390 build
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390 build
hello all i am new to the forum and have some questions on my 390 build. I just took in my block to get poked .040 over, line bored, decked and vatted. my heads are d2teaa and are getting match ported to my aluminum intake. cam is a 292 with .560 lift, by big question is pistons, I am looking to go 10 or 11 to 1 and having a hard time figuring out what i need, any help/part numbers will be appreciated!
Fleet Mechanic
Joined: Nov 2010
Posts: 1,501
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From: Axtell, TX
Welcome to FTE!
As long as you get the pistons with the 1.776 compression height there are lots of choices. If you just get the flat tops with valve reliefs you can achieve a CR of 10-10.2:1 with mr gasket steel shim head gaskets. The H395P are one of the flat tops.
The 360/390 4v have a compression height of 1.776"
The 390 truck have a compression height of 1.68"
Be careful when ordering, many parts stores will make the mistake of selling you the 1.68" truck replacements.
Do you know about the oiling mods that IMO every FE should have? Now's the time when its all torn down.
As long as you get the pistons with the 1.776 compression height there are lots of choices. If you just get the flat tops with valve reliefs you can achieve a CR of 10-10.2:1 with mr gasket steel shim head gaskets. The H395P are one of the flat tops.
The 360/390 4v have a compression height of 1.776"
The 390 truck have a compression height of 1.68"
Be careful when ordering, many parts stores will make the mistake of selling you the 1.68" truck replacements.
Do you know about the oiling mods that IMO every FE should have? Now's the time when its all torn down.
Last edited by Sleepy445FE; Feb 28, 2011 at 11:31 PM. Reason: failing mind..
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I have not bought any pistons yet, it was a 360, and I bought a crank and rods to convert to 390, I plan on buying new ones, been looking at kb862, but want to make sure with my heads I will get 10 to 1, and yes I did address the oil problems, cleaned up the drains in the valley, and chamfered the main oil holes myself, the machine shop was going to drill some passages out.
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Fleet Mechanic
Joined: Nov 2010
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From: Axtell, TX
sure thing. Oh and I did the exact math and you would have a CR of just under 10.5:1 so there ya go, right where you were aiming.
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Fleet Mechanic
Joined: Nov 2010
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From: Axtell, TX
Well the short answer is 8-12° btdc initial and about 34-38° total. Usually in by 3k. I'm ***-u-ming you know how to set it. If not let us know and we can help you get it in tune.
To know what octane you can run you will need to know your Dynamic Compression Ratio(DCR). You'll need to know your cams Intake Valve Closing point ABDC. To figure this take the adv. duration (292) / by 2, add your Intake Center Line, and then subtract 180. This will give you your IVC point.
Here it is layed out: (adv. dur./2) + ICL, - 180 = IVC.
Here is an example: 274/2=137, 137+106=243, 243-180=an IVC of 63°.
Your DCR is much more important to the characteristics of your motor than SCR. Get your IVC and report back. Then we can figure your DCR. Once we know that we will be able to tell you what octane fuel you will be able to run.
To know what octane you can run you will need to know your Dynamic Compression Ratio(DCR). You'll need to know your cams Intake Valve Closing point ABDC. To figure this take the adv. duration (292) / by 2, add your Intake Center Line, and then subtract 180. This will give you your IVC point.
Here it is layed out: (adv. dur./2) + ICL, - 180 = IVC.
Here is an example: 274/2=137, 137+106=243, 243-180=an IVC of 63°.
Your DCR is much more important to the characteristics of your motor than SCR. Get your IVC and report back. Then we can figure your DCR. Once we know that we will be able to tell you what octane fuel you will be able to run.
Laughing Gas
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Fleet Mechanic
Joined: Nov 2010
Posts: 1,501
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From: Axtell, TX
I've used their calculator for SCR but they are a little off on their IVC for figuring DCR. The easy formula will give you the exact number. Once you have it, then you can plug it into their calculator.
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a couple more questions to pick your brains, i have not yet got my cam in so i cant figure out what fuel to run but my question right now is intake, i have the factory 4 barrel that is port matched or should i buy aftermarket, and if so what brand part number, also what seems to be the best ignition to run, granted this is a mud racer so it cant be anything that can be harmed with mud
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Joined: Feb 2011
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From: Spokane, Wa.
I have heard good things about the Edelbrock performer Rpm intake (pn# 7105). I have never used one, I'm still running on everything 45 years old and stock. When matched with Edelbrock performer Rpm heads and cam and performer carb and some headers it made 418 hp and 434 ft lbs. Out of curiosity, are you having the exhaust side ported and putting bigger cobra jet valves in while your at it?