[Healeys] 100 engine rebuild
bspidell at comcast.net
Tue Nov 7 09:16:30 MST 2017
100 crankshafts are known to break if driven much over 4K RPM (and
possibly at lesser speeds). If I was going to mod a 100 engine--and was
filthy rich--I'd look into a billet crank or whatever treatment could
improve the strength of these. Some definitive info here:
On 11/6/2017 1:22 PM, WILLIAM B LAWRENCE wrote:
> I just started my engine after about 2 years of rebuilding. Sounds great.
> I installed 88.5mm pistons from Denis Welch. They are sized precisely
> enough that the machinist just has to bore to the nominal size and
> they fit. They incorporate new tech metric piston rings to minimize
> blowby. So far they are performing as advertised. They also sell these
> pistons in 88mm and 89 mm. I think there is a lot of meat in the block
> and I've heard of people overboring them to 0.100"
> I also installed their performance head gasket which is a MLS
> (multiple layer steel) design. This is supposed to eliminate the
> typical leak at the number plate.
> I'm running an iron head which had never been cut and tested with no
> cracks. How many of those have you seen recently? I'm running an 8.5:1
> compression ratio.
> I'm using a set of H6s that I built up from spare parts on a set of
> Denis Welch manifolds with their heat shield. For jetting I just went
> with the 100M spec OA6s. I plan to run it on a chassis dyno to check
> the mixture and adjust the tuning (Burned a couple pistons a while
> back so I'm very leery of pinging.) I've added a set of 2-3/4"
> velocity stacks and a Pipercross double air filter. This
> will just fit under the shroud but I've got to have a hatch fabbed
> into the shroud to allow for servicing. Fortunately I've found a good
> sheetmetal guy who is refurbishing the shroud as we speak.
> The camshaft has been ground by Iskendarian to their Z-99-E4
> specification (I have been running this specification for over 10
> years). It has durations of 260 degrees and a valve lift of .425".
> These numbers are a little more radical than the 100M/S grind, but it
> runs smoothly without a noticeable lope. I sent them a used camshaft
> and they ground it and heat treated it for $135 plus shipping. I
> bought Denis Welch's vernier cam sprocket and I've set the cam timing
> ahead 4 degrees to optimize low end torque. I am building the car for
> long distance touring and with 3.54:1 final drive gears I doubt if
> it will spend much time over 4,000 RPMs.
> Good luck with your project.
> Bill Lawrence
> BN1 #554
> *From:* Healeys <healeys-bounces at autox.team.net> on behalf of
> warthodson at aol.com <warthodson at aol.com>
> *Sent:* Sunday, November 5, 2017 7:32:16 PM
> *To:* healeys at autox.team.net
> *Subject:* [Healeys] 100 engine rebuild
> I am beginning a complete 100 engine rebuild & am looking for advise.
> - I would like to build an engine that will produce as much power as
> is possible consistent with the following specifications:
> Fast road driving, not road racing. Premium fuel, not racing fuel. In
> the USA Approx. 91-92 octane rating. I think that results in about
> 9.5:compression. What compression ratio would you recommend?
> The engine will include:
> -an aluminum head
> -Carbs: twin H6's
> I also need a new cam recommendation & am considering either Denis
> Welch "#DW1 or #DW4 cam? Suggestions, please.
> Also, I would like to over bore the engine. Is there any reason to not
> bore it out to 89mm, other than that might not allow for any future
> over bore?
> What piston sources would you suggest for this application?
> Any related suggestions, recommendations or questions would be
> Gary Hodson
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