Mild 360 Magnum Build

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DMC_78 said:
Thanks so much for sharing! I will be starting a build just like this very soon. I have the same heads as you, and have been on the fence about what pistons to use.

do you know your cranking pressure in the cylinders?
What octane did you run, and what do you plan on running the engine with? I am also in Canada, and limited to 91 at best.

thanks again for sharing!
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FYI we did not do any compression testing… this thing will run on 87 just fine…we even killed it at the end of a pull at around 2500 rpm and it shut off without even a knock or shake…
 
Great job! Iq52, told me if you use ported heads you can use less cam to reach your goal. Again well done.
 
I just looked at the time line on the dyno sheets…after a 5 minute warm up the first pull was at 6:14pm and the last one was at 6:32pm…that was 5 pulls in 18 minutes…carb spacer install between pull 3 and 4 took 7 minutes…pull 3 made 400.9hp with no spacer
 
So @ .515 lift your taking advantage of the 275 cfm bowl porting very well. Nice! Very goooood. That’s how you do it!
 
rumblefish360 said:
So @ .515 lift your taking advantage of the 275 cfm bowl porting very well. Nice! Very goooood. That’s how you do it!
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It seems to have worked out…I was sure it would go past the 375hp mark no problem…but in the back of my mind hitting 400hp at around 5000rpm where the cam was finished pulling would be touch and go…
 
That’s what she said until later on when the torque hit on the greater lift, it was all smiles from there….
 
Here is pull 3 with no spacer

0A49F306-A2DF-48A0-B6FE-1C7A366C02DE.jpeg
 
Last pull with all information for those who are interested in this sort of thing…

E274CE99-54C1-446B-84FA-64FC18085630.jpeg
 
Judging by the AFR there’s more in it. Probably another 10-15hp or so
 
TT5.9mag said:
Judging by the AFR there’s more in it. Probably another 10-15hp or so
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Another local engine shop had a 340 with 10.5 comp and a bigger cam on the same dyno recently…. It made 415hp at over 6000 and a lot less torque… a part of me want to stuff more timing in the magnum and jet the carb until it went 416….but that would be just for ego and that’s not my thing
 
67autocross said:
Another local engine shop had a 340 with 10.5 comp and a bigger cam on the same dyno recently…. It made 415hp at over 6000 and a lot less torque… a part of me want to stuff more timing in the magnum and jet the carb until it went 416….but that would be just for ego and that’s not my thing
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I’ve never run the EQs but I can’t imagine that chamber wanting as much timing as you put in to it or even more. It’s hard to argue with results though. I’ve seen the best power at 36deg on closed chamber magnum stuff.
 
You have a nice engine that should be a lot of fun in whatever vehicle you stuff it in. As long as you’re happy with it then numbers are just numbers. I say well done.
 
TT5.9mag said:
I’ve never run the EQs but I can’t imagine that chamber wanting as much timing as you put in to it or even more. It’s hard to argue with results though. I’ve seen the best power at 36deg on closed chamber magnum stuff.
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The pistons are 50 down the hole....the thing is likely not even 9:1...I bet I could have put 42 degrees in it
 
mopowers said:
Will this build ever see a track??? It's nice to have MPH #'s that back up dyno #'s.
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It might make it to the track...although it could be sold to a friend who needs a small block for his project...if it does make the track it will post the weight/mph
 
67autocross said:
It might make it to the track...although it could be sold to a friend who needs a small block for his project...if it does make the track it will post the weight/mph
Click to expand...
Talked to the guy tonight….it’s sold
 
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