Engine & Exhaust / Tech Articles

Ask Away! with Jeff Smith: Money-Saving Tips for LS Swapping a ’66 Chevy II

I have a 1966 Chevy II with a 327 and a four-speed. It’s a great car because it’s light and kinda nimble for a ‘60s car. I’m considering an LS engine swap rather than building another small-block Chevy. I know it will cost more to do the conversion, but I really like the idea of an all-aluminum LS7 with its stock 505 hp rating. My goal is 400 rear-wheel horsepower but to use a carbureted style intake and my throttle body EFI so I can keep the traditional look. The problem is that engine is guaranteed to exceed my budget. I’d like to hear your thoughts. – K.S.

Jeff Smith: Everybody says that there’s no such thing as too much power. But with a little Chevy II with fairly narrow back tires, I think it’s fair to say that this would represent an aggressive amount of power for your car.

We’re making several assumptions here, but let’s run with this. Let’s assume a stock rear leaf spring suspension with a 245/60R15 tire which is probably close to the biggest tire you can stuff under the stock wheel wells. Those are somewhat short and not very wide tires which lays down a relatively small footprint on the pavement.

The GM LS7 is a stout engine rated at 505 hp at 6,300 rpm and 470 lb-ft of torque at 4,800. Besides the power, this all-aluminum engine will remove roughly 100 pounds from the front of the car, which will help reduce the car’s nose-heavy weight distribution.

All of this is achievable, but also a bit pricey. Summit sells the LS7 crate engine for a little over $12,000. GM offers a warranty and the engine has a great reputation. But consider that you will also need new headers, motor mounts, an oil pan, and a complete accessory drive. This engine also uses drive-by-wire throttle which will require the pedal and controller kit. That’s another $1,300.

While researching, we looked for other long blocks that might be a little less expensive. One package that caught our eye was the BluePrint Engines‘ iron block 6.0L version (BPLS364OC). This started life as an iron block LQ4 engine from an early 2000’s truck. Bored an additional 0.030-inch, the block is fitted with forged pistons, 6.135-inch I-beam rods, and a cast 6.0L, 24x crankshaft that displaces 369 cubic inches.

BluePrint fits the block with its own hydraulic roller with specs of 223/223 degrees at 0.050 with a 114 degree lobe separation angle and 0.556-inch valve lift for both intake and exhaust. The short block is topped with a pair of factory rectangle port heads with 2.165/1.60-inch valves. The BluePrint website says that with an LS3 intake (and presumably headers) that this engine will make 470-plus horsepower and 455 lb-ft of torque.

[Note: To learn about effectively upgrading the LQ4 engine, read: LQ4/LQ9 Engine Upgrade Guide: Expert Advice for LQ4 & LQ9 Mods to Maximize Performance.]

Taking this a little further, I’ve always felt that LS street engines that aren’t aimed directly at all-out peak horsepower can benefit from cathedral port cylinder heads.

I recently tested an LQ4 iron 6.0L engine that had roughly 150,000 miles on the rotating assembly, which included the original pistons and ring. We added a very mild 219/227 degrees at 0.050 COMP Cams hydraulic roller cam with 0.607/0.614-inch lift and a pair of mildly ported 5.3L heads.

I used the 5.3L heads because the smaller chamber creates around 10.4:1 compression with the stock, dished LQ4 pistons. Then we added a stock Trailblazer SS intake to this package which is a tall, EFI truck manifold. The advantage is this manifold makes excellent torque and is also very affordable. We also used a large 102mm throttle body although a 90mm version would have made the same power.

This package made 496 hp at 5,600 rpm with peak torque at 495 lb-ft at 4,800 and even managed 410 lb-ft of torque at 3,000 rpm.

This is nearly the same peak horsepower as the much larger LS7 and our engine makes more torque! That Trailblazer SS intake may not fit under the stock hood of a Chevy II and it would not fit into your carbureted look. But substitute a dual-plane intake and carburetor and it would still make 475 hp.

This is great power and you could build it for much less than a brand new crate engine although it will be roughly 100 pounds heavier since it’s an iron block.

Either way, you will have plenty of power. All of this is easy. The hard part with any near-500 hp engine in this Chevy II will be hooking it up. Traction can be achieved, but will require some sticky tires and plenty of suspension tuning to make it all work.

These ideas offer a wealth of opportunities to choose from across a broad spectrum of cost, power, and displacement. It’s a great time to be adding horsepower!

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  1. Good recommendations. K.S.’s Nova is a 4 speed car. Left out of the concerns are the potential costs for a transmission and rear end upgrade as 470 ft. lbs. of torque will not be kind to those components. Also, I understand Jeff’s deserved pride in his LQ4 150,000 mile combination posting good numbers, but his gleeful comment of outperforming an LS7 is an unnecessary reach. With all due respect, we know that car mag build ups run no power sapping accessories on the dyno, and are typically pointed towards showing peak numbers to generate interest. Point is, comparability of GM stated 505/470 vs LQ4 496/495 is not that valid unless run under same conditions on same dyno.

    • Gary D. – thanks for your comments. The comparison between my LQ4 engine and the LS7 was merely to show how efficient a homebuilt LS engine combination was in terms of power. If you want to be very specific – then you are correct that a comparison of that 7.0L against my 6.0L isn’t even close to fair – that LS7 has 427 ci and my engine displaces a mere 364 inches. True, GM rates their engines using a different correction factor – it’s worth around 5 percent in difference of power – so add 25 hp to the LS7 and add another 15 hp for the accessory drive – that’s high by the way – my testing reveals roughly 10-12 hp. So now the LS7 makes 545 hp. That 427 uses rec port heads – my engine uses lightly ported 5.3L cathedral port heads with tiny valves. The LS7 has 11:1 compression – my engine has barely 10.5:1 Plus, my engine was designed and the focus was to make street torque – and my enhanced LQ4 makes more torque at 3,000 rpm than the LS7 even though the LS7 enjoys much shorter cam timing and more displacement. So – with all due respect my point was to show that building your own engine can produce equal power for an affordable budget if you are willing to do some work yourself. If we did run the engines side-by-side and then applied Engine Masters rules – I am confident my engine would win – plus I’d put fresh rings in the engine and make even more power. Ultimately, that same LQ4 with Summit TFS cathedral port heads makes 557 hp and 501 lb-ft of torque and still made 426 lb-ft at 3,000 – just for the record.

  2. HAROLD LOVETT says:

    Jeff, I am new to the LS engine family. Can you replace the stock piston with a flat top piston and what head would you use with this combination? What is the Summit P/N for the Comp-Cam’s cam and the P/N for the Trail Blazer intake? I Plan on getting the engine from the local Pull A Part yard. What years and vehicles should I look for for the best engine to pull and any ideas what to look out for. I want to put this in a S-10 with a power glide.

  3. Brian Nutter says:

    Harold. You can swap in a LQ9 piston. Another option are the new Summit Pro LS Pistons. You can read about those here:


    As for heads, the TFS As-cast 220’s are a heck of a deal and make great power. They’ll bump compression too!

    CCA-54-456-11 is the part number for the Comp Cam. The 2008+ intakes have the better design of the TBSS intakes so that could save you some money.

  4. Even cooler would be to put a set of shaved 243s on a LQ9 with valve reliefs for that cam. Get you up to around 550hp. Do it. I did!

  5. Travis Jones says:

    I’d run an aluminum 5.3, it would have the same high winding characteristics of the factory 327, be 100lbs lighter and still capable of making 400 to the tire, if you spin it out past 7k rpm.

  6. Did you retain the OEM front suspension? if so what oil pan did you use or recommend? Any room for a 5sp. trans without extra modifications? Cooling system upgrade? Headers??

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