Information wanted on 265,283 HP ratings

[Old School]

Wasn't the highest horsepower for the 327 carb engine 365? I think the 375 rating was only for the fuel injection. Exact same engine except one had a carb the other fuel injection.

I agree the L79 350 hp had 2.02 valves.

[pamotorman]

Wasn't the highest horsepower for the 327 carb engine 365? I think the 375 rating was only for the fuel injection. Exact same engine except one had a carb the other fuel injection.

you got it.

[oldhead]

OK.I got it, the 350,365 and 375 hp had 2.02/1.60 RIGHT Just like I said on Nov.27, Oldhead

[pdq67]

If not mistaken, the notch on the rear cam journal was so that it could, if wanted, be used in the '55 engine because of its funky oiling system.

It was designed w/o a real oil filter system, (it used a top mounted, can), and also didn't have the, "full", oil groove behind/under the rear cam bearing. Most guys just used a small angle grinder and cut the needed groove by hand in the rear journal if their cam didn't have it so that it could be used in the '55 265 engine.

My junk -097 cam's notch that I had in my junk301 was hand ground. A hand ground notch is something like a 1/2" long, 3/8" wide and maybe an 1/8" deep and centered...

pdq67

[WerbyFord]

TOTALLY awesome thread I just discovered here!
I had read that the 283/283 and 283/290 were identical, but this thread got me thinking more - so I looked up a hunch in Colvin's "Chevy by the numbers 1960-64". Sure enough, the exhaust manifolds got better in 1958-up, that looks like the difference - same engine but better iron exhaust.
From there to the 283/315 it looks like just heads, plus another 0.5 compression.

The better 58-up exhaust iron helps all the 283's but the vanilla engines don't really care, they pick up 2-3 hp on the Gonkulator. But the 283/290 shows a full 7hp gain in the Gonkulator (as well as the rating).

For the early solid cam 265/210 and 265/225, I have a GUESS of 208-208 duration and 110 LSA, vs the later Duntov at 229-229 duration, and the Big Duntov at 254-254 (all at .050 lobe). Can anybody improve on that 208-208 guess?

As far as making their ratings, I have done a lot of work lining up my own DeuceCoupe Gonkulator aka WerbyFord Gonkulator with ratings, road tests, dyno tests, etc. I conclude that the 283's pretty much made their ratings, but the 327s and 350s started to drift off - they make their ratings if you use open headers, but typically not with iron exhaust. Some confirmation comes from road tests of the day - the Big Duntov 254-254 cam doesn't really MPH any better than the Duntov 229-229 cam. I don't think it helps much without headers (hopefully open). In cars like the Nova things get even worse - the dealer conversion 327's and even the L79 didn't run that good in the Nova because you got tiny little 283 vanilla exhaust iron. But add some fenderwell headers and watch out!

I too tend to live in the past on these things - I think there is a lot of value in the history of this era - it will never be repeated or matched by today's computer cars.

THANK YOU.But not the answer I am looking for...How did the 1955,265,PP 180 hp get to 210 hp in 1956? How did the 283,283HP get to 290 hp and then in 1961 get to 315 (I think alum heads from a next year 327?) THANKS FOR TRYING Oldhead

[pamotorman]

If not mistaken, the notch on the rear cam journal was so that it could, if wanted, be used in the '55 engine because of its funky oiling system.

It was designed w/o a real oil filter system, (it used a top mounted, can), and also didn't have the, "full", oil groove behind/under the rear cam bearing. Most guys just used a small angle grinder and cut the needed groove by hand in the rear journal if their cam didn't have it so that it could be used in the '55 265 engine.

My junk -097 cam's notch that I had in my junk301 was hand ground. A hand ground notch is something like a 1/2" long, 3/8" wide and maybe an 1/8" deep and centered...

pdq67

big notch hyd and small notch solid lifters. a mod to the cam bearing and you don't need the notch

[kirkwoodken]

THBOMK, the 340 and 360HP 327 were '1962 only and used the 097 cam. The 62 had the funny looking, one year, FI and was 360 HP. The 340 HP had an AFB.

The 30-30 cam came out in 63 and was used in the 365 HP 4bbl, and the 375 FI engine from 63-65.

The AFB, and the two Carter WCFB's, both had 8 sq. in. of venturi area. I chose the duel quad WCFB's for my 340hp 327 and always out ran the single FB engines. My logic was better fuel distribution with the two small carbs as long as the venturi area was the same. Seemed to work.

[kirkwoodken]

The 30-30 Duntov is REALLY more like a mid 230 degree cam when you look at valve lift at .075". The 254 degrees are very misleading numbers for picking that cam because of large tappet clearances and long slow ramps. My street roller cam is 255-255@ .050" lift, and nothing like a 30-30 Duntov @.050" lift. Rumor has it that the 140 cam is a copy of a Mercedes cam.

[fdicrasto]

The 62-63 Chevy Corvette fuel injection engine was 360 hp. 340 hp with the afb carb. The 375 hp F.I. was 64-65.

[pdq67]

If not mistaken, the notch on the rear cam journal was so that it could, if wanted, be used in the '55 engine because of its funky oiling system.

It was designed w/o a real oil filter system, (it used a top mounted, can), and also didn't have the, "full", oil groove behind/under the rear cam bearing. Most guys just used a small angle grinder and cut the needed groove by hand in the rear journal if their cam didn't have it so that it could be used in the '55 265 engine.

My junk -097 cam's notch that I had in my junk301 was hand ground. A hand ground notch is something like a 1/2" long, 3/8" wide and maybe an 1/8" deep and centered...

pdq67

big notch hyd and small notch solid lifters. a mod to the cam bearing and you don't need the notch

Are these both GM, "STOCK", -097 type cams?

I have seen the little notch many times, but never a big notch?

pdq67

[pamotorman]

a 097 cam would be a solid lifter cam so it would have the small groove.

[Ed Wright]

If not mistaken, the notch on the rear cam journal was so that it could, if wanted, be used in the '55 engine because of its funky oiling system.

It was designed w/o a real oil filter system, (it used a top mounted, can), and also didn't have the, "full", oil groove behind/under the rear cam bearing. Most guys just used a small angle grinder and cut the needed groove by hand in the rear journal if their cam didn't have it so that it could be used in the '55 265 engine.

My junk -097 cam's notch that I had in my junk301 was hand ground. A hand ground notch is something like a 1/2" long, 3/8" wide and maybe an 1/8" deep and centered...

pdq67

big notch hyd and small notch solid lifters. a mod to the cam bearing and you don't need the notch

Are these both GM, "STOCK", -097 type cams?

I have seen the little notch many times, but never a big notch?

pdq67

I agree. I don't remember seeing that big notch.

[pdq67]

TOTALLY awesome thread I just discovered here!
I had read that the 283/283 and 283/290 were identical, but this thread got me thinking more - so I looked up a hunch in Colvin's "Chevy by the numbers 1960-64". Sure enough, the exhaust manifolds got better in 1958-up, that looks like the difference - same engine but better iron exhaust.
From there to the 283/315 it looks like just heads, plus another 0.5 compression.

The better 58-up exhaust iron helps all the 283's but the vanilla engines don't really care, they pick up 2-3 hp on the Gonkulator. But the 283/290 shows a full 7hp gain in the Gonkulator (as well as the rating).

For the early solid cam 265/210 and 265/225, I have a GUESS of 208-208 duration and 110 LSA, vs the later Duntov at 229-229 duration, and the Big Duntov at 254-254 (all at .050 lobe). Can anybody improve on that 208-208 guess?

As far as making their ratings, I have done a lot of work lining up my own DeuceCoupe Gonkulator aka WerbyFord Gonkulator with ratings, road tests, dyno tests, etc. I conclude that the 283's pretty much made their ratings, but the 327s and 350s started to drift off - they make their ratings if you use open headers, but typically not with iron exhaust. Some confirmation comes from road tests of the day - the Big Duntov 254-254 cam doesn't really MPH any better than the Duntov 229-229 cam. I don't think it helps much without headers (hopefully open). In cars like the Nova things get even worse - the dealer conversion 327's and even the L79 didn't run that good in the Nova because you got tiny little 283 vanilla exhaust iron. But add some fenderwell headers and watch out!

I too tend to live in the past on these things - I think there is a lot of value in the history of this era - it will never be repeated or matched by today's computer cars.

THANK YOU.But not the answer I am looking for...How did the 1955,265,PP 180 hp get to 210 hp in 1956? How did the 283,283HP get to 290 hp and then in 1961 get to 315 (I think alum heads from a next year 327?) THANKS FOR TRYING Oldhead

IMHO, when Chevy brought out the 2.5" dia. outlet ramshorn exhaust manifolds, power took off because it allowed the old 30-30 cam to sing!

I do know that no more than a short piece of 2.5" dia. pipe straight down from the outlet right at the 90 degree bend really wakes them up!! BUT so f** noisy!!

pdq67

[pamotorman]

TOTALLY awesome thread I just discovered here!
I had read that the 283/283 and 283/290 were identical, but this thread got me thinking more - so I looked up a hunch in Colvin's "Chevy by the numbers 1960-64". Sure enough, the exhaust manifolds got better in 1958-up, that looks like the difference - same engine but better iron exhaust.
From there to the 283/315 it looks like just heads, plus another 0.5 compression.

The better 58-up exhaust iron helps all the 283's but the vanilla engines don't really care, they pick up 2-3 hp on the Gonkulator. But the 283/290 shows a full 7hp gain in the Gonkulator (as well as the rating).

For the early solid cam 265/210 and 265/225, I have a GUESS of 208-208 duration and 110 LSA, vs the later Duntov at 229-229 duration, and the Big Duntov at 254-254 (all at .050 lobe). Can anybody improve on that 208-208 guess?

As far as making their ratings, I have done a lot of work lining up my own DeuceCoupe Gonkulator aka WerbyFord Gonkulator with ratings, road tests, dyno tests, etc. I conclude that the 283's pretty much made their ratings, but the 327s and 350s started to drift off - they make their ratings if you use open headers, but typically not with iron exhaust. Some confirmation comes from road tests of the day - the Big Duntov 254-254 cam doesn't really MPH any better than the Duntov 229-229 cam. I don't think it helps much without headers (hopefully open). In cars like the Nova things get even worse - the dealer conversion 327's and even the L79 didn't run that good in the Nova because you got tiny little 283 vanilla exhaust iron. But add some fenderwell headers and watch out!

I too tend to live in the past on these things - I think there is a lot of value in the history of this era - it will never be repeated or matched by today's computer cars.

THANK YOU.But not the answer I am looking for...How did the 1955,265,PP 180 hp get to 210 hp in 1956? How did the 283,283HP get to 290 hp and then in 1961 get to 315 (I think alum heads from a next year 327?) THANKS FOR TRYING Oldhead

IMHO, when Chevy brought out the 2.5" dia. outlet ramshorn exhaust manifolds, power took off because it allowed the old 30-30 cam to sing!

I do know that no more than a short piece of 2.5" dia. pipe straight down from the outlet right at the 90 degree bend really wakes them up!! BUT so f** noisy!!

pdq67

those cams were designed to be used with open exhaust because the racers had to use the stock cam but were allowed open exhaust and headers

[pdq67]

One other point is that 302 Z-28 engine guys can tell if you have a 30-30 cam in your 302 engine because they sound different!

pdq67