390 or 460
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From: west sacramento ca
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Some of my single buddies are strokin it but I am glad I am married
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From: St. Libory
Yikes. Totally taken out of context.
Maybe I should re-phrase this:
I'm starting to like the idea of putting in a crankshaft that will lengthen the stroke of the engine.
-Jake
Maybe I should re-phrase this:
I'm starting to like the idea of putting in a crankshaft that will lengthen the stroke of the engine.
-Jake
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We are all alittle sick minded. It's ok I knew what you were saying.
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From: St. Libory
Haha, I'm glad someone did.
So, I posted this in the FE forum with 0 responses so far (seems that group isn't what it used to be) so I'll ask here.
I found cast stroker cranks on ebay for half the price of forged ones. Should I go for it or stay away from them? They come in 3.980, 4.125, and 4.250 with no price difference.
I'm also thinking of just putting a torque cam and headers in this thing and seeing what that does. I'm afraid I'd be fighting low compression though. Is there anyway to guess what my compression ratio is without tearing it down and knowing exactly what pistions are in it? I'm guessing it has D2TE heads, either that or C8TE, but I doubt they're C8's.....
-Jake
So, I posted this in the FE forum with 0 responses so far (seems that group isn't what it used to be) so I'll ask here.
I found cast stroker cranks on ebay for half the price of forged ones. Should I go for it or stay away from them? They come in 3.980, 4.125, and 4.250 with no price difference.
I'm also thinking of just putting a torque cam and headers in this thing and seeing what that does. I'm afraid I'd be fighting low compression though. Is there anyway to guess what my compression ratio is without tearing it down and knowing exactly what pistions are in it? I'm guessing it has D2TE heads, either that or C8TE, but I doubt they're C8's.....
-Jake
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Cast cranks are good aslong as your not building a race engine. The cam, headers and air intake will wake it up. And 390's aren't low compression engines, the 360's are. A 390 is somewhere around 9.5ish a 360 is only 7.5.
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From: St. Libory
Weren't the truck 390's about 8.6:1 or so? When I rebuilt my first 390 I used 360 pistons to bump the compression up. It has worked out nicely. My fear is that this 390 in my Highboy is the low compression truck engine, limiting my cam selection. It has been overhauled 10 years ago, but doesn't have very many miles on it.
-Jake
-Jake
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From: Alvarado, TX
Like Ohio said, cast steel is fine. How often do you hear of guys breaking stock iron crank in truck engines? There are nodular iron ones available too which are stronger than stock and cheaper than steel. When it comes down to it, they all come from the same plant in china so it doesn't matter which one you choose. I was going to use an RPM unit because of the 4.375" stroke.
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From: Lost
Weren't the truck 390's about 8.6:1 or so? When I rebuilt my first 390 I used 360 pistons to bump the compression up. It has worked out nicely. My fear is that this 390 in my Highboy is the low compression truck engine, limiting my cam selection. It has been overhauled 10 years ago, but doesn't have very many miles on it.
-Jake
-Jake
In theory, you can swap in a 3.98 crank, using the same pistons/rods from a truck 390, since the truck 390 pistons were the original 410 pistons. This would yield a CR of around 10-10.5:1. Talk about a "cheep" stroker kit....... The aftermarket 3.98 cranks can be spec'd with stock rod bearing size and internal balancing, so no special parts would be needed to keep it from shaking.
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Check out summits pistons , Z381P vs ZT304P .
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I ran a desk top dyno on stroke and compression ratios .
The Total HP was about the same for each stroke , but the 3.780 stroke peaked 309 HP @ 4500 rpm where the 4.375 stroke peaked 309 HP @ 4000 rpm .
3.780 stroke = 415 tq @2000 rpm
3.980 stroke = 438 tq @2000 rpm
4.125 stroke = 455 tq @2000 rpm
4.250 stroke = 469 tq @2000 rpm
4.375 stroke = 482 tq @2000 rpm
with every thing else remaining constant .
390
4.050 bore
9.0 compression
700 cfm
.500 lift flat tappet cam
small tube headers w/ mufflers
dual plane intake
As for compression on the 390 with only the compression ratio changed .
HP is @4500 rpm , Torque is @ 2000 rpm
8.0 = 290hp / 396tq
8.5 = 300hp / 406tq
9.0 = 309hp / 415tq
9.5 = 318hp / 425tq
10.0= 326hp / 432tq
The Total HP was about the same for each stroke , but the 3.780 stroke peaked 309 HP @ 4500 rpm where the 4.375 stroke peaked 309 HP @ 4000 rpm .
3.780 stroke = 415 tq @2000 rpm
3.980 stroke = 438 tq @2000 rpm
4.125 stroke = 455 tq @2000 rpm
4.250 stroke = 469 tq @2000 rpm
4.375 stroke = 482 tq @2000 rpm
with every thing else remaining constant .
390
4.050 bore
9.0 compression
700 cfm
.500 lift flat tappet cam
small tube headers w/ mufflers
dual plane intake
As for compression on the 390 with only the compression ratio changed .
HP is @4500 rpm , Torque is @ 2000 rpm
8.0 = 290hp / 396tq
8.5 = 300hp / 406tq
9.0 = 309hp / 415tq
9.5 = 318hp / 425tq
10.0= 326hp / 432tq
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