4bbl. vs. 2bbl. HP

Several years ago a lady in her 70s brought me a Maverick Grabber for a tune-up. She wanted to be sure that when finished it would run like it was supposed to. She said when she stepped on the gas she expected it to GO. I test drove it. It would GO. No one would imagine that lady driving such a car.

hello, i have a 1964 olds. dynamic 88 with 394 engine.finally found a dual exhaust manifold,will be doing that shortly. i have a 2 barrell now ,but i have a 4 barrell intake and was thinkink of swithing ti a holly or edelbrock. car has 28000 miles ,dont want to mess with the cam, any thoughts? thank you

If the 4V (barrel) intake is stock, then use the Rochester or Carter carburetor that was stock for this year. If you want a larger carburetor, then you need a new aluminum intake manifold and headers as well as the dual exhaust.

I believe there were two 2V versions of this engine, a low compression and a high compression. All the 4V and 3-2V versions were high compression. Most had a high lift, short duration cam for low end torque.

This may have had an exhaust system that had both a muffler in the center of the car and a small resonator near the tip. You may want to consider straight through pipes to the rear where the resonator is and then use a muffler in place of the resonator. This will keep the exhaust pipes hotter and reduce corrosion. The problem with most dual exhaust systems of that era was that the pipes past the muffler stayed too cool and the corrosive exhaust gasses would condense and rot them out. This helps with the HP as well.

Edit: If you need to open those valves a little more to take advantage of the larger carb, you could change the rocker arms to a higher ratio. Just be careful not to go to far or you could end up with the valves hitting the pistons, but that isnā€™t too likely with a mild cam and low compression to begin with.

It is also a myth that a large carburetor will bog down an engine.

thanks kieth, problem is its hard to find a 4 bbl. for my car, and it is a high compression engine

the 4 bbl. on my car was an option

Iā€™d suggest using the Edelbrock carb on the manifold you have. It is the old Carter 4 barrel design updated by Edelbrock. donā€™t go too big, around 575 to 675 CFM will get the job done nicely and this carb will be a bit more fuel efficient and idle better than the Holley.

I respectfully disagree with @keith on the muffler placement. Only for the sound, not any technical points. If the muffler is mid-car and you leave off the resonators, there will be less drone noise in the car. It also means you can go with a lower restriction muffler because the tailpipes will kill some of the sound. Adding a crossover pipe between the mufflers and the engine will also add quiet things down and add a bit of torque.

If a proper Rochester Q-Jet isnā€™t available the Edelbrock 4 bbl runs a close second in my book. Holleys just donā€™t come close to the hassle free operation of the Q-Jet and Edelbrock.

And my old book confirms that both the 2 and 4 bbl V-8s had 10.5 compression but could be had with 8.75 by special orderā€¦ Maybe for cabs, I guess.

Most new cars have the muffler in the rear, but they use a resonator pipe in the middle which is a pipe with ribs in it. I suppose he could just swap the resonator with the muffler or find a muffler shop that makes custom exhausts (most do so they donā€™t have to stock a large selection of pre-bent pipes) and have them fabricate the center pipe out of resonator pipe.

They do this for packaging and heat management. The fuel tanks are in the middle of the car these days, and they are often plastic. Not at the rear like this Olds.

They are usually located over the rear axle assembly. Putting the muffler at the rear may have some packaging advantages but it also has a performance advantage. The exhaust gasses will cool down and contract a little while traveling down the pipe so any given muffler will have a little less back pressure at the rear compared to the middle.

They also muffle a little more effectively further back as the pressure pulses tend to spread out as they travel, blending together. That is also what the muffler is trying to do is blend the pulses together. That translates to a smaller muffler to do the job so that would save the manufacturer some money, but Iā€™m sure cost savings has nothing to do with the manufacturers decision.:wink:

Not unless you are driving a Gen3 or 4 Camaro or Firebird they donā€™t have the tank over the rear axle. My RWD Mustang has the tank under the rear seats, as does nearly every FWD car on the market today. Thatā€™s why you can change the fuel pumps by removing the seat lower cushion and popping off the access cover.

Iā€™ve had cars with both rear and mid-mufflers and find the mid-muffler cars are easier to quiet with less volume of muffler than the rear mounts, not the other way around.

One reason trucks still use mid-mount mufflers is there is no need for a resonator. The tailpipe allows quite a bit of destructive interference in the sound pulses. It also happens that the spare is in the way of rear mufflers on trucks as well.