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The "blocks" are the same, but internally the L-79 is quite a bit different. While the 327/250 and the 327/350 both used the same "870" block, just about everything else was different, cam, intake, carb, etc. To rebuild it as an L-79 though wouldn't be much different than any other rebuild. You'd normally be replacing things like the cam, pistons, etc, anyway, so you'd just have to find the right carb, intake and exhaust manifolds. If you want to rebuild it as a Corvette L-79, you'll want to make sure it's a Flint block and not a Tonawanda one, as Corvettes only used small blocks from Flint.
. If you want to rebuild it as a Corvette L-79, you'll want to make sure it's a Flint block and not a Tonawanda one, as Corvettes only used small blocks from Flint.
Aside from the stamped codes between Flint and Tonawanda blocks, is there any other difference?
If the code for “Tonawanda” is still on the block, then wouldn’t the “ full-size” suffix also still be present?
One noticeable difference between a Tonawanda block and a flint Michigan block is the oil pressure sending plug that is on the front of the block near. The timing cover does not exist in the tonawanda block. Many of the Tonawanda blocks use a two digit date code on the back of the block for instants A 12 3 would be a Flint block. A 12 63 would be a tonawanda block. also, some Tonawanda blocks the casting number is smaller than a Flint block.
Aside from the stamped codes between Flint and Tonawanda blocks, is there any other difference?
If the code for “Tonawanda” is still on the block, then wouldn’t the “ full-size” suffix also still be present?
Flint blocks have a threaded hole with a square plug for an oil line on the front of the block, just to the right of the stamp pad, above the timing cover. They're also dated differently, Flint blocks have a single digit for the year while Tonanwanda dates use two digits ("5" for 1965 vs "65" for 65).
Yes the "T" and passenger car suffix code could still be on the pad as long as the block wasn't decked. If in an attempt to make it appear to be an L-79, the block was decked and/or restamped, the plug and date would still be give a ways that it wasn't a Corvette engine.
If your passenger car block was cast in Flint rather than Tonawanda, it will have the same appearance as a Flint block for a Corvette. But a 327/350 and even a 327/300 use different heads than your 327/250 heads.
If your passenger car block was cast in Flint rather than Tonawanda, it will have the same appearance as a Flint block for a Corvette. But a 327/350 and even a 327/300 use different heads than your 327/250 heads.
Ok, I need to do some more numbers research on what I have for heads.
If your passenger car block was cast in Flint rather than Tonawanda, it will have the same appearance as a Flint block for a Corvette. But a 327/350 and even a 327/300 use different heads than your 327/250 heads.
For 65 the 250 horse used the same "461" head casting. The only difference being 1.94 valves for the 250 vs 2.02 for the 350 horse. What I can't say for sure is if the passenger car version of the 327 used 461 heads like the Corvette.
For 65 the 250 horse used the same "461" head casting. The only difference being 1.94 valves for the 250 vs 2.02 for the 350 horse. What I can't say for sure is if the passenger car version of the 327 used 461 heads like the Corvette.
Sorry this is not a correct statement the 250 hp 65 Corvette used a power pack head, which is a head with a point on the head marking not a double hump, 300 hp was the 461 double hump heads. The 461 casting came in two configurations the 194 valve used in the 300 horse and the 202 valves used in the 365 horse and the 375 hp.
Several years ago, I started adding an oil pressure gauge directly to the block, up front, on all my engines. Since Tonawanda blocks did not have the drilled passage and the square head threaded plug, it is TOOOOOOOOOOO EASY to drill and tap a passage.
The Tonawanda blocks already have the same boss where the passage is drilled on Flint blocks. I use a long drill bit and "eyeball" the angle for drilling into the center passage. Then use a 1/8in pipe tap for threading the upper end of the hole. I do this BEFORE sending a block to the machine shop so that all the metal particles will be removed.
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This is the 400 (Tonawanda block) we built for my son's 73
This is the engine that was in the T-bucket before our son destroyed it.
And the boat engine (420SB).
Olds blocks also have a threaded oil hole up front (tube at far right). This is the Olds 455 I built for the Cutlass.
Sorry this is not a correct statement the 250 hp 65 Corvette used a power pack head, which is a head with a point on the head marking not a double hump, 300 hp was the 461 double hump heads. The 461 casting came in two configurations the 194 valve used in the 300 horse and the 202 valves used in the 365 horse and the 375 hp.
Everything I ever saw said the 62-64 327/250 used the Power Pac head, but for 65 it was replaced by the 1.94 valve 461?
On early cars, such as Corvettes and more frequently, on Chevelles, GTOs, etc, the obsession continues to increase for a correct, original block.
But, for Tom Parsons, the goal is for function and dependability. For example an 327 block is a 327 block, or a 454 block is a 454 block. PERIOD. For MOST OF THEM, the ONLY difference is the casting date and the stamped numbers up front.Otherwise, for replacing or building an engine, they are all identical in very way and the end result when built will give the same result.
I love a correct, authentic matching everything car, but my desired end result is dependable function. PLUS, when a built 350-383 will be a pure, drip-in, bolt-in, drive it away swap-------------WHY NOT?????????????
That's why I built and dropped in an FI SB400 to replace the wennie 265.
Oh ya, and it's a super nice driver instead of an NCRS show queen!
Yeah, my car will never be a show queen. A nice driver yes. But I would like to have a 350 HP engine instead of this HP 250 one. Pretty sure 100 HP will make a significant difference in SOTP feel.
Yeah, my car will never be a show queen. A nice driver yes. But I would like to have a 350 HP engine instead of this HP 250 one. Pretty sure 100 HP will make a significant difference in SOTP feel.
If your plans are to go with more cubes and more power, then you might as well go with a well built 383-400. The effort will be the same, the additional expense will not be that much and EVERYTHING for a small block is a bolt-on fit.
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Differences between full size Chevy Block and Corvette Block
