The holes in the gasket for the exhaust ports were much bigger than the exhaust ports themselves so I left those alone. The rectangular intake port entries now measured 1.654" x 1.417" (C/S area 2.342 sq. I also ground the gasket within the lines that I'd scribed so the gasket holes and intake ports were perfectly matched. I blended the now larger port openings into the remaining port by removing progressively less material as I moved down into the intake port. I ground the intake port entry walls, roof, and floor inside the lines that I'd scribed up to a depth of 1.5" into the head. I scribed a line around each port to match the edges of the gasket, and scribed a line around each gasket hole edge to match it to the opposite side of each intake port. The holes in the gasket did not line up properly with the intake ports and were offset by at least 1mm on either side. The first step of the porting procedure was to match the intake port entries to the combination manifold gasket. Intake port entries and exhaust port exits The stock camshaft also works optimally with this higher CR. The reasons for this were more HP/TQ, better fuel economy through improved thermodynamic efficiency, and better emissions. I also wanted to increase the compression ratio (CR) of the engine from 8.8 to 9.1:1. They recommend that you use a die grinder but since I couldn't find one, I used my electric drill instead. The knowledge gained from this article will help you to get the best results and to avoid making mistakes that can ruin the head. It was a very helpful article and I recommend anyone who's contemplating home porting cylinder heads to read it carefully. I followed the Standard Abrasives DIY head porting guide to do this procedure. After cleaning it thoroughly and removing the old gasket material, I ported it using the Standard Abrasives deluxe porting kit. STANDARD ABRASIVES DELUXE PORTING KIT FULLI bought a good used '95 HO head with a full set of valves from a junkyard for only 213 US dollars. STANDARD ABRASIVES DELUXE PORTING KIT PLUSUnfortunately this head cost a whopping 1349 US dollars and I wasn't willing to spend that much money plus more for shipping, so I took a more economical approach. This produced a dyno-proven 16hp gain on a stock 4.0L engine and a 22hp gain on a 4.6L stroker engine. At the time, the ultimate cylinder head conversion was the Accurate Power big valve head with 2.02" intake/1.60" exhaust valves. The factory HO head is fairly efficient but there's room for improvement particularly in exhaust port flow. Forced induction was not on the agenda, and I wasn't keen to tear into the short block either since the engine was still in excellent condition at 163k miles, so installing a ported head was the obvious way to go. The only way to increase the outputs further was to either add forced induction or to internally modify the engine. STANDARD ABRASIVES DELUXE PORTING KIT MODSAfter completing all the external bolt-on performance mods (Stage 1), the engine was producing an estimated 220hp and 262lbft.
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