LouieM

I hope this is in the right Forum, since it is about (maybe) buying a midyear.

What are the visible mechanical differences between the 1967 327/300hp and 327/350hp engines? I'm looking at a car with a "327/350" and (probably) a restamped block. Except for the aluminum, vs. iron intake manifold (easy to fake), distributor number (ditto), higher tach red line (ditto) and engine internals (who knows?), are there any external differences? I want to pay a 350 price for a 300 motor. :nonod:

LouieM

Oops. Change the last sentence to: I DON'T want to pay a 350 price for a 300 motor!

provette67

On the drivers side front of the motor there is a there is a pad that sticks out in front of the head, a 300hp car will have a suffix of HO,HE,HH,orHR while a 350hp motor has a suffix of HD,HT,HP,or KH Pancho

LouieM

Pancho,
Thanks, but I know about engine code numbers on the right front pad--- HT in this case. But, I think that those numbers may have been restamped when the engine was rebuilt. So, I don?t know if the car is a real 350hp car or a 300hp car that has had a 350hp code stamped on the engine pad.

Except for the obvious stuff on the engine (aluminum valve covers, aluminum intake manifold) and the higher red line tach, are there other visible parts of the car that are different between the 300 and 350 cars. I know the clutches have different diameters, and the compression ratios are different, but that's all hidden. Can someone just plug a 350hp engine into a 300hp car, change the tach red line, and the car becomes a "real" 350hp car? :confused:

68shark

Presuming you have no build sheet....or other documentation, pretty hard to tell a good fake. All L79 cars were 4 speed (no auto available), would have the larger 8" balancer (again easy to replace, especially when rebuilding an engine). Not many people would replace a tach (this is an L79, not L88 or L89 where price difference is huge!). I would think if you have an M21 (more popular in the L79 than M20, so I'm told) and 3.70 gears or higher, combined with the right tach, that it probably was a 350hp car. :cheers:

LouieM

No, the car has no build sheet or other old documentation. You can see just scraps of the build sheet thru the gas door cut out. It's a 4-spd car with 3:70 posi and M21. You're right, sounds like an L79, and not many people would fake a small block. Since nobody can come up with 300 VS 350 differences that I don't already know about, I feel better about giving the car a harder look. Thanks. :)

68shark

One other thing....in my '68 owners manual, it indicates that the M21 was only available with the 350hp version of the 327, not the base engine. Presuming this was also true in '67, that fact alone would guarantee that the car was an L79. To confirm, the trans. case also contains the serial number derivative on the case, just like the engine pad. A code "B" denotes and M21, "A" denotes an M20. :cheers:

LouieM

In my 67 owners manual (from my first midyear, bought in 68 and sold long ago :nonod: ), it also shows the M21 not available with the 300hp engine. So I am looking at an original L79. I'll check for a serial number derivative on the transmission case. Thanks for the tip! :seeya

Louie

crooner66

350 motor has a chrome oil filler tube and cap. :cheers:

LouieM

You're right. I've seen several "350 hp" cars with all the stuff in the engine compartment correct, but with a 5500 rpm tach (= 300 hp), instead of the 6000 tach. I'm relying on the correct tach more than on anything else while searching for a 67 350 4-speed roadster.

Alwyn678

50 hp

vigoriton

The 350 horse has a different water pump. #3859326. The 300 horse used the 3782608. You probably can't see it without taking the fan and clutch off though. Then again it may not have either!!!

LouieM

Wow, there's a little-known bit of :chevy knowledge. In the Corvette by the Numbers book I just got, I see that the 67 300hp pump was also used in the 1970 LT-1, so it must work OK in base 67s. Thanks for the useful info. :) Always nice to hear from someone who knows about even the small things.

Louie

wallyknoch

One problem with the Tach, only solid lifter cars were red lined at 6500 all 350 hp 327 ci cars were hydraulic and red lined at 5500 and were coded HT and manual trans. :)

wallyknoch

Thats because a 300HP and 350HP are both hydraulic engined motors and ALL hydraulic engined cars are red lined at 5500. There are no 6000 red lined tachs. The higher tach, 6500 was only available in the solid lifter cars. Normally the first thing I look at on a Vette is the tach to see if the owner is telling the truth. Most people dont change the tach but simply add stuff to the engine. Easy check for :bs

sb69coupe

Interesting that the '67 did not have a higher redline for the 350hp motor. I know that in '69 the 350hp does have a higher redline than the base 300hp configuration.

Shannon

achapman

Whoa, the 300 HP is redlined at 5500 and the 350 is redlined at 6000, I just saw both motors and both tachs last night at the cruise. The 300 is in my 63 SWC and the 350 was in a 67 Coupe. That's what the tachs said, also the 350 HP has an aluminum intake. :yesnod:

wallyknoch

I beg your forgivness, my mistake. Of all my Vettes, I've never owned a hydraulic cam car. My 63 coupe was injected and that was my only C2.

I checked Corvette Central and they do offer a new gauge face for the 350Hp at {6000} red line tach. :cheers:

LouieM

We're all wrong. Acc. to Noland Adams' midyear book (p. 287), the L79 350hp tach had BOTH 5300 (not 5500) and 6000 redlines. Some early 1965 L79 tachs had a yellow zone from 5000 to 5300 and a redline zone from 5300 to 5500). All later 1965 and up midyears had a yellow zone from 5700 to 6000, then a red zone from 6000 to 6200. Think of all the time Noland must have spent to learn a ton of details like that!