# 67 non HO engine performance ??



## 68gtohawk8369 (Oct 26, 2009)

I was wondering is the hp figure of 335 gross or net in the past I have read many articles saying many of the older cars were underestimated . Is it safe to assume that a good free flowing exhaust and an hei distributer would bump that figure up to say 350 hp


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## Too Many Projects (Nov 15, 2008)

Pre-71 ratings were gross, at the crank with no accessories. After 71, the figures are net at the crank compensated for accessories. Many of the factory ratings were understated for insurance reasons. HP ratings were generally taken at max rpm, which is not were peak HP or torque occurs. Like wise no manufacturers stated their torque ratings, which is really what gets a car moving in the first place. Look at the 70 455 engine. The HP is rated at a paltry 360 yet the torque is 500 LBS-FT at mid rpm range.... If we could see a curve chart of the hp and torque thru the rpm range, I'd be willing to bet they were very close together at about 425-450 hp and lbs-ft.somewhere on the chart.
Finding more power in a stock engine is very likely and can come from the mods you mentioned and a good tune. An HEI isn't really necessary either. You can attain a hot, multi spark with a points distributor and an aftermarket enhancer, such as MSD.


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## geeteeohguy (Feb 2, 2008)

Too Many hit it on the head. The '62-'63 421 Super Duty was rated at 405 HP, and dyno'ed out at something like 485, box stock. I have found that many makes under rated power back in the day, and others over rated. A '67 HO 400 is the same as a '67 non HO 400 except for: 068 spec cam instead of 067, high flow HO exhaust manifolds and exhaust pipes, and an open element type air breather. I wouldn't worry too much about horsepower numbers. It's torque that lifts the front wheels off the ground and burns the rear tires into oblivion. There are many knowledgable folks on this forum that would be glad to help when the time comes for your build/upgrade. Simple, well thought out mods are often the best and most cost-effective. I've been running the stock points type distributors in both my GTO's for almost 30 years without issue. They work fine. But they need to be verified as good and in spec. It's items like compression ratio adjusted for todays fuel, cam profiles, and fuel metering that you need to worry about. Good luck.


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