opodden

Thanks again for good input. I don't know where I got the idea that the big ports had bigger valves; I've been looking at so many web sites now that I've lost track. I'm getting more and more sure that I will take the advice and go for a modified 7K-E at moderate revs, although a little more than the standard engine. Cleaning up the ports, free flowing air filter and exhaust and a new cam should be fairly easy to do. With the risk of sounding stupid again...is it possible to regrind the original hydraulic cam with a moderate increase in lift without converting to solid lifters? The original lifters can take up some slack, but how much? As long as max revs are kept to around 6500, that would be the absoulutely easiest way of doing it, right? Even finding lifters with the same bore but slightly longer would be easier than converting to solid lifters and adjustable valve train?

I was just wondering what TRD ke70 meant by this. Are the 7K-E ports only bigger against the manifold? Or will the performance detoriate if the exhaust ports in the 3K big port are opened up? I'm not a native English speaker, and I certainly not an expert on K engines, so my question could certainly be better formulated. I was thinking of a big bore 7K-E engine when I wrote the question. In that context there are some reasons for going for a 3K head: You can use flat top pistons, which are easier to find than dished pistons. Flat top or domed pistons can allow for shorter compression height and lower weight of the piston, which will allow for a slightly longer con rod and a more rev happy engine. You will get adjustable valve train, which is good for installing a reground cam....I believe the valves are already bigger in the big port, which is crucial in order to get the 7K revving better as well. I have already confessed that I'm not an expert, so I won't be upset if someone sets me straight in these matters...

So, are 7KE ports bigger than 3K big ports or not? Would it be possible to bolt a 3K head to a 7K block, just leaving out the extra 3 bolts that the 7K head has?