Thread: Greetings from the UK

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freewheelx1, I could post the picture from the Motor's Manual but it would seem that you have the 249 straight eight engine. The manual says the stock compression ratio is 6.5:1 which is pretty low. Actually 190 ft. lb. of torque @ 2000 rpm is not too bad considering the Ford flathead V8 was only about 175 ft. lb. at 1900 rpm (3 3/4"stroke, not the later Merc 4" stroke). Other folks with the early Chevie six engine note the loss of a carb heater if you use headers. You can continue to research the turbo angle and I am sure Tech1 will help a lot with the details. Still with a low CR the Motor's Manual says the main bearings are the more modern insert type and hence a bit stronger than the old poured babbit bearings, so it might be possible to do a "poor boy hopup" the way a financially limited high school kid would have done in the '50s. That would be to increase the compression ratio by shaving (resurfacing, milling) the head and adding a fabricated set of headers for that neat look of two pipes out the rear. I do not know how much you can safely shave from the head but it might be in the range of 0.050" but probably not more than 0.100". On the flathead Ford V8 the heads could be shaved about 0.070" but the combustion chambers could be entirely different on the Pontiac 8 cyl. When shaving a flathead, too much is too much and two problems may emerge. Without "relieving the block" around the valves the flatter combustion chamber may actually restrict the flow of fuel-air mixture and of course you don't want the pistons hitting the underside of the head! Check with a machine shop about the limit for your head if you decide to do this but I am GUESSING that 0.050" would work. I recall a wild guy who was a driver of a GMC van employed by Howard Johnson Restaurants to taxi employees and he wanted more performance from his work machine. Between the morning pickup and the afternoon take-home he visited a local machine shop and in a matter of three hours they took off the head, milled it 0.100" and replaced it in time for him to take the waitresses home; all without the knowledge of the van owner! 0.100" is a lot to "shave" but the shape of the pockets in the GMC OHV head are different from a flathead. From a restorer point of view a shaved head might give 5 to 10 more H.P. and even a slightly better mpg value and would not show at all on the outside. Headers and dual pipes would cross the line from restorer to rodder but might add another 5 H.P. Have fun.

Don Shillady
Retired Scientist/teen rodder