|
|
|
|
Timing
What a topic. Much can be discussed on the need of timing, here are some basics. I like to see the use of a GM HEI rebuilt 8-10 degrees idle with no vac line hooked up 20-25 with vacuum line 36 full load no vacuum 40-50 with no load on highway with vac Best to use a adjustable timing light. These cost around 75.00. Your engine will thank You. Torque Plate use
In my mind, a torque plate is a must when honing a block for new or used pistons. Proper ring seal is a must. Why give away the HP and torq from faulty sealing rings? I have performed measurements of the bores in 250 and 292 engines while honing. When torqing the head bolts down to spec, the block will distort by .004 around each head bolt. This distortion will go down into the block 1" deep in the bore. So there will be 4 distortions in each cylinder. The torque plate will do away with this problem. |
Camshaft Break In
Steps must be taken for proper break in of a new camshaft. Most engines are first run in a auto chassis of some kind, so that is what I will discuss. The engine must be run at 2000 RPM for 20 minutes at first start up! Failure of the cam lobes will certainly happen if this is not done. This is a hard task to achieve if you are not prepared. So here are steps to take to get you on your way.
Keep in mind 2000 RPM is a bunch on a new motor for 20 minutes. It will put out plenty of heat and exhaust. 194-230-250 harmonic damper bolt
These engines are not always equiped with a damper bolt. This is important. When the engine is being worked on, always drill and tap the crankshaft snout for a 7/16 fine thread bolt. Drill it 1.5 deep and thread 1.25 deep. This hole will be used to retain the balancer and install the balancer. |
Camshaft Gear Installation
This is a job that is messed up a bunch, so pay attention.
1. Heat your oven to 500 degrees, lay cam gear on one of the racks
2.Install the cam gear retainer plate and ring/spacer. Inside chamfer
of spacer toward camshaft
3.Install camshaft key
4. Place cam in freezer
5. Get your heavy duty oven mitts on, get a helper to hold cam and
a block of wood to go under cam
You will also need a large dead blow hammer.
Pull gear out of over after at least 20 minutes and
insert onto the cam, provide dead blow wacks as needed to seat
the gear down.
Let it cool, you are done.
Do not press gear on, it will certainly walk of later. You will not like it.
CAM GEAR INSTALL VIDEO
Why you need to heat your intake manifoldWHY YOU NEED TO HEAT YOUR INLET MANIFOLD
(Yes, even in California)
The most frequent complaint I have is from customers who complain that since they’ve installed their multiple carbs, the engine hesitates and stumbles at low speed on normal acceleration, from a stop, even after warm-up. The most blamed culprit is the darn Rochester Carburetor. Usually it is falsely accused!
Usually while installing dual exhaust manifolds or headers, the production exhaust heat supply to the inlet manifold is eliminated because (with the exception of Edmunds Inlet Manifolds and recently Clifford intake manifolds,) there is no provision or instructions to provide heat. Why? I don’t know and could only guess. In any event heat will be required to achieve good driving response and reasonable fuel economy. Here’s why:
As liquid fuel enters the manifold from the carburetor, the vacuum vaporizes the fuel and causes a chilling effect on the walls of the manifold much like the chilling effect of spraying an aerosol on your skin. Now you have a cold manifold. If you do not supply a continuous supply of heat, the manifold will remain cold and even build frost under some conditions. At this point, if an acceleration is attempted, the vacuum will drop, fuel will no longer vaporize, and will in fact condense on the cold manifold walls until they are completely saturated with wet fuel. This takes about three seconds, during which time no fuel is going into the engine (and thus no power or an extended hesitation). After the walls are fully saturated with fuel the air flow finally picks up this ultra rich mixture and floods some of the cylinders but not all of them because liquid fuel is notoriously bad for equal distribution.
More fuel (bigger jets) will only slightly help this problem and actually worsen the over rich condition and spark plug fouling and fuel economy.
The solution: Moderate, and continuous heat supply to keep the walls of the intake manifold warm and the fuel in vapor form. Exhaust heat is fast but requires a butterfly valve in one manifold to force the exhaust flow. Water heat is slower but very clean and not corrosive to aluminum manifolds. This method utilizes the water pump to continuously supply warm water to a passage underneath the manifold. (See attached drawing.) It is sometimes necessary to weld a heat channel to the manifold, but be sure to obtain intimate contact between the coolant and the manifold wall or floor. Simply tack welding a closed wall pipe to the bottom of the manifold will not result in sufficient heat transfer.
Our heat plates are not sold with a gasket, but a gasket is definitely required. Use the gray color RTV or make a paper gasket and add gray RTV (ideal) or a factory type gasket with
(Yes, even in California)
The most frequent complaint I have is from customers who complain that since they’ve installed their multiple carbs, the engine hesitates and stumbles at low speed on normal acceleration, from a stop, even after warm-up. The most blamed culprit is the darn Rochester Carburetor. Usually it is falsely accused!
Usually while installing dual exhaust manifolds or headers, the production exhaust heat supply to the inlet manifold is eliminated because (with the exception of Edmunds Inlet Manifolds and recently Clifford intake manifolds,) there is no provision or instructions to provide heat. Why? I don’t know and could only guess. In any event heat will be required to achieve good driving response and reasonable fuel economy. Here’s why:
As liquid fuel enters the manifold from the carburetor, the vacuum vaporizes the fuel and causes a chilling effect on the walls of the manifold much like the chilling effect of spraying an aerosol on your skin. Now you have a cold manifold. If you do not supply a continuous supply of heat, the manifold will remain cold and even build frost under some conditions. At this point, if an acceleration is attempted, the vacuum will drop, fuel will no longer vaporize, and will in fact condense on the cold manifold walls until they are completely saturated with wet fuel. This takes about three seconds, during which time no fuel is going into the engine (and thus no power or an extended hesitation). After the walls are fully saturated with fuel the air flow finally picks up this ultra rich mixture and floods some of the cylinders but not all of them because liquid fuel is notoriously bad for equal distribution.
More fuel (bigger jets) will only slightly help this problem and actually worsen the over rich condition and spark plug fouling and fuel economy.
The solution: Moderate, and continuous heat supply to keep the walls of the intake manifold warm and the fuel in vapor form. Exhaust heat is fast but requires a butterfly valve in one manifold to force the exhaust flow. Water heat is slower but very clean and not corrosive to aluminum manifolds. This method utilizes the water pump to continuously supply warm water to a passage underneath the manifold. (See attached drawing.) It is sometimes necessary to weld a heat channel to the manifold, but be sure to obtain intimate contact between the coolant and the manifold wall or floor. Simply tack welding a closed wall pipe to the bottom of the manifold will not result in sufficient heat transfer.
Our heat plates are not sold with a gasket, but a gasket is definitely required. Use the gray color RTV or make a paper gasket and add gray RTV (ideal) or a factory type gasket with
Cam Bearings
Keep in mind when changing cams to pay attention to the bearings. Here is a abbreviated article from King Bearings on Cam bearing failure.
Structures and Materials of Camshaft Bearings
The typical structures and designs of camshaft bearings are presented. The most traditional design of camshaft bearings is a steel tube with a layer of lead based Babbitt alloy applied onto the inner surface (bush type camshaft bearing). The bearings of this type may be supplied in semi-finished (un-bored) condition. Then the bearings are bored after installation in the engine. However, the precision (bored) finished type is more popular. A relatively thick and soft Babbitt layer provides good conformability of the bearing. The material allows fitting its shape to misalignments. Babbitt also has very good embedability, which is important for bearings operating with contaminated oil. The main disadvantage of Babbitt bearings is their low load carrying capacity. Babbitt alloys are soft; therefore they have low fatigue strength. Also, the fatigue limit of the lining is directly dependent on its thickness: the thicker the layer the lower its fatigue limit. Since the Babbitt lining is relatively thick, its fatigue strength is low (~2,000 psi). Bi-metallic camshaft bearings, with a lining made of aluminum alloy, have a much greater fatigue strength of at least 5,800 psi. The bearings are split shells type, rather than bush. King Engine Bearings manufactures camshaft bearings made of aluminum/silicon alloy: K-788 . Their load capacity reaches 8,000 psi.
A bimetal structure with an aluminum alloy lining is the best solution for camshaft bearings. Aluminum alloy is not too hard, therefore it has good conformability. Also, it is stronger and more wear resistant than Babbitt. In contrast to a tri-metal structure, aluminum alloy bimetal bearings have superior conformability, and can tolerate far greater wear since they do not have a thin overlay. The thickness of the aluminum lining is approximately 0.010”. If the load applied to camshaft bearings exceeds the fatigue strength of aluminum alloys, tri-metal materials having a copper based intermediate layer and very thin (up to 0.0008”) soft Babbitt overlay are used. Tri-metal materials have greater load capacity, but their conformability and maximum wear are limited by the very low thickness of the overlay. Once the overlay is locally worn out and the bronze intermediate layer is exposed, seizure of the bearing by the steel journal becomes very probable. Since misalignment and excessive wear due to oil starvation are typical causes of camshaft bearing failures, tri-metal construction is rarely used in the design of camshaft bearings.
King Bearings are made using the K-788 Aluminum/ Silicon Alloy. These are the bearings I recommend.
Pictures of failed cam bearings. Notice how the soft babbit flows over the oil hole.
Keep in mind when changing cams to pay attention to the bearings. Here is a abbreviated article from King Bearings on Cam bearing failure.
Structures and Materials of Camshaft Bearings
The typical structures and designs of camshaft bearings are presented. The most traditional design of camshaft bearings is a steel tube with a layer of lead based Babbitt alloy applied onto the inner surface (bush type camshaft bearing). The bearings of this type may be supplied in semi-finished (un-bored) condition. Then the bearings are bored after installation in the engine. However, the precision (bored) finished type is more popular. A relatively thick and soft Babbitt layer provides good conformability of the bearing. The material allows fitting its shape to misalignments. Babbitt also has very good embedability, which is important for bearings operating with contaminated oil. The main disadvantage of Babbitt bearings is their low load carrying capacity. Babbitt alloys are soft; therefore they have low fatigue strength. Also, the fatigue limit of the lining is directly dependent on its thickness: the thicker the layer the lower its fatigue limit. Since the Babbitt lining is relatively thick, its fatigue strength is low (~2,000 psi). Bi-metallic camshaft bearings, with a lining made of aluminum alloy, have a much greater fatigue strength of at least 5,800 psi. The bearings are split shells type, rather than bush. King Engine Bearings manufactures camshaft bearings made of aluminum/silicon alloy: K-788 . Their load capacity reaches 8,000 psi.
A bimetal structure with an aluminum alloy lining is the best solution for camshaft bearings. Aluminum alloy is not too hard, therefore it has good conformability. Also, it is stronger and more wear resistant than Babbitt. In contrast to a tri-metal structure, aluminum alloy bimetal bearings have superior conformability, and can tolerate far greater wear since they do not have a thin overlay. The thickness of the aluminum lining is approximately 0.010”. If the load applied to camshaft bearings exceeds the fatigue strength of aluminum alloys, tri-metal materials having a copper based intermediate layer and very thin (up to 0.0008”) soft Babbitt overlay are used. Tri-metal materials have greater load capacity, but their conformability and maximum wear are limited by the very low thickness of the overlay. Once the overlay is locally worn out and the bronze intermediate layer is exposed, seizure of the bearing by the steel journal becomes very probable. Since misalignment and excessive wear due to oil starvation are typical causes of camshaft bearing failures, tri-metal construction is rarely used in the design of camshaft bearings.
King Bearings are made using the K-788 Aluminum/ Silicon Alloy. These are the bearings I recommend.
Pictures of failed cam bearings. Notice how the soft babbit flows over the oil hole.