This is often called pocket porting and the area just below the 45-degree valve seat is where you can gain the greatest airflow improvement for the least amount of effort. Earlier valves are 0.250" on both intake and exhaust valves. ), domed pistons must be used unless the chambers are welded and machined smaller. The valves of this head are the same 1.94" by 1.50" that Chevy is so fond of. Vortec heads come equipped with valves having a 30 degree back cut to help flow. Yet guys on our site are using .708 reach without any problem. (Image/Jeff Smithi). Go to the website of your local auto repair shop or online parts distributor, and plug in your VIN to find all parts applicable to your 4.3 Vortec engine. Crane p/n 144845: Performance hydraulic roller cams, PAC enhanced wire, no damper, Manley p/n 22410, fit without machining, allow 0.520" lift. Maximum spring seat diameter is 1.44". Normal rates of gap growth are as follows: Four-Stroke Engines: 0.01~0.02 mm/1,000 km (0.00063~0.000126 inches/1,000 miles) I have a 97 Chevrolet pickup truck with a 5. INSTALLATION NOTE: Match with Edelbrock head gasket sets. Designed for longer-than-stock 2.200" and 1.650" valves. Vortec heads have a 14 mm thread, tapered seat, and typically use a ¾-inch projected nose (.750) reach, small (5/8") spark plug socket. The truth is they do not crack any more than ANY modern lightweight production head, although there have been problems associated with leaking intake gaskets on Vortec engines that may have caused more than the usual number of cracked heads. Bare heads will have valve guides and seats installed, but will require final sizing and a valve job to match the valves you will be using. Your question relates to porting the Vortec heads to improve the flow, which is a great idea. Completely assembled with 1.94”/1.50” valves, Camshafts with more than 0.475" lift require machining valve guide bosses and checking valve seal to valve spring retainer clearance, Accel P526S U-Groove “shorty” Double Platinum (approximately 3/16″ shorter than AC R44LTS), Add the results to the lobe separation angle (LSA). This is because the zincs and phosphates gunk up converters, costing OEM's money for warranty claims, so they've been outlawed. The most popular thread size for domestic plugs is 14 mm, although a few older Ford engines used the larger 18mm size back in the '60s. These are important refinements to getting power out of the chamber by burning everything that gets in, the older chambers threw a lot of fuel out unused or incompletely used which is the "why" for all the emissions gadgets on the engines of the 1970’s and 80’s. Because of the superior port and combustion chamber designs, total timing requirements for maximum power is 30-32 degrees BTDC, or about 4-6 degrees less than the earlier non fast burn heads. Guide plates can also be installed at this time if desired. If you have aftermarket springs designed for the earlier heads, you must remove the inner damper because the damper ID will be too small to fit over the guide boss without it being cut smaller. The stock Vortec valve springs are single wound without a damper and are 1.250" diameter. Then tighten the plug as specified below: With a Torque Wrench: Please note there are slight variations in torqueing recommendations between spark plug manufacturers. If guide plates are not used, self aligning rockers MUST be used. ARP SBC Vortec, Intake Bolt kit. Drop in fit, machine work not required up to .550" Lift, Hyd Flat Tappet. As a last resort this can be done using files. Autolite AR94 Spark Plug-5/8 Hex, .708 Reach, Tapered, Power Tip, Hot $4.99 MSD 5554 Street-Fire Spark Plug Wires Set, Small Block Chevy 350 HEI Use a 3/8” drive 1/2” socket and a soft mallet to gently drive the seals fully home. So if you're building on a Vortec block from 1995 or later it is at least provisioned for a roller cam if a 95 and from 96 up it has a roller cam. Note: If using guide plates, non self aligning rockers need to be used. In fact c/n 906 heads having the hardened inserts are actually preferred by some performance engine builders, mainly for marine applications. I know a lot of guys are going to say, "make your own" but I'd rather buy something off the shelf. Let me preface this by saying I feel pretty silly just noticing this tonight after owning the car a few months. Spark plugs. Small port; Large port Small port Vortec head The heads are equipped with 1.940"/1.500" valves from the factory and the stock valve springs are compatible with a maximum valve lift of up to 0.450". Is your spark plug hole stripped? The reach is defined as the length of the threaded portion of the spark plug. This page has been accessed 441,846 times. At the least, a fixture to guide the drill bit and tap should be used. If self aligning rocker arms are used, there cannot be a guide plate used. This page was last modified on 10 July 2020, at 22:22. Most Chevy heads place the spark plug squarely between the head bolts. Along with that, the guide boss OD can be machined down from 0.852" to a smaller common diameter, like 0.785" of the original Gen1 SBC heads, so aftermarket springs (double or with dampers) can be used. These stand an excellent chance of being good, as long as the other things listed here pass inspection. All the heads for those years are the same. 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