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Discussion in 'Engine Topic' started by matt71Camaro, Jan 21, 2021.
Thank you for that breakdown and the link. I will be sure to look at that.
I don't think it is numbers matching. The block is most likely original, but my dad put on 292 "Turbo" heads and a SY1 intake so he could race it and he was pretty fast. I'm not worried about changing stuff based on how it would affect the value of it, but its difficult for me because this was my dads first car that he bought when he was 15 and its been in our family ever since. My dad passed away about 15 years ago so there is a sentimental factor that weighs heavily on me when changing things.
I thought about doing that but this was my dads car and I want to keep the engine, or at least the appearance of the engine, the same as what my dad had it. The engine is the heartbeat of the car and I don't want to change the heads or intake. I feel like if I buy a different engine and put it in that I might as well just go buy a different muscle car and make it my own because it would no longer be his. I know I could put new aftermarket heads and make it run harder but I want to preserve my dads car as best as I can but make it better for me at the same time
I guess I get it... although I'm not sure why the heads are any more sentimental than the crankshaft. But if that's what you want...
Very important aspect to consider here: The 292 heads are a very old design with 64cc combustion chambers. They are not going to be able to cope with a ton of compression on pump gas. When building a 383, a standard flat-top piston set with 64cc chambers will put static compression ~10.6-1. With the size cam, you are going to want in this engine, the 292 heads will not support that much compression on pump gas.
Do the build with dished pistons and keep the compression under 10-1
My thought on it is that on the outside it is the same: same carb, intake, heads, block, but inside the components will be different. I feel like if I put some aluminum heads on, it will look different. I also kinda like the nostalgia affect of it in that they were from the 70s and built for racing. I know heads today are much better and its something I might do in the future. Just right now I'm taking baby steps in changing things.
That's good to know about the CR to keep it at 10:1. I'm guessing its better to bring the CR down to make sure it runs optimally rather than keep the CR higher and have to retard the timing which could negatively affect performance. Right now it runs on pump gas but I bet it doesn't run as well as it should if tuned correctly and with the correct gas. Thank you for your input.
I get it.
You are correct. In a non-EFI application, it's better to control detonation with lower compression than timing. Really the only reason you can get away with it in EFI applications is that the knock sensor will monitor spark and retard automatically.
For the record, with a 350's 3.48" stroke a flat-top piston, and 64cc chambers, the engine should be ~9.7-1 compression right now. It might actually be lower if the pistons are dished.
Trick Flow makes aluminum heads that are externally identical to the "double hump" heads such as the 461, 186, 292, etc castings. Painted orange no one will know the difference unless they have a magnet. The claimed to be 60cc combustion chambers and 170cc intake ports IIRC. Worth a look. As much as I liked the Smokey Ram/SY1 intake cause it looks cool, it isn't very good for a street car.
I broke a pushrod and rocker arm a couple years ago and the mechanic looked down the bore with a scope and he commented on how big the domed pistons were and said its likely to be "at least 12:1". This would make sense because my dad use to race it and I remember him telling me how he used to put airplane gas in it if he couldn't find race gas. In the 90s and 2000s before it was parked for 15 years, the only thing we put in it was premium fuel which had a better octane than today's premium gas though it still probably wasn't high enough for what it needed.
That is a good point. Right now the heads are black so I could repaint it to match and have a better head. As you said, I love how the SY1 looks and the comments it generates. From what I've read and learned, it does take some finessing to get it to run correctly and it likes high RPM so it may not be the best on the street. I'm hoping that by having 4.11 gears (my dad had 4.88s) and a 4 speed that it will keep my RPMs up and make the SY1 fun to have.
so ... get a NEW GM shortblock SP/ZZ350 or SP383 and a NEW pair of those alum 60cc TFS DHC 175 heads w/roller spring option; pick your slide-in roller cam & lifters then paint it your choice of color.
Throw down some whoopazz & make Dad proud.