engine build help

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91 or anything higher, around here you can get 93 at a couple stations. good luck, o i see your looking at a 400hp 318, very do able should be very fun :thumbup:
 
An iron headed engine will need at least 91 octane and careful timing to run well on the street. Pay attention to the details of the tune.
A tight centerline cam (IE; 110 or less) will allow pressure to bleed off and the ablity to run what your asking about.
 
That's what I need to do with my 318. Man there are some possibilities with that little motor.
 
so would i have to advance or retard timing? and whats the best way to make power with this motor with out having to worry about timing and high octane?
 
"I just built a 360 with magnum heads. It's has zero deck KB107 flat top pistons, and 0.039 head gasket which results in 10.6:1 compression. I am running a Comp Cam XE268 cam, with a Professional Products CrossWind dual plane manifold (copy of an Edelbrock RPM Air Gap). I have 1 5/8 headers with a 2.5" dual system with an x-pipe and Flowmaster 50 series mufflers. I am currently running a Holley 600cfm vacuum secondary carb. The engine is in a 68 Barracuda with an A833OD 4spd and 3.55 geared sure-grip rear end. I now have a little over 1500 miles on the car since installing this engine. Below are my impressions;


how is dgc333 able to run 89 octane with that compression?
 
DusterBoy15 said:
so would i have to advance or retard timing?
Click to expand...
In a performance engine you would advance the timing.

DusterBoy15 said:
and whats the best way to make power with this motor with out having to worry about timing and high octane?
Click to expand...

Lower compression. Iron headed IMO (though nothing is in concreate and subject to many peramiters of the build,) 9.0-1 without a worry, 9.5-1 the max.
1 full point more for a aluminum headed engine.

Are you saying 9.0-1 isn't enuff to yourself? I thought I heard someone think that. Well, think again and about this. The Dodge trucks, the old Craftsman racing class were limited to a 9.0-1 ratio but yet pumped out over 700 hp in a 355 small block.
 
DusterBoy15 said:
"I just built a 360 with magnum heads. It's has zero deck KB107 flat top pistons, and 0.039 head gasket which results in 10.6:1 compression. I am running a Comp Cam XE268 cam, with a Professional Products CrossWind dual plane manifold (copy of an Edelbrock RPM Air Gap). I have 1 5/8 headers with a 2.5" dual system with an x-pipe and Flowmaster 50 series mufflers. I am currently running a Holley 600cfm vacuum secondary carb. The engine is in a 68 Barracuda with an A833OD 4spd and 3.55 geared sure-grip rear end. I now have a little over 1500 miles on the car since installing this engine. Below are my impressions;


DusterBoy15 said:
how is dgc333 able to run 89 octane with that compression?
Click to expand...
It is attention to details and knowledge about quench. OR aka the squeezzeed area and relationship of the piston distance to the head as well as the combustion shape of the head.

His flat top pistons come up to the same height as the block. This is called zero deck (Of the pistons) The gasket being .039 is about as ideal as you can purchase off the shelf and in general, not much less is a good idea. Some claim closer, but I'll stay at this distance myself. Old, poor rods will strech while the engine is running and let the piston hit the head. Been there got hurt by it.
Another thing is the cam is on a 110. This bleeds off presure to a degree.

He could run 87 if he retards the timing. This would incure a HP lose penalty and it is not worth bothering to do. You'll lose more power in retarding the engine than through most anything else you could do.
IE, wrong size carb, exhaust, valve etc....
Click to expand...
 
ok so if i got 9.0.1 compression i should be good correct? on wat octane?

and should i go small or big 360 valves meaning 2.02 or 1.88 intake? also should i get mildon valves or juse stock ones thanks
and since the rpm air gap intake says to use 360 or 340 heads i should port the 302 heads to the 360 size right? or no
 
9.0-1 is fine on 87 if it is timed advanced a little bit, great on 93 advanced a lots bit. It also depends on the heads chamber and how far the piston is away from it.

Smaller valve on the 318. Build dependent, valve size changes. You may even want the stock valves. And speaking of which, on valve choice. Make that a sperate question on a new thread. I think the racers and/or head porters can answer that one best. I have not used there valves.

The head should be ported to the intake windows size.
 
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