Engine Advice

[MattK]

I have a 1983 Bronco with the Inline 6 and NP435. I have a ZF42 transmission that I plan to install so I can keep the crawler gear and get OD too. It has the stock 3.5 gears (stock 8.8 rear and dana 44 front). I am planning on 33x12.5 R15 tires. If I need to change the ratios I will adjust accordingly.

The question I have is what to do for the engine. I also have a 351W (roller block) pulled from a 91 f150 that needs to be rebuild and will need to be bored 30 over if I use it. I also have carb intake so I can skip the 1991 EFI and computer.

I have a few options I am considering and want some advice. These are in no specific order. I want to keep the costs reasonable. What are your experiences and recommendations.

1) Keep the inline 6 stock (has been de-smoged).

2) Upgrades to the 6.

3) Mild build of the 351W. Bored 30 over. Sniper EFI.

4) 393 stroker kit for the 351w, carb intake with sniper EFI.

My use for the Bronco is recreational day and weekend adventures in the cascades. I don't plan to daily drive it. I also am not making a off road only rock crawler either. I am looking for something that is reasonably comfortable to drive on the mountain highways, FS roads and confidently tackling 4x4 trails. I live in the NW so we deal with hills, mud, and snow. Since it is not a daily MPGs are not critical, but I do want to keep it reasonable.

 

[Gary Lewis]

My advice is to keep the six, at least initially, to see how you like it. You can always build the 351W later and put it in, and it won't cost any more than going with the Windsor initially. And you may well like the six enough to keep it.

Luckily the two engines have the same bolt pattern so the transmission is the same. But they take different perches, so you can swap out the perches later if you pull the six in prep for the Windsor.

As for gear ratios, I think the stock gearing will be good as the six has good low-end torque so will take off from a stop in 2nd in the ZF pretty well. I'm running 33" tires and 3.55 gears in Big Blue and he pulls away from a stop just fine in 2nd.

So I'd go that way and see what you think. Then if you want more power or need different gears you can make changes based on actual experience rather than what others say. But I think you'll like the 300 six/ZF5/3.55 gear combo well enough to keep it.

[85lebaront2]

My advice is to keep the six, at least initially, to see how you like it. You can always build the 351W later and put it in, and it won't cost any more than going with the Windsor initially. And you may well like the six enough to keep it.

Luckily the two engines have the same bolt pattern so the transmission is the same. But they take different perches, so you can swap out the perches later if you pull the six in prep for the Windsor.

As for gear ratios, I think the stock gearing will be good as the six has good low-end torque so will take off from a stop in 2nd in the ZF pretty well. I'm running 33" tires and 3.55 gears in Big Blue and he pulls away from a stop just fine in 2nd.

So I'd go that way and see what you think. Then if you want more power or need different gears you can make changes based on actual experience rather than what others say. But I think you'll like the 300 six/ZF5/3.55 gear combo well enough to keep it.

I agree with Gary, a little work on the 6 and it will have a load of torque for rock crawling.

[Jake Papageorge]

6 main bearings and 7 main caps = one stable bottom end! Torque all day long and a very reliable combination!

It it is torque and reliability you seek, stick with that 300!

I have a 351W in my 85 F150 and I can tell you, for what I do with it (farm truck and pulling the race car and trailer around) I think if I had the option, I would be plenty happy with the 300!

Now if fuel was not so expensive......MOVE EM ALL ASIDE and give me a 460 all day long!

[Rembrant]

I also have a 351W (roller block) pulled from a 91 f150 that needs to be rebuild and will need to be bored 30 over if I use it. I also have carb intake so I can skip the 1991 EFI and computer.

Is the 351W engine newer than the truck? I didn't think the 351W roller block showed up until 1994. I know the 302 started getting the roller block (but still with flat tappet cam) in the mid/late 80's, but it didn't get the roller cam until 1992.

 

[MattK]

I also have a 351W (roller block) pulled from a 91 f150 that needs to be rebuild and will need to be bored 30 over if I use it. I also have carb intake so I can skip the 1991 EFI and computer.

Is the 351W engine newer than the truck? I didn't think the 351W roller block showed up until 1994. I know the 302 started getting the roller block (but still with flat tappet cam) in the mid/late 80's, but it didn't get the roller cam until 1992.

I am not 100% sure about the age of the 351w block. My friend who is giving it to me thinks it was out of a 1991 F150. But it could be from a different donor. He said it was a roller block. My bronco is a 1983 and the 300 is the original engine.

 

[MattK]

6 main bearings and 7 main caps = one stable bottom end! Torque all day long and a very reliable combination!

It it is torque and reliability you seek, stick with that 300!

I have a 351W in my 85 F150 and I can tell you, for what I do with it (farm truck and pulling the race car and trailer around) I think if I had the option, I would be plenty happy with the 300!

Now if fuel was not so expensive......MOVE EM ALL ASIDE and give me a 460 all day long!

So for the 300 lovers out there what do you recommend doing to it? Leave it stock or make some improvements? If so what improvement do you recommend?

 

[Gary Lewis]

So for the 300 lovers out there what do you recommend doing to it? Leave it stock or make some improvements? If so what improvement do you recommend?

You aren't going to get a whole lot more from the 300 than stock w/o doing serious things to it. You can get a bit more "high end" power with the EFI intake and exhaust, but with a stock engine I'm not sure it is worth it. And you could go with an aftermarket intake but again, unless you are going to rebuild the engine, up the compression and change the cam I doubt it is worth it.

My advice is to keep the engine stock, do the ZF5, and see what you then think you need. If you really want to go fast then think about the 351W. If the 300 does the job but you need a bit more then think about some of the options.

[MattK]

You aren't going to get a whole lot more from the 300 than stock w/o doing serious things to it. You can get a bit more "high end" power with the EFI intake and exhaust, but with a stock engine I'm not sure it is worth it. And you could go with an aftermarket intake but again, unless you are going to rebuild the engine, up the compression and change the cam I doubt it is worth it.

My advice is to keep the engine stock, do the ZF5, and see what you then think you need. If you really want to go fast then think about the 351W. If the 300 does the job but you need a bit more then think about some of the options.

Gary,

It was my understanding that the ZF swap causes the drivelines to be modified. If I do all this to add the ZF to the 300 and want to swap to a 351W later is the engine a direct swap? Hopefully the new transmission mounting location does not have to change again. I think the 300 is longer.

[Gary Lewis]

Gary,

It was my understanding that the ZF swap causes the drivelines to be modified. If I do all this to add the ZF to the 300 and want to swap to a 351W later is the engine a direct swap? Hopefully the new transmission mounting location does not have to change again. I think the 300 is longer.

If I remember correctly I reused the same rear and front driveshafts when I installed the ZF5 in Dad's truck. The ZF is ~1" longer but the shafts still work.

But the tranny doesn't move when you swap engines. The engine moves. The perches for the 300 are very different and in a different place than those for the 351W. You can see the 300 perches on the Pictures tab on the page at Documentation/Exterior/Frames/Engine Perches. I don't think we have the Windsor ones on there, but they are similar to the 351M/400 perches - similar but different so you need the right perches.