You can put one on a stock engine and if the carburetors are a good match, it can be tuned to run very well. However, most people don't put them on stock engines.
Their purpose is to gain velocity with the air/fuel mixture. As the mixture enters the runners of the tunnel ram, it gets a "running start" if you will going into the cylinders and packs more air and fuel into the cylinders. More velocity = more power.
They are made to introduce very large amounts of air and fuel into an engine and make more power and usually in the upper RPM range.
There are exceptions, though. Tunnel rams with long runners lend themselves well to low RPM horse power and torque and can be tuned very well for the street. Edelbrock even made a "Street Tunnel Ram" Specifically designed for lower RPM and power. They worked really well. Never made for a big block, though.
The best choices for a street big block are two. The Weiand and the Offenhauser. Out of those two choices, only one is still made. The Weiand for the RB engine. Othwewise, you will have to look for a good used one.
The Offenhauser tunnel rams had a little longer runners than the Weiand, but not by much. The Offenhausers are very rare units and they are not cost friendly when they pop up. They have also not been made in many years and I doubt they will ever be made again, as Offenhauser has for all intended purposes gone out of business.
I have been kinda looking for a Weiand tunnel ram myself for my 383, but people want a lot for them. I am not going to pay big money for a thirty year old tunnel ram, regardless of how "rare" they might be. I will probably just stick with my Torker 383 and 950 three barrel vacuum secondary Holley.
