390 Rebuild Help
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390 Rebuild Help
Hi, I have a D3TE truck block bored out to 428 specs (4.130) and was needing some help on picking a crank, rods and pistons. I would like to have the final compression ratio between 9 and 9.5. I am going to be using C6AE-6090-R heads and they are suppose to have 71.2-74.2 combustion chamber. I have several question and would greatly appreciate all the help I can get.
1. What is the deck height of the block?
2. Would it be best to use a 390 or 428 crankshaft to acheive my desired compression ratio?
3. What rod length would I use with either crank to acheive right compression and piston deck clearance.
4. Is the standard rod length in a D3TE motor 6.54? (I don't have them)
The motor is going in a 66 F-100 that I mainly just cruise around in but occasionally do use it to tow. I am not looking to build a race motor, just a nice strong motor to put in my truck. Thanks in advance for any help that you can give me.
Ronnie
1. What is the deck height of the block?
2. Would it be best to use a 390 or 428 crankshaft to acheive my desired compression ratio?
3. What rod length would I use with either crank to acheive right compression and piston deck clearance.
4. Is the standard rod length in a D3TE motor 6.54? (I don't have them)
The motor is going in a 66 F-100 that I mainly just cruise around in but occasionally do use it to tow. I am not looking to build a race motor, just a nice strong motor to put in my truck. Thanks in advance for any help that you can give me.
Ronnie
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From: Mddl A MexCans
Since you don't want a race motor and it's already bored. My vote would be to use a 390 crank as it will be easier to obtain and less $ and it will be plenty ballzy without overkill. Then get pistons with a 1.76 pin height like (Speed Pro ZH395P) to fit the bore, using 390 crank/rods. Mock up the rotating assembly and see where the deck height is. Wild guess is .033 if it's never been decked. Physically CC your heads so you can be sure what it is instead of assuming. Then you can have the heads and block milled according to what you want to achieve. If like most blocks it will require a decking just to be square (mine was .007) and after mockup still isn't exact with about .003 more meat on the 5-8 bank and more so at the rear of the block "inclining". Keep in mind that over .020 IIRC will require the intake to be to be milled as well. Rough guess is that with the heads milled for cleanup .0025/.004 and the block .007 / .011 you'll be just about where you want with a steel shim gasket.
Bottom line, read the advice that comes in, but don't do the work/math. Don't be bummed when it isn't correct.
Bottom line, read the advice that comes in, but don't do the work/math. Don't be bummed when it isn't correct.
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From: Montana
Everything Redman says is correct and the best way to do it. I would add using ARP rod bolts if your going to have OEM Ford rods reconditioned. I had such a hassle finding 8 good 390/427 heavy duty rods (most have big ends that have been angle cut and ruined), that next time I would consider buying aftermarket... Eagle, Scat or such, then the rods have good bolts, weights would be matched, machining dead on, etc.
I would also suggest having your block bored/honed with a deck plate to keep the bores round for best piston ring sealing, and having the block decked by an outfit that has a CNC machine that will index off the crank mains and cam bores so you have a perfectly square block when your done. The local machine shop we have does the best they can without CNC, but everything is off several thou no matter how hard they try.
In comparison, I sent my 360 Dodge block out to a shop with CNC capabilities, the block checked out nearly perfect in every dimension. I was impressed, and still am.
I would also suggest having your block bored/honed with a deck plate to keep the bores round for best piston ring sealing, and having the block decked by an outfit that has a CNC machine that will index off the crank mains and cam bores so you have a perfectly square block when your done. The local machine shop we have does the best they can without CNC, but everything is off several thou no matter how hard they try.
In comparison, I sent my 360 Dodge block out to a shop with CNC capabilities, the block checked out nearly perfect in every dimension. I was impressed, and still am.
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From: Montana
You may have trouble finding pistons that fit the 428 bore, and fit a 390 compression height. It may cost $$$$. Consider spending less $$$ on a 428 stroke crank, then the pistons would be easy to find. Or buy a stroker kit that has crank, rods, pistons all as a set.
Realize that boring the 390 truck blocks to 428 specs is pushing the limits of those truck blocks. If the block has been sonic checked thats great. If a cylinder wall fails due to thin material thickness after all that boring, pistons can hydraulic lock which will quickly and completely ruin your entire engine... maybe the carburetor would be ok.
A more stout way to do it is keep the 390 cylinder size, bore it 0.03 over, and use a 428 stroke crank. You will have 416 cubic inches, and plenty of cylinder wall thickness to handle anything you would throw at it.
Realize that boring the 390 truck blocks to 428 specs is pushing the limits of those truck blocks. If the block has been sonic checked thats great. If a cylinder wall fails due to thin material thickness after all that boring, pistons can hydraulic lock which will quickly and completely ruin your entire engine... maybe the carburetor would be ok.
A more stout way to do it is keep the 390 cylinder size, bore it 0.03 over, and use a 428 stroke crank. You will have 416 cubic inches, and plenty of cylinder wall thickness to handle anything you would throw at it.
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Joined: Feb 2005
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Great advice from Redman. You might consider contacting Survival Motorsports....they have broad knowledge of these FE's...they also sell stroker kits that could be a good option for you depending on your budget. I'm not a big fan of the 428 cranks as they are externally balanced. You can have them internally balanced, however the more you spend on one the better a stroker crank looks or just going with a 390 crank. For a good strong truck motor you can get tons of torque out of an FE with the 390 crank....it's all in the total package....target a compression ratio around 9.5 to 1, pick the right cam, intake, exhaust package and you've got a good deal.
Good Luck!
Tracy
Good Luck!
Tracy
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Thanks for your advice guys. I've been doing all kinds of research on cranks, rods and piston's. I never realized how much work there was into getting the right combination of the rotating assembly to end up with the right compression ratio. I now have a lot more respect for people that build these motors. My main concern is to have a dependable motor and I don't care to spend a little more money to get it right the first time. I talked with a guy at my local parts store and he gave me the phone number of a guy that has been building FE motors for years. He is just about an hour away from me so I am going to take my block to him and have him sonic check it and build it for me. There is no way I would build this block without sonic checking it first. I am going to talk it over with him when I take the block to him next week. I at least know a little more about building a motor now so I can talk with him about it and have a good idea of what he is telling me. I really appreciate you guys taking the time to post your thoughts and I will be mentioning some of the things you said to him. Thanks for your help.
Ronnie
Ronnie
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