318 Build-up Questions

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7

73DartSport

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Hey all, pretty new here, but doing a build on a 318 for my Dart Sport and would just like some feedback on the things I am doing from others that have been there and done that.

Block is a 68 model-year 318, bored .040 over and decked. (Side-Note--68 Model year 318s were 9.2:1 comp ratio from the factory) 9.5:1 pistons going in, with a Voodoo 256/262 duration and .454/.475 lift cam (60401). Also have an Edelbrock Streetmaster 318 Intake, and a set of 360 heads from a 78 Cordoba reworked for the top end. Carb decision has not been made so far, but I am just wondering if these changes will give me a noticeable upgrade in power. I basically just want the car to be streetable and fun to drive...long haul plans are to do another engine swap for a 340 at a later date but don't have the funds for this right now as I have found that 340s are pricey and pretty sought after. Thanks for any advice.
 
is that the compression ratio with the 360 heads figured in?i believe you like some 302 casting,318 heads better,and the streetmaster intakes seem to quit flowing after 4500 rpms.i know,because thats what im running right now.my 318 has home proted heads,chet herbert cam,similar specs as the voodoo,but more exhaust lift,matching valve springs,eddy streetmaster intake,heads and intake were gasket matched to 360 size gasket(planning for eddy rpm later or victor 340)i have 1-5/8 headers,with 2.5 inch exhaust,with old flowmasters.the combo is awsome off the line,will really smoke the tires,the mid range is great too,it just stops pulling after 4500 rpms.but my pistons are stock,might have something to do with it
 
Your CR will be low with 360 heads. Use some different pistons or different heads to get the CR up. You could also mill the 360 heads but dont forget to mill the intake sides correspondingly to maintain correct geometry and intake fitment.
 
The guy that does my milling knows everything that is going into my engine and is correctly calculating everything so that my compression ration comes out to 9.5:1. He is the same guy that I have been using for many many years so I trust that what he tells me that I need will be correct. If I had my choice I would much rather have a set of "X" heads, but again as I mentioned before I am not looking for a pricey build...If I were, there would be a SUPER FRESH 340 sitting in my garage. I am just lookng for a fun, driveable car. Thanks for the advice and I would be interested in hearing more about what I could do to make my build run better and if anyone thinks my choices are/aren't the correct ones.As far as my intake goes I thought about changing that part of my build to a Weiand Stealth... any thoughts on this change??
 
318 will not be fun to drive with big valve heads,the bores are too small.I know some guys would tell you otherwise,but ive tried it myself before.it just so happens i burnt a valve in the 360 heads,and had som 302 casting heads from an 86 ramcharger i bought.just swapping to the 302 heads,with fresh valve job,woke my engine up!it felt like it doubled the power.i couldnt spin a tire with the 360 heads,and now traction is a real problem,even in second gear it will get side ways!
 
Your small cam and engine displacement should keep to the small intake manifolds and heads with smaller valves for a high port velocity and a constant smooth quick velocity from carb to cylinder fill. By doing this it helps creste a ramming like effect rather than a large slugish filling atempt that won't have any real speed to continue to try to fill the cylinder.

The Stealth hi rise intake and ones like it will need to have the cylinder heads port matched to the intake for smooth flow. It'll probably provided a minor top end punch in HP, but the rest of the RPM range will make less power. Something noticeable to you.

For a carb, a 600 cfm unit will feed it nicley.
 
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