300hp/350hp differences?

[mcditalia]

Besides the aluminum intake manifold, what accounts for the 50hp and redline difference between the base motor and the L79's for 66 and 67? What's needed to build a base 300hp motor to L79 specs?

[Tom Bryant]

The L79 350 horse engine had the 11:1 pop up pistons that the fuelie '65 and the 365 horse used. It also had a performace hi lift hydraulic cam and 2.02/1.60 inch valves as opposed to the 1.94/1.50 inch valves used in the 300.

Change pistons, cam, inlarge the valves and add the intake and your basically there, specification wise. You could just leave the old flat tops in there as you are only talking about 1/2 point and it is hard enough to buy gas for 10.5:1 as it is.

Tom

[Mac]

Funny how the small blocks changed, isn't it? As the years passed, the base engine became less and less potent until finally the trend reversed. Perhaps this is why I'm shocked when I see a Shark running it's original engine. Seriously- why keep a 165 hp engine when the same block could sustain 400 hp and, given modern technology, it would likely get better gas mileage!

-Mac

[bossvette]

didn't the high output engines have forged cranks, "pink" rods and 4 bolt mains?

[Tom Bryant]

I think all small journal cranks were steel. They did have a better rod but the 4 bolt mains and "Pink" rods were a 350 thing.

I'm glad that they stopped the 327 before they started reducing the power in Corvettes. The last year for the 327 in Corvettes, 1968, the L79 350 horse was the most popular engine with nearly twice as many installed as the base 300 horse engine. The second most popular was the 427/390 and the base 300 was third. This shows you how great the L79 was as it made up nearly 1/3 of 1968 production.

Tom

[Donny Brass]

In addition to the intake, pistons, camshaft, and heads, the other differences are

8" finned balancer
timing cover for larger balancer
rear breather tube for crank case ventilation
aluminum finned valve covers
chrome oil fill
water pump with by pass fitting
vacuum advance canister

and, of course, the 350 hp air cleaner sticker

[Tom Bryant]

Oh, and that reminds me that the 350 and 365 had a special open back air cleaner assembly.

[Donny Brass]

the 66's and 67's all came with the open element 14" chrome air cleaner..........

[61 Silver]

Everyone did such a nice job describing the differences between the 350hp & 365hp, how about the differences between he 1963 340HP and the 1964 365hp.

[Tom Bryant]

I guess I was thinking about the '65. I had a friend that bought a new Nassau Blue 2 top '65 with the L79 and 4.11 gears. I can still remember how fast that car was.

The 340 was a 360 fuelie with a carb and the 365 was a 375 fuelie with a carb. Without digging too deeply the 340 had 11.25:1 compression and the 365 had 11:1. I'm not sure if it was due to piston dome volume or chamber size. The 340 used the original 097 Duntov cam that was used in the 283 and 327 solid lifter cars from 1957 on and the 365 used the '64-'65 30-30 Duntov commonly referred to as the 375 fuelie cam. Also they both used the 3782461 heads but the 350/365/375 engines went to 2.02 /1.60 intake/exhaust valve sizes.

On top the 340 used an aluminum intake with a Carter AFB and the 365 used a redesigned aluminum intake with a Holley. The 365 probably used the finned balancer and other 350 horse items as listed above. The 350 and 365/375 long blocks were the same except for the camshaft.

Tom

[Viet Nam Vett]

Originally Posted by Mac

Funny how the small blocks changed, isn't it? As the years passed, the base engine became less and less potent until finally the trend reversed. Perhaps this is why I'm shocked when I see a Shark running it's original engine. Seriously- why keep a 165 hp engine when the same block could sustain 400 hp and, given modern technology, it would likely get better gas mileage!

-Mac

What cracks me up is that the SB is still around ..of course in a different configuration but still a OHV Push rod Motor Now Sporting 500 HP In the new 7 Liter Z06 with a dry Sump Lub System...



We don't need no stinken Over Head Cams........

[Tom Bryant]

We made it through the dark ages then we came back even stronger than before.

[Viet Nam Vett]

Originally Posted by Tom Bryant

We made it through the dark ages then we came back even stronger than before.

Yeah Baby.....