help! question concerning deck height.
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help! question concerning deck height.
Well i'm going to build a 347 for my F150. I'm trying to keep the compression at 9 to 9.5 -1. If i was going to run flat tops i would be pushing about 10-1. So i went with a dish piston 13.8cc(the first dished piston). The tech said this would get me about 9 to 9.3 to 1 with the E7 heads. Well i sat down and did all the math with the only variable being the fact is it is not assembled to check deck height so i figured it for 0.025 from the top of the piston to the to top of the block. Anyhow the compression worked out to 8.76 to 1 and its a bit lower than what i want. if i cut the deck to 0.0 it will get my compression back up to 9.23 to 1. If i do this will i need to do any thing to the valve train?? or will the hyd. roller lifters soak that up? It seems like it should not be a problem but i was talking to a "chevy" guy and he was talking like i would have to install shorter custom push rod. i cant believe that .025 is going be a issue. By the way is going to be running the stock non - adjustable valve train.
Hotshot
Joined: May 2003
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From: south louisiana
You need to also figure the material removed from the heads when they're rebuilt. .020 by itself isn't a problem. In fact it'll likely work in your favor if you're using a bigger than stock cam. When I did my 331, I had the block milled .010, the Canfield heads are milled .060. Cam is a Ford Racing Z303 with 1.7 rockers (Comp Cams full rollers) The factory length roller pushrods are dead on correct for this. In short, I don't think you'll need to change pushrods at all. You will be choking the 347 with unported E7's though. Once you've done the final assembly, then check the rocker geometry to see if something needs changing.
Postmaster
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if you are useing good aftermarket rods I would deck the block to -.010 that would put the piston .031 from the head...perfect quench (sp)...tight quench will allow you run higher compression so it's a win win all the way around.....set it up with the pistons .010 out of the hole see what you get. I ran a 11 to 1 302 with them .010 out of the hole, stock rods and it would take 93 pump gas.
just how I think I guess......
just how I think I guess......
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i already hand ground the heads and matched the gaskets. i openedthem up alot and took the air port out of the exhaust.
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deck height
shuttle, most 347 kits will have a piston compression height to work with the 3.4 crank and either a 5.4 rod or a 5.315 rod and an 8.206 deck height and have the piston within .010 of the top deck, most stroker kits I have seen would not put the piston that far down in the hole. what year is the block?
I would mock up the crank rod & one piston and check to see where the piston sits. if it is within .010 of the top deck, leave it. closer is better, but if it's within .010 and the decks are flat, don't think it's worth the money.
13.8 dish is a lot.
on the heads, any work you can do to blend the bowl/seat cutter marks and reduce the valve guide boss will help a bunch with airflow.
Jeff
I would mock up the crank rod & one piston and check to see where the piston sits. if it is within .010 of the top deck, leave it. closer is better, but if it's within .010 and the decks are flat, don't think it's worth the money.
13.8 dish is a lot.
on the heads, any work you can do to blend the bowl/seat cutter marks and reduce the valve guide boss will help a bunch with airflow.
Jeff
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Jeff
its a 89 mustang block. i dont recall how mush work i did in the bowls but i plan on popping the valves back out and inspecting everything. I may have a slightly burned valve i had detonation isssues for some time with #5. i had to chip it to get enough fuel to it by the time i did that i think i already hurt the engine. i think the easiest way to get what i want is to knock .025off the heads since they have never been resurfaced. That should get me close to the 9 to 1. This also makes it so i dont have to tear down the engine a extra time an d send it the block in to the machine shop
its a 89 mustang block. i dont recall how mush work i did in the bowls but i plan on popping the valves back out and inspecting everything. I may have a slightly burned valve i had detonation isssues for some time with #5. i had to chip it to get enough fuel to it by the time i did that i think i already hurt the engine. i think the easiest way to get what i want is to knock .025off the heads since they have never been resurfaced. That should get me close to the 9 to 1. This also makes it so i dont have to tear down the engine a extra time an d send it the block in to the machine shop
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