425 RPMs...

[mepr]

Will a stock 425 be able to handle 3500rpm for long periods of time? Im wondering becouse im getting ready to figure out what size tire i need and what not. Thanks.
And also what would the highest rpm be that i should wind it out to?

[CadilaChris]

The only thing I would be woried about is the temps climbing to high. The 425 should be able to handel everything a 472 can since they share the same crank. But, how long is a long time at 3500? You might need to open up the water pasiges in the head a little. Bone stock, they can make it up to 4500-5000 befor braking a rooker and I think 5500 befor a rod goes. The stock tourqu peek is around 2500, so their is realy no need to go to 3500. And I think the temps stay around 190-210 on goods days.
That little LUV truck should realy boogy. Good luck.
Chris

[STDog]

Will a stock 425 be able to handle 3500rpm for long periods of time? Im wondering becouse im getting ready to figure out what size tire i need and what not. Thanks.
And also what would the highest rpm be that i should wind it out to?

It'll handle it fine, but you won't like the fuel consumption. Much better to get a rear+tire combo that puts you around 2600 for those long stretches. And a torque convertor with a 2000 or less stall.

If you are using a non stock cam, use the sweet spot on that cam instead, but you really want to run there not higher.

[mepr]

well im wondering becouse i may have found a good bolt in axle for the LUV, only problem is the gears. Im going to try running an Isuzu 12 bolt rear, they came in second gen troopers and what not. They are an 8.6" ring gear diameter and have about a 3" thick ring gear. They make Dana 44s and GM 8.5 10bolts look like garbage. But here comes the problems, those axles were made for a heavy 4banger truck so the only factory ratios are 4.55 and 4.77. Whith after maket 5.13s being availible. So i figure whith running about 27" tire in back at 60mph ill be running 3500rpm. Thats where my question comes from. As far as duration i whant it to be daily driveable so i would like to be able to run it like that for 3hours at time, so i would be able to drive from Tacoma back home to Spokane (330 miles). But if heat is the only problem that will probly compound my idea of running rear mounted radiators... :?

[STDog]

so the only factory ratios are 4.55 and 4.77. Whith after maket 5.13s being availible.


I don't think you'd like that on the hwy at all. for the light little thing, I'b be looking for about 2.5 8)

I belive you need to finds a different rear end. where you can get appropriate gears, or much bigger tires.

But if heat is the only problem that will probly compound my idea of running rear mounted radiators... :?

:?: :?: :?:

Rear of what, the truck or the engine bay?
You can get a lot of ar and a big radiator in the back of the truck, which is good, and you'd have cool air flowing over the engine, also good.

Remeber, the Cadillacs that these engine came out of had big radiators, not the little bitty think from a small pickup. And they stioll tended to run warmer than most engines :shock:

[mepr]

Yes ill be running the rad. in the bed of the truck whith the fuel cell and battery. I plan on fabbing up some luvers or something to bring air in from the top of the tanour cover and in the sideds of the bed. And ill probly be running a pusher and a puller fan on the rad for lots of air flow. The reasoning behind the Isuzu rear end is that its bolt in and the lug paterns of the wheels will match making it more stock in apperance and they have discs from the factory that will be compatable whith the trucks curent braking system. I may just end up running taller tires or something...

[rockhog]

What width are you looking for wms to wms??? Something between 56" and 60" I assume??

[mepr]

im not 100% shure what the width of the axle is on an Isuzu truck.

[firebird500]

Last year i bought some parts from a hotrod builder. He had a ford a with a homemade rearend. It was a 9 inch ford centersection with volvo 240 ends. The volvo end bearings was the same size as a smalbearing ford 9" so he could use resplined ford axles. The best of it all is that the volvo axle tubes is a bit smaller so with a little machine work he could stick them in the ford centersection and weld it together now he had a narrowed rearend with a good cheap disc brake setup. Maybe you could use a ford centersection in your car too. 4.56 is only for 6 speed t56 users and remember izusus probably has 5 speed overdrive transmissions so try and run a izusu in 4th gear.

[mepr]

well i think i have things figured out. Im going to give the Isuzu rear axle a go at least for a while untill i get a costum 9" Ford. Ill be running 265/70R15s. Those measure out to about 30". That should keep my cruising speed down around 3,000rpms at 60mph. And it should top out at just under 100mph which is about all the faster i think i will whant to LUV to go. My stocker feels goofy at 80 :lol: