I have a 1991 F250 4x4 EFI 351w V8 with hooker shorty headers, true dual exhaust with 3 inch stainless steel piping with flowmaster super 44s.

I've been looking at hydro rollers and I need to know if "computer controlled" is important because almost every one I look at isn't "computer controlled compatible".

Thanks.

 

Dual 3" all the way back? That's too much exhaust for a 460 so you're losing quite a bit of low end torque.

Rockers or camshafts? If it's rockers you're talking about that rating doesn't apply.

That truck has the SD EFI system on it which means if you you're changing the cam it has to be compatible with that system or "computer controlled", in general that means no less than 114 degrees LSA and no more than 210 deg duration at 0.050" lift. However you will find some cams that meet those specs(or are very close) that aren't rated computer controlled so there are a few more options available. Your motor currently has a flat tappet cam in it as well and converting to a roller involves using linkbar roller lifters and shorter pushrods which drives up the price quite a bit, but considering how many flat tappet cam failures we're beginning to see it's probably worth the expense.

 

It's a 351w not the big block 460.

So it doesent matter what it says as long as I change the rockers and lifters? Or are you saying that I have to go into the computer and change stuff in order to get a bigger cam?

 

Yes exactly.. so you have 2 times too much exhaust for that motor, even a single 3" is overkill.

Neither of those, what I'm saying is it doesn't matter if the cam us rated "computer controlled" or not as long as it has no less than 114deg LSA and no more than 210deg duration at 0.050" lift. The rockers don't have to change at all but if you select a roller cam you have to use linkbar roller lifters and shorter puchrods and not the stock parts.

 

Ok, thank you I know what to look for now

 

What would happen if I installed a cam with a bigger lift such as this COMP thumpr 35-600-8 - Thumpr