Horsepower rating stock 350??

[silvertonguedevil]

I have a '72 Cheyenne with a stock 4 bbl 350cid. Anyone know what kind of horsepower these kick out? Thank you.

[70cst]

My 70 350 was rated at 300hp. Yours would be about 275hp. This is with a 4 barrell. I might be wrong but this should be close.

[TotalChevy1]

In 72 I think the 350 was rated with less than 200 hp or just a little over. Back in the day to get 350 out of a 350 made you a god.

[cdowns]

they were rated right at 170HP

[70cst]

Wow...was I wrong. I stand corrected. I didn't realize the hp dropped that much. My 70 Chevelle was a 350/300hp. Did it make a differeance if it was a car or truck 350?

[BB72CHEVKT]

The manual on my 69 with a 350 says 250hp w/ 4 barrell

[70cst]

Originally Posted by BB72CHEVKT

The manual on my 69 with a 350 says 250hp w/ 4 barrell

http://www.ss396.com/1970/Chevelle/p...0_Chevelle.htm

I had to check to make sure my mind wasn't playing tricks. The 70 Chevelle was my first car and I ordered it with a 350/300hp engine. I wanted a SS but I could not afford insurance. Now that I'm 50 I can't afford a real SS Chevelle so I have the next best thing. A 70cst w/402BB with buckets, tach, etc.

[Blazer1970]

The factory rating for the 4bbl 350 for 1972 was 175 net hp. Basically the exact same motor had a rating of 255 gross hp in 1971 and prior.

[70cst]

Originally Posted by Blazer1970

The factory rating for the 4bbl 350 for 1972 was 175 net hp. Basically the exact same motor had a rating of 255 gross hp in 1971 and prior.

The standard 350 was rated at 250hp in 1970 with an optional 350/300hp engine avaliable (see above link) which is what I had in my 70 Chevelle. The question that I have was the truck 350 differrent than the passenger car 350? Just curious?

[Blackbird66]

Originally Posted by 70cst

The question that I have was the truck 350 different than the passenger car 350? Just curious?

as I've found there are some differences between the two. All 350 Trucks seem to have 4 bolt mains, and only the more performance cars got this. It is standard on the old vette, but optional on a camaro. I know the heads on a truck are usually different also, but the optional 300hp/350 may be the same motor regardless of what it came in..............but I'm no expert. This is a guess based off of my experinces pulling these motors apart, and doing motor swaps.

[ChevyC102007]

Originally Posted by Blackbird66

as I've found there are some differences between the two. All 350 Trucks seem to have 4 bolt mains, and only the more performance cars got this.

All truck engines were different from car engines due to this fact and the deck heights were different (9.8" for the car and 10" for the truck motors). As for the heads...truck heads are designed for low end torque, while the car heads are designed for mid-upper rpm horsepower.

Corvettes all motors, Some Chevelles and Camaro motors had 4 bolt main blocks i.e Cross Fire Z/28 RS 302 Camaro (little more than a bored and stroked 283) ZL-1 427 Camaro, COPO Camaro's and 454 Chevelles. The 396 for some reason only had a 2-bolt main block even the 375 hp version but the 402 (bored .30 over) had the 4-bolt main.

Almost forgot the 327

[Gray Ghost]

While there is a 427 BB truck block with a taller deck, I don't recall the 350 truck blocks being any different. The motor in mine is coded for pasenger cars and trucks [010 block,1970]. As far as I know there was never a truck block 350 that had a taller deck.

BTW....I've owned two trucks with 2 bolt main 350s [original motors].

[Billla]

Originally Posted by ChevyC102007

All truck engines were different from car engines due to this fact and the deck heights were different (9.8" for the car and 10" for the truck motors)

Deck height for all GEN I SBCs is 9.025.

Deck height for Mk IV BBC is 9.8 for passenger cars, 10.2 for trucks.

[WorkinLonghorn]

Any HP rating before 1972 that was expressed in GROSS horsepower was not necesarily accurate.!972 and on they used SAE Net ratings. You can't make a meaningfull comparison between a "250 HP" 1971 engine and a "175 HP" one rated in '72.
Here's part of a wikipedia article;

SAE gross horsepower
Prior to the 1972 model year American automakers rated their engines in terms of SAE gross horsepower (defined under SAE standards J245 and J1995). Gross hp was measured using a blueprinted test engine running on a stand without accessories, air cleaner, mufflers, or emissions control devices and sometimes fitted with long tube "test headers" in lieu of the OEM exhaust manifolds. The atmospheric correction standard (e.g. barometric pressure, humidity and temperature) that was utilized in obtaining the Gross ratings was more idealistic than that which is used under the SAE net rating system. The resulting Gross power (and torque) figures therefore reflected a maximum, theoretical value and not the power of an installed engine in a street car. Gross horsepower figures were also subject to considerable adjustment by the manufacturer's advertising and marketing staff under the direction of product managers. The power ratings of mass-market engines were often exaggerated beyond their actual Gross output, while those of the highest-performance muscle car engines often tended to be closer in actual output to their advertised, Gross ratings. It should be noted that no pre-1972 "muscle car" engine in its unaltered, production line stock form and in its as "as installed" (SAE net) condition has ever yielded documented, qualified third party validated power figures that equal or exceed its original Gross rating. Claims that such engines were "under-rated" are therefore highly dubious. It is therefore more accurate to say that the ratings of the highest performance engines from that period tended to be less exaggerated than those of more typical passenger cars, but still exaggerated relative to what could be obtained in the SAE net configuration. For example, the ultra-rare and exotic 1969 427 ZL1 Chevy (rated @ 430 Gross HP) is frequently cited as one of the most "under-rated" high performance engines from that period, yet it could only produce 376 SAE NET HP. [5]

http://en.wikipedia.org/wiki/Horsepower

[jimfulco]

Trucks used the net horsepower rating well before they started using it on cars. Some even had it on one of the ID plates, I think on the door jamb.

[Blackbird66]

I'm sure that all small block chevys have same deck height. otherwise they would not interchange heads and intakes. Fords have different deck height from 260-289-302 to 351w. This is why I don't like Fords.
302 chevy is a 283 stroke w/ 4.00 bore.

[67_C-30]

The deck height is NOT different on SBC's between trucks and cars.


To answer your question 70cst, the difference is heads and compression ratio. The car 4bbl 350's had double hump (492, 186, etc) or 041 heads with 64 cc chambers and had a compression ratio of 10.25 :1. The 4bbl truck engines came with 76cc heads like 993's, 487's and beginning in '70 882's. They produced 9:1 CR for use with the lowest grade fuels. Some "truck" spec books list the 300HP 350 as an option but it misleading because they also El Caminos. The high CR 300HP 350 was never installed in pickup truck. After 1970, no 10.25:1 CR engines were offered in cars either, so the above info only applies to 69 - 70.