My L82 is going to get a top-end swap to some 64cc modern aluminum heads, today's dumb newb question from me is: "How do I know which intakes are going to be a relatively close match to which heads?"


I'm just going to buy as-cast aluminum heads, because that's what's in the budget, so I'm not looking to pay someone to port match the intake to the heads either (I want to remain married after this build). How the heck do I ensure that the heads and intake are still going to be an as-close-as-possible match to avoid killing air flow / air velocity?

My whole top end build and headers will will focused on maximizing low-end torque so air velocity is my key concern.



Right now I'm strongly leaning towards these guys: http://www.high-performance-engines....p/sbc64195.htm

They're modified Profilers, essentially; no raised exhaust ports so you don't have header fittament issues.

I could be convinced to go Dart, or the newest Patriot Freedoms, too; but I'm really looking for one of the super new aluminum 64cc designs that focuses on velocity and AFRs are certainly way out of the budget; Broderick's probably out of the budget, too.


Adam

 

I did a similar swap on my 383 Road Runner last year. I wasn't sure about matching everything together until I spoke with the Edelbrock people while at Carlisle. They have top-end kits that include: completely assembled aluminum heads, matched alum. intake, cam, timing chain & sprockets, lifters, all gaskets & ARP bolts. Complete kit is about $2300. Or, you can call Edelbrock & assemble just the parts you need.
I swear by this kit. Great low & mid-range. Top-shelf quality & service & no guess work or opinions.
Good luck, Tim

 

The heads you linked are 195 cc intake runners. If you want to keep velocity up then a 180 head is probably a better choice.

Given that the corvette offers little room for more than a couple different dual plane intakes you shouldn't have any issues coming very close in intake to head match as far as size is concerned. The L-82 already has an aluminum intake and is a decent candidate for the new heads as it is.
I wouldn't recommend Dart simply because of the intake tract volume vs their advertised volume. A 180cc head comes to you, as cast, around 197cc's on a Dart SHP head. Assembled the quality is really sub par as far as I'm concerned.
Any head you buy do not just bolt it on if it's pre-assembled. It needs to be disassembled and checked for guide clearance, valve leakage and general quality of the port as well as combustion chamber finish. Sharp points in the chamber are an invitation to detonation.
How many miles on the L-82? Do a leak down to check ring seal. Too little and by bumping the compression you may end up with an oil burner.
If you are changing the heads then a cam change would maximize your desire to keep the low end sharp. The L-82 cam is old school with slow ramps on the cam leading to a weaker bottom end.

 

Thanks for the detailed response.

You're of course correct about the 195cc vs. 180cc intake runners; I simply copied the wrong link. Fully planning on 180cc or 185cc (varies by company).

I've read a guideline to look at the original intake runners and increase by 15-20%, which would be 185-190CC for Gen1 SBC. -You think sticking to the lower end will help more with low-end torque? (I definitely wouldn't go over 185cc.)

I was already leaning away from the DART SHP because there seems to be a controversy that they might actually be 67cc chambers and I want as much of that CR as I can get!

I haven't looked at whether Trick Flows would be in my budget or not, but the Patriot Freedom's are definitely within my budget and when HotRod did their recent budget SBC head shootout their 185cc, 65cc performed very well especially for the money.


On the intake front; understand the clearance issues and I DEFINITELY want to keep my L82 dual snorkel and stock hood, BUT I'm doing an EFI conversion this winter and the Holley Sniper is very high on my list so I'm going to need a new intake anyway and there HAS to be some technology improvements in intakes in 40 years, right?

-I'm pretty confused at where to go with intakes, honestly. Again, I want to focus on low end torque; that means long runners, right? -EFI is also supposed to like long runners, if I'm not mistaken.

I'm still a newb so I don't fully understand it, but doesn't a dual runner intake imply a shorter runner length which means more top end and less torque?

At some point in time I thought that I had identified a Weiland intake that fit the bill pretty well but now I can't find where I may have saved that information. Again something that maximizes low end torque and works well with an EFI system AND fits below the stupid 79 L82 hood.


-The engine's got only 14.9k miles on it so I'm probably not going to bother with a leak down. If it starts to burn oil and cause a problem then I've got a justification to do a more major rebuild and get one of those expensive retrofit roller cams in it. (My wife lumps expenses into "nicety" vs. "necessity"- Necessities get automatic funding.)

Adam

 

I really, REAAAALLY want to make sure that the whole system is optimized to work well together and focuses on really fun low end torque / acceleration on the low end.

My car's first major mod (September) is a 4L60e trans swap which will get it that awesome super low 700r4 1st gear; that plus the new heads, intake, and (if I HAVE TO) new cam --I'm really hoping for a super fun torquey Vette that can behave and cruise at low RPMs on the highway. (Paddle shifters will make it more fun for fooling around and will allow me to upshift sooner to save MPG if I feel like driving in eco mode (as will multiple trans and engine profiles between the trans controller and EFI).)



The other thing I really need help with is matching a CAM to my goals and car/engine. Just like i often hear conflicting information regarding the L82 aluminum intake ("it's good-don't change it" vs. "yea, it was good in 1979, but that was a long time ago"), I hear the same conflicting opinions regarding the L82 CAM. Again, I want to re-iterate that I want to focus on low-end torque, but to be honest I'm also looking to not do anything that's going to make the fuel economy get worse.

It's my understanding that the CAM recommendation depends upon a lot of factors, but most here know how heavy these cars are (mine had a curb weight of 3,650 lbs; now 3,550) and what the L82 engine with a modern aluminum head swap is like. My exhaust is now a true duals, with dual high flow mufflers (well high flow in like 1981 anyway- the exhaust was replaced then and cats dumped); I'm having headers of some sort installed and because it's just easier and cheaper I'm leaning towards shorty headers that can just be bolted in with no welding to my existing exhaust which is connected to the nasty manifolds. --I have no idea how to tell whether I'm going to be exhaust limited and should go with a dual profile cam to keep the exhaust valves open more or not given all these factors. Anyone really good at balancing these things and figuring out what kinda cam profile I should have given my car and goals?

EFI requires a less lopy cam, and my low-end torque goals do too. -Is there really going to be a significant jump by swapping the cam? (I do NOT have the ability nor patience to do that swap so I'd have to pay a professional, which is a factor for me, too.) -Again, if I'm really going to get a major improvement in performance (low end torque and an improvement in efficiency if I do the cam swap, then I'll do it.

I've run the comp camps software and it gives like 20 recommendations. -I looked at their new EFI-specific cams but they seem designed for super modern super high perf LS motors and not some old GEN1 SBC with a TBI EFI conversion...



Adam

P.S. Let's take retrofit roller cams off of the table. I get the advantages and I get that it helps my torque AND fuel economy improvement goals but the cost for what you get is exorbitant and it's just not an appropriate use of my funds for this build. I would lose the ability to do something else that I'd rather do if I went retrofit roller. -When I have a major engine breakdown then I can justify the cost in a rebuild with my wife; lol!

 

I realize that I can't pickout an appropriate lockup for the 4L60e trans torque converter until I figure out all the engine/CAM stuff, so I'm trying to get everything locked-in. Once I buy the trans+torque converter I'm committed so I'm really trying to think through everything and do it right the first time.


Headers: Given my goals and where I'm looking to go (modern 64cc /180cc aluminum heads w high velocity flow), what diameter headers should I be looking at? -It's my understanding that I want to go with the minimum size required to bring the exhaust in balance with the airflow coming from the intake side. My best guess is 1 5/8" -sound right?

Also: to aid high velocity flow, should I really just suck it up and go with mid length or long headers and pay some exhaust shop to cut and weld my existing exhaust? (My plan, because it's easy, was to go with coated shorty 1 5/8" but if it's going to be a major choke point and slow down that flow and kill my torque, I'll reprioritize. )

-I'd also love recommendations on inexpensive, well-fitting headers that are less likely to create clearance problems both ground clearance and a possible Borgeson or Rack and Pinion (Steeroids) conversion later. (Note: Headers of some sort is happening either way; I want the flow, the sound, the reduction in heat under the hood (coated), the weight loss, killing the stupid A.I.R recirc port thingy, and I need an O2 sensor welded in to support my winter EFI conversion anyway.)--There's too many reasons to get headers.

Could I make up for the shorty headers by putting 1.6 ratio rockers on the exhaust side of the heads?

That brings up another question: everyone says that going with 1.6 ratio roller rockers is a really cheap source of extra power - but is it something that hurts torque / air velocity at the cost of high-end HP that I'd never use / enjoy?


Adam

 

Re: Intakes: I watched the Edelbrock "Performance Intake Manifolds" videos; have now confirmed that dual runner intakes focus on torque. I'm still pretty sure that EFI systems prefer long runner intakes so I'm not quite sure what to do about that. Not sure if the EFI + Long runner recommendation applies to all EFI or just TBI or just PORT fuel injection systems...

Here's the Weiand "Street Warrior" I was looking at; dual plane, 0-5,500 RPM; not sure about the 4" manifold height + EFI + stock air cleaner w dual snorkels, though... https://www.summitracing.com/parts/w...make/chevrolet

-I like that the description of the intake specifically says that it was designed for these modern higher velocity flowing heads on Gen1 SBCs; I also love that from day 1 it will work with my Qjet and it would work with a Holley-style carb or EFI later, too. Now I just need to know whether it'll fit under my 79 L82 hood such that I can still use my dual snorkel cold air system and whether it's an ok match to the heads I'm considering...

I'm also mildly concerned that when I go on the Holley site and select "Dual plane intakes", "SBC" and then click "EFI" -it filters out all options and says to call their 800 number. (Starting to make me think that dual plane and EFI don't get along well after all...)


Adam

 

I understand going with a top-end kit is "safer"/ ensures you get parts that are all well-matched, I'm just not sure I'm in the Edelbrock heads fan camp; intakes, ok fine. There's a lot better performing, lower cost heads and heads are where I want to focus the bulk of my engine investment so that's kind of moving me away from an Edelbrock top end kit at the moment. http://www.hotrod.com/how-to/engine/...head-shootout/

 

This reminds me of another newb question I have: Do you HAVE TO / are you strongly suggested to replace timing chains and sprockets when replacing a cam? -I know you have to replace the lifters, but if you've got a very low # of miles on your engine do you really need to replace the timing stuff? -If so, why?

I've seen a couple recommendations on doing that when swapping a cam and I have no idea why. (Mostly because I don't really understand what that stuff does / what "timing" it's even involved in.) --I think I roughly understand distributor timing- you want to make sure the spark ignites the compressed air fuel mixture at the right time to maximize your balance of compression and airflow and to not shoot fireballs out of the cylinders in either direction; but what the heck does the timing chain even DO!??

The crank shaft just spins and has some rods that push the pistons around ; I don't understand what needs to be "timed" -is it about syncing the crank shaft and the cam shaft so that the valves open and close at the right time? (yea, that actually sounds like an intelligent thought; i'm going with that one....)




Adam

 

If you would state what your total budget would be then a better evaluation could be done

 

It really depends on the whole combo ie, heads, cam, exhaust, gears and stall (if auto) if your not changing the cam I'd go with the performer or didn't the L82 come with an aluminum intake?

 

I would do a matched package like the Edelbrock one. I would lean towards 170 or 180 sized ports on a 350 to keep the velocity up. The 200 tend to work better with 383+ if one wants to keep the velocity up.

Is the bottom end of the motor in good shape?

 

Here's what I can tell you about your questions based on my complete rebuild of my L-82 in June 2014. Yes do a compression and leak down test to see where your pistons/rings are at. Definitely, get a new double roller timing chain and gears since the GM set has nylon cam gears and the Stock timing chain stretches...my nylon gears were intact but the timing chain was stretched with 65,000 OEM miles. I can't comment on heads since I used AFR 180 64CC aluminum heads which are arguably the best for a Gen 1 SBC but pricey and I went roller cam with Howards retro fit roller (.525/.525 lift, duration 219/225. LSA 110) versus the stock cam's specs of .450/.460, duration 222, LSA 114. I was looking at the Lunati Voodoo flat tappet cam 262/268 (lift .468/.489, duration 219/227, LSA112) before the decision to go roller which has great specs and lots of folks love this flat tappet cam. I also used a .015 head gasket to help a bit with compression. I did reuse the L-82 OEM aluminum intake since I was told by my builder, researching intakes, and because I wanted to keep the motor as much L-82 as possible and reuse the OEM cold air intake system that the L-82 aluminum intake is indeed very good (aftermarket aluminum intakes will net you MAYBE 5-7 hp..save your money!) for a street motor operating from idle to 6,000 RPM (roller cam range is 1,500-5,600 RPM with tremendous mid range torque) and the motor is a monster now. Extremely pleased with the whole combination....The motor has better manners than the stock L-82 with a ton more power..100-125 more HP!

 

I went with the lunati 262/268 cam myself... flat tops and 64/180 iron dart heads... combo works very well..VERY big improvement over the L82 cam. Because I had the high rise hood I was able to go with a polished rpm clone intake but for factory the performer intake is the way to go unless you have the l82 intake which you do which is almost identical in performance as far as anyone has ever shown... Since your bottom end has under 20k on it im sure your timing chain and such is find.

I know exactly what your saying about keeping things on a budget... I mean we have to have funds for the homebrewing right? I just dropped some coin on 2 7BBL kettles for the taproom I'm hoping to open as soon as I find a location.

I have less than 8k in my vette including cost of the car, the new engine, wheels, interior and paint I am all to familiar with justifying the upgrades and keeping things on a budget.

 

Buy the Dart 180 Platinum bare and assemble yourself......
The bare 2.02/1.60 uses shelf length valves and spring/lock/retainer.....
The last three sets of bare Platinum heads had gorgeous five angle valve jobs and the ports are wet flowed......
I agree on having Dart assemble them.........I have seen some shoddy work on the assembly part.
To me...Dart was always an "engine builder" head......buy it bare and DIY.
I can tell you that Dart also makes a dual plane manifold that is a very close match to their ports in the heads......
An Edelbrock Air gap is also very close.

Victor Jr. and Team G single planes are awful.......the Weiand Stealth is "ok"........do not bother with the China repops.....

FYI.....Brodix makes a killer low profile daul plane.....but not sure how they line up nowadays......

Good luck and keep us posted with what you do.....

Jebby