fe rods
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From: Ste Genevieve
fe rods
Question. Has anyone here, or know of anyone who, successfully used the longer 360 rods with a 390 crank? I'm having difficulty finding a production aftermarket piston with a higher pin height. It must exist, I can't be the only one whose ever wanted to try this.
Fleet Mechanic
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From: Axtell, TX
It's not a good idea. The long rods of the 352/360 are weaker than the short rods and the combination w/390 crank throws off your quench and CR. Do it the right way and you'll have plenty of piston choice, a stronger rotating assy, and better quench.
6.488 (short) rods, 390 crank, and 1.776 compression height pistons is what you want.
Here's a link you may find interesting https://www.ford-trucks.com/forums/1...-makeover.html
6.488 (short) rods, 390 crank, and 1.776 compression height pistons is what you want.
Here's a link you may find interesting https://www.ford-trucks.com/forums/1...-makeover.html
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You won't find off the shelf pistons for what you ware wanting because nobody does it.
And for a reason, the rods suck and there is no reason to do it.
Otherwise you could shell out $1200+ for Diamond, Arias, Ross, Wiseco or Race Engineering custom pistons. And even then you'll have trick pistons and crappy, spaghetti rods to hold them.
Josh
And for a reason, the rods suck and there is no reason to do it.
Otherwise you could shell out $1200+ for Diamond, Arias, Ross, Wiseco or Race Engineering custom pistons. And even then you'll have trick pistons and crappy, spaghetti rods to hold them.
Josh
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From: Near Madison, WI
Long rod 390 sounds interesting. I've never looked into it, but keep an open mind when looking at pistons, especially if you don't plan on much of a cam. You might be able to find something with a similar pin size and the appropriate height by looking at pistons for other makes. Custom pistons from diamond or cp would be in the neighborhood of a grand, but they could be made any way you want. Good luck with it. Please reply if you come up with something.
-Jared
-Jared
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Here are the tolerances:
332- 6.538-6.542
352- 6.538-6.542
360- 6.538-6.542
390- 6.486-6.490
406 -6.486-6.490
410 -6.486-6.490
427 -6.486-6.490
428- 6.486-6.490
The only "long" rod worth anything is the 352HP or Police Interceptor. It is slightly beefier than the normal rods, but nowhere near a stock "short" rod.
Josh
Fleet Mechanic
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From: Axtell, TX
Correct. The "short" rods of 6.488" are used for 390/406/410/427/428s. The 427 and SCJ 428 used a heavier and stronger LeMans rod with cap screws (the cap screws are different between each). The best non LeMans, so I hear, is the C2AE-D rods because of the larger 3/8" bolts.
Dang. Beat me to it...lol
Dang. Beat me to it...lol
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Correct. The "short" rods of 6.488" are used for 390/406/410/427/428s. The 427 and SCJ 428 used a heavier and stronger LeMans rod with cap screws (the cap screws are different between each). The best non LeMans, so I hear, is the C2AE-D rods because of the larger 3/8" bolts.
Dang. Beat me to it...lol
Dang. Beat me to it...lol
The 428 SCJ did use the Lemans rod, but was considered too heavy and was quickly swapped for the normal 3/8" rods with stronger bolts rather than the CJ/PI 13/32 rods. (And of course ditching the hatchet behind the balancer) Even those that had the regular Cobra Jet found themselves swapping to regular 3/8 rods from the 13/32.
Why? The smaller rods have just "that" much extra meat around the bolts and with stronger bolts are overall stronger thana normal CJ/PI rod.
A little FYI but the 13/32 rods are sometimes called Marine Rods, since a lot of Christ Craft boat engines used that rod.
All production rods were forged with SAE1041 medium carbon steel and likely the most common forging the C6AE is what most will come across all the way to the 1976 FE engines.
Josh
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I should have said the RACE TEAMS swapped out the LeMans rods for the smaller variety.
A race prepped 427, especially a Holman-Moody engine used the NASCAR rod, bigger and beefier than the LeMans rod and requires a special Nascar crank.
So there ya go 4 rods...
Regular Production 3/8"- 13/32" CJ/PI- LeMans- NASCAR
Josh
A race prepped 427, especially a Holman-Moody engine used the NASCAR rod, bigger and beefier than the LeMans rod and requires a special Nascar crank.
So there ya go 4 rods...
Regular Production 3/8"- 13/32" CJ/PI- LeMans- NASCAR
Josh
Fleet Mechanic
Joined: Nov 2010
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From: Axtell, TX
I should have said the RACE TEAMS swapped out the LeMans rods for the smaller variety.
A race prepped 427, especially a Holman-Moody engine used the NASCAR rod, bigger and beefier than the LeMans rod and requires a special Nascar crank.
So there ya go 4 rods...
Regular Production 3/8"- 13/32" CJ/PI- LeMans- NASCAR
Josh
A race prepped 427, especially a Holman-Moody engine used the NASCAR rod, bigger and beefier than the LeMans rod and requires a special Nascar crank.
So there ya go 4 rods...
Regular Production 3/8"- 13/32" CJ/PI- LeMans- NASCAR
Josh
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From: Ste Genevieve
I appreciate the replies guys. I'm not doing it for extra power though. I'm trying to make the most fuel efficient 390 I can without sacrificing the existing power. Longer rods have always been one good way of doing that by allowing a slightly longer period of time with air/fuel under compression after firing. Along with this, I know comp cams still offers a grind that is supposed to slightly increase both mpgs and pwr.. I figure these along with the typical windage tray, headers, and opening the bowl after installing the larger exhaust valve only on my c8ae-h heads, I should be in good shape.....Hmm, now im wondering if anyone ever made an aluminum 2bbl manifold........
Fleet Mechanic
Joined: Nov 2010
Posts: 1,501
Likes: 1
From: Axtell, TX
I appreciate the replies guys. I'm not doing it for extra power though. I'm trying to make the most fuel efficient 390 I can without sacrificing the existing power. Longer rods have always been one good way of doing that by allowing a slightly longer period of time with air/fuel under compression after firing. Along with this, I know comp cams still offers a grind that is supposed to slightly increase both mpgs and pwr.. I figure these along with the typical windage tray, headers, and opening the bowl after installing the larger exhaust valve only on my c8ae-h heads, I should be in good shape.....Hmm, now im wondering if anyone ever made an aluminum 2bbl manifold........
There is already a recipe for getting the best mpgs: Headers, straight up timing set, small 4bbl carb (600cfm), RV cam, electric water pump, tall rear gears (something like 3.00s), and properly aired up street tires. The windage tray and head mods you mentioned are good as well. You should be getting about 16mpgs or so after all that. MAYBE 1-2mpg more if it's all flat highway. That's about all the FE is gonna get.