They said they just cut the seats out larger to suit the new valves so I suppose it's cool, if not new seats will be going in I would think.
It's just that if bigger diam. valves are used, the seats and porting should also be the larger diameter, or it just doesn't achieve anything
Someone say 'Farrea'!!!!! Once again, CZP comes through with the goods. What you see is a full set of intake and exhaust valves 1mm oversize, Z1 Performance valve springs, bronze valve guides, new valve collets and $800 of indivdually wrapped hydraulic lifters At least after this the heads will be as new and will see this black duck out I took the valves in yesterday and the builder says he will have the seats cut for the new valves on Friday so the heads will come home tomorrow and get introduced to my newly aquired Standard Abrasives deluxe port and polish kit
ooo.. i got one of those too (SA P&P kit) my machine shop thinks 1mm will be too much for the stock valves to take interesting to see some pics
minivan, did you mean the stock seats?, thats where I'd be concerned, the seats are prety small and if you open them out 1mm (0.5mm a side) you're not leaving a lot. Interesting I'd still go the seats to match the valves
yeah i did mean the stock seats.. so im interested to see the result.. im gunna go .5mm oversize and the stock seats will be fine and kade... cheers.. i was gunna do a . 'look ay my paint job post' but i couldnt be bothered..
hahaha yeh as soon as i saw ur sig i did a search for it thinking i missed out but no lol. looks good mate, bit of mystery never hurt anyone
KArl, I have just got through reading this blog. If I understand properly. You have done this head work and you are fitting standard manual cams back in??? Dude. The big gains are from the higher lift cams. If you go to the trouble of doing head work its false economy not doing Hi lift cams. The returns for the bigger valves are a fraction of what a good set of hilift cams are going to be.
Yes Graham, you have read correctly and I have chosen this path of doing things for a couple of reasons. The cams were free and cost nothing to put into the heads since they were being dismantled anyway. There is a 20HP difference in top end power at stock power levels so I expect a linear increase with more power from the larger turbos, etc. The larger valves cost an extra $85 dollars to put in and to change my mind down the track to change to larger cams and get the benefit out of larger valves and ports would be rather unwise not to do it now. I have been conversing with a few extremely expereinced performance builders with VG30DE engines (outside the forum) and they all agree that the larger valves and matching the ports makes a vast increase over heads that have no modification, even with stock cams. As you would appreciate, increasing the cross sectional area of the valve port and seat will make less restriction allowing more air to enter the cylinder on each intake stroke. The other thing people have missed here is I did this head work because the valves and seats were stuffed, not to chase the big big power! It just so happened that the difference between OEM valves and Farreas was negligible. It was also just good maintenance practice to replace the lifters and springs while I was at it.
Heads are ready for assembly. The seats were only just big enough for the oversized valves so for the people questioning it, there you go The porting job did not take anywhere near as long as I thought. The ports themselves arn't too bad apart from the huge lip under the seat. First pic you can see one inlet and exhaust port that was done by the shop to show me what needed to be done. Close up One head done I also gave the ports a rub through with 120 grit flap wheel to smooth out the cast flashings Take them back to the shop on Monday for assembly with the new bronze valve guides. The crank has been ground for the new main bearings and the rotating assembly has been sent away for balancing. The ligth at the end of the tunnel is getting much brighter
good on u Karl . I knew it would work. Your motor will make massive power thats for sure. The port job looks similar to mine, i got rid of that huuge lip under the seats and removed the seams on each side, then just finished it up nice with a flap wheel.
Couple of questions. 1. Were they hardness tested? ( the heads) 2. Is that that the final finish of the mating surface?( you can still see where the old gasket sealed around the pistons, can you feel it?), tell me they still have to be surface ground , you said the valves and seats were "stuffed", who convinced you not to replace the seats?
Not hardness tested. No point as they came off the motor that had never been overheated. Yes they still have to be surfaced. The valves and seats needed to be cut as they were leaking and the stock valves do not leave much there to do anything with. The rebuilder convinced me the seats were fine and another very respected member on this forum had his ground out to fit the same oversized valves and having been running them for the last few years with no issues.
Another stumbling block encountered. Block was going to be assembled today until the builder gives me a call and informs me the passenger side oil check valve is siezed! Tried blowing air and a vacuum pump and the little sucker won't budge. Have ordered a new one from Nissan at a cost of $20. According to my knowledgeable reference (Wizard) he had the exact same issue with his rebuild, even on the same side. The block he used was also one that had been sitting around for a while. Providing nothing else gets in the way it should be back at home ready for assembly on Friday
