Aussie heads for 351M
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Aussie heads for 351M
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right now i have a 351M with edelbrock carb and intake with headers on it. With stock heads how much horsepower and torque would puting aussie 2V closed chamber heads. They have 3-angle valve job, hardend exhaust seats, 60cc quench chambers, new valve guides, 2.040" Int/ 1.660" Exh valves with single groove keepers, new high performance valve springs setup to be used with up to .550" valve lift.
right now i have a 351M with edelbrock carb and intake with headers on it. With stock heads how much horsepower and torque would puting aussie 2V closed chamber heads. They have 3-angle valve job, hardend exhaust seats, 60cc quench chambers, new valve guides, 2.040" Int/ 1.660" Exh valves with single groove keepers, new high performance valve springs setup to be used with up to .550" valve lift.
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With the stock 351M piston being about .015 below deck, I don't think you would gain any quench benefits. Going from stock 78 to a 60cc size chamber will increase compression approx. 1.75 points. According to D. Vizards book calculations that would be worth a 3.25% increase in power however based on a dyno test article about compression increases, I would say it can be worth up to 9%. Assuming you don't create any detonation issues with the high compression, I'd guess you're looking at 10-25+HP.
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From: Eastern Pa
If you are looking at one purchase to make to increase your power I don't think the heads are the way to go. If on the other hand you changed pistons in order to achieve quench with those heads and put in a cam to lessen the likelyhood of detonation then you are talking a new game. The single thing you could do to wake up that engine is to get a timing set that will allow you to set the timing straight up at 0 instea of 4 degrees retarded. Changing the cam while there would enhance that alot more. Tell us what you have to work with money wise and people will chime in here to tell you how to get the best bang for your buck.
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I had planed on changing the cams to comp competition cam with an rpm range of 1,500-5,500, and 218 duration @ .50" Int and 218 duration @ .50" Exh and .494" lift Int and .494" Exh and putting a 400 crank and 400 flathead pistons. in addition to the heads is it still a 10 to 25 hp gain and how much torque do u think i might gain. thanks
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Aussie heads are more beneficial to a 351M than a 400. With a 400, quench and excessive compression become big issues. If you build one to the specs mentioned you will have 0 quench, almost 11:1 compression and something that runs poorly on pump gas. Learn how to calculate compression ratios and what quench is before going any further with this project. Remember, Aussie heads are not God's gift to the 335 series. Most people who spend a lot of money on them get very little in return.
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From: Eastern Pa
Well if you just go with flat tops and the aussie's you'll have problems, however if you go with the pistons Tim Meyer sells (no plug intended) you can have the cr any way you want it and have quench. To get an idea of what cr you are playing with with various combos use a calculator like this one.
http://kb-silvolite.com/calc.php?PHP...8a4c4f13feafcd. The heads will give you just as much on a 400 as a 351 if youi get the combination right with the cr.
http://kb-silvolite.com/calc.php?PHP...8a4c4f13feafcd. The heads will give you just as much on a 400 as a 351 if youi get the combination right with the cr.
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From: iowa
Originally Posted by fordtruckman78
I had planed on changing the cams to comp competition cam with an rpm range of 1,500-5,500, and 218 duration @ .50" Int and 218 duration @ .50" Exh and .494" lift Int and .494" Exh and putting a 400 crank and 400 flathead pistons. in addition to the heads is it still a 10 to 25 hp gain and how much torque do u think i might gain. thanks
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