I have started compiling a build plan for a modest budget build of the V6 in my Capri - let me know if I have left anything out.
The intended function will be a reasonable street engine capable of doing a sprint or hill climb.
Fuel is to be PULP of 95/98 RON, max safe rpm is to be 6500, but honestly I think it would be very rare to go past 6000 as I expect it will run out of puff around 5800.
 
Block: bore out to minimum, say 30thou over. Use KS pistons (any point free floating the pins?) and deck the block to raise CR to 9.2/9.3:1 (I'd like slightly higher, 9.5:1, but how much can you skim the block?). Replace cam bearings, use alloy cam gear (already have one) and a reground camshaft from Clive Cams (specs to be decided after taking to them). Keyhole crank oil mains, new small end bearings in rods. Flywheel? Think I'll leave this std, lighter would be nice but the balance work is a pain. Std oil pump - I think I'll make a oil drive shaft from a long snap-on hex drive or similar. Std water pump.
 
Heads: D port heads (I have them, but without the std rockers/push rod guides, as in they do not have any). Unleaded conversion on Ex valve - port pocket and remove much of the guide boss. Inlet valve enlarged to 1.75" (may as well do this while engine is apart), pocket port to match, clean out guide boss, clean up port but no major work. Bronze valve guides. As the heads have no rockers etc I was looking at SBC roller tipped rockers. Screw-in studs (I can do this myself). Up-rated single valve springs.
 
Intake: I have D-port intake manifold and a Holley 500 plus adaptor, K&N pan filter. The manifold is missing the W-plate, which is a really curious device - is there any point to re-shaping the inlet to the plenum to radius the entry to the front/rear cylinders?
 
Ignition: Aftermarket electronic distributor. I cannot be faffed with points these days and the original distributor would have to be pretty worn by now. Coil and points - nothing special with these.
 
So that is the basic plan. Have I missed anything that would make a difference to reliability/performance?
 
 
 
 
 
 

Hi Neil
 
Burtons website has a section on engine tuning and this site also has some info.
 
https://www.essexengines.com/tuning%20the%20essex%20v6%20page%201.htm
 
Swaymar had a tuning guide, I cant find my copy but someone here might have it handy.
 
My thoughts are be careful with decking the block, it can cause problems with manifold alignment and sealing due to the V shape.  A holley 500 might be too big.  Swaymar used a 380, the 350 on my old engine many years ago was too much for it.
 
I now have the weber on mine with only 30 thou bore and the mildest cam that Kelford had.  I also have a pertronix ignition system fitted to the original dizzy, it only needed a new top bush to replace the worn one.  I stuck with standard oil pump as HP can strip the drive.  Pacemaker headers and a larger dia pipes, 2 mufflers to resonators, still louder than I would like.  I still have mech fuel pump.  With only those changes it goes to redline in a heartbeat in 1st and 2nd, (with a 3.09 diff), and is a very noticeable difference to my other one that has a stock engine.
 
I had an alloy gear and took it out due to excessive noise, it was horrible.  If you get one be sure to inspect it carefully.  The first one they sent me had casting defects in the teeth.

Thanks for the reply. My car already has headers on it, which I hope will match up to the D-port heads. I've never used a holley before, but am very tired of weber's so I am keen to try it. The 500 has lower flow than the 4 barrel 390 - they test under different conditions, why I have no idea. Decking the block may require some adjustment to the intake manifold, but it's a lot cheaper than getting pistons made. I resigned to the extra noise from the alloy gear - I suspect it may be quieter than the steel option and I wary of the original gears given their age and my intended use. Thanks for the confirmation on the fuel pump - I was unsure how much they can supply.

Neil
 
the 500 has lower flow than the 390 due to just that; bigger CFM means "longer legs" but slower acceleration.
One thing the V6 doesnt need is to do 200kph with a 1:1 top gear as in std tranny with the revs going "nuts".
The 2 barrel 38 Weber in my D-port 165HP performs absolutely brilliantly with breakneck acceleration compared to
any other stock V6 Capri. H500 OR 390 would never be my choice for hillclimbs or sprints. The W38 excels here. I reckon the Ford Engineers got this 100% spot on.  Mine is a Genuine OEM factory oem D38Weber. I don't know what the new aftermarket Webers are like ? ....could it be 1 of these non-gen that's disillusioned you ?
 I run basic ULP with SOO(Super Outboard Oil) at 300:1 ......  I found 95/98 RON to be under-performing, which I found explained to me by experts, much more knowing than me. Sounds contadictory i know. Facts speak for themselves. My Capri also reckons they are right! .........  the 20% $ saving is immaterial but nice source for $ for SOO!
 
Alloy timing gear is GUARANTEED to be noisier and less reliable than the Mk2 Cast Iron with the peripheral Fibre teeth.
Maybe the one you cited is 100% ALL steel? ......Let me know as I have no experience with these.
I agree with Steve re shaving the block: that's asking for trouble, esp as GOOD replacement blocks are non existent.
We have a very steep hill in South Frankston 3199 called BANGALAY AVENUE and I'm blown away with the HUGE torque in my D-port that seems to handle this EVEREST as if it was a flat road ! What a rip-snorter !
Can't wait to try an even steeper and much longer road called the Arthurs Seat Road where there's a new supersonic Chairlift operating !
https://www.google.com.au/maps/search/ARTHURS+SEAT+CHAIR+LIFT/@-38.3537478,144.9484023,17z

The Holley 390 and 500 are not analogous, but I don't know what you mean by 'longer legs'. The 390 is the 4bbl vacuum secondary carb from the performance range and the 500 is a 2bbl from Holley's 'economy' series. They are tested/rated differently. 4BBL Holley carbs are rated such at 1.5"Hg and 2BBL Holley carbs are rated such at 3"Hg. To convert a two-barrel rating into a four-barrel rating, divide the two-barrel rating by 1.414.
 
This means the 500 is at 353CFM on the 4BBL scale and a 350 is 247cfm. Even this is a bit misleading given the nature of the 2BBL/4BBL carbs and the difference in venturi velocity at different vacuum levels.
 
Holley 4BBL maths works out as follows: MAX CFM = engine cubic displacement x Max RPM x 0.000289 x %VE.
So if we assume a 3lt capri with a slight overbore is 185cu/in, then capacity x max 6000rpm x 0.000289 x 85% VE (this may be generous) we get 272cfm.
 
The speedpro book on Holley uses different maths: cubic capacity x 50% x max rpm / 1728 x VE. This works out as follows: 92.5 x 6000 / 1728 x 85% = 273cfm ... pretty consistent.
 
So the 350 would seem a little too small and the 500 a little too big.
However practicality override some of this as the original Weber is worn and a rebuild was quoted significantly more expensive the it was to purchase the Holley 500. I'm sure to find out in due course.
Re PULP fuel - there is no benefit to any increase in RON if there is no need WRT compression ratio. The Heron head of the Essex is not an efficient design, but it is all there is.
The nylon/steel timing gears are all 35 years old at least. I think the alloy is fine and comes strongly recommended.
 
 
 

Talk with John McCallum Capri spares Qld. He will blow your brain on what he knows and what can be acheived. He will give any option you like and does it in his own shed. 3.4ltr Essex with billet cam whatever compression you like but will tell you straight up if your idea or budget won't work. Last I heard he imported a few Dports. Not cheap but reasonable and our Aussie Ric Wood if you ask my opinion. Plus he keeps all the parts in stock. Legend.

I have a 4 barrel D Port inlet manifold if you want to use your 390, yours for $250.  get yourself an electronic distributor - better to use Performance Ignition or Ignition Developments, I have not had too much luck with the drop in conversions.
 
The alloy gear will whine initially.  Use Moreys engine oil additive on the teeth at install.  It sounds like a blower at first but will bed in and get quieter after 6 to 12 months 

Good advice JR. I had a swaymar intake for the 390 carb. Really comes down to motor setup and jetting to make everything work. Alloy gears need to bed in sound better after some time. Like the Morey's tip.

GTV6 is you manifold the one on ebay?

Hi no, I have one in Melbourne, not sure if its a McCallum conversion, or a Pierce Manifolds one from South Africa