Hot Cams (not XXX) and Heads (that is cylinder)

[ArthurDaley]

At some point I wanna swap to a hot cam and head, but I wanna know others feedback on what kind of difference it makes. I was thinking of a stage 3 or 4 cam.
How is driving affected? Is it a pig in traffic? Do you notice a performance increase?

 

[zedhead260]

I recently drove a 260Z with a mild cam in it and it felt great. The car wasn't lumpy at all, but it did benefit from a balanced bottom end which keeps things moving nice and smooth.
The wilder the cam, the lumpier the tick over will be. I would guess that stage 3 or 4 cams will give a lumpy tick over, but once "on cam", the car will fly.
When looking at heads, you must consider compression ratio and valve size. It depends on what size pistons you have for the best choice of head.

 

[ArthurDaley]

When looking at heads, you must consider compression ratio and valve size. It depends on what size pistons you have for the best choice of head.

RU saying change the compression/valvle size - because this will be set to standard 260z 2+2 stuff right now?

 

[zedhead260]

If you have a 2.6 then you are limited on valve size. I think 42mm comes as stock, so you wont be able to go bigger without mod's to the block.
The earlier E88 head has smaller combustion chambers than the later cars, and is therefore the prefered head. Increasing the piston size (86mm/ 2.8) also increases compression. And of course, the head can also be skimmed.
The thing is, a 2.8 really benefits from 44mm inlet valves (like in the 280ZX), but the combustion chambers are larger on the 280 heads, so you lose a bit in compression.
Ideally an E88 head fitted with the bigger 44mm valves on a late 280 block (good breathing / good compression).
Don't forget that a late 280 block has flat top pistons, and these will need to be notched so they don't mash your valves (depending on cam). You could use the dished pistons from an earlier car, but then you lose all that compression again.
It's a vicious circle that depends on how deep your wallet is.

 

[zedhead260]

I think I may have been wrong by saying that you can't use a 44mm inlets on a 260 block. I checked one of my heads today that has 44 mm valves in it, and it came off an L26. So to be sure I had to measure the piston diameter to see if it had been bored out to 86mm - it hadn't. Whilst inspecting this head, I noticed that it had injector notches on the inlet ports. It's an E88 head as well, which confused me even more. The fact that it had room for injectors tells me that it must have come from a 280ZX. I didn't think that 280's used the E88.
So, my question for the forum is - Is there a stock E88 head with 44mm inlets, or have the bigger valves been fitted at a later date ??
If it is standard, then it must be a good head to use because of the bigger valves. Although, if used with carbs my guess that the space for the injectors could cause some unwanted turbulance in the inlet ports.
We live and learn &nbsp;<img src="http://www.zclub.net/iB_html/non-cgi/emoticons/confused.gif" border="0" valign="absmiddle" alt='???'>

 

[Mr.F]

Late 260Z heads may be E88 with injector notches and thus equivalent to the 280Z head used in the USA cars. On an 83mm bore, 44mm valves should require "eyebrow" notches to clear the edge of the valve. The parts fiche shows the same part number for intake valves across all Z heads, ie. 42mm. The 280Z had 44mm valves the same as our early 280ZX has in the N42 head. Thus I would have to assume that your 44mm valves in a U.K. E88 head have been fitted as a modification to original spec. I would still advise anyone fitting a 44mm valve head to an unbored 83mm Z block to carefully check for clearance at full valve lift!

 

[ben240z]

do not over cam a datsun engine full stop &nbsp;that is the advice from all the experts. what ever cam you go for dont forget to get the valve train geometry right again. be carefull skimming heads as the distance between the cam and the crank gets closer therefore the timing chain tensioner has to come out further to keep the chain tensioned and if you go too far then the tensioner will jam up and not work as it was designed.and then thecam timing will not be able to be set where it was designed for the cam and then it wont work as it was designed to and so you have now spent alot of money buying things and machining and you could have been netter off sticking to a standard engine.but it is great fun experimenting and i wish you well. &nbsp; &nbsp; <img src="http://www.zclub.net/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=''>

 

[Mr.F]

Head saver cam tower shims as detailed in"How to Modify Nissan OHC" are now available on a regular basis over here. Shims are .015" thick and can be stacked to help preserve chain tension without popping the tensioner. Take care when resetting the cam towers to avoid stressing the camshaft. I know the books say don't remove them, but it can be done safely....