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327 engine horsepower

Old 01-08-2019, 02:00 PM
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wglassmyer
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Default 327 engine horsepower

I recently purchased a 1964 327 corvette. It was sold as a 365 Hp engine non-numbers matching, but period correct. How can I easily confirm the engine is truly a 365 Hp engine (in lieu of a 250 or 300 HP engine)? It has one hump heads, but I did not take the valve covers off to check the head casting numbers. It has a Rochester Quad-ra-jet carb. the tachometer redlines at 6500 rpm's. The engine numbers were decked. I'm told this is common with rebuilt engines. Milling the engine removes the engine numbers. The air intake has no snorkles.
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Old 01-08-2019, 02:27 PM
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The 365 HP had double hump heads(461's that were also used on the 300 HP. The 365 did have larger diameter valves than the 300 HP, even though they both used the 416 casting.)

In 1964, there were no Quadrajet carbs on any GM vehicle. That was a 1965 invention to be used on low horsepower applications.

The 1964 365 HP had an aluminum intake manifold with a Holly double pump carb.

Also, the 1964 365 had a solid lifter cam and you could feel the ground shake when the engine was running. The 250 and 300 versions had ultra smooth idling hydraulic lifters.

Unfortunately, it appears that you have a "make believe" engine that is so common in fake restorations.

Last edited by JoesC5; 01-08-2019 at 02:33 PM.
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Old 01-08-2019, 04:04 PM
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Great answers and very helpful to me too. My question is........can you really run a 365 HP 327 on today's pump gas? I think it had 11:1 compression, which really sounds high for today's gas. I was somewhat interested in a 1965 with 365 HP engine, but then thought a 350 HP 327 with hydraulic lifters might be a better choice.

Butch
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Old 01-08-2019, 04:10 PM
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Dan Hampton
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The 6,500 redline on the tach might be a good indicator, assuming it wasn't changed out. Dual snorkel air cleaner did not exist on the 365 L 76, either.
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Old 01-08-2019, 04:19 PM
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This is what I ordered Tried of rebuilt https://www.gmperformancemotor.com/parts/19210007.html
Had the same problem you never know exactly what you have.all NEW GM and warrenty.
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Old 01-08-2019, 05:23 PM
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Originally Posted by 62cruiseer View Post
........can you really run a 365 HP 327 on today's pump gas? I think it had 11:1 compression, which really sounds high for today's gas. I was somewhat interested in a 1965 with 365 HP engine, but then thought a 350 HP 327 with hydraulic lifters might be a better choice.

Butch
If everything is up to snuff and meets factory design on components and tune, they'll run fine on 92 E 10. Either one of them.
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Old 01-08-2019, 05:37 PM
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The Quadrajet carb is a dead giveaway that is probably not a 365hp engine...does it have an aluminum intake? The 6,500 tach if original is for the 365, probably NOM
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Old 01-08-2019, 05:51 PM
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no al. intake.
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Old 01-08-2019, 06:02 PM
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Did the car come with finned valve covers and the 365 hp sticker?
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Old 01-08-2019, 06:27 PM
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Default 327

you will never know what it is until you take it apart.
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Old 01-08-2019, 06:29 PM
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Mike is right; the 365 horse engines as built by the factory will run on today's top grade of 92-93 ethanol added fuel. Those figures of 11.25 compression ratio were, ummm, optimistic. They were more like a true 10.7 to 10.8 cr as measured. And the carb wasn't a Holley double pumper. It was a # 2618 single inlet vacuum secondary 600 cfm.
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Old 01-08-2019, 07:02 PM
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461 casting guessing the 416 was an accidental typo

You can pull a spark plug out and using a cheap borescope see what kind of piston you have, that will tell you if it has flat tops or domed pistons.

Hopefuly it was the right engine that someone perhaps lowered the compression and stuck a hyd. cam in it, was common back then. Get the sinking feeling the seller was full of it or got snowed himself and doesnt know any better.
Wuthout the #s on the deck its anyones guess...just a 327. Doesnt mean you cant upgrade it if theres a bore job left in it. Does the harmonic balancer have a bolt in the end of it or not?

Theres a dark side to this hobby which is people getting fleeced on cars like this...they arent cheap either! Try to make lemonade out of it. 327 is a small motor but can make outstanding power with the stuff out today.
For instance..https://www.summitracing.com/parts/tfs-30210002?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-trick-flow-specialties&gclid=EAIaIQobChMI_MOi1Kff3w IVqh6tBh1pUgUKEAQYASABEgJCGPD_BwE

11:1 compression, Isky 280 cam, headers, decent dual plane, Holley DP your car will seriously haul azz.
A friend had a 63 swc with exactly that only well ported stock heads with 4.11s it was a little rocketship.

Last edited by cuisinartvette; 01-08-2019 at 07:14 PM.
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Old 01-09-2019, 02:40 PM
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Originally Posted by 62cruiseer View Post
Great answers and very helpful to me too. My question is........can you really run a 365 HP 327 on today's pump gas? I think it had 11:1 compression, which really sounds high for today's gas. I was somewhat interested in a 1965 with 365 HP engine, but then thought a 350 HP 327 with hydraulic lifters might be a better choice.

Butch
Yes if you de tune it and loose about 100 HP. I had one and it would ping unless I kept the timing correct and the right octane. I left my distributer loose so I could turn it in the event that I had to use pump gas. When I put the high octane in the tank and moved the timing to a mark I put on the manifold the engine came to life and burned the tires. with pump gas I could barely get them to squeel.
Lots will not agree but the HP loss on pump gas is HUGE.

Dom
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Old 01-09-2019, 04:59 PM
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Originally Posted by vettsplit 63 View Post
Mike is right; the 365 horse engines as built by the factory will run on today's top grade of 92-93 ethanol added fuel. Those figures of 11.25 compression ratio were, ummm, optimistic. They were more like a true 10.7 to 10.8 cr as measured. And the carb wasn't a Holley double pumper. It was a # 2618 single inlet vacuum secondary 600 cfm.
2818 Holley
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Old 01-09-2019, 05:03 PM
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Originally Posted by domenic tallarita View Post
Yes if you de tune it and loose about 100 HP. I had one and it would ping unless I kept the timing correct and the right octane. I left my distributer loose so I could turn it in the event that I had to use pump gas. When I put the high octane in the tank and moved the timing to a mark I put on the manifold the engine came to life and burned the tires. with pump gas I could barely get them to squeel.
Lots will not agree but the HP loss on pump gas is HUGE.

Dom

Just wondering..................

Did you do your own work or did you have a paid professional to work on it and did the one that did the work have any idea what was in the engine or tune?

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Old 01-09-2019, 05:06 PM
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Originally Posted by domenic tallarita View Post
Y
Lots will not agree but the HP loss on pump gas is HUGE.

Dom
I agree, run just under 12:1 and get away with it due to the cam profile, a nice combustino chamber shape, keeping temps cool & a good tune
91 pump around 32 degrees timing and Im easy on it. If I put some Torco or Wild Bills Supreme 100 in it I can run 34ish degrees the car just comes alive
Instead of pulling hard it just hazes the tire whenever I want. Love compression it makes all the difference in the world!
Will never drink the soup of low compression cammed up motors again.
Just because some Nascar supertruck did it or a magazine posts a dyno sheet doesnt mean its worth a damn on the street.

Last edited by cuisinartvette; 01-09-2019 at 05:07 PM.
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Old 01-09-2019, 05:16 PM
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Mike,
Yes, I did my own work as I was a mechanic at Chevy and did that on a daily basis. At the time I was considered a paid professional. But that was in 1971. Later as the gas octane went away is when that 327 didn't like what I was feeding it. All my engines had the highest dome pistons and thin SS head gaskets that were used in marine engines. I was a firm believer that GM was smarter than myself when the designed the engines. I am from the old school and like compression. I have my own fuel supply but on a long drive have to limp home on pump gas. I had marks that were very close when I twisted the distributor.
Water injection also did the trick to get the pinging stopped and keep the HP high when I had to use pump gas.

Dom
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Old 01-09-2019, 05:28 PM
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Originally Posted by Redbird View Post
2818 Holley
fat fingers
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Old 01-09-2019, 06:12 PM
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Originally Posted by domenic tallarita View Post
Mike,


All my engines had the highest dome pistons and thin SS head gaskets that were used in marine engines. I was a firm believer that GM was smarter than myself when the designed the engines. I am from the old school and like compression. I have my own fuel supply but on a long drive have to limp home on pump gas. I had marks that were very close when I twisted the distributor.
Water injection also did the trick to get the pinging stopped and keep the HP high when I had to use pump gas.

Dom
Originally Posted by domenic tallarita View Post
Yes if you de tune it and loose about 100 HP. I had one and it would ping unless I kept the timing correct and the right octane. I left my distributer loose so I could turn it in the event that I had to use pump gas. When I put the high octane in the tank and moved the timing to a mark I put on the manifold the engine came to life and burned the tires. with pump gas I could barely get them to squeel.
Lots will not agree but the HP loss on pump gas is HUGE.

Dom

I thought the OP was asking about a OEM stock engine. My error?
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