Adding more power to my 390 four barrel?

[tbbob]

At about 100K the 390 in my '66 was feeling quite tired. I had the engine completely rebuilt but doing so didn't really make a noticable difference (actually wondering if the engine shop even did the rebuild or simply repainted it - rather poorly). So I'm looking for pointers on the easiest way to increase the engine's HP.

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[Mseries63tbird]

At about 100K the 390 in my '66 was feeling quite tired. I had the engine completely rebuilt but doing so didn't really make a noticable difference (actually wondering if the engine shop even did the rebuild or simply repainted it - rather poorly). So I'm looking for pointers on the easiest way to increase the engine's HP.

It sounds questionable whether or not your 390 engine was rebuilt because if it was you should notice a difference. 390 is a considerable power plant. I️ would ask for a compression test and see what the results are. If that checks out, the easiest way to boost HP, although not factory correct would be to add a 1962-1963 M Code Tri-Power setup to your 390 engine. JC

 

[vinnie]

A power adder - supercharger or turbocharger. A rebuilt engine that was in reasonably good condition may not yield a noticeable increase in performance. Longevity may be the likeliest benefit.

 

[tbbob]

It sounds questionable whether or not your 390 engine was rebuilt because if it was you should notice a difference. 390 is a considerable power plant. I️ would ask for a compression test and see what the results are. If that checks out, the easiest way to boost HP, although not factory correct would be to add a 1962-1963 M Code Tri-Power setup to your 390 engine. JC

Thanks JC. I actually have two '66 birds, a convertible and the landau, both with 390s. The convertible is far pepier than the landau which is another reason, I suspect the engine shop never rebuilt the sluggish 390. I think I'll do the compression check first.

 

[tbbob]

A power adder - supercharger or turbocharger. A rebuilt engine that was in reasonably good condition may not yield a noticeable increase in performance. Longevity may be the likeliest benefit.

Thanks Vinnie

 

[Sierra977]

100 shot of nitrous. Motor drives like normal until you want more power. Drivability is unaffected like so many "more power" modifications that render a fun car virtually undriveable.

 

[captrick]

Be careful with any power additives like superchargers or even Nitrous. Both of them need fine tuning of your timing and compression of the engine. The safest way is to start out with a recurved distributor. The most timing you want is 35 degrees @ 2800 rpm. by limiting the amount of advance in the distributor to maybe 10 degrees you can have the initial timing higher and have better throttle response at a lower end. You can also go to a newer Holley carburetor and have it jetted for your engine. The other way is to have a new cam shaft installed that will give you better low end torque to get the car moving. Be careful with what you do because you are dealing with a 51 year old engine. Not designed for all the new power additives. Good Luck Rick