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Ok still on the fence here, should i just do headers and true duals on the stock 1980 L-82 or should i go and do the heads...I am not looking for major hp maybe 30-60 tops is all i need.
Heads seem like a lot of work to get the right ones with the least amount of complications. From what i have read headers true duals and a good tune up seem to get me right where i want to be?
I am torn between the cheap aluminum heads and the expensive ones and i will admit my basic knowledge of parts swapping vs tech knowledge of everything that needs to be done or looked for is intimidating.
Without pictures, it's hard to say. I can absolutely say that your 80 will be about one million times more fun to drive with a manual transmission, possibly to the point that you don't worry about hp. But that swap can get expensive quick
In terms of budget, catalytic converter removal and advancing the timing is probably the cheapest HP gain out there for c3’s. You could meet your 30-60hp gain for probably $50. Check with your local state laws to see if you are allowed to modify exhaust though.
If you buy new heads you really gotta consider the motor as a whole. New heads aren’t going to do much if you keep the low compression pistons and small lift cam.
He says it's an L82, not a L48. So if indeed it is a L82 it has forged flat top pistons, not the dished low compression pistons of a L48. Also the L82 cam isn't a bad cam at all. So I think any Aluminium heads would be an upgrade that would be a noticeable improvement. That with headers, exhaust and recurving the distributor would really wake her up.
the L82 is a very good base to work on.
He says it's an L82, not a L48. So if indeed it is a L82 it has forged flat top pistons, not the dished low compression pistons of a L48. Also the L82 cam isn't a bad cam at all. So I think any Aluminium heads would be an upgrade that would be a noticeable improvement. That with headers, exhaust and recurving the distributor would really wake her up.
the L82 is a very good base to work on.
Exactly. Just a recurve will probably do a lot. OP, email @lars for his timing and Q-Jet papers, if you haven't already. His email is all over this Forum.
But with the stock torque converter, it will still be a dog. If the transmission is out to be rebuilt right now, do some research on fixing that problem.
before you go jacking around with distributor springs etc..
note the L82 along with cam and pistons also has a great vacuum advance already, all in 2000 rpm and limited advance..(at least in 79 maybe someone has the manual for 80)
for what you are looking for .. no way am i changing heads.. (budget).
tune it up, NGK plugs good oem wires, cap rotor.. exhaust ( i would not even go headers for budget) but for sure duals no cat if you can.
all on budget and all can support other upgrades.
consider unless carb very nice a Lars rebuild..no better value/ knowledge and engine tested performance. Thread below https://www.corvetteforum.com/forums...l82-q-jet.html
The L-82 is a good platform for upgrades without having to replace everything. The cam is acceptable the way it is if you're not looking for a ton of power. Headers and true dual exhaust will do a lot for you as well. L-82 has flat top pistons. That with a 64cc volume chamber and you'll be in that 10:1 CR range that is desirable.
The stock heads are quite a cork in the system.
If you get new aluminum heads decide if you want to keep the cam and stay flat tappet or go roller cam.
There are lift and valve spring differences.
Next, how much you spend on those heads is almost directly related to the quality you will receive. You can get decent heads for the $1200-$1500 range. If this is for the street look for 180cc or close to that for intake side volume. 2.02 intake valves. 195 cc heads will be a little lazier and shift the power to a higher RPM range.
For $2000 ish dollars are the AFR eliminator 180 heads.
The enforcer's are a lot cheaper and as cast vs cnc'd. around $1300
Cast iron, you could get a set of vortec heads. Those can be found cheaper and provide pretty good flow increase over stock.
Headers, Duals, a nice timing curve and a 2101 Performer intake with the Fel Pro 1204 intake gasket that blocks off the heat riser port will give you significant gains......a lot of people will say the intake is not worth it but I have done it dozens of times and have tested it on a dyno and they pickup 20hp on any small block......the original 4 barrel manifold flows very poorly and will not support more than 325hp in any application, the Performer will support 400hp......PLUS, you get to look at the condition of the engine inside, get to block the nasty heat riser port that sends an extra 100 degrees of heat to the carb base.....and it cleans up the engine dramatically....also a 30 lb. weight savings on a 68-79......later were aluminum but had zero improvement in flow......
A set of 1.52 roller tip rockers and good pushrods will help too......the stock rockers are so **** poor in quailty control that the ratio can be a shitty as 1.4.....
I do not recommend 1.6 rockers on a stock head as they almost always rub on the pushrod hole in the head......
The stock L-82 timing curve is not what you really need either as you would have to dial 20 degrees initial to get 36 total.....which is optimum.....actually the L-48 distributor with lighter springs is a better choice.......also with the L-82 vacuum can......
The L-82 heads flow a tad better so all of the above mods including long tube headers will put down 280hp to the tire and 350 on an engine dyno........
BUT....here is the bolt in the gears.......stock heads are pretty terrible as I have said over and over........and most are wore out in this day and age.....BUT, if you can find a nice set, or yours are in very good condition and the guides/seats check out....you can buy a brand new set of valves for about $40 from Enginetech, $15 for premium valve seals, and $100 for a Z/28 spring, lock retainer kit from Elgin.......now purchase a nice carbide bit set for $100 and a die grinder for $50.........I can port and blend a set of these stock heads now in about 4 hours.......removing the heavy ledge in the bowl....and some port match on the face of the runners. If I have a block available....I bolt it on and scribe the chamber from the bottom, then grind the chamber back to that scribe to unshroud the valve..........take your intake/exhaust valves to a machine shop and have them backcut for $50......assemble these heads......now you are at about 390 hp......and it is a very nice running engine.......the extra head flow is a boost all over the curve for hp and torque.......I have done this about a dozen times over the years......and plan to do it soon to my L-69 spec 305 in my 82' Z/28.....it is just so cheap to do......and very backyard satisfying.....make sure to lap your new valves in really good.
A blended L-82 head with backcut valves will flow in the upper 230's on the intake......from the 2.02 valve......a 1.94 heads about 5 less cfm.....
BUT....I have ported a lot of heads and know where and what to grind.......not everyone can get there or cares to.......I basically only do it for my own stuff but I did a pair of 68' 327/300 heads recently and that engine pulls very strong.......
This is why heads are available to buy.........but $$$$$$......
Jebby
Last edited by Jebbysan; Apr 13, 2023 at 09:08 AM.
Thanks Jebby, after all these years I feel vindicated.
I was doing that stuff to these cars when they were new. You are spot on with all your observations.
Headers, Duals, a nice timing curve and a 2101 Performer intake with the Fel Pro 1204 intake gasket that blocks off the heat riser port will give you significant gains......a lot of people will say the intake is not worth it but I have done it dozens of times and have tested it on a dyno and they pickup 20hp on any small block......the original 4 barrel manifold flows very poorly and will not support more than 325hp in any application, the Performer will support 400hp......PLUS, you get to look at the condition of the engine inside, get to block the nasty heat riser port that sends an extra 100 degrees of heat to the carb base.....and it cleans up the engine dramatically....also a 30 lb. weight savings on a 68-79......later were aluminum but had zero improvement in flow......
A set of 1.52 roller tip rockers and good pushrods will help too......the stock rockers are so **** poor in quailty control that the ratio can be a shitty as 1.4.....
I do not recommend 1.6 rockers on a stock head as they almost always rub on the pushrod hole in the head......
The stock L-82 timing curve is not what you really need either as you would have to dial 20 degrees initial to get 36 total.....which is optimum.....actually the L-48 distributor with lighter springs is a better choice.......also with the L-82 vacuum can......
The L-82 heads flow a tad better so all of the above mods including long tube headers will put down 280hp to the tire and 350 on an engine dyno........
BUT....here is the bolt in the gears.......stock heads are pretty terrible as I have said over and over........and most are wore out in this day and age.....BUT, if you can find a nice set, or yours are in very good condition and the guides/seats check out....you can buy a brand new set of valves for about $40 from Enginetech, $15 for premium valve seals, and $100 for a Z/28 spring, lock retainer kit from Elgin.......now purchase a nice carbide bit set for $100 and a die grinder for $50.........I can port and blend a set of these stock heads now in about 4 hours.......removing the heavy ledge in the bowl....and some port match on the face of the runners. If I have a block available....I bolt it on and scribe the chamber from the bottom, then grind the chamber back to that scribe to unshroud the valve..........take your intake/exhaust valves to a machine shop and have them backcut for $50......assemble these heads......now you are at about 390 hp......and it is a very nice running engine.......the extra head flow is a boost all over the curve for hp and torque.......I have done this about a dozen times over the years......and plan to do it soon to my L-69 spec 305 in my 82' Z/28.....it is just so cheap to do......and very backyard satisfying.....make sure to lap your new valves in really good.
A blended L-82 head with backcut valves will flow in the upper 230's on the intake......from the 2.02 valve......a 1.94 heads about 5 less cfm.....
BUT....I have ported a lot of heads and know where and what to grind.......not everyone can get there or cares to.......I basically only do it for my own stuff but I did a pair of 68' 327/300 heads recently and that engine pulls very strong.......
This is why heads are available to buy.........but $$$$$$......
Jebby
Jebby, what is your estimate for increase in power by blocking the heat rise in intake for l82 alum manifold stock engine 79? assume you need to add electric choke?
Jebby, what is your estimate for increase in power by blocking the heat rise in intake for l82 alum manifold stock engine 79? assume you need to add electric choke?
Well Gale Banks says 100 degree decrease in temp is worth 10 hp with no other changes at this level....and I believe it......so your 20hp from the Performer may be a ringer......but you end up with much better drivability.....off idle performance in traffic....and will help quelch dreaded beer store Vapor Lock......when you combine the block-off with ceramic coated headers......the underhood temps can drop by that same 100 degree amount.......the cooler, the better.....no matter what anyone says......
Yes, you need an electric choke and they are cheap and easy to install........earlier models are harder and more expensive to convert......but most who block the plate say it just takes a bit longer to kick off with the stove.
Another thing that works really well is the oil splash pans in the valley that Moroso and others sell........keeps hot oil off the bottom of the intake.......the intake is going to heat up one way or another...there is water going through the front, sometimes the back and the heads will eventually transfer heat to the intake through the bolts.......but every bit helps........oil temp is hotter than water temp so you can see how this will work.....
I run my car with the rubber flaps out of the upper A-Arms so the air from the fan has somewhere to go.......this helps a ton........
The last thing is to make sure you use the proper 1/4" spacer/gasket for your Q-Jet........I use 1/4" phenolic for Holley's......the correct gasket is available from Cliff's........
With proper timing, and all of these mods....you will **** how much cooler the engine is under the hood from stock.......
I have a 1980 with an L48 and after alot of reading I ended up doing top end rebuild, TKO600 5 speed conversion, rear end swap to 3.53 gears, dakota digital dash and Lars rebuilt my Qjet. Once you start it's a slippery slope.
Here are the links to what I did based on feedback from the fourm.
dont i know it all started with a repaint, then i had to the seals in the rear end which lead to a gear upgrade to 3.73, then the front seal on the trans started leaking so that is going out for a rebuild then intake gasket started leaking, then after it was going in the right direction someone said the interior looked rough so its basically a on frame resto....
@Jebbysan so i bought the intake you suggested. and i found these heads on market place will the 205 runners cause me any problems. thanks for your help in advance.
"Speedmaster aluminum cylinder heads for SBC, 2.02 intake valve, 1.60 exhaust, 210 intake runners, 64 cc. Valve springs are good up to a 650 lift flat tappet cam, guide plates, $800 for the heads and $950 with the scorpion full roller rockers 1.5 ratio. good heads, have a couple of scratches"
@Jebbysan so i bought the intake you suggested. and i found these heads on market place will the 205 runners cause me any problems. thanks for your help in advance.
"Speedmaster aluminum cylinder heads for SBC, 2.02 intake valve, 1.60 exhaust, 210 intake runners, 64 cc. Valve springs are good up to a 650 lift flat tappet cam, guide plates, $800 for the heads and $950 with the scorpion full roller rockers 1.5 ratio. good heads, have a couple of scratches"
Intake port is way too large…..and the last two pairs of Speedmaster heads I had here I had to spend 6 hours blending the bowls and the **** CNC port match….and these were Ford Windsor and Pontiac heads…..
I would walk away….
pretty sure those speedmaster heads are just rebranded pro comps... I bought the "other" chinese castings. The 64cc 190-200cc heads and have been happy with them.. skip white sells them assebled as well as AFR as the enforcer series but afr machines them for thier valve stems and such.. Either of these would be a good choice or around a grand for the pair loaded. If you do go with these, go with the 190cc if you can find them vs 200 or 205.
1980 Budget build
