Newbie with history questions

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biffa
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Joined: 21/01/2016 - 09:54
Newbie with history questions

Hi all, 

I started this hobby purely through curiousity thanks to my late grandfather who had kept a westwood gemini rotovator in his garage for over 20 years that hadnt run. When my grandfather passed away i thought i would have a tinker as i love messing with old engines... after a bit of work and new coil etc etc i got it to run and working. 

I have also recently bought a suffolk super punch professional 17". Was advertised as spares or repairs and needed a fuel tap and pipe. (Bought already). Having given it a quick look over it has a spark and good compression. I do however need a new throttle cable as the brass thread thing has broken. 

 

I would like to know more about how they could be and what engines i may have as the rotovator uses a different cylinder head. I believe the super punch 17" uses the 75g4 engine?. 

Could anybody be kind enough to post up some brochure pictures and possible dates so i can put an age to these machines?. I will post in due course :).. 

 

Many thanks in advance

 

Rob

wristpin
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Joined: 23/05/2012 - 22:09
Welcome,

Welcome,

It's possible that your cultivator has a 75cc engine and the mower a 98cc one, both with cast iron cylinder blocks. As you have observed the cylinder heads are different , the 75 having six head bolts and the  98, eight. Later Geminis and Punches had the 98cc , Tecumseh derived aluminium block engine. 

You refer to your machine as a rotovator; strictly speaking Rotavator  with a capital R and two a,s  was  ,and possibly still is a registered trademark of who ever owns the Howard Rotavator brand. The original Howard Company was  liquidated and the name was then acquired by Dowdswell who in turn hit troubled times and, I believe, sold it on.

The spelling of  Rotavator is a palindrome - reads the same backwards as forwards and that was used in Howard's advertising material, along the lines that only a genuine Rotavator  had that attribute!

 

 

biffa
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Thanks for the info, 

Thanks for the info, 

This does make sense in regards to the engine differences. Its been a while since i took a good look at the cultivator due to the cylinder wall cracking. Quite unusual from what i can gather

( split inside the bore). Having completed a complete rebuild on the cultivator and using it for a fair few months without a single problem then the block cracked only visible from the bore. 

 

My plan is to tinker with the suffolk super punch  abd hopefully have it running on my next set of days off and post some pictures up. 

My further plan is when i need to use the cultivator, swap the engine from the super punch and drop it into the chassis of the cultivator. This should work shouldn't it?.  

Also i was wondering.... should i use  a lead additive to add to the petrol?. Being built in i guess... the early to mid 60's.. lead free petrol wasn't available. If so would it be best to use castrol lead replacement?. Having used this previously in my triumph dolomite a few years ago, it comes highly rated and reviewed in the classic car world. 

 

Thanks

Rob

wristpin
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That's an unusual failure.

That's an unusual failure. The real idea as to what would cause it, the possibilities that enter my mind are blocked cooling fins causing differential expansion  or hosing down a hot engine , but why only visible internally. Not as though it had a cylinder liner to crack.

Unleaded valve erosion.  Normally in a mower application I would suggest that the engine is unlikely to work hard enough for it to be a problem but a cultivator does work a bit harder so a drop of additive may not go amiss. The bigger problem these days, particularly in engines that are only used now and again, is the increased ethanol  in pump fuel causing a general degradation of the fuel and even attacking some of the materials used in older carburettors etc.

hillsider
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Time for some detective work

Time for some detective work re the cracked bore on your engine, does the crack run horizontally round the bore or vertically up and down? 

Also the location of the crack may be significant, can you check to see if the crack runs adjacent to a threaded hole for a head bolt? If so where is the crack located in relation to the length of the tapped hole i.e. Is it full length or just near the bottom of the hole?

biffa
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Last seen: 5 years 7 months ago
Joined: 21/01/2016 - 09:54
Thanks for the replies and i

Thanks for the replies and i have recently posted a thread in the general section. 

 

I have also found briggs and stratton fuel fit additive that claims to decrease the effect of the ethanol in petrol so if it works... should help :). 

 

Also the crack was completely invisible from the outside despite being quite a large crack/split. Big enough to cause the piston to get stuck and stop the engine immediately. The engine is now being use as a donor for the 98cc engine.. already donated its rebuilt and jetted carb and a few other small bits. 

The head was torqued down in the correct way to spread the pressure evenly.. it ran fine for months without needing anything.. suddenly one day, got warm, choke reduced and then choke off... touched the throttle and steadily increased and bang. End of engine. Had to strip the engine partially to reveal what wad going on. Plus side is.. my 98cc has the metal pullstart and from my readings, is d kuch better setup. The 75cc suffolk ate pullstarts for breakfast and could be difficult to start at times. Mine certainly was hard to start when it didnt want to venture out.. ( was fine most of the time in fairness but did have its moments but one up abd running was fine and never needed anything except a few pullstarts after the rebuild). 

 

Rob