Once disassembled, the cylinder heads need to be placed into the hands of the machine shop of your choice for cleaning, assessment, critical measurements, machine work, and assembly. I would advise against taking any shortcuts to save a few dollars here, and trusting your machine shop is a great idea. Over the years, I’ve heard of machine shops advising customers to spend the extra money to have hardened valve seats installed in cylinder heads from older engines such as our 429, yet I have never been approached about this by the shops I use. Everything I’ve learned indicates that hardened valve seats are not a necessity. If you think back many years, some people ran unleaded AMOCO white gas exclusively in their cars and I don’t recall these cars burning valves at a prodigious rate.
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Step-1: Prepare Cylinder Heads
After being cleaned and media blasted, the cylinder heads are placed into the cylinder head station. The first step is to level them in relation to the tool.
Step-2: Remove Valveguide
With the head level in the machine, a drill and ream remove the existing integral valve guide. The new guide will re-establish proper clearance between itself the valvestem. The replacement valve guide is pressed into the cylinder head by another driver.
Step-3: Replace Exhaust Valves (if applicable)
While the OE intake valves (right) showed no signs of wear or galling on their stems, the exhaust valves, as is often the case, did not fare as well. We’ll be replacing the exhaust valves with a set from Speed Pro, while the intake valves will be cleaned, re-faced and reinstalled.
Step-4: Inspect Replacement Valves
The Speed Pro replacement exhaust valve (right) is crafted from stainless steel and will be more resistant to high temperatures than the OE valve (left) that it replaces.
Step-5: Check Length of Aftermarket Stems
Note that not all aftermarket parts are exact replacements for OE parts. Variations may exist, if not compensated for, may cause problems with fit and function. While the stem length of the two valves is the same, the split lock groove machined into the stem of the replacement exhaust valve is different from the original Ford valve. We can easily compensate for this by using the correct offset keepers. (Aftermarket keepers are available with offsets up to sixty thousandths.) If installed with the OE split locks, this difference could have caused the valvespring to bottom out or have too much seat pressure.
Step-6: Finish Valve Sealing Surfaces
The sealing surfaces of the valves are returned to true angles and proper finish using this valve grinder. A stone set to a pre-determined angle removes small amounts of material until the edge of the valve is restored. The term “threeangle valve job” refers to the fact that the faces of the valves are cut at three angles to improve sealing, flow, and heat dissipation. The angles are normally 30, 45, and 60 degrees, although some engine builders will use slightly different angles to gain additional performance for racing applications.
Step-7: Cut Cylinder Head Angles
Here, the corresponding valve seats in the cylinder heads are cut to proper angles and finished with the bits of the Neway valve seat tool. This will ensure a good seal between the valves and their seats.
Step-8: Neway Valve Seat Machine
The Neway valve seat machine has a complete set of bits to accommodate the various angles required for grinding seats in both automotive and industrial cylinder heads.
Step-9: Alternate Method
This old-school, handheld, offset valve seat grinder has attachments for stones that vary in face angle and finish. It is still used from time to time for specific jobs such as grinding hardened valve seats rather than relying on the modern Nu-Way tool, which uses bits to cut and surface.
Assembling the Cylinder Heads Step by Step
Step-1: Measure Valvespring Height (Special Tool)
A barrel micrometer and a dial caliper are two tools found in a machine shop or good home workshop that are used during cylinder head assembly. Since we’ll be using aftermarket valvesprings, we’ll use the barrel mic to measure valvespring height and ensure that it is within limits to avoid spring pressure or bind. If you do not have access to a barrel micrometer, you can make this measurement with a dial caliper.
Step-2: Install Valves
The cylinder heads have been cleaned, Magna-Fluxed, had new valve guides installed, and the seats refaced. Now it’s time to install the valves. In this case, the OE intake valves are within tolerance, so they’ll be refaced and reused, while the exhaust valves will be replaced with aftermarket stainless-steel valves.
Step-3: Inspect New Valvesprings
Even though we’re using new valvesprings that came as part of the camshaft kit, we still check each spring to ensure that it is within advertised tolerance for pressure.
Step-4: Assemble Valvesprings
The aftermarket valvesprings will be assembled using the OE spring seats (left) and retainers (right). OE valvestem keepers will be used on the intake valves, while offset keepers are required for the replacement exhaust valves.
Step-5: Note Retainer Type (Standard or High-Performance)
A standard Lima-series valvespring retainer (left) is stamped steel, while those used on the 429 Cobra Jet engines (right) are machined, high-performance parts.
Step-6: Place Valvestem Seals (Performance Tip)
We will utilize Teflon-lined PC valvestem seals (top) in place of the stock umbrella type (below) to achieve a more positive seal with the valvestem and stand up better to high temperatures.
Step-7: Check Valvespring Height
Prior to installing the valvesprings, a barrel micrometer is used to check the valvespring height as shown.
Step-8: Assemble Cylinder Heads
Using a pneumatic valvespring compressor makes the job of assembling the cylinder heads go much faster. This is one advantage a machine shop has over the average home workshop.
Step-9: Cylinder Heads Ready
Here are the freshly refurbished and assembled cylinder heads ready to go back on the engine.
Written by Charles R. Morris and Republished with Permission of CarTech Inc
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