318 build with dyno session

Stock stroke or 4" stroker?

  • Stock stroke 318

    Votes: 48 88.9%

  • 4" stroker 318/390

    Votes: 9 16.7%
  • Total voters
    54
  • Poll closed .
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If you have good pistons and a quality balance rpm is your friend on a small displacement engine, it’s the only way you can increase displacement. Good head work and a cam that will make max hp around 6300 will give you 30 plus hp over your 5000/5500 limit.
 
Oldiron440 said:
If you have good pistons and a quality balance rpm is your friend on a small displacement engine, it’s the only way you can increase displacement. Good head work and a cam that will make max hp around 6300 will give you 30 plus hp over your 5000/5500 limit.
Click to expand...
Who exactly are you talking to here?
 
Be curious to see how this engine turns out.
I ran this engine( in the below link)at the track with a cam similar to what is being planned for this build( not the 248@50 cam this motor was dyno’ed with) and it had enough grunt to run right at 116 mph at 3400 pounds in a 71 Duster street car with full bench seat interior, factory 5/16 line stock gas tank setup.

https://www.hotrod.com/how-to/0901phr-mopar-318-magnum-engine/
 
B3422w5 said:
Be curious to see how this engine turns out.
I ran this engine( in the below link)at the track with a cam similar to what is being planned for this build( not the 248@50 cam this motor was dyno’ed with) and it had enough grunt to run right at 116 mph at 3400 pounds in a 71 Duster street car with full bench seat interior, factory 5/16 line stock gas tank setup.

https://www.hotrod.com/how-to/0901phr-mopar-318-magnum-engine/
Click to expand...

did you own the crank shop they talk about or just had work done there?
 
B3422w5 said:
Be curious to see how this engine turns out.
I ran this engine( in the below link)at the track with a cam similar to what is being planned for this build( not the 248@50 cam this motor was dyno’ed with) and it had enough grunt to run right at 116 mph at 3400 pounds in a 71 Duster street car with full bench seat interior, factory 5/16 line stock gas tank setup.

https://www.hotrod.com/how-to/0901phr-mopar-318-magnum-engine/
Click to expand...
Thanks for the link! That's a good read. This one wont be anywhere near as scienced out, and certainly wont make that much power.
 
I had read that article a few years ago.. i love that oil pump mod, just too chicken to do it myself :)
 
NC Engine Builder said:
Thanks for the link! That's a good read. This one wont be anywhere near as scienced out, and certainly wont make that much power.
Click to expand...
Like Adney said in the article, the crank work likely won’t/ didn’t show on the dyno, but is a benefit at the track.
Those heads went low 270’s at 550 lift, as I recall. Did have the cheapie Chinese dual plane on it that I ran. I also got him to throw in the 950 they ran it on the dyno with. I continued to use that old 950 hp on other stuff until very recently. I sold it with the 360 short block I had in my current car before going to my current stroker I now run.
The cam I ran with that 318 was in the 230’s at 50, over 600 lift with the staggered rocker gear ratio’s he had.
I think that motor( with the original dyno cam, and in a more typical 3000 ish pound bracket car)would have dipped into the 10’s.
But I had instructions from the boss, no bars allowed, so mid 11’s was my goal for that car, and it accomplished that with a 4.10 gear.
 
So this is more of a PSA update, but while getting it ready to line hone, I remembered ARP has finally updated the stud kit to include bolts for the rear cap, (where people would reuse a stock bolt for clearance to the pump.) That's GREAT, but you must make sure the bolt holes are bottom tapped deep enough for the bolt to clamp the cap before bottoming out! 318 caps are shorter than 340 caps, making this a critical check! I have seen a 340 with a broken main saddle due to this!

20250426_122312.jpg


20250426_122049.jpg
 
NC Engine Builder said:
So this is more of a PSA update, but while getting it ready to line hone, I remembered ARP has finally updated the stud kit to include bolts for the rear cap, (where people would reuse a stock bolt for clearance to the pump.) That's GREAT, but you must make sure the bolt holes are bottom tapped deep enough for the bolt to clamp the cap before bottoming out! 318 caps are shorter than 340 caps, making this a critical check! I have seen a 340 with a broken main saddle due to this!
Click to expand...

Nice catch!
 
Got "rodney" in the block surfacer for a haircut, and as this engine has been rebuilt probably more than once previously, when I measured everything up, the block is surprisingly straight front to back, however one side of the block is right at .012 taller than the other. The shorter side cleaned up with only a .0015 cut, and the pistons are positive .002 on that side, so I will simply cut the "tall" side to match, and end up .002-.003 positive deck. Perfect!

20250428_111224.jpg
 
Rodney the 318? As in, “I get no respect” Rodney?
 
And this is another sorta "psa" post, it's been discussed many times, that the 318 and 340 main caps are the same. They are NOT! they will interchange, but 340 caps are taller, and have more material around the bolt holes. Hes a few pictures to show the difference. Rodney's 318 caps on the right, '71 340 caps on the left

20250430_095926.jpg
 
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