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Right weight for a 1700 Supersprint Flywheel


eric

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  • 1 month later...

the road test : 400 miles revs still limited to 4000

 

Torquey and more powerful than my former smokey 1600 engine. But somewhere same caracter due to the use of an A2 cam. A better engine even if the old was very good.

Low fuel consumption, same noise may be a little more. Due to the lower weight of the allow head and the alloy bell housing, the 7 is lighter when pushed by hand in the garage *smile*. May be my own weight raised as it is very difficult to know if the difference of performance is due to lower weight or the power.

However : a better and smoother running due to the excellent work of CTM Performance in Dagenham. But I need to explore the 4000 to 6800 revs ...

Report soon I hope

 

Eric

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  • 1 month later...

as I decided to rebuild my original engine, the 1600 sprint engine at a French Formula Ford engine specialist workshop : I have the answer concerning the weight of the original Caterham flywheel : it is 5.9 Kg

 

For the story : all the rings were broken, and the pistons need to be replaced.

I fit std, in 1600, the head is a stage 2 iron, with stainless exhaust valves.

Some work on the head and the conrods have been done, all balanced with cometic gaskets. Compression ratio is 9.4 : 1 and I hope this time the temperature wil not be like an oven. *smile*

 

The 1720 has a problem of hot running and low oil pressure, it will be opened at a professional workshop with me to see what were the causes. I will keep it or sold it , I don't know yet.

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The AX 1600 sprint engine is now finished and will be in my Caterham next week.

The report on the result will be here soon.

 

The big 1720 Ax will wait for opening in my garage, it is a pity with all the nice spares in it. But It is like cooking, you can put nice ingredients but it is not a garanty the meal will be good. The story will continue...

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  • 4 weeks later...

The 1720 engine is now arrived at the builder workshop.

 

It is on test and will be dismantle to see what happened.

 

 

The O/E engine that had been rebuilt but with less expenses, std 1600 pistons, new rings and schells, new chain and tensioner, competition gaskets, arp conrods bolts ...

all balanced and careful assembled by a well known race engine builder is in perfect shape, runs very well with the adequate oil pressure and water temperature.

 

No more oil leak under the car !!!!

 

 

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the 1600 sprint engine runs very well, lot of power, very fun ... at no more than 4000 /4500 revs by now.

 

 

The 1720 has been dismanteled : no lubrification on the crankshaft . So it was normal that this engine ran hot with a low oil pressure but we don't know yet WHY

 

As I stop it very early, nothing is damaged except the schells.

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  • 4 weeks later...

The 1720 is leaving the english workshop, finnally the crankshaft need to be machined. However except it was a lubrication problem, we don't know why these happened . And I would like to know ...

 

The O/E engine is running perfectly well, lot of torque, good power, revs still limited to 4500, no more than 400 miles by now.

 

The 1720Ax engine could be perhaps for sale but not before all the causes will be known .

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I received a first explaination:

 

Your engine failed because your mecanic in France didn't prime the oil pump as he was told to and he altered the cam timing.

I think you should tell everyone on blat chat that it wasn't the fault of the english engine builder but your man in france who couldn't follow instructions.

 

In a way, I will prefer that , if I can add that I am still very friendly with any mechanics as I am aware that it is a very difficult work, a problem can happen to everybody or to every engine (and more often when it is an old engine)

 

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  • 1 month later...

The 1720 had been dismantled again by my friend , a French Motorist.

 

All verified and mesured. The french mechanician who fits the engine in the Caterham did not see that there was no oil pressure and he did the road test without oil !!!

We see that the new accralite pistons were damaged. The clearances are however ok for a competition engine but not for a road engine. The main reason was a perhaps a new faulty high pressure high capacity oil pump ...

 

The crankshaft is on test and the conrods too.

 

 

So this engine cannot be sold . I will keep it for spares or I will re manufacture it in 1600 with liners and std pistons . End of the story .

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Eric,

I am a little confused here, did you have the engine re-build after the 1st failure, only to have it fail again? And the second failure was due to the engine fitter not putting any oil in it ? I think you should be avoiding this mechanic in future... That was real hard luck.

 

Jon

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results of the tests : pistons damaged, useable but not strong

Pity for new accralite expensive items.

Conrods 3 same and 1 different. Not nice

Crankshaft not quite straight but useable even if it is better not to re use as the professional told me.

 

So now 2 solutions only : I keep for spare the alloy head which is new and in perfect order. I can also keep the Ax block, the double chain and the vernier pulley, the clutch, the steel flywheel. All for spares parts.

 

Second solution : I buy again but not yet : a steel crankshaft, steel conrods and new 84 mm accralite pistons and my friend motorist will do a nice engine.

 

However I am so happy with my 1600 O/E sprint engine that I am not in hurry to spend some money. And by now only my shelves will be happy.

 

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  • 6 months later...

We have found the cause of the oil pressure problem. The conrods had to be changed before the first rebuild. Too much clearance beteween the schells and the conrods. So not enough oil pressure and the engine was dammaged.

 

So I will certainely use new forged pistons and H conrods with a new crankshaft

and keep this engine for spare or for sale

 

If it can help.

 

 

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  • 1 year later...

the ax block is now sleeved in 1600 with Nural Piston

the stage 2 alloy head and a 234 cam

 

We found a problem on the oil pick-up pipe, not enough clearance and a weak lubrication. This can be the cause of all the problems.

 

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