Lotus Elan

Re bore

PostPost by: potleyu18 » Mon Mar 04, 2019 1:34 pm

Just stripped my plus 2 big valve engine apart as compression was very low in all cylinders and now looking for a company to carry out the re bore its +30 as present so can only go one more step up to +40 and don't want to make any mistakes.
Can anyone advise of a reputable company to do this i'm based in Camberley at the borders of Hampshire, Berkshire and Surrey. Don't mind travelling if its worth while.

Secondly and advise on the piston manufacture naturally Omega is the fist choice but are there any others to recommend.

Cheers

Steve
potleyu18
First Gear
First Gear
 
Posts: 45
Joined: 17 Oct 2012
Location: Camberley

PostPost by: Craven » Mon Mar 04, 2019 2:19 pm

You need to make sure your bores will clean up with just 0.010” that’s just 0.005 step or groove.
There is very little price difference between forged, superior, and cast pistons these days but Mahle is a top quality cast piston.
Talk to http://www.ocservice.co.uk/
Craven
Fourth Gear
Fourth Gear
 
Posts: 754
Joined: 14 Sep 2013
Location: south coast uk

PostPost by: nmauduit » Mon Mar 04, 2019 3:31 pm

you may want to have your block carefully inspected by a reputable shop and whom advice you can trust, there usually are a number of options to consider for re bore (+0.20 0.30 0.40 0.60 / 83.5mm 83.65mm 84mm 85mm etc )
see for instance (no affiliation ) https://qedmotorsport.co.uk/qed-shop/lo ... am/pistons
Last edited by nmauduit on Mon Mar 04, 2019 5:29 pm, edited 1 time in total.
S4SE 36/8198
User avatar
nmauduit
Fourth Gear
Fourth Gear
 
Posts: 985
Joined: 02 Sep 2013
Location: France

PostPost by: pauljones » Mon Mar 04, 2019 3:54 pm

Your not to far away from my old place of work. Id consider Saunders Engineering in Southamton. Theres a few in Liss but never tried them and names escape my aging brain.
Kick the tyres and light them fires...!!!!!!!
pauljones
Fourth Gear
Fourth Gear
 
Posts: 953
Joined: 09 Feb 2008
Location: Gosport sur la mer,South hants

PostPost by: prezoom » Mon Mar 04, 2019 4:26 pm

Before the block is bored, the cylinder wall thickness should be determined that the block can additional boring. If itc has sufficient wall thickness for a cleanup bore, then determine which pistons you want to use. Purchase the pistons and follow the manufacturers recommended piston to wall clearance. Give the pistons to who ever will be doing the boring, and have each piston matched to its respective bore and marked.
Rob Walker
26-4889
50-0315N
1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

Lotus is a life sentence with no parole
prezoom
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1110
Joined: 16 Mar 2009
Location: Escondido, California

PostPost by: Matt Elan » Wed Mar 06, 2019 8:54 pm

Steve - I'm in Fleet, just down the road and I use Roe Engineering - and have done for my engine work for 40 years. They have recently moved from Kings Road down to Redfields Industrial Estate in Church Crookham. Last used them to replace the sleeves in my 'L' block and bore them to fit a set of standard pistons for my Plus 2's Twin Cam. Did a good job at a reasonable cost.
Matt
User avatar
Matt Elan
Third Gear
Third Gear
 
Posts: 347
Joined: 27 Oct 2011
Location: Fleet, Hants, UK

PostPost by: Elan45 » Thu Mar 07, 2019 4:19 am

Are you sure you couldn't just do w/ a honing and new rings? You need to have a skilled professional look at your block and pistons. There are other reasons to change the pistons such as ring thickness and spec and split skirt vs drilled holes to release the oil scraped from the oil ring groove.

Roger
'67 Elan S3 SS DHC
'67 Elan FHC pre-airflow
'67 Elan S3 SE upgrade to 26R by Original owner
'58 Eleven S2 (ex-works)
'62 20/22 FJ (ex-Yamura)
'70 Elan +2S RHD
'61 20 FJ project
'76 Modus M1 F3
Elan45
Fourth Gear
Fourth Gear
 
Posts: 751
Joined: 23 Nov 2008
Location: Ohio, USA

PostPost by: JJDraper » Sun Mar 10, 2019 10:06 am

Elan45 wrote:Are you sure you couldn't just do w/ a honing and new rings? You need to have a skilled professional look at your block and pistons. There are other reasons to change the pistons such as ring thickness and spec and split skirt vs drilled holes to release the oil scraped from the oil ring groove.

Roger

+2 on this one. I do wonder if folk are a too eager to scrape away irreplaceable metal in a rebore. I say this from my perspective of my engine with +60 bores. The block was bored before my ownership, but I have done over 100k miles with the bore only now showing a slight wear lip. Compression is still OK, but nothing lasts forever. If my engine is on +60, and I have done 100k miles on them, either it has done stellar mileage, or folk have jumped too early for rebores... Inspect the old components well & replace if needed - rings, consider stepped rings, pistons - check ring lands. My next step? Sleeves....

Jeremy
PS engine & head are matching numbers for the car.
User avatar
JJDraper
Fourth Gear
Fourth Gear
 
Posts: 948
Joined: 17 Oct 2004
Location: Buckingham, UK

PostPost by: potleyu18 » Mon Mar 11, 2019 1:15 pm

Thanks for all of the responses. All are very informative and helpful.

I had the block re honed and fitted new rings when i last re built the engine two years ago, after 400 miles had a rolling road set up only to find the compression's were down significantly and the cause was over fueling due in correct main jets, which is very frustration as thought the person who carrier out the carb re refurbishment knew what they were doing.
I have only done limited mileage since then but its now at a stage where it cannot be left any longer. going to the Gerard Sauer talk on Thursday and hopefully get more information then.

Steve
potleyu18
First Gear
First Gear
 
Posts: 45
Joined: 17 Oct 2012
Location: Camberley

PostPost by: pauljones » Mon Mar 11, 2019 1:38 pm

Are you saying that the over fueling has caused premature wear? Id be having words to be honest.
But a cheap confirmation exercise would be a halfords compression tester. Mine works fine and is accurate.
Check it first as is, then add a small squirt of oil and do it again.

Hopefully if its the case, it may just need a ring set.
Kick the tyres and light them fires...!!!!!!!
pauljones
Fourth Gear
Fourth Gear
 
Posts: 953
Joined: 09 Feb 2008
Location: Gosport sur la mer,South hants

PostPost by: Matt Elan » Tue Mar 12, 2019 9:44 pm

What is the 'Gerard Sauer talk on Thursday'? I'm always keen to learn so if there is a talk on the twin cam I'd be interested?
User avatar
Matt Elan
Third Gear
Third Gear
 
Posts: 347
Joined: 27 Oct 2011
Location: Fleet, Hants, UK

PostPost by: mikealdren » Wed Mar 13, 2019 10:31 am

Matt Elan wrote:What is the 'Gerard Sauer talk on Thursday'? I'm always keen to learn so if there is a talk on the twin cam I'd be interested?

He did a talk to the Sussex Club Lotus group last night, it was excellent, he is a real expert.
mikealdren
Fourth Gear
Fourth Gear
 
Posts: 884
Joined: 26 Aug 2006
Location: Surrey England

PostPost by: potleyu18 » Thu Mar 14, 2019 5:22 pm

The talk by Gerard was fascinating and what he doesn't know about twin cams for a race set up is not with considering. Will certainly use the advice when it comes to running in the engine when all reassembled.

The Block is now at CTM engineering courtesy of Gerard who kindly dropped it off and waiting to hear back from them. will update when i have more info.
potleyu18
First Gear
First Gear
 
Posts: 45
Joined: 17 Oct 2012
Location: Camberley

PostPost by: pauljones » Sat Mar 16, 2019 6:22 pm

CTM are just few miles from me, in fact theyre next to Southern GT, makers of a GT40 replica.
Ive never used them before. Be interested in feed back if you could.
Kick the tyres and light them fires...!!!!!!!
pauljones
Fourth Gear
Fourth Gear
 
Posts: 953
Joined: 09 Feb 2008
Location: Gosport sur la mer,South hants

Total Online:

Users browsing this forum: No registered users and 3 guests