Back in the day, Muscle Cars were high performance factory hot rods. If you were like me,when you got your hands on one you always played with it to see if you could get more power. I remember my first car. It was a 76 Chevy Nova with a two barrel 350. It took me all of a few hours to have a set of headers on it. Within a few weeks I had found a 4 barrel manifold and read up on how to port match a set of heads to the manifold. This is a basic D.I.Y. performance boost that can really help your engine breath better by smoothing the flow of the air-fuel charge while it goes into the intake runner. You'll want to gently smooth out any rough surfaces and casting flash that are usually under the valve seats and the short side of the exhaust ports. Of course if the cash flow is there,having them done professionally is always the best way to go about it.
These modifications were all fine and good, for a little while. Then of course I wanted more...lots more!
So,the small block was bored and a set of 10-1 flat tops were installed. After removing any sharp edges from the pistons and combustion chamber and properly adjusting compression by milling the piston boss and leaving the decks of the block alone. I wasn't interested in not being able to use other combinations of parts with my block. I rebuilt a set of 1970 2.02 factory angle plug heads with a porting and polish job.
A set of 1.5-1 roller tipped rockers were used as well. These were cheap so they seamed like the logical course of action. Most factory rocker arms are actually a smaller ratio then advertised and as a result,give less lift.
With the camshaft grinds available back in the 80's pretty much anything with performance sounded like it too..lol. Modern camshafts are vastly superior and allow for more accessories with much less effect on power brakes. And of course the option of 1.6-1 rocker arms can increase lift from a stock lift to a performance lift. And with lower costs of roller camshaft grinds,it just makes sense to get rid of more friction and increase life of the engine at the same time. A full roller valve train allows for more rpm and better fuel economy. Another benefit is faster valve open and closing times that can help with more precise timing too.
While you have the bottom end apart,think about using a windage tray to help keep oil where it's supposed to be. The more oil you have sloshing around the more weight you have moving inside your engine. It just makes sense to control it.
Now I never did use a spacer plate on any of my carbureted engines until I needed to adapt a Holley carb to a spread bore intake manifold on a crate motor I installed in an 85 S-15. I build a spacer plate for my throttle body application with very good results. I added a bit of a twist when I used a large fine thread tap in the holes. I believe the benefit came from the air-fuel charge bouncing off the threads along the outside of the holes. On the dyno my throttle body spacer made 20 horsepower on the stock 350 in my 1990 Chevy truck. While I do have the paper to prove it,I have no idea where it is. However I digress. On Carbureted applications you want to smooth out the air flow going into the carb as much as possible to increase air flow efficiency.
There's a couple other things I want to mention like back cutting the intake valves to help with flow and removing the excess material under the valve seats to help increase the velocity or the air-fuel mixture into the cylinder. Consider the ride height of the vehicle you're building too. Drag co-efficiency plays a big roll in over all performance. The less air you have going under your Muscle Car,the less drag it's going to have and the faster you're going to accelerate! Hope you all had a good weekend,more later.
 |
| Ported Cylinder Heads |
The other side of porting is done on the exhaust manifolds or headers. While there's no replacement for a good set of headers,you can realize horsepower and torque gains from a well done porting and blending job on the inside of the exhaust runner. Blending or smoothing the inside of the runner helps the exhaust gases flow out more efficiently greatly helping with scavenging all the spent gases from the combustion chamber.
These modifications were all fine and good, for a little while. Then of course I wanted more...lots more!
So,the small block was bored and a set of 10-1 flat tops were installed. After removing any sharp edges from the pistons and combustion chamber and properly adjusting compression by milling the piston boss and leaving the decks of the block alone. I wasn't interested in not being able to use other combinations of parts with my block. I rebuilt a set of 1970 2.02 factory angle plug heads with a porting and polish job.
A set of 1.5-1 roller tipped rockers were used as well. These were cheap so they seamed like the logical course of action. Most factory rocker arms are actually a smaller ratio then advertised and as a result,give less lift.
With the camshaft grinds available back in the 80's pretty much anything with performance sounded like it too..lol. Modern camshafts are vastly superior and allow for more accessories with much less effect on power brakes. And of course the option of 1.6-1 rocker arms can increase lift from a stock lift to a performance lift. And with lower costs of roller camshaft grinds,it just makes sense to get rid of more friction and increase life of the engine at the same time. A full roller valve train allows for more rpm and better fuel economy. Another benefit is faster valve open and closing times that can help with more precise timing too.
While you have the bottom end apart,think about using a windage tray to help keep oil where it's supposed to be. The more oil you have sloshing around the more weight you have moving inside your engine. It just makes sense to control it.
Now I never did use a spacer plate on any of my carbureted engines until I needed to adapt a Holley carb to a spread bore intake manifold on a crate motor I installed in an 85 S-15. I build a spacer plate for my throttle body application with very good results. I added a bit of a twist when I used a large fine thread tap in the holes. I believe the benefit came from the air-fuel charge bouncing off the threads along the outside of the holes. On the dyno my throttle body spacer made 20 horsepower on the stock 350 in my 1990 Chevy truck. While I do have the paper to prove it,I have no idea where it is. However I digress. On Carbureted applications you want to smooth out the air flow going into the carb as much as possible to increase air flow efficiency.
There's a couple other things I want to mention like back cutting the intake valves to help with flow and removing the excess material under the valve seats to help increase the velocity or the air-fuel mixture into the cylinder. Consider the ride height of the vehicle you're building too. Drag co-efficiency plays a big roll in over all performance. The less air you have going under your Muscle Car,the less drag it's going to have and the faster you're going to accelerate! Hope you all had a good weekend,more later.
