L26 Cam into L28?

[geordieggg]

Ok guys, have read on here a few times that an L26 cam is slightly better than an stock L28 cam, is this correct? My S31 has an N42 head, flat top pistons, extractors, everything else is bone stock, and I have a GRS30 with L26 motor which is bone stock as well.

 

Having heard the above about the cams, I figure it's a cheap way of getting a bit more response from the car, as I drive it pretty hard, get to the track occasionally in it etc. It's not a full-on racer, more of a show-car, so looking for something to improve the motor a little more without spending the big $$$'s while I save for the race car.

 

The other things that concern me is that the cam that's in the S31 now doesn't have the oil spray bar on the cam towers, is it just a case of swapping the towers over to use the spray bar? Is there any reason I cannot do this while the head is still on the car (aligning cam towers etc)?

 

Thanks

[OlderThanMe]

Yes the L26 cam will work in the L28. It is a LITTLE bigger than the other stock cams. Can't answer the question about the towers...you do need to have it externally oiled though.

I don't know what a GRS30 is though? My 260 is a RLS30...and 280s were HLS30's I think...

[geordieggg]

I don't know what a GRS30 is though? My 260 is a RLS30...and 280s were HLS30's I think...

Someone else will probably go into more detail, but GRS30 is RHD 260z 2+2 and yours LHD 2 seater.

 

When you say a "LITTLE bigger", does anyone know if it'll make much difference? Is it worth the swap, or should I just not worry about it? I don't want to buy a mild cam for this engine then have to get another one when I build the stroker, this engine is just for a bit of short-term fun, that's all.

[JMortensen]

I'd strongly suggest you step up to something larger. You can have a cam reground for about $65, and then you can get something big enough that it will actually make a difference.

 

Search Delta cams and search 260 cam and you should find specs and details on regrinds.

[geordieggg]

I'd strongly suggest you step up to something larger. You can have a cam reground for about $65, and then you can get something big enough that it will actually make a difference.

I take it from your post that there's not that much of a difference between the stock L28 and L26 cams. Everything I read pointed to the L26 being better, but no-one could say how much better..........

 

Is there a particular grind I should be looking at getting, considering the minor upgrades I've done? I've asked Kelford Cams here in NZ what they'd recommend, but I know nothing about duration/lift etc...........

 

Like I said, this car isn't a race car, but when it's driven, it's pushed hard (and I do mean hard!!) and does get to the local track occasionally, but there will be no more upgrades for this motor.

[Mack]

here ya go.... here is a list for prettymuch all common factory produced L6 cams.

 

CAMS

 

many thanks to blue. as you can see, the L26 "C" is 256degrees. I have one on my car. I did a bunch of upgrades at once, so I cant tell you hoew much of a diff it makes. DEF going reground this winter tho.

[piper5177]

The difference is not worth the effort since everything needs resurfacing if it's not new. You can't swap the cam towers since they are machined for the particular head they are on and won't line up exactly. If you are going to do it, the cam will need to be resurfaced anyway unless it is brand new because it will have different wear patterns. Your best bet is to have it reground with not more than a .460" lift if you are using stock springs and get a longer duration of say 270 degrees if it still has enough metal. That will give you a decent boost especially over the stock 280 cam. Make sure you get new lash pads, probably .17" or .18" thickness for a 270 degree cam and have your rockers resurfaced.

[JMortensen]

The difference is not worth the effort. You can't swap the cam towers since they are machined for the particular head they are on and won't line up exactly.

I agree with you about the cam, but the thing about the cam towers is not true. The cam towers are swappable without any trouble at all. I swapped mine from a P79 to my E31 25K or 30K miles ago.

If you are going to do it, the cam will need to be resurfaced anyway unless it is brand new because it will have different wear patterns.

Never heard that one before. I know lots of guys are using the "C" cam, and lots of turbo guys run the NA cam, I can't imagine that they've all had the cam ground or polished or whatever "resurfaced" means in order to run it.

Your best bet is to have it reground with not more than a .460" lift if you are using stock springs and get a longer duration of say 270 degrees if it still has enough metal. That will give you a decent boost especially over the stock 280 cam. Make sure you get new lash pads, probably .17" or .18" thickness for a 270 degree cam and have your rockers resurfaced.

I've swapped my cam out twice, still using the original rockers, never resurfaced them. I think the "MUST have new/resurfaced rockers" thing comes from the Schneider cams which are apparently softer than other cams (search, lots of info on that issue). My own experience, and that of most of the guys I used to race with is that you don't need to do anything other than set the lash pads up correctly. So long as you're using a quality cam or a regrind, the rockers will hold up fine in my experience.

 

As to the recommended lash pad thickness, that one gets a little tricky when you start changing things around in the head. I never really understood how a company could recommend a lash pad thickness with any degree of accuracy. Do a valve job, lash pad thickness changes. Replace valves, thickness changes. Replace seats, thickness changes. It would seem that most of our 30 something cars should probably have had some work done that makes the recommendation questionable.

 

Here's a thread you can read on lash pads: http://forums.hybridz.org/showthread.php?t=112184

 

Main thing to remember for running stock FI is that the stock FI sucks. Keep that in mind, because it can't handle a very big cam at all. .460/280 seems to be about as big as you can go, and that's pretty small when you really consider what is possible. I know http://www.deltacams.com has a regular regrind that they do for stock FI engines, and it runs $65 per cam I think. They'll also resurface your rockers for $3 each if you want to do that. My opinion is that Delta or some other cam grinder is the way to go.

[piper5177]

You can do it without resurfacing, but the cam and rockers will wear much faster. If you don't mind adjusting your valves often or the possibility of flattening a cam lobe then don't worry about resurfacing. For the small amount of money and elbow grease you are better off having them resurfaced. Also, if you are going through the trouble just get the hotter cam grind. The lash pads are assuming the top of the head hasn't been messed with. I know machinists who would cringe at the thought of switching cam towers from different heads. The cam towers are machined to line up perfectly for the oil races on a given head and if they don't there is a lot of friction and heat build up on the cam (i.e. bad for the engine). I guess if you are using all of the cam towers they should line up, I would never mix and match them. Maybe I am anal about contact surfaces on a head but I'd rather do it right than just throw it together. I've tried that method before and seen cams with flat lobes after 10,000 miles (though it was a CFC stamp cam and not a Japan stamp cam)

[JMortensen]

You can do it without resurfacing, but the cam and rockers will wear much faster. If you don't mind adjusting your valves often or the possibility of flattening a cam lobe then don't worry about resurfacing. For the small amount of money and elbow grease you are better off having them resurfaced. Also, if you are going through the trouble just get the hotter cam grind. The lash pads are assuming the top of the head hasn't been messed with. I know machinists who would cringe at the thought of switching cam towers from different heads. The cam towers are machined to line up perfectly for the oil races on a given head and if they don't there is a lot of friction and heat build up on the cam (i.e. bad for the engine). I guess if you are using all of the cam towers they should line up, I would never mix and match them. Maybe I am anal about contact surfaces on a head but I'd rather do it right than just throw it together. I've tried that method before and seen cams with flat lobes after 10,000 miles (though it was a CFC stamp cam and not a Japan stamp cam)

I think you're wrong about everything you've said there. I'm not saying that these aren't commonly held beliefs, I just think they're wrong. Hopefully we'll get BRAAP or some other expert to chime in and help us out.

 

Do you have some proof of cams "wearing much faster" with old rockers or "lots of friction and heat build up on the cam"? I've done the verboten things in question, and I haven't seen either of those effects. It sounds to me like you're passing on the same incorrect info that everyone else believes to be true.

[piper5177]

I have personally experienced mismatching the cam towers when I had two heads apart and got one tower from a different head mixed up (they were marked similarly) and they were slightly off, just enough to produce friction instead of the cam spinning freely. I didn't even think of installing it this way because I am sure it would have ruined the head. As I said above, I can theoretically see using a full set of towers on a different head because the mating surfaces on both the head and the towers should be even. The towers are definitely a matched set. I have also reused a used cam and rockers from a different head on a new head without resurfacing and the new path of wear for the rockers on the cam was different between the two heads. Since there is a ridge between the old wear pattern and the new wear pattern there was increased wear on the small section that had more metal on it. Both the cam and the rockers wore unevenly until an even surface was created. There was definitely more metal lost because of this and the valves were slightly out of adjustment once it wore down. I am not saying my way is gospel but from everything I have seen others do, done, or read it is the "proper" way to do it.

[JMortensen]

I could well believe that mismatching within a set of cam towers would be an issue. I think we're in agreement on that point.

 

I haven't seen the cam wear as an issue, and in fact when I last had new valves installed in my head the machinist asked what the advertised lift and duration were and checked them for me. He said he was surprised because usually the quoted numbers aren't accurate at all, and mine was dead on. So no adverse cam wear and no frequent adjustments on my particular motor after years of racing and hard use.

[geordieggg]

here ya go.... here is a list for prettymuch all common factory produced L6 cams.

Thanks, shows there isn't much of a difference after all!

 

I guess if you are using all of the cam towers they should line up, I would never mix and match them.

I'd use all the towers anyway, as I'd be installing the spray bar at the same time.

 

I think the "MUST have new/resurfaced rockers" thing comes from the Schneider cams which are apparently softer than other cams (search, lots of info on that issue).

I think that recommendation comes from most cam manufacturers anyway, as they can use it as a way out of warranty claims if something goes wrong and you didn't change the rockers etc.

 

.460/280 seems to be about as big as you can go, and that's pretty small when you really consider what is possible.

Thanks, at least now I know what sort of figure to aim for!

 

I know www.deltacams.com has a regular regrind that they do for stock FI engines, and it runs $65 per cam I think. They'll also resurface your rockers for $3 each if you want to do that.

Ummm only two problems, firstly I'm in New Zealand, so freight would be prohibitively expensive to send a cam there, get it reground, and sent back. And second, the above link is actually for a web cam site! Not good when you're at work! Try www.deltacam.com. I'll continue my search for a place within NZ to regrind my cam.

 

Thanks to all for the advice.

[Tony D]

Webcams is about 5 minutes from my house... he he he!

You can swap cam towers, you just have to take measures to get them lined up without a bind. There are various methods from simple to complex, but most commonly it involves snugging them incrementally and nudging them with a mallet one way or the other till the cam in unbound, and then continuing while rotating the cam to determine how it's going.

 

Paeco in Birmingham would take any set of cam towers, and put them on any head. They also would bush the towers if there was a lube failure to the top end, and with the bushings they were done undersize, and then line-bored same as you would do like a crankshaft.

 

I have occasionally done the "Odd man out" cam tower swap from parts in a bucket.... If it didn't work (started binding) went and got another one and tried it till I found one that worked. People put a bit too much emphasis on stuff sometimes. If it works, it works. That's the end of the discussion in my book.

 

Sure, you can weld every cam tower undersize and line bore them on the head, that would be what a "machinst" would recommend, but in my experience, machinists make very poor mechanics---they tend to overwork items that have nothing wrong with them, and make very simple problems have exceedingly complex solutions.

 

People have been switching cam towers on L-Engines since their introduction in the 60's. Usually it happens as a set. If someone thinks L-Heads never have the cam towers removed, think about a proper head resurfacing entails: EQUAL amounts of material taken off the gasket AND the Top Surface of the head (warpage on the bottom will transfer to the top, and if you DON'T remove the top metal, you run the risk of the cam towers going out of alignment and putting the cam in a bind once up to operating temperature!

 

Then there were those Iron-Headed L-4's, and the Iron Cam Towers with Bushings... But that story is for another day.

 

I am in agreement with the "go bigger"---the ONLY reason the L26 Cam (hell, really if you want the "best" stock cam, check out the early carbbed L20A!) is so popular is that the aforementioned L20A Dual Carbbed Cam is NLA, and people running ITS or other restricted "Stock" Racing Classes need every advantage they can get, and that little bit, added with another little bit, added to another little bit, makes the competitive edge they want.

 

Bigger cam is easier.

[geordieggg]

I'd strongly suggest you step up to something larger. You can have a cam reground for about $65, and then you can get something big enough that it will actually make a difference.

Got a price today, $295 + Freight!! (Yes that's NZ$), so now I'm looking at just buying a new cam out of the States or Australia (if I can find someone over there).

 

Anyone got any recommendations of which companies to contact and which ones to avoid? So far Isky seem to be about the best, $160 US$ for a brand new cam........

[JMortensen]

I would be shocked and amazed if you couldn't find a cam grinder anywhere in NZ.

[Collectindust240Z]

I'd go with a Delta regrind. They'll sell you a cam without a core. I think I paid $100 for mine. .500 lift/ 300 dur. sounds NASTY, but too big for your use. I think they have a pretty extensive cam library. Their sevice is awsome too. Real nice guys.

[geordieggg]

I would be shocked and amazed if you couldn't find a cam grinder anywhere in NZ.

That price above is acutally for a reground cam!! The other price is $210.94 + freight, which isn't too bad (well starting to look better anyway!!) There's only 2 places that I've found so far that do it, will keep looking though.

 

I'd go with a Delta regrind. They'll sell you a cam without a core. I think I paid $100 for mine.

Sounds like a good price, I'll email them and see what they say.

 

Thanks guys.

[geordieggg]

Just heard back from Delta Cams, not too bad!! $65 US + $30 core charge, only killer is the approx. $60 shipping, so it'll be around the $225 NZD mark by the time it gets here.........

 

Got a couple more options that I'm waiting on answers for, but if price is about the same, I think I'll go for the newer cam................. everyone's talking about the same specs, which is good as well.

[racerx260]

As long as you switch all the towers you shouldn't have a problem. I have done it several times to get the spray bar oiling. After pulling appart a dozen junk yard engines and comparing cam and tower bering wear. the spray bar cams are in much better condition over all.I bolt in the towers and tourqe the head to in sure there is not any binding before putting in the rockers. You should be able to turn the cam with two fingers before the rockers are installed to test for binding.