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here is my ?. I have a 97 350 vortec block with old style heads, edelbrock performer and 650 carb tranny is 700r4. stock rear end. I personally rebuilt motor 3 years ago and has less then 500 miles on it.. I want to make it in to a street rod. so I would like some advice on motor set up. cam , stall heads and headers. thanks
For a basic peppy street car with the engine you have; I'd go with a shift kit, a constant pressure valve body, and a 2500 stall in your trans, a set of long tube headers with 2 1/2" dual exhaust and some free flowing mufflers all the way out the back. If you don't mind cracking your rebuilt motor open again, I'd go back to the Vortec heads, dual plane Vortec aluminum intake, and something like a Performer RPM cam; just watch the lift on the stock Vortec heads. I think something like .440 is max on the stock heads. That should give you some nice burnout power off the line and good low to mid RPM power; which is what I like for a street car.
Ok, thank you. What is your thought on port and polish? Does it gain enough for the tear down ?
Also thinking of adding turbo ?
If I owned your car and wanted a little more from it, I'd leave the motor alone for now and change rear gears and converter. Assuming you don't do a lot of high-mile travelling on the freeway, I'd opt for a set of 3.73/4.10 gears and locker in the diff and a 2500-2800 stall converter. I'd use a genuine 10" converter, not a 12" unit with the fins bent over. With these two changes, you'll think you've bolted in another motor. If you dink with the motor first, you're gonna need to change the converter and diff gears anyway, so why not do converter and gears first and maybe leave the motor alone for a while?
If you add a turbo, you really need to know the static compression ratio of the motor so that you know the limit of boost to use. I would not turbo a motor that was over 8.5:1 static compression ratio because of the risk of detonation on pump gas. I would want to disassemble the motor to widen the ring end gap and tighten up the squish/quench to prevent detonation and maybe even change pistons, depending on what pistons you used in the rebuild.
"Port and polish" is a term left over from the '60's. We still port heads and we still polish the exhaust ports, but the intake ports are normally left about as rough as a lady's steel fingernail file. It has been found that this works better than a perfectly smooth intake port. We have also found out that cutting the head and intake ports to match the gaskets is a waste of time and a waste of performance. When you cut the head and intake material to match the opening in the gasket, you create a port that resembles an Anaconda snake that has swallowed a pig, in the side view of the port. As the fuel/air mixture passes this point, it senses an increased volume and slows down. As the charge of mixture slows down, fuel that was formerly held in suspension, drops out of suspension. This leaves a lean mixture to be pulled into the intake port until the next time the intake valve opens and sucks up the wet fuel from the port floor. So, you have a lean mixture, then a rich mxture, then a lean mixture, then a rich mixture an so on an so on. If you just leave the intake and heads alone and hope for the best, you will get the best results.
As a matter of airflow research, the lion's share of the mixture flows right down the center anyway, so the ports being a little mismatched around the edges will not hurt a lot. You can set this right in your mind by thinking about a stream or small river. The major part of the water goes right down the middle, with the water at the shore and at the bottom of the stream moving very little or not at all. Same thing, doesn't matter if it's air or water. Same physics.
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You’ll probably gain as much or better airflow just by going to stock Vortec heads as you will porting the older heads. Plus your compression ratio should be better with Vortecs. I’d have to agree with Tech Inspector on your rear end gears. At least check and see what gears you have but I think factory gears on that car is probably a 3:42 or a 3:73. Anyone know what the 84 ‘birds came with?
Thank you for your input. I’ve built my stock motors for 25 yrs . And wanted to see if I can get more power. Thank you again .