What's in an inch? 7 Litre Lightweight Prototype 428 to 427

[Clive Austin]

Hi,

I'm bored of lockdown so thought I'd start a thread on here about my engine change.

I bought AK1318, the one off MKIV Lightweight prototype back in October 2019.  Many of you have been very helpful in helping me pull the history of the car together and this is hugely appreciated.  The car was originally fitted with a 428CJ FE engine rather than a 427 s.o.  Not entirely sure why but hey ho.  Thunder Road had undertaken quite a bit of fettling on the car since I bought it so I asked them to pull the engine out for me to rebuild during winter and lockdown.  All was going well until a chap I had entrusted the block to for cleaning dropped the block and cracked it.  Not good. After a financial settlement and much thought, I decided to step up from a 428 to a 427 side oiler.  Much further thought regarding original vs aftermarket steel vs aftermarket Aluminium and I eventually decided to source an original steel 60's side oiler block from the US.  Also to stick with an original forged steel $ crank.

Even that wasn't straight forward - one block which was supposedly "mint" arrived only to find that it had two sleeves - so it went back. Second time lucky however and I am now the proud owner of a virtually unused original late 60's side oiler block.  I have also found an original $ crank which has been hot rodded to 3.98" stroke. Combined with a hone to the first oversize (+017) this should produce a 454ci FE side oiler.

I am going for period look where possible but modern performance.  As such, FE guru Blair Patrick is preparing a set of custom CNC "Pro-Port" heads and carburation expert Jim Inglese (who worked on the original Cobras back in the day) has supplied a Webber-esque 8 stack injection system to sit on top of them.

The only downside is timing.  Apparently there is a global shortage of cam cores and mine requires a custom grind.  The earliest this will be available is end April meaning that the engine probably won't be back in the UK until end May and back in the car until end June.

Very much looking forward to that however  :)

If I can work out how to insert images, I'll post pics as we get progress but for now I'm afraid it's mostly "before" plus a few pictures of "bits" as I've got hold of them.

[Clive Austin]

Can anyone advise on posting pics?  I tried including an image link from Onedrive but it didn't appear in the post? The only way I can seem to do it is via attachments which are bit clunky.  In the meantime, here's a few attachments of "before" and some of the engine "ingredients".

[Clive Austin]

And then these are the latest acquisition. Borla throttle bodies with Holly ECU by Jim Inglese.  Ideas on filters much appreciated.  I gather foam options can kill the 8 stack power and, more worryingly, can lead to fires.

[mjf]

Rousch do some individual filters which fit on the Borla trumpets, but I prefer the look of the wire mesh filters which will stop rocks and small animals.

[Clive Austin]

Thanks.  I've just pulled this off the Borla site.  Has anyone used any of these three designs?  First one looks like it keeps out the most dirt but perhaps robs the most performance? Also maybe marginal on bonnet clearance.  Last one looks best imo but not sure how it performs.  Thoughts and expereinces much appreciated.

[westcott]

very late reply but a reply :-)

The nitpicker in me always want to protect my investment and a 427 side oiler block is quite an investment.

You will not notice a drop in horse power caused by an air filter with an engine like that in a MK IV.

You will see the results on a dyno sheet or if you go racing that animal you could also feel it.

For the filter design I would prefer neither of the above and choose a 60s to late 70s typical double filter element in rectangular or oval shape as we used them for all mods with Webers back in the days on BMWs or Fords..... :)    If they work with the angled orientation of the throttle bodies on the FE intake?

Sure they will hide the clean design of the Weber like Borla EFI but they look period without that cheap appearance of the K&N rubber filter elements and they work.

With our MK IVs the hood clearance is the limiting factor but the filter elements are available in different heights and you will find some compromise between clearance and performance.