Just 9s?
318 Rebuild: Looking for some parts & build suggestions for a more hp street-able (fun when needed) ride.
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AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I concur.
I've had several 318s and I have done a lot of stupid things with 318s;
Like a 340 top end onto a factory rated 8/1 engine with the factory stall A904, and with 2.94 gears into a 71 Monaco; all the no-no's you can imagine, and what a dog that thing was until it got up on the 340 cam. Great passing power beginning at 75mpg ..... in second gear.
3.55 gears were not enough.
a 2800Tc made it better. 4.11s finally got it half-decent acceptable.
Did the 340 top end swap a few more times, for demanding friends over the years, on smogger-318s. Cylinder pressure was down in the basement. That 340 cam just killed the bottom-end deader than dead. I told them. ...... but I took their money just the same, lol.
I'll never do that again.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Knowing what I now know, if I had to stay normally-aspirated, I'd install closed-chamber alloy heads, at a decent Quench, and target 185>195psi, with whatever appropriate cam that will get me close . and; I'd run solid Flat-tappet lifters in an LA, with enough spring to buzz her up to 7000, cuz that sounds so cool.
as for me, I no longer care about big power numbers. I am much more about big torque in Second gear at 30/35mph, where some 95% of my daily-driving takes place.
All-in-all, it's just easier to hit the marks with more cubes. Not long ago I was a big fan of 360s, for this reason. But, if a guy spends his money in all the right places, I now realize, reluctantly, that a 318 can get close, but there will be sacrifices. starting with the budget, forgetabout it.
and ending with hiway fuel-economy, you can forget that as well.
If I was doing a 318, no question I would super/turbo charge it; small cam and overdrive. Lots of torque-multiplication at 30/35 mph, and let the turbo make it happen. I might even try a remote set-up.
as for me, I no longer care about big power numbers. I am much more about big torque in Second gear at 30/35mph, where some 95% of my daily-driving takes place.
All-in-all, it's just easier to hit the marks with more cubes. Not long ago I was a big fan of 360s, for this reason. But, if a guy spends his money in all the right places, I now realize, reluctantly, that a 318 can get close, but there will be sacrifices. starting with the budget, forgetabout it.
and ending with hiway fuel-economy, you can forget that as well.
If I was doing a 318, no question I would super/turbo charge it; small cam and overdrive. Lots of torque-multiplication at 30/35 mph, and let the turbo make it happen. I might even try a remote set-up.
Dartswinger70
Well-Known Member
318s are like a puzzle with missing pieces ...you'll never get to the finished product with them without hassle. Yeah I know someone will come on here and tell me I don't know and I don't... I bailed on them long ago and went 340 I figured out what I wanted as a finished product and decided 318 wasn't it.
MOPAROFFICIAL
If it has tits, it's a liabilititty.
It's got to pull 20 inches of vacuum at idle for all the power accessories too and get 30 mpg
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Don't forget riding around on 23 year old BFGs bakin um down and slidin sideways everyday.
Agree. And if you choose 4" stroke with 3.55 and 3500 stall it will run even better.
ir3333
Well-Known Member
4" stroke for a heavy B body or truck but a shorter stroke might be preferred by some for a light vehicle?
ir3333
Well-Known Member
Lots of variables. The 4" stroke engines usually don't rev as quickly as similar displacement engines with a
shorter stroke but produce more low rpm torque.
shorter stroke but produce more low rpm torque.
Or some people don't want a lot of power but also don't want a powerband like a truck they want it to turn some rpms by some rpms I don't mean excessive, people seem to want a performance engine make peak power somewhere between 5,000-6,500 rpms, different strokes for different folks. 325hp at 5,000 rpms suits some and 325 hp at 6,500 rpm will suit (probably lot fewer 
) others and a lot in between and some still outside of that range.
) others and a lot in between and some still outside of that range.
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ir3333
Well-Known Member
yup...no right or wrong choice, just please yourself! Now that i'm older my choices are very different from when i was younger. Love to get on it when safe but not comfortable at high speeds now.
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Woody500
Well-Known Member
That's exactly what I said on another thread , that Nascar engines are using a similar bore size & seem to have no problem making Horsepower.
If the aftermarket would pay attention, they could sell a lot of zero deck(and other ) pistons for a 318, and probably many more parts, if they'd stop dragging their feet. People on here keep saying what's needed & nobody pays attention to what is wanted. Or wants to produce it for an affordable price.
How about 'nail style' direct replacement valves, good for 3cc(IIRC) chamber reduction per cylinder(every cc helps!)
Bet you've all got a part idea.
Woody500
Well-Known Member
When does the rod angle of a longer stroke start causing excessive cylinder & piston wear? Or don't we talk about that?
ir3333
Well-Known Member
and i wonder how inefficient high piston speed is?
David Vissard claims the gm 383 is by far the best bore x stroke ratio for making power per cubic inch.
a gm 383 stroker is 4.03 x 3.75,
a mopar 347 stroker at 3.94 x 3.58 would be very relative...just a hair smaller
a mopar 371 stroker at 4.06 x 3.58 should also be a very desirable and efficient ratio.
David Vissard claims the gm 383 is by far the best bore x stroke ratio for making power per cubic inch.
a gm 383 stroker is 4.03 x 3.75,
a mopar 347 stroker at 3.94 x 3.58 would be very relative...just a hair smaller
a mopar 371 stroker at 4.06 x 3.58 should also be a very desirable and efficient ratio.
In my opinion it's not an issue. Others may disagree and I am open to hearing what they have to say about it.
The rod ratio on a 4" stroke 318 is the same as a 4" stroke 360. It is also the same as a sbc 5.7 rod 383. I don't recall any issues with excessive cylinder or piston wear in those.
I could be wrong but, for as many sbc 383's that have been built over the years if rod ratio was an issue with excessive cylinder and piston wear I would think they would stop building them and or we would hear about it.
I remember people debating when stroker started become a popular option about there longevity and it's seems to been overblown, never hear of strokers wearing out extra quick but it does eat some power through extra friction especially at higher rpms but most seem to enjoy there trade offs.
If the online calculator I used is right a 318 with a stock stroke @ 6038 rpm has the same mean piston speed as a 4" stroke 318 at 5000 rpm. All other things equal you will need to turn the stock stroke 318 more rpm to equal the power of the 4" stroke 318. Might be close to a wash. I don't know.
And if you calculate the theoretical airflow (cfm, displacement over time) at same VE% they both will move (displace) about same amount of air, cid x rpm x ve% / 3456 = cfm = similar hp potential.
100% VE
384 x 5,000 rpm = 556 cfm
318 x 6,038 rpm = 556 cfm
390 x 6038 rpm = 681 cfm
ir3333
Well-Known Member
Am i missing something?
Won't a piston with a 3" stroke travel 75% as fast as a piston with a 4" stroke at the same rpm?
At 70 mph the pistons should only be travelling 75% as far as a 4" stroke piston would as well?
Won't a piston with a 3" stroke travel 75% as fast as a piston with a 4" stroke at the same rpm?
At 70 mph the pistons should only be travelling 75% as far as a 4" stroke piston would as well?
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