HOW-TO: X35Designs Phenolic Spacer Improvement.. | Ford Explorer Forums - Serious Explorations

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HOW-TO: X35Designs Phenolic Spacer Improvement..


Mad Scientist
Elite Explorer
March 29, 2015
Reaction score
City, State
Orangevale, California
Year, Model & Trim Level
2015 Ford Explorer Sport
..and think I found a small way to improve it...

Got it today and looks like a great product and look forward to getting it installed to see if it can mitigate IM heat soak issues further. I still need to order the additional gaskets before I can install it.

When I mocked it up and placed the hardware in the holes so I can see if I would need to do any port matching, I found it suffered from the same issue as the BBK throttle body. Not the fault of the spacer, but more the fault of the IM. The bolts holes are just too large for the hardware and allow for a lot of play. This would make any attempt at port matching it futile as it would be difficult to place properly when installing it. So...just as with the BBK, I used the same logic here. and it worked perfect...

Spacer with gaskets installed:

Thickness of spacer for those curious:

Dowels created for improvement:
5/16" OD, 0.035" wall thickness, 304 stainless tubing, cut to about 0.8" length (can't be any longer than 0.9")

Picked any 2 holes far apart from each other and drilled with 5/16" drill bit:

Drilled matching holes in spacer, same 5/16" drill bit:

Dowels installed into spacer:

Perfect tight fit onto IM:

Will need minimal port matching, mostly just a little of the spacer needs to be matched to the ports, but Steve did a great job of getting it super close.

There ya go. I can probably drill the bolt hole very slightly using the same 5/16" drill bit for the match holes in the heads and push those dowels through the spacer slightly. That would get this setup 100% dead-nuts tight and centered from head to spacer to IM...

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Finally have a few sets done if you are interested.


I know there were a few on other boards that showed interest, just hit me up here and I'll DM you paypal info if you are interested. It'll be $20 shipped. Thanks.

Just got done port matching my spacer to my intake runners. You can't even feel a change in the transition it's so smooth. This process is not possible without the alignment dowels.

Now, when I get my heads exposed, I'll entertain the idea of matching the bottom part of the spacer to the openings in the head...

"Those balls look smooth as eggs!!!" - Dave Chappelle


UPDATE Ladies and Germs!

Finally got this thing mounted onto the engine (video forthcoming on that), but here's a video on me doing the porting on the head side of the spacer...


Nice writeup. I just added another 3 months to your Elite membership for the article. You are good until May 2022:chug:

What’s your paypal ?
Let em double check if I have some on hand. I have been running low on this part and need to get another batch done up. Don't want to charge you if I don't have any available at the moment.

Did this spacer provide any sort of improvement?

Did this spacer provide any sort of improvement?
Hard to say as I did a huge amount of other upgrades at the same time. I did not do a true before/after log.