So there you are, elbow deep in lifter valley goo trying to trace down the overly suspicious knocking noise in your precious engine and you strike gold. Or bearing flakes. Ouch. So out she comes for a rebuild. But maybe while you're in there you might as well up the ante a little and add some power to the old wheezer. The problem is, the budget is already stretched pretty thin and with an unpredictable economy, you don't necessarily want to put all your eggs in this basket.
What could possibly be a solution to this dilemma? Well, your trusty staff at PHR has consulted with several engine builders from around the country to compile a list of quick and easy tricks that will pick up power and not blow out your wallet. Naturally, you don't have to have a blown engine to get started making more power, and many of these tips are easy to do without yanking the engine. The power and price estimates we've given can vary by application, but are fairly average throughout the industry. Nevertheless, it's not uncommon to bring that tired 200-horse 350 Chevy to well over 350 horses with just the tips here.
When setting up your camshaft,...
When setting up your camshaft, it is critical that you check piston-to-valve clearance if you have a tight lobe separation or have advanced the cam significantly.
20-50 hp for $300
Sliding your finger to the bottom of the page has been the traditional man-method of picking cams for generations, but a recent conversation with Scooter Brothers of COMP Cams shed some light on the proper methodology. First and foremost, make a determination as to what you expect from your car. Is it street? Strip? Do you have vacuum-operated accessories or power brakes that could be affected by your cam choice? Once you have a clear and realistic vision on what you want from your car, consult directly with the cam manufacturer or use inclusive cam-suggestion software like CamQuest from COMP Cams.
If you are picking your own cam, remember that typically, most mild hot rods do well with around a 10- to 20-degree increase in duration without causing too many adverse affects. At 20 to 40 degrees bigger, you're pushing the limits of a daily driver. In previous Engine Masters Challenge engines, lobe separations as tight as 99 degrees have helped the competitors take advantage of scavenging during overlap and build a tremendous amount of power in the 2,500- to 6,500-rpm range, but at the expense of idle quality and lack of idle vacuum. Again, befriend the cam company tech lines for the best advice.
The back-cut Manley intake...
The back-cut Manley intake valve on the right picked up 5-10 cfm between .100-.500 lift.
5-30 hp for $0
Making sure your new or reused cam is installed correctly can add a great amount of driveability and power. Longtime engine builder Randy Malik commented that one of the tricks for big-block Fords built in the '70s and '80s was to install an early model timing chain to advance the cam since the factory decided to retard their cams by 7 degrees for emissions requirements. Moving the cam back to the original "early" position is worth 30 horses all by itself! Again, Scooter chimed in: "If it is more street-driven, you can advance the cam a little bit. If it is more track-driven, you can retard it a little bit."
Lash The Valves
0-15 hp for $0
Even on a hydraulic cam, making sure all the valves have the same amount of lash or preload is a good way to get the engine to work in the rpm range you want. Loosening the lash slightly tends to pick up a little power on the street, since it fools the engine into thinking it has a smaller, torquier cam, and tightening the lash tends to work a little better at the track to raise the rpm range. With hydraulic cams, they may come with .060-inch preload on the lifter. Randy Malik says that reducing the preload to around .020 inch with adjustable rockers or shims has been shown to raise the usable rpm range of some engines up to 500 rpm.