
• K&N filter to compliment the better breathing. I use my dual-snorkel air cleaner with OEM cold air system (same as L82)
• Good spark plug wires. I use 8mm Taylor Spiro Pro wires
• OEM R45TS AC spark plugs with .045 gap
• Accell performance coil (I think 45,000 volts)

This is essentially what I had in my '80 L48 (I have FM H345NP pistons) before roller conversion. It ran (and still runs) like a scalded dog spinning the tires off the line from a dead stop all the way into 2nd gear where it finally hooks. I have 700R4 (LOW 1st gear) and 3.55 gears that contribute to the incredible launch from a standing start. I used Bow-Tie "TV made EZ" adapter to properly set throttle geometry preventing stumble between the hard 1-2 shift (no stumble at ANY throttle position). I was seeing 225rwhp on dyno before my retro roller cam conversion which made the engine a solid 325hp engine (on engine dyno w/out accessories). I hope to put it on chassis dyno this year to see what the roller cam added. I am hopeful to see 350hp (gross) and 250hp at wheels (or better) with the top-end refresh I added. My 180cc DART IE heads with 72cc chambers have the flow but not the smaller 64cc chambers. With the smaller chamber, you may see more hp/tq. I run 92 octane only.

 

What size budget are you working with? There are several routes you can go. As Mako said a leak down test is a good place to determine what shape your bottom end is in.

 

It is unlikely that at this point that your engine is even making it's rated HP. To get it running to it's potential is a process.
1.Start with getting the timing curved properly. This can have a dramatic effect on your low end torque.
2.either rebuild your q-jet using this book


Or send it to Lars to get it rebuilt. I recommend getting the book either way since you'll learn about your q-jet and how to tune it properly which is priceless information for a good running engine. Each time you change something on the engine you'll need to re-tune the carb for best performance.
3. Get some headers and eliminate catalytic converter, add good flowing mufflers, 2 1/2" exhaust. Nice 1 3/4" headers with ceramic coating to keep heat down.

Do these things first. Then decide where you would like to go from there, you'll be surprised what a difference it will make.
You can spend many $$$ on heads and cams and still have a crappy running engine because you never addressed the timing, carburation, and exhaust issues.
This will get those tires burning rubber with that 3.73 rear end you have and won't break the bank.

If I understand you goals correctly I don't see you having any use for a single plane intake or rpms above 5500.

 

All good advice. I suspect an ignition, timing curve/ advance, carb issue or combination of the 3. That thing should roast the tires and plaster you into the seat with 3.70 gears and a 4 speed.

 

Mako is so right .you can find good prices for the heads he listed ,on Ebay ,or at competition products .

 

No question that a good tune is the best place to start - especially with a likely very tired Q-Jet.

A Vortec top is around $1,000 all-in and will get you in the power bracket you're looking for. https://sdparts.com/details/scoggin-...nter/sd8060kit

The Q-Jet is a difficult call - great carb, but tuning expertise and parts are difficult to come by. If you choose to go that direction, you may want to wait to do all the upgrades you're planning and have it tuned *once*.

 

Headers and distributor, hands down, the best thing you can do to a late 70's Corvette motor. The difference will be night and day.

I've rebuilt 4 Q-Jets in the last year for local friends and with a nice running Q-Jet they've all been very capable performers; including a 76 L-48 and an 80 LG-4 (yes, the 305 with E4ME).

If the QJet is bad, investing in a rebuild is worth the effort. If you'd like to DIY I'd be glad to help you over the wire, and you'll come out at about $100 invested for a great kit from Cliff R.

I do not agree on single plane intakes for any car not designed to rev much past 5. You'll give up lots of low end torque and *average HP* for some peak numbers. Meanwhile, you would have been faster overall with the dual plane.

As for the LT-1 intake manifold, that was a dual plane:

 

The nice thing about a well tuned carb and in particular the Q-jet, is that it is responsive, sensitive and gets good fuel economy, and can still provide excellent power when you want it.
The Q-jet in my vette runs better than the fuel injection in my 2008 Mazda 3. Not really a fair comparison since one is performance and one is not, but the responsiveness and sensitivity to tune in the Q-jet is excellent.
Believe me, learn how to tune that thing and you'll never be sorry you did. I spent the entire winter two years ago learning everything I could about the Q-jet and it has paid off well. I have beat better and bigger engined cars ,I believe, due primarily to the tune of my carb.
Just consider that how completely and efficiently your fuel burns directly affects how much torque you produce.
How well that fuel is delivered by the carb is a huge factor in how well it will be delivered to the cylinder.