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Comet 600?

youngjohn

Well Known and Active Forum Website User
Non-VOC Member
I have a spare Comet engine which I'd like to build as a 600. I've looked at the Terry Prince kits, but before I decide, are there others available, and if so, how do they compare? How does it affect reliability, and how much performance benefit is there?
If anyone can give me some advice or feedback on this I'd be very grateful.
 

Ken Tidswell

Well Known and Active Forum Website User
VOC Member
The quickest route to 600 is via Terry Prince you should get about 40BHP from it. So you could shadow gear it. The problem then is lack of amps from the generator , So you would have to speak to Norman Walker of this parish for his car altenator conversion.
 

Upstreeter

Well Known and Active Forum Website User
VOC Member
I have such a device. My Comet engine was built by the late Ian Hamilton and goes like stink. Remember his ad 'give your Comet the performance of a Rapide'? I would think your best bet would be the Terry Prince route. The build sheets on my engine are so comprehensive and prove that hardly anything is 'regular' at all...so some interchangeable parts would be good! It also had a propensity for burning JE pistons at 100 squids a throw. We discovered eventually that a valve just 'kissed' the edge of said piston which caused a hairline crack to develop with inevitable results...all occured at the good old Montlhery events of yore. Although road registered I don't run lights so the alternator business doesn't apply. Norman's stuff works very well I believe.
 

davidd

Well Known and Active Forum Website User
VOC Member
Dear Youngjohn,

I believe that Terry is the only person providing a "kit" to do the job. I think that he may have sold out of his last batch, so you would need to contact him as to availability. There are engine builders who have made 600cc motors with the stock engine parts and upstreeter is the lucky beneficiary of one. Bob Dunn has made some 600 Comets and made their owners quite happy. There is nothing like cubic inches! I will say also that careful preparation of a 500 will also get you loads of power. I think it comes down to what you want to do and how interested you are in tuning for speed. If you opt for Terry's kit, I would purchase his cam also.

David
 

Upstreeter

Well Known and Active Forum Website User
VOC Member
Did I read somewhere that Patrick Godet was building big bore Comet engines? He's an engineering artist in my opinion, plus you get the benefit of a nice trip to Rouen!
 

vibrac

Well Known and Active Forum Website User
VOC Member
I run a couple of big bore Comet engines in Bens Racer plus a methanol one undergoing modification 2 are just a bigger hole in the middle with standard studs and one is a Ron Kemp job with special smaller studs and holes none have given us any trouble all now have venolia pistons to my design running at 11:1 or 13:1 (Methanol) 40bhp is about right perhaps a bit more on methanol but hardly worth the hassel
Ignoring the pistons you dont need to spend a fortune to sort this out yourself sub contracting as required
What I have in mind now is reducing the stroke on one motor and making a big bore short stroke 500 (You get more points for a win on a 500)
 

Tom Gaynor

Well Known and Active Forum Website User
VOC Member
My Comet has Ian Hamilton's name in the log-book too! It was never raced though.

It'll be built as a 600, because I had Bob Dunn do the big end about 100 years ago, so I'm not going to stroke it. 92 mm bore gives 598 and I think I can leave the studs where they are. Non-standard bits will be pistons and liner - and the head which had been ported out to 1 1/4". That is serendipitous, since I have an 1 1/4" TT carb.

(Nobby (Dutch member) has a 600 Comet, and it is impressively quick.)
 
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