Unleaded AX?

[scotto]

All, I have a 1985-87 caterham Sprint spec SAMCOR AX 711M 1600 Kent engine.

I think these were among the last new Kent engines Caterham could source for the Scholarship kits. Do these have unleaded heads? Caterham could not help.:nopity:

And while we're at it, what cam came in the 1600 "Sprint" spec? Thank you.

Edited October 27, 2012 by scotto

[tikijose]

Here's the Sprint data from my Caterham build book (dated 1996):

Bore: 80.98mm

Stroke: 77.62mm

Capacity: 1599cc

Compression: 9.0:1

Cylinder Head: Standard (There's no note about whether it's unleaded)

Camshaft: Ford GT Profile

Flywheel: Lightened and balanced

Clutch: Uprated competition cover assembly and drive plate.

Ignition: Caterham distributor with Lucas electronic ignition.

Rocker Cover: Caterham cast alloy wiht "Super 7 Sprint" script

Inlet manifold: Caterham cast alloy

Carburation:Two Weber twin choke sidedraft 40 DCOE 151

Air filtration: Two K&N performance filters

Performance data: max power 100BHP @ 6000RPM, max torque 95 lbft @4800rpm.

 

Ignition timing 14deg BTDC

Valve clearances: Inlet .010", Exhaust .022"

Spark plug type NGK BP7ES

Spark plug gap .025"

Firing order 1-2-4-3

Fuel: 95octane

Oil pressure 3>4 BAR (normal temp)

 

Apparently many of these engines of this era were supplied by GP Enterprises (Gordon Palmer). Mine was. He certified it as a new block, probably one of the South African ones, and new and re-conditioned parts. I forget what the code on the block is. (83x? maybe) I hope this answers your questions.

[scotto]

Thank you. Can anyone answer the unleaded question? Yes, there is an 83 in there. here are the block #s:

31K95AX 831C60115B/R34

:auto:

[11Budlite]

I can't say for sure but I don't think your cylinder head is set up for unleaded. Here's a thread from Blatchat that addresses the unleaded issue. Pay attention to the post by Roger King who, if I remember correctly, is a pretty well regarded Xflow engine builder in the UK.

 

[/url]http://www.blatchat.com/t.asp?id=149691

[11Budlite]

Just read in the production evolution section of my "The Magnificent 7" book that Caterham modified the ignition timing to allow the use of unleaded in 1989. This seems to verify what Roger King said in his post from the above thread. I had my '64 MGB cylinder head upgraded to hardened valve seats on the exhaust and it wasn't that expensive. Hope this helps.

[danilo]

As above not a big deal.. just have valve seats inserted into the pig iron head casting

[tikijose]

It's a little late to jump in again, but my 1997 did not have hardened valve seats. I just did a valve job and had seats installed. The original seats had recessed significantly and were beyond repair. (my engine was built by GP Enterprises, and this head was not new at the time of their build.) I'm now looking for anyone's advice on ignition timing. I think 14 degrees may be a bit much for the 91 octane unleaded we get here in California, but would like to hear from anyone who has experience with this who can chime in. May start a new thread with the question if I can't find anything.

[bball7754]

Another AX block Crossflow owner here. My engine is at the start of a rebuild, and while my exhaust seats were changed to hardened, my intake weren't. Interestingly, they apparently have held up fine. But, they are going to be changed as part of the rebuild.

 

I had my distributor recurved last year (Advanced Distributors), and it now needs 16-18. I thought that the cam had a large impact on the advance. I know on Blatchat that 14 seems to be the general recommendation.

 

Steve