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Hi All! I have been building hot rods for 40 years but this is my first LS adventure. I just bought a rear-ended, 130000 mile Chevy Express 3500 with an LQ4 6.0 and 4L80. I was able to drive it 60 miles back home. No lifter noise, no check engine light, shifted great.
This combination will be transplanted into a 1965 Corvair sitting on a G-body frame. It should weigh in at 2200-2400lbs. I have a set of 243 heads to raise the compression to 10:1.
I will be installing LS7 lifters, .080 pushrods, new rockers, valve springs, and LS G-body swap headers. I want to remain N/A with a lopey idle and drivability. It will be driven regularly and shown throughout the summer season. It will most likely have a vintage air unit installed.
I have read lots of cam/intake swap articles but all have contradictory outcomes. I’m looking for real world numbers and suggestions!
Last edited by ‘65_Corvair; 05-16-2024 at 08:44 AM.
Reason: Forgot something
The 243 heads are "cathedral" style.
You will need a much lower profile intake manifold than on your LQ4. An LS6 intake would be a good choice; since authentic ones are expensive, the Dorman LS6 replica might be a good choice.
Everyone has a favorite cam and therefore everyone will have an opinion, biased to their own of course. My only suggestion is to avoid "Thumper" type cams as they are oriented toward noise and neither power nor driveability.
Learn what Camshaft "Overlap" means. Since most camshafts are sold by duration and not overlap, you need to use a camshaft calculator which takes intake/exhaust duration and lift and something called LSA (lobe separation angle).
Like this one: https://mgispeedware.com/camshaft-calculator.
Positive overlap will give you a lopey idle.
I don't think that any OEM camshaft has had positive overlap (at 0.050") since like 1970 as it also hurts emissions. Many GM OEM camshafts have like Negative 15 degree overlap.
The positive overlap will also gain you like 75+ HP over the stock camshaft.
I suggest you aim for something between 6 and 9 degrees of positive overlap. It will give you a lopey idle but still good drivability. Stage "2" cams are often in this range. (I personally go with much more overlap, but it hurts drivability and becomes a bitch to tune.)
People often get confused about LSA. If you use camshaft calculator, you can ignore it because the calculation takes it into account. In short, every degree of reduction in LSA increases overlap by one degree.
I would also suggest a cam gear which has adjustable advance/retard, typically +/- 3 degrees. When you advance the cam, you gain better drivability and more power at low RPM at the expense of max power at high RPM.
When reviewing cam specs be sure you look at the amount of lift and make sure your selected valve spring support it. Since the stock springs are not designed for above .550" lift, and many 6-9 degree overlap cams will have around .590 lift, you will need a spring kit too. Quality Beehive spring kits support .600 or .625 lift with some leeway. Don't bother with dual valve springs for your setup.
If you are looking for complete kits, including a camshaft, lifters, pushrods and springs, I have been very satisfied with products from BrianTooley.
Is this the kind of info you are looking for?
Last edited by mrvedit; 05-17-2024 at 07:25 PM.
Reason: correction
I am looking for a camshaft/intake/throttle body/injector combination that will give great power and decent drivability. I’ve read a lot of articles and haven’t found any real answers. I’m hoping that someone with a similar drivetrain can provide some insight.
I crammed a 2006 LQ4 with 243 Heads, TR 230/236 Cam in it, into my 1984 MCSS with a Built T56 6spd behind it, so I think I'm pretty much the expert on what you are trying to do. Can't get any more Gbody than that. I have Heddman Long Tube Headers, 1 7/8" Primary 3" Collectors, the 3rd set they made as a fitment test into my car. LS6 Intake with LS6 Injectors. Stock Cable Throttle Body. It makes plenty of power.
I crammed a 2006 LQ4 with 243 Heads, TR 230/236 Cam in it, into my 1984 MCSS with a Built T56 6spd behind it, so I think I'm pretty much the expert on what you are trying to do. Can't get any more Gbody than that. I have Heddman Long Tube Headers, 1 7/8" Primary 3" Collectors, the 3rd set they made as a fitment test into my car. LS6 Intake with LS6 Injectors. Stock Cable Throttle Body. It makes plenty of power.
Looks like Thunder Racing is out of business. Your setup is very close to what I am looking for. I’m now trying to find a cam with similar specs.
that said, if this is your first LS, and you aren't already best friends with a good tuner, i would take that LQ4 as it sits and drop it right in. a stock, well running engine, with a stock tune and stock sensors, will have excellent (stock) driveability even in a swap application - best chance of success. then put a cam in a later, that way you know its the only thing you're changing at that time.
That cam is not available according to Summits website.
There is a (somewhat) famous car shop close to me that has a chassis dyno. They will tune the car.
The engine will be modified before going into the car. The exception may be the intake. I’m not sure if I will have room for the FAST LXRST. I want everything to fit under the stock hood.
That cam is not available according to Summits website.
There is a (somewhat) famous car shop close to me that has a chassis dyno. They will tune the car.
The engine will be modified before going into the car. The exception may be the intake. I’m not sure if I will have room for the FAST LXRST. I want everything to fit under the stock hood.
Drivability Vs performance...there will be compromises
Wider splits on the duration OR tighter LSA (lobe separation angles) will give you the "chop/lumpy" sound, but both can effect drivability if you go too far, and both can/will effect MPG.
You need to pick which one you want more and which one you can live with.
Drivability Vs performance...there will be compromises
Wider splits on the duration OR tighter LSA (lobe separation angles) will give you the "chop/lumpy" sound, but both can effect drivability if you go too far, and both can/will effect MPG.
You need to pick which one you want more and which one you can live with.
I’ve been looking at a lot of camshaft numbers. I may now be more confused than when I started. LOL! Drivability is definitely more important than the choppy idle. I’ve seen hp/tq graphs that are lower for a good sounding cam, and higher for a smoother idle. I’d rather have the hp/tq than the sound.
The "thumpr" type cams have the lower HP/TQ numbers with good sound; I said to ignore those. They are for "kids" who only want to install a cam but not upgrade springs and other components needed for "real" performance cams.
For "real" performance cams, the higher the HP, the lower the drivability because all the torque comes at high RPM.
I tried to condense my 50+ years experience with cams into one short post #4.
Your selected cam has 10 degrees of overlap, moderately high lift at .600" and is a "real" performance cam.
However, it will have noticeably degraded drivability, poor gas mileage, require a 900+ RPM idle, be prone to stalling and may not produce enough vacuum for your power brakes.
Sorry, you may be going down the path we see often here where someone over-cams their engine, regrets it and then goes back to a modest "Stage 0" upgraded cam, such as the GM LS1 "Hot" which has -1 degrees of overlap. I wouldn't go that modest; but not go over +6 degrees over overlap. The Brian Tooley "Truck Norris" cam is a popular one with exactly +6 degrees of overlap; however it has only .525 of lift; I would suggest .600 lift with +6 degrees overlap.
(BTW - On the LS2 and LS3 engines in my '81 Camaro, I have had cams with +16, +15, +14 and now +19 degrees over overlap; first thing I had to do was install HydroBoost braking system as there was insufficient vacuum for regular power brakes.)
The "thumpr" type cams have the lower HP/TQ numbers with good sound; I said to ignore those. They are for "kids" who only want to install a cam but not upgrade springs and other components needed for "real" performance cams.
For "real" performance cams, the higher the HP, the lower the drivability because all the torque comes at high RPM.
I tried to condense my 50+ years experience with cams into one short post #4.
Your selected cam has 10 degrees of overlap, moderately high lift at .600" and is a "real" performance cam.
I have not yet “selected” a cam. I have been building hot rods myself for over 40 years. I’ve been down the path of “overcamming” an engine.
This is my first ls. I want to avoid common mistakes. That’s why I asked.
Looks like Thunder Racing is out of business. Your setup is very close to what I am looking for. I’m now trying to find a cam with similar specs.
Yup, I think they went out a while back. It makes good power and a solid powerband from 2800-6500RPM where I shift it, could probably go higher but no need. Being a manual car I like it to have a solid pull from the low end, I have the tune setup to ramp in the fuel at 2800 and there's no lack or stumble anywhere. Hit the go pedal and hang on.
Specs of it here when I bought it before I installed it.
I’ve been looking at a lot of camshaft numbers. I may now be more confused than when I started. LOL! Drivability is definitely more important than the choppy idle. I’ve seen hp/tq graphs that are lower for a good sounding cam, and higher for a smoother idle. I’d rather have the hp/tq than the sound.
The truth of the matter is that most cams of similar duration numbers and lobe separation angle will make very similar power. If you want to get a great sounding cam that runs great, look at the BTR Truck Norris cam. I tune a lot of combinations with that cam using Holley EFI and the cam check sll of your requirements. It sounds great, has good manners (with some careful tuning) and makes great power.
I have not yet “selected” a cam. I have been building hot rods myself for over 40 years. I’ve been down the path of “overcamming” an engine.
This is my first ls. I want to avoid common mistakes. That’s why I asked.
Excellent news that you have so much experience too.
Not surprising actually as people interested in Corvairs tend to be in the late 60s or even 70s.
When selecting a cam, honestly evaluate if your intake and exhaust systems have restricted, average or well above average flow. If either is restricted and you over-cam the setup, you won't gain any power over a more modest cam, only have worse drivability
IMHO, even a very modest cam in your 6.0 LS engine is going to give you STUPID power levels in a Corvair. .
The truth of the matter is that most cams of similar duration numbers and lobe separation angle will make very similar power. If you want to get a great sounding cam that runs great, look at the BTR Truck Norris cam. I tune a lot of combinations with that cam using Holley EFI and the cam check sll of your requirements. It sounds great, has good manners (with some careful tuning) and makes great power.
Andrew
Great advice for you @65_Corvair. I mentioned that cam in an earlier post and here you have someone who could provide you with an excellent remote tune for that cam!
05-16-2024, 08:17 AM
So Confused! LS newbie. 
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