Short skirts!

Technical advice Q&A

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MarkW
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#1 Short skirts!

Post by MarkW » Tue Feb 20, 2024 9:55 pm

I’m about to embark on the rebuild of a badly restored 3.8 engine that was performed when Noah was still in short trousers. The engine did less than 20 miles after and has stood untouched since.

Big questions:

1/ The accepted wisdom is to renew 4.2 liners are a matter of course - does the same apply to 3.8’s?

2/ Crank damper looks dodgey- will a 4.2 damper fit/ be appropriate?

3/ Although the original pistons (old school Powermax) have done less than 20 miles I am seriously interested in some lighter short skirt pistons (not forged). Does anyone have any experience/recommendations for these?

I am looking to build a responsive engine with low reciprocating mass and a light(ish) 19 lb flywheel. It appears that the 4.2 boys have better options in many respects…

Mark
June 1962 FHC Opalescent Dark Green (currently dark rust basket case).

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Gfhug
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#2 Re: Short skirts!

Post by Gfhug » Wed Feb 21, 2024 9:14 am

Mark, are you planning to do all this work yourself or ask an engine shop to do some or all of it? CMES are well respected and near you https://cmesuk.com/
Fitting liners would need someone like their help. Search for “liners” on here. As has been suggested on here, if you’re getting liners from say Rob Beere then it would be wise to get him to fit them. He can also help with other items such as dampers. That’s another word to search on here and you’ll find various comments about what is good, bad or indifferent.

Geoff
S2 FHC Light Blue
S2 OTS LHD - RHD full restoration

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malcolm
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#3 Re: Short skirts!

Post by malcolm » Wed Feb 21, 2024 9:41 am

I agree with Geoff about CMES. Excellent place. Worth talking to Paul there even if you are doing the work yourself, or even just taking a look! Don't be put off by the shabby exterior
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S

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MarkW
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#4 Re: Short skirts!

Post by MarkW » Wed Feb 21, 2024 7:24 pm

Totally agree about Classic and Modern, they have done other work for me and I was very impressed when they took me on a tour of their workshop. Deffo they are in the loop for acid dip and honing of the block if keeping existing pistons/liners but they could only offer SNG Hepolite old- school pistons if replacing the liners. They had lovely 4.2 pistons with a more modern shape which I am looking for but to fit a 3.8.
Mark
June 1962 FHC Opalescent Dark Green (currently dark rust basket case).

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Paul bow
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#5 Re: Short skirts!

Post by Paul bow » Sat Feb 24, 2024 8:31 am

For definitive advice give Carl or rob (rob Beere) a call, there’s no one on the planet that knows more about these engines than them, really helpful too. They sell only the best products. I rebuilt my engine and lightened the flywheel to 19lbs, runs perfectly at that weight, no engine stalling.
Had Rob machine the head, bigger inlets etc, produced a respectable 260 at the wheels and 300 torque, drives superb, I know they have pistons made from the USA, albeit I believe them to be forged (£££) give him a call you’ll be pleased you did .. good luck with it 👍
Previously...S1 OTS E type (sold)
S1 2+2 manual. (Sold)
S2 rhd OTS full resto finished 8/23
S1 3.8 coupe (full restoration yet to start!)

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MarkW
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#6 Re: Short skirts!

Post by MarkW » Sun Feb 25, 2024 11:02 am

Paul, out of interest was yours a 3:8 and did you stick with standard cam profile? Keen to gather as much first hand info as possible…
June 1962 FHC Opalescent Dark Green (currently dark rust basket case).

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Paul bow
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#7 Re: Short skirts!

Post by Paul bow » Thu Feb 29, 2024 8:41 am

Mine was a 4.2, I used Robs updated fast road cam profile(Rbc4), had the inlet valves at 1.8 and ported the head (gasket matched), silicone bronze valve guides and oversize buckets (1.4) Rob did all the machine work and I assembled it.
The block I used new rods, sportsman version these are nothing short of excellent with AP bolts, used hepolite pistons from SNG rob said the rings on these are very good (made in Japan if I recall correctly) then updated the oil pump (30% more flow) timing chain and tensioner and guides (Rob) then took about 10lb off the flywheel.
From talking with Rob on many occasions he sources all his parts from reliable sources, a lot coming from the USA, almost all the engineering is done in house. You won’t find better.
For what it’s worth I Also used Jenvey heritage throttle bodies.. this turned out to cost a lot more than I bargained for.. the kit now is over 10k + vat !!!
I had Northampton motorsport fit the loom and rolling road session for mapping, an excellent job they did to, however if I’m being honest a set of 45 webbers would have been a 3rd of the price and ok the drivability might have been not quite as good I still believe there’s no better sound or fly down the road on the planet than a trio of webbers opened up at full chat !
I don’t believe SU’s respond as well to a fast road cam, personally I’ve never done it but been told so…
I’ve wasted much money on rolling roads I’d never go anywhere other than to Troy at Northampton, fully booked always 3 months in advance, expensive, and the best by a country mile.
I’ve got to say this is the best e type I’ve built (my 3rd so no expert) took it out yesterday, behaves in traffic sits at 800 RPM and no hesitation shoots off like a scalded car, really nice to drive.
..stopping power came from fosseway (once again excellent) and Rob does a conversion for vented rears which is easy to fit (disassembled IRS) and now it stops on a six pence !!
I can here the cry’s from the purists as I type this 🤣🤣
Good luck pal 👍
Previously...S1 OTS E type (sold)
S1 2+2 manual. (Sold)
S2 rhd OTS full resto finished 8/23
S1 3.8 coupe (full restoration yet to start!)

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Paul bow
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#8 Re: Short skirts!

Post by Paul bow » Thu Feb 29, 2024 8:46 am

I forgot to say I acid dipped the block, albeit removing the liners allows for 100% of the crude to be got at, tbh I made a mistake here, I would definately remove the liners on my next rebuild, I also have the block line bored (Gosnay engineering) and then obviously everything balanced.
Previously...S1 OTS E type (sold)
S1 2+2 manual. (Sold)
S2 rhd OTS full resto finished 8/23
S1 3.8 coupe (full restoration yet to start!)

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MarkW
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#9 Re: Short skirts!

Post by MarkW » Thu Feb 29, 2024 11:53 am

Thanks for an excellent run-down Paul. Rob's uprated oil pump, Sportsman rods, 9kg flywheel and the larger valves etc. are definitely now on the shopping list!

There have been many comments about a torque dip at around 2200-2300 RPM even with a mild cam, I would guess you have been able to offset that through your fuel injection mapping?

Mark
June 1962 FHC Opalescent Dark Green (currently dark rust basket case).

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bitsobrits
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#10 Re: Short skirts!

Post by bitsobrits » Thu Feb 29, 2024 2:17 pm

Mark,

The oft mentioned torque dip can occur with those awful tubular manifolds with the large fan shaped 3 into 1 collectors on an otherwise stock engine. With the build you are planning it shouldn't be an issue.
Steve
'65 S1 4.2 FHC (early)

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Paul bow
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#11 Re: Short skirts!

Post by Paul bow » Fri Mar 01, 2024 10:29 am

Yes your absolutely correct, the mapping sorts out any torque dips, like I mentioned if you run dcoe webbers with a updated cam you’ll prob over come that as well as long as you go to a decent rolling road., and I heard chat about petrol smells etc. well from my experience they’ve been spot on, I used the 5 hole progressive version from southern carburettors, (Gatwick area) the whole kit was around 3k (linkage, manifold etc) these are better to tune and better at low RPM.

I use a tubular stainless exhaust from Hayward Scott, these are very well made and give a few more bhp with the correct set up, in my opinion it can be a tad more noisey popping etc..

My honest advice would be to have a chat with Rob, that guy don’t take your money if not needed the amount of times he put me right and said unnecessary ..
Also book well in advance Northampton motorsport, simply fantastic they are 2 hrs away from me and I wouldn’t contemplate anywhere else. Trust me, I have no affiliation with them, but I’ve wasted £000’s on crap rolling roads, others on this forum steered me to them, I’m pleased to pass that on where I can..
Good luck with it all 👍
Previously...S1 OTS E type (sold)
S1 2+2 manual. (Sold)
S2 rhd OTS full resto finished 8/23
S1 3.8 coupe (full restoration yet to start!)

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