I called XDI today and they mentioned that the roller tapped will be different (which you found out). They couldn’t confirm that the spring was the same size on both pumps to seat the roller.
If they are the same size, the pumps are the identical, besides the fuel inlet connection.
if not, they said I can exchange the pump for a 10% restocking fee. They are also out of stock of the RS pumps.
Let me know if the springs are the same size on both pumps.
Also, I saw your post on an RS thread under the WTB section asking about cam caps… guess it’s just not an option.
I was however wondering if you can drill the fuel lobe housing instead of adding material to the cam cap? I’m sure that has already crossed your mind.
Give this thread a full skim. I think it'll help.
The springs are not the same size.
3 lobe gets a flat tappet with a smaller diameter spring
4 lobe gets roller tablet with larger diameter spring.
The fuel inlets are the same size. Only the Flex fuel Ti-VCT has a different sized fuel line (and electrical connector)
There is also discussion in this thread about why you can or can't buy cam caps.
@Moment has recently pulled a Cam cap from a 2.3L RS. still waiting to see if it runs. The debate is on the tolerances (all cam caps are line bored to the head).
Drilling the fuel lobe housing isn't possible. you'd have to drill pretty much on top of the lobe's wall.. putting the bolt longwise through the wall. Potentially destroying the seal channel, and definitely drilling right through the re-designed oiling vein. The oil comes up from the bottom now. and travels right where the old bolt hole was.
Something that hasn't been discussed yet is boring out the ST Lobe housing. Just thought of this. And it might be possible, but the Roller tappet adds height to the HPFP stackup. You would have to bore out the lobe housing, re-cut the oil groove on the I.D., and then add a spacer on the top so that the 2.3L fuel pump has the height needed for the roller tappet. - Now this might actually be a way avoid the welding method I did. At least you can buy the lobe housing covers for both RS and ST pretty cheaply.. And drop it off at a machine shop while they do this work... Now if just someone made a spacer..