Lotus Elan

Engine continuing saga

PostPost by: "James G. Foster&quo » Sat Jan 15, 2005 11:39 pm

WHen I pulled the engine apart, a friend looked at the parts. He is
familiar with twin cams and listed all the things which had been
done;
1)sleeved cylinders (apparently thick wall sleeves bored .040 over)
the cylinders need another .020" to be correct
2) the block was decked by about .010"
3) the block had been line honed or bored Not sure as of yet
4) Weber head had been shaved .060"
5) spring seats had been counter bored
6) stock "c" cams have been reground to something much
more aggressive
7) These cams were not timed with offset dowels so I don't
know whether they were correctly set up
My friend, an old T.C. and other car racer and mechanic/machinist
suggested the block may be weakened at the main bearing bolt webs by
the overboring and sleeving. Suggesting another block or a Kent Tall
block.
Will the tall block fit into a +2 without bumping the bonnet?
Any other thoughts on the subject which may help me make a decision
would be appreciated.
Regards
Greg
"James G. Foster&quo
 

PostPost by: lotuselanman » Sun Jan 16, 2005 8:55 am

Gidday Greg,
You are in the usual situation for an engine of this age.
To answer you comments in order.
# 1 : Sleeve it again.
# 2 : No problem.
# 3 : Fine.
# 4 : Getting a bit heavy but still ok.
# 5 : This the old method when fitting cams with big lift.
# 6 : Most Grinder etch there profile # on the end of the cam. Measure the cam at the peak of the lobe and the base and across the base circle at 90 degrees to the first measurement. Subtract the small for the large and that gives you lift. If the result is over 380th then that is why its been bored.
# 7 : Fine.
Your friend is a wise man, now you need to make the decision, originality or tall (1600cc) block.
Yes it will fit a +2 OK as I had one in mine.
Now the pros and cons.
# 1 : Are your pistons good enough for another bout in another block ?, if in doubt turf 'em out.
# 2 : A / For a tall block you need a 1600cc X-flow short motor, all the 1600's are better than a 'L'. 9I can source you a short motor ex Australia)
B / Steel caps if required but late (691 up) have square iron caps fitted or rob a 1100 or 1300 for its caps. Either way line bore with shaved caps to allow the use of run of the mill X-flow shells.
C / Bore the X-flow to suit your required bore size.
D / The TC pistons will be around 250th down the bore now, decide what C/R you want, cc the finished head, add the head gasket area and the lumps and flycuts of the pistons the have the required amount machined off the top of the block.
E / : Included in the above is the normal procedure for a hard working engine such as crack testing shot peening etc.

For the head, what do you want, std, hot or a racer ?
# 1 : what size valves are in it now ? Seems it may have been a racer at some time. Are they ok ? If not now is the time for an unleaded conversion.
# 2 : Cams, well that's up to your application.

Comments : With the shaved head and block you can easily lower you C/R witha 1600 block.
The 1600 is strong and you immediately gain 100cc.
If I can be of any assistance please call.
See ya, Les




----- Original Message -----
From: James G. Foster
To: ***@***.***
Sent: Sunday, January 16, 2005 9:39 AM
Subject: [LotusElan.net] Engine continuing saga



WHen I pulled the engine apart, a friend looked at the parts. He is
familiar with twin cams and listed all the things which had been
done;
1)sleeved cylinders (apparently thick wall sleeves bored .040 over)
the cylinders need another .020" to be correct
2) the block was decked by about .010"
3) the block had been line honed or bored Not sure as of yet
4) Weber head had been shaved .060"
5) spring seats had been counter bored
6) stock "c" cams have been reground to something much
more aggressive
7) These cams were not timed with offset dowels so I don't
know whether they were correctly set up
My friend, an old T.C. and other car racer and mechanic/machinist
suggested the block may be weakened at the main bearing bolt webs by
the overboring and sleeving. Suggesting another block or a Kent Tall
block.
Will the tall block fit into a +2 without bumping the bonnet?
Any other thoughts on the subject which may help me make a decision
would be appreciated.
Regards
Greg








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PostPost by: rgh0 » Mon Jan 17, 2005 11:08 am

Greg

I would agree with what Les said in terms of the state of your
current engine and the options.

In a plus 2 for road use I would tend to go for the extra torque of
the tall block rather than spend a lot of money building a new second
hand 1500 block or rebuilding your existing block. If your building
it for competition then the rules will determine what is possible.

Most reground high lift cams are too long in duration for a road
engine and also most race engine application, worthwhile taking them
to a cam grinder and having the profile measured to detemine exactly
what you have. With a high lift cam and bored valve pockets you need
to be careful about component selection and assembly of the valve
train components to get it right, most of your current components are
probably non standard ( and if not they should be) so be careful
about changing out any individual component (valves, springs,
retainers, collets, buckets, cam base circles).

When rebuilding a heavily modified engine of unknown providence as
yours appears to be spend the time to determine exatly what you have
before replacing any component. It helps to have a knowledgeable
person to talk to ( or this list) to determine likely differences in
components and how to identify them and what is the best way to
achieve the end result you want.

Rohan
In God I trust.... All others please bring data
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rgh0
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PostPost by: lotuselanman » Tue Jan 18, 2005 10:00 am

Gidday,
No arguement with these comments, horses for courses.
See ya, Les
----- Original Message -----
From: Rohan Hodges
To: ***@***.***
Sent: Monday, January 17, 2005 8:54 PM
Subject: Re: [LotusElan.net] Engine continuing saga



Greg

I would agree with what Les said in terms of the state of your
current engine and the options.

In a plus 2 for road use I would tend to go for the extra torque of
the tall block rather than spend a lot of money building a new second
hand 1500 block or rebuilding your existing block. If your building
it for competition then the rules will determine what is possible.

Most reground high lift cams are too long in duration for a road
engine and also most race engine application, worthwhile taking them
to a cam grinder and having the profile measured to detemine exactly
what you have. With a high lift cam and bored valve pockets you need
to be careful about component selection and assembly of the valve
train components to get it right, most of your current components are
probably non standard ( and if not they should be) so be careful
about changing out any individual component (valves, springs,
retainers, collets, buckets, cam base circles).

When rebuilding a heavily modified engine of unknown providence as
yours appears to be spend the time to determine exatly what you have
before replacing any component. It helps to have a knowledgeable
person to talk to ( or this list) to determine likely differences in
components and how to identify them and what is the best way to
achieve the end result you want.

Rohan








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