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Discussion Starter #1
I have a 1988 bronco with a 351w and I want to change it over to a roller motor. I have recently scavenged all the necessary parts from a 97 mountaineer (liters, dog bones, spine, spider thingy). As I studied a little more I realized that in addition to needing to drill and tap the valley, the litter bores are too short and require a reduced radius cam. I have a couple questions...
1. Is converting it to roller cam really worth it? I am changing over to maf, gt-40 heads, headers and a bigger cam to bump torque...roller will let me run a more aggressive cam but will it really free any HP?

2. Are there issues with the reduced radius cams? Are there severely restricted cam choices when using one of these? I got all my parts (lifters ,dog bones, and spine) for free, so if I could just get a cam and pushrods, that would ease my budget.

3. haven't opened my block yet, but was wondering if bosses will be present and just need to b drilled and tapped, or will I be just drilling into normal valley material? I do have an 89 302 open and noted it has bosses that are drilled and tapped...???

Bratcop
 

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Discussion Starter #2
Did I fuss someone on here or what? Second post with enough views but no posts...can I get a bump?
 

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You are not going to have any luck doing it that way the lifter bores for a flat tappet 351w are not tall enough for proper oiling you will need a roller cam conversion kit.
 

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I already studied this one there is a conversion kit to do what you wanting but it is a little on the pricey side. The lifter kit was around $400 that was excluding the cam. One other thing you need to do if your considering this is to get the roller cam compatible distributor gear. The roller cam will free up up some HP. I planned on doing the same thing to mine but it's almost as cheap just to by a roller cam 351w block.
 

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I was under the impression that is what a reduced diameter cam did, drop liters lower...no?
Yes. Your issue is limited cam selection.


The difference between a roller and a non-roller block is the height of the lifter bore. Ford replacement roller lifters are taller than flat tappets. If you simply drop roller lifters in the non-roller bores, they will stick up so high that they'll starve for oil. The other issue is that flat tappet lifters are supposed to spin in their bores. Roller lifters have to be perfectly aligned at all times.


In order to upgrade your 5.8L non-Roller Block, you have basically two options:

1. Use a Hydraulic Roller Retro-fit Kit, which includes "dog bones" and a "spider", to maintain alignment of the roller lifters. This will also require a "small base circle cam" which will reduce the height of the lifter. Camshaft selection may be limited unless you choose a custom grind. These retro-fit kits require drilling and tapping in the block lifter valley to bolt the "spider" in place and minor clearancing around the "dog bones" so they will lay flat. This is a cost effective option as stock Hydraulic Roller Lifters may be used. A Hydraulic Roller Retro-fit Kit will run about $45.00.

Comp Cams Hydraulic Roller Retro-fit Kit





2. Use special length Retro-fit Hydraulic Roller Lifters which come with "link-bars" to maintain their alignment. These are very expensive compared to stock Hydraulic Roller Lifters but you can use a "standard base circle cam" which will allow you a wider selection. These type of lifters cost between $500.00 and $600.00 a set.

Comp Cams Retro-fit Hydraulic Roller Lifters





 

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Discussion Starter #8
Right, I have the back bone, dog bones and stock lifters from a Mercury Mountaineer (the cost me nothing). If I am not mistaken then all I need is a small base circle cam, and to drill/tap the block? How much can the cam really be? Like $300? The way I figure it, it should be significantly cheaper to find a small base circle cam (assuming there is one that really helps me breath) and use the parts I have. Otherwise, it's new lifters ($3-500) plus a new roller cam, $200, and the dizzy gear. Am I missing anything. Has anyone actually used a small base circle cam? I read someone had questioned their strength due to the reduced amount of material in the cam....Thanks for the replies, BTW.

Bratcop
 

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The way I figure it, it should be significantly cheaper to find a small base circle cam (assuming there is one that really helps me breath) and use the parts I have.

Bratcop
Again, that is the trade-off. Have you actually tried looking for a small base circle cam that will work with your application?
 

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I would advise : Get a "F4" roller ready 351w, or just buy the additives and put it in the oil and keep the flat tappets.

I wanted to put rollers in my 351w until I found out how much it would be. I wanted the E303 cam.
 

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Discussion Starter #11
After advise and research, I've decided go/stay flat tappet. Thanks for the advice and insight, now on to researching cans that make monster bottom end torque...
 

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if you are keeping the stock EFI then leave the stock cam!
Do a search in the tech section
Yep, you are correct. For a SD friendly cam it has to have a seperation of no less than 114 degrees.

Unless you're converting to mass air
 

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you may also have to get a Tweecer for you maf eec, depends on how big a cam you plan to run.
 
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