This page shows the work I did to the '66 289 heads I got from a friend that were originally built by PAW. They have 1.94" intake
and 1.60" exhaust valves. The heads combustion chambers are 54.5cc which will put my 351w at 12.7-1 compression. That is way
too high for a turbo application. I also found the larger valves were shrouded and the ports were tiny, especially the exhaust ports.
BOLT HOLES
This shot shows how I had to drill the headbolt holes out to fit the larger 351w bolts. Drill the heads to 9/16" being careful not to let the bit bind in the cast iron. You can also see the teflon valve seals, hardened guide plates, and screw in studs that came with the heads.
BOWL REWORKING
This shot shows the tiny factory ports on the right hand cylinder and the ported bowls in the middle. The exhaust port measured a little over an inch below the valve. Also the valve guides were blunt. As you can see in the left cylinder I basicly opened and smoothed the valve openings and smoothed the bowl area. It is important to think how the air has to flow and only work on the areas that prevent that flow. On the intake side I tried to get the sides of the port walls opened as much as I dared so the air could flow around the valve stem. On the exhaust side I tried to make a smooth even transition around the valve stem and out the head.
EXHAUST PORT REWORK
Here is the exhaust port work. This picture leaves a lot to be desired so bear with me. The right hand port is factory, you can see the dreaded exhaust bump. On these heads the tightest spot is right where the valve guide goes through the head. I opened the port up to the brnoze guide and worked a little channel in on both sides of the valve stem. I also opened the side of the port wall, especially where the emmisions bump was. Hopefully I'll get a swirl effect and that will keep the air from stalling in the port. Being a turbo application my goal is to keep the air mass from slowing down and losing any heat.
CUMBUSTION CHAMBER
Combustion chambers are the heart of a motor. They determine the compression ration and design determines how efficiently the air gets into the cylinders. Here on the left is a factory cast chamber. Note that the valves in both chambers are at .500" lift. These valves are 1.84 intake and 1.54 exhaust from my 351w heads, not the 1.90 intake and 1.60 exhaust that belong here. As you can see on the stock chamber the valve only has 1/16" clearance to the chamber wall. the middle chamber shows how much material was removed to unshroud the valves. The goal was to undercut the chamber as much as possible and still keep a smooth flow of air in and out of the valves. You can see the scribe marks that were used as a guide to keep the work in the chamber. I'll end up drilling more coolant passage hole in the head because the 289 passages didn't line up with the 351 passages completely. After this work was done the compression dropped from 12.7 (est) to around 9:1. The engine runs on 93 octane with 6-8lbs of boost without any detonation problems.
INTAKE PORT REWORK
Here is the intake portwork. The left two are done, the right two are stock. The biggest restriction on the intake side is the pushrod holes. They really restricted the portable size. I opened up the side wall as much as possible and increased the top and bottom sides of the port to help increase the area in this section of the port.
Back to Jamies Geocities Site (under construction)