Rookie Posted December 18, 2011 Share Posted December 18, 2011 Ok what I'm after is a ya or neh on whether a cam upgrade on a standard 1600 crossflow is worth while. The reason I ask is that I have a standard kent in my lotus 7 while I'm building up a dry sumped race motor for it, and I have to pull it out to sort some oil leaks, so I'm wondering if it would be worth while to slap the 234 (i think) cam in it while it's out or will the stock head mean that there won't be any apreciable gains? The car has twin 40 dhlas and extractors. Cheers Guys Quote Link to comment Share on other sites More sharing options...
Raizer Posted December 19, 2011 Share Posted December 19, 2011 234 would go well since you already have the 40's and extractors. Porting would make it better again lol Quote Link to comment Share on other sites More sharing options...
KKtrips Posted December 19, 2011 Share Posted December 19, 2011 If you are OK with going to the extent of changing cam and manifolds then why not also slap the head off your original motor onto the replacement kent. They can build the bottom end up and when its all done then and you are ready to get the new motor in, chuck in the dry sumped bottom end and send the original head off to be rebuilt. it shouldn't take longer than a few days to tickle the head up while you fettle with the dry sumped motor and sort things like oil lines etc. Unless your motor you are getting rebuilt is a twin cam Lotus and in that case I'll stop talki.... Quote Link to comment Share on other sites More sharing options...
Rookie Posted December 19, 2011 Author Share Posted December 19, 2011 There's a good reason why I'm not going to put my good head on it KK, its had pretty big combustion chambers machined into it, so with the heron pistons it would have like 6:1 CR. Looks like this: Quote Link to comment Share on other sites More sharing options...
KKtrips Posted December 19, 2011 Share Posted December 19, 2011 Ah yes - thats good reason and fuck those are big valves.. By 234 cam, do you mean 234 degrees of duration or is it the lift? If it is lift, whats the duration? PS - heron pistons?? Quote Link to comment Share on other sites More sharing options...
Escorto. Posted December 19, 2011 Share Posted December 19, 2011 By 234 cam he means a Kent 234 i believe. Specs here Mine has a Kent 244 cam in it. Quote Link to comment Share on other sites More sharing options...
Rookie Posted December 19, 2011 Author Share Posted December 19, 2011 A 234 is a cam made by Kent Cams http://www.kentcams.com/product-details/5/Camshaft/Camshaft/234-Fast-Road/ And also a Heron combustion chamber is when you have a flat head and a dished piston. http://en.wikipedia.org/wiki/Heron_cylinder_head So what I was trying to say is the uber low CR from having a combustion chamber in piston and in the head will be poose. So the consensus is: yes, cam = good? Quote Link to comment Share on other sites More sharing options...
KKtrips Posted December 19, 2011 Share Posted December 19, 2011 Ah yes I see now - that has 280 degrees duration (I base my cam ideas around the AD) So that would be fairly grumpy for road but not overkill. Would definitely benefit from some decent porting but running it with a non ported head wouldn't be horrid - though you will most probably need to retune the carbs to suit the lower airflow. IMO 290 degrees is as much as you would go for on a car that sees the road. And even then I would just run it on a car that would be an occasional weekend driver. I'm not pretending to be an expert - far from. But its how my thought process would approach the question. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted December 19, 2011 Share Posted December 19, 2011 The cam will make it more fun to drive. Do it, but also do the cam followers at the same time. That performance head will be interesting. Quote Link to comment Share on other sites More sharing options...
Rookie Posted December 19, 2011 Author Share Posted December 19, 2011 By doing the cam follers UJ, you just mean replacing them? Quote Link to comment Share on other sites More sharing options...
KKtrips Posted December 19, 2011 Share Posted December 19, 2011 You can get new ones or you can have them surfaced as long as not too much has been taken off previously or you could run out of adjustment on the tappets. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted December 19, 2011 Share Posted December 19, 2011 ^ What he said. Yours will probably be 13mm shank if you do decide to get new ones, but it is cheaper to re-face the existing ones. The guy who grinds your cam will be able to do the followers at the same time. Additionally: If your new head has been shaved lots or your block has been decked then you may need to change to shorter pushrods. We used Corolla KE70 pushrods in the 120E pre-crossflow motors but I can't remember what we used for the 1600 blocks. It may have been 120E pushrods in the 1600cc motors? You will also want some spacer plates under the rocker pedastals. That is a good time to reduce the size of the rocker shaft oil feed hole. I think I ran a 4mm oil feed when I was drysumped. At a glance that head will perform well at high revs and wide open throttle. Torque and midrange may not be quite so good and there is a high chance of cracking between the seats. That is just the way it goes with a stressed Kent. Quote Link to comment Share on other sites More sharing options...
Rookie Posted December 19, 2011 Author Share Posted December 19, 2011 Ah that could be a problem, as the cam has been run in a 120E block and the motor it's going into is a 711M. What's the course of action in this case? Quote Link to comment Share on other sites More sharing options...
Unclejake Posted December 19, 2011 Share Posted December 19, 2011 The camshafts are the same between the 711 and 120E (assuming the 120E cam you are using is a wide lobe) so it should fit straight into a 711. Quote Link to comment Share on other sites More sharing options...
Rookie Posted December 19, 2011 Author Share Posted December 19, 2011 Are the lifters the same size? so can I put the lifters that match the cam into the 711M block? Quote Link to comment Share on other sites More sharing options...
Unclejake Posted December 19, 2011 Share Posted December 19, 2011 No. The 120E lifters will have an 11mm shank. Sorry. Quote Link to comment Share on other sites More sharing options...
BobbyBreeze Posted December 19, 2011 Share Posted December 19, 2011 Just send your 711M followers down and i'll reface them at lunchtime for you. For a blowie. Typical kent not giving duration figures at 50 thou. I'd have no worries about running that on standard compression. Will still go harder than stock and the car weighs nothing so loss in tractability isn't really an issue. Quote Link to comment Share on other sites More sharing options...
dominic Posted December 20, 2011 Share Posted December 20, 2011 If your planning to stick this in an other wise stock motor, i would check the valve to piston clearance first. The 234 has a very high lift compared to the stock cam, and from what the kent catalog suggests, it will need valve pockets machined in to fit. Quote Link to comment Share on other sites More sharing options...
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