A Regal Small-Block
Tom Jackson; Buffalo, MO: I have an '85 Buick Regal with a 350 SBC, stock bore, crank, and pistons. It has the stock iron 882 heads with a three-angle valve job with Z/28 springs and the ports cleaned up. It also has a Summit racing cam with 0.465/0.488-inch lift and an Edelbrock Performer intake and Jet Performance Q-jet carb. The trans is a 700-R4 with a shift improver kit and 2,000 stall, and the rear is a 7.5-inch with a posi and 3.73:1 gears. I need better heads. I can get a set of Procomp street/strip Pro-series aluminum heads with 190cc runners, 64cc chambers, and 2.02/1.60-inch valves. My big question is, do the heads flow well and are they worth the trouble? I am on a pretty tight budget, and I'm not building a strip car, just a toy. If the parts are all right, I'd like to add an Edelbrock Performer RPM intake and change to a Summit Racing 0.488/0.510-inch lift cam. I'm hoping to add 100 horses. What do you think?
Uh-oh, custom vans are coming back.
Jeff Smith: Your choices are well thought out and should add power over a set of stock 882 heads. The Procomp 190cc intake ports are as-cast, and the company claims flow numbers of 227 cfm on the intake at 0.500-inch lift and 180 cfm at the same lift on the exhaust side. In this age of 300-plus-cfm flow numbers for rec-port LS engines, these flow numbers are a bit tame, as there are many aftermarket heads with 10 percent (or more) better flow numbers in the midrange valve lift area. The midrange flow numbers are of critical importance for your application because your cam does not reach 0.500 inch lift. This means that flow numbers in the 0.300- and 0.400-inch valve lift range are of far greater importance. The only price we could find on these heads was for bare castings at $312.99 each at Jegs. This makes a bare pair at $624.98. The assembled price will obviously be much higher, but it's doubtful you could assemble them yourself for less than the assembled price. One other point of improvement is that the 64cc chambers will bump the static compression over the iron-head, 76cc chambers. Estimating the deck height and head gasket thickness, it appears that this change alone is worth moving the static compression from 8.75:1 to 9.9:1. With one point of compression worth roughly 3 to 4 percent power, just increasing the compression should be worth as much as 14 horsepower as well as a similar percentage increase in torque.
The camshaft you selected is a Summit flat-tappet hydraulic with 234/244 degrees of duration at 0.050-inch tappet lift with the aforementioned 0.488/0.510-inch lift numbers ground on a lobe-separation angle of 114 degrees (PN 1107). This 114-degree angle between the lobes will reduce the overlap and improve the idle slightly, but it will still be somewhat lumpy. This is an increase in duration of 10 degrees over your current cam. I'd be tempted to swap the heads and intake first and see how much power these components will deliver before changing the cam. The thought behind this is that your current cam has less duration, which means it will help create more torque in the midrange where your car spends most of its time when accelerating. The longer cam will make more peak horsepower but might contribute to a slower e.t. on the dragstrip or less responsive acceleration on the street in the engine speed range you probably do most of your driving. As to your 100hp goal, it's a bit optimistic. We ran a similar test several years ago on a 350 Chevy with aftermarket heads offering similar flow numbers and gained 50-plus horsepower over a set of 441 iron heads. Your engine enjoys the advantage of a slightly bigger camshaft with more lift, and the Edelbrock Performer RPM intake could also contribute another 10 to perhaps 15 hp when combined with these heads. Your combo may deliver 65 to 70 hp over the stock iron heads, but that's about all you should expect. Since the heads continue to show a flow increase at 0.500-plus-inch lift, you might consider a set of 1.6:1 rocker arms to bump the lift. An increase from 1.5:1 to 1.6:1 generally will deliver an additional 0.030 inch of additional valve lift, which puts your smaller cam right around 0.500-inch lift, and with the bigger cam, you'll gain a little more.
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