Sonic test results
- Thread starter Jax
- Start date
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MOPAROFFICIAL
Oogliboogli
Screenshot and post it as a picture
Inertia
Well-Known Member
Keep in mind, boring 0.020 over, you remove 0.010 material .
The thicker the better. Adding cubic inch displacement in this fashion is the worst way to add it on and the longevity of the block goes down along with a stiffer cylinder wall which makes more power.
Overbore as little as possible at all times.
This applies to 95% of all the people here. The other 5% (or probably less) are building dedicated and specific race engines.
Also sometimes there’s no care about the block, just the need (probably weed in science) for a big bore to aid the cylinder heads flow avoiding or minimizing shrouding issues.
Overbore as little as possible at all times.
This applies to 95% of all the people here. The other 5% (or probably less) are building dedicated and specific race engines.
Also sometimes there’s no care about the block, just the need (probably weed in science) for a big bore to aid the cylinder heads flow avoiding or minimizing shrouding issues.
dusterbing the peace
FABO pyrite member
First off, did the machine shop provide their recommendation? Those closest to the work, with the most experience, typically have the best ideas.
Center/Back of “cylinder 1” is your thinnest on both, with a twenty thou advantage on the 77. With that in mind you could go 40 over on the 77 and be where you’re at in the 79 without having touched it at all. My opinion for a mostly drag build be to go 60 or 70 over in the 77, leaving about 150 at the thinnest part. This is still less original material than you’d remove putting in a 3/32 sleeve.
Also keep in mind that “center” is roughly 3” down, which is pretty much bottom of stroke. Most of the high energy from the ignition event is gone and bleeding out from the exhaust valve opening, and the intake valve is still hung open at the bottom of the compression stroke. More opinion here - ring seal and bore distortion down there have less impact on power output.
Last but not least, the water comes in right there so cooling should be sufficient to mitigate a hot spot.
Whats 77 ?
446acuda
Well-Known Member
The first sonic test picture is a '77 casting date block. The second is a '79 block.
k, I see, I only download the first apparently
What size of valve you plan on using?
rule of thumb is intake valve max 52% of bore, 4 inch = a 2.08 valve
Plus I would rewrite those with the different overbores to get a better visual of each but that's me
rule of thumb is intake valve max 52% of bore, 4 inch = a 2.08 valve
Plus I would rewrite those with the different overbores to get a better visual of each but that's me
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If I could go .030 that’s where I would go. Then when it needs to go .040 I’d go there. By time I’ve rebuilt and raced it for that many years it’s going on my junk pile. My 408 is at .030 now so hoping it lives a long life. 2nd year on it.
Inertia
Well-Known Member
I'll just re-post this as your at that 77 ish year break .
Others may not understand your concern .
Cheers .
Others may not understand your concern .
Cheers .
Which book is this ?
Inertia
Well-Known Member
That 1979 block gets a sleeve in #1 if it was mine.
Inertia
Well-Known Member
Gotta link ?
No you’ll have to find it yourself. It was said the same for 440s 400s till the major engine builders found out differently (after sonic testing 100 or more blocks from all years). That book was a COPY of what was ‘thought’ before.
Inertia
Well-Known Member
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