Hi all,
I'm chasing some advice.
I have a 1600 cross flow with a Cortina sump mated to a 5 speed celica box fitted to a MK3 Sprite, I was reasonable happy with the engine but I've had a bit of clutch slip for a while.
 
The engine is a 1600 Crossflow ford 681F engine, AccuSpark distributer, 45mm Side draft webber, 711 flat head, extractors (30mm inner diameter primaries) 4-1, 2" exhaust, Nural style pistons, standard bore, 30mm exhaust valves, 34mm intake valves, I've pulled the engine out because it had a rear seal leak, whilst it was out I pulled the head off for a look, bore looks good with crosshatching still evident.
 
I've bought new seals, new clutch, skimmed and lightened the fly wheel, whilst the engine was out I thought I'd put some hardened seats in the exhaust, change the exhaust valves to 34mm, change the inlets to 39.3mm, Kent 234 camshaft or similar, double valve springs and possible increase the size of the extractors. Mild port and polish.
 
I'm looking to make it a little more lively without spending stupid money.
Is the Kent 234 Camshaft a reasonable choice for road, any other recommendations?
 
Kent 234 Camshaft require a 100 thou pocket for valve clearance, am I likely to need this with the Nural style pistons with the recesses cut already for valves?
 
Will I get by with my 30mm inner diameter extractors or should I go to 32 or 35mm inner diameter extractor?
 
Any suggestions or comments welcomed.
 
Thanks,
Rick
 
 
 
 

Hi Rick

Sounds like a nice set-up
The 234 seems to be the cam of choice for fast road, I used the BCF3 which from memory uses a bit less lift and a bit more duration to achieve similar results without needing to machine the pistons (depends on a number of factors, check it first)
If you do the head work and replace the cam your inlet/induction will likely be holding the engine back rather than the exhaust, iirc twin 40s are a minimum for the 234 cam to be worthwhile
It all depends what you want the engine to do and what your budget is, I'd be surprised if you got change from $1000 for the cam/machining and the gain in performance is not going to be massive. If it were me I would do the hardened seats and get it tuned properly then leave it at that.

Cheers Nick

Hi Nick,
 
Thanks for the reply, I was happy with how the car went before except for the slipping clutch.
 
I didn't think my carby would be the restricting factor, I love the look of twin 40's but I'm not sure if I want to commit to changing out the carbies.
 
A bit more thinking to do before I put it back together.
 
Thanks again.
 
Rick

No problem, good luck with the rebuild

A good tuning guide is listed here.