phantaz Posted March 27, 2006 Share Posted March 27, 2006 Just out of curiousity for you carbourated fans out their... is there a "better" head to use if you switch to triple webers?? My Dad has triples on his 81block motor ( i positive they are the 40s not 45s) and the head is stock besides the hot cam from motorsports and heavy duty valve springs ... no 3angle valve job or other head work done... has the 6-2-1 header into 2 1/2 exhaust.. sounds great and lopes like a wild animal but sometimes seems to not like to wind up and besides tuning the webers which he has done on and off for about 12 years now.. could the head be the problem?? its the head that came with the 81 block n/a.. any suggestions or ideas...or did i just open a can of worms regarding best head LOL thnx Paul Quote Link to comment Share on other sites More sharing options...
johnc Posted March 27, 2006 Share Posted March 27, 2006 Oh boy, here we go... Ultimately the answer comes down to how much you want to spend. If its thousands of dollars, head choice doesn't really matter because whichever head you choose will be modified so much that it really isn't what it was to begin with. If you have hundreds of dollars then you're probably better cleaning up and mildly preping what you have while also giving it a good full radius (Serdi) valve job. But, that advice is too simple... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 27, 2006 Share Posted March 27, 2006 Just search. We've been down this road too many times. Quote Link to comment Share on other sites More sharing options...
hoov100 Posted March 27, 2006 Share Posted March 27, 2006 to answer the wuestion, i use a n47 converted to externally oiled, raises your C/R alot, but ultimately is cheaper and easier to find then some of these othe heads. Quote Link to comment Share on other sites More sharing options...
phantaz Posted March 28, 2006 Author Share Posted March 28, 2006 ahh..sory about that... hadnt realized that there would have been many dicussions on which head to use if carb'd.... what was i thinking LOL basically he is just looking for the right head that is stock for the l6... then putting his cam and valve springs init along with now rockers and lashpads.. i had had a brief thought of a turbo head because i was under the assumption they flow better but i really dont know much about heads other than i have to adjust the lash pads every now and then =).. ill do a quick search and mabye post some refresher questions as to what i find.. once again thnx for the comments and suggestions.. Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted March 30, 2006 Share Posted March 30, 2006 The fastest carbed cars on this forum have all used N42 heads. Does this prove anything? Probably Not. Later,Norm Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted March 31, 2006 Administrators Share Posted March 31, 2006 Read these two threads completely through. They should help guide your decision as to which head best fits your Z car budget. Heads… http://forums.hybridz.org/showthread.php?t=105653 Big and Nasty head work… http://forums.hybridz.org/showthread.php?t=104420 As for hands down Carbed power, money no object, as Stormin Norm mentioned, either the E-88 or N-42 with welded chambers like the on in this thread… http://forums.hybridz.org/showthread.php?t=108398 Quote Link to comment Share on other sites More sharing options...
phantaz Posted April 1, 2006 Author Share Posted April 1, 2006 Read these two threads completely through. They should help guide your decision as to which head best fits your Z car budget. Heads… http://forums.hybridz.org/showthread.php?t=105653 Big and Nasty head work… http://forums.hybridz.org/showthread.php?t=104420 As for hands down Carbed power' date=' money no object, as Stormin Norm mentioned, either the E-88 or N-42 with welded chambers like the on in this thread… http://forums.hybridz.org/showthread.php?t=108398[/quote'] i had found the first one but not the second one..great links thnx Braap Quote Link to comment Share on other sites More sharing options...
phantaz Posted April 1, 2006 Author Share Posted April 1, 2006 and as for "money no object" for my dad that would cover the 6 pack to drive to the nearest u pick it and pull a diff head. i guess i need to clarify a little on my orignal question .....with out doing any porting/polishing...is there a better head for carbs compared to F.I. i know thats a simplistic view but my Dad hasnt ever wanted to really trick the motor out..just the "outside" goodies. like webbs, exhaust and cam. i realized that head work makes a Huge difference depending out how much money you want to spend and what your doing with the car (racing/outox/street) but what about just bolting on a diff head?? most of these questions my dad has asked me to post and to be honest i need the info also. i did come to the conclusion after reading about the maxima head i realize here in OK that thing would just detonate like crazy with the crappy gas we have and this is going to be on a mild street car..with trip 45 webs and mild street cam stock bottom end except for a lightened fly wheel off a 240sx.. he really just streets it, and that very rarely now so he doesnt want to buck up for a modified head....It was his daily driver for about 10 years when he was a high school teacher.. hes just curious if his stock n42 is going to be fine with the heavier springs he installed...umm 10 years ago LOL sometimes..after wiping away the nosebleeds from all the serious indepth uber techspek you guys use..i realize how little i know about cars and how they work. but i am learning that the combustion chamber is where a great deal of power is made..you just have to modify it depending on your engine set up. great info on the heads though.. i know who im going to for my first HiPo head.. just annoyed that i found this site AFTER i moved from Portland. Any Datsun head/engine builders in the ok/ks/tx area that you can recommend to give a shout out to.. Or seems a bit far to drop off a head =) hmmm great excuse to go visit though. THnx Braap and Norm for the replies Quote Link to comment Share on other sites More sharing options...
Silent Posted April 2, 2006 Share Posted April 2, 2006 ']The fastest carbed cars on this forum have all used N42 heads. Does this prove anything? Probably Not. Later' date='Norm[/quote'] for now at least Quote Link to comment Share on other sites More sharing options...
briann510 Posted April 2, 2006 Share Posted April 2, 2006 i raise my hand on having a N42 making a little bit of hp on our carbed stroker. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 2, 2006 Share Posted April 2, 2006 i raise my hand on having a N42 making a little bit of hp on our carbed stroker. What's funny is that your head is welded up so that it looks more like a P90 than an N42... Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted April 2, 2006 Administrators Share Posted April 2, 2006 ..... i guess i need to clarify a little on my orignal question .....with out doing any porting/polishing...is there a better head for carbs compared to F.I. i know thats a simplistic view but my Dad hasnt ever wanted to really trick the motor out..just the "outside" goodies. like webbs' date=' exhaust and cam. i realized that head work makes a Huge difference depending out how much money you want to spend and what your doing with the car (racing/outox/street) but what about just bolting on a diff head?? ...... THnx Braap and Norm for the replies[/quote'] Paul, You answered a lot of questions that helps narrow down what would be the ideal head swap for this particular L-28. With triples, mild cam, exhaust mods but limited to pump gas and only driven on occasion, that does make it hard to justify an extensively modified custom cylinder head. As far as which head to choose for use with EFI vs Carbs, the head choice would still be the same except the E-88 would need injector slots machined and intake mounting holes drilled and tapped for use with OE EFI style intake manifolds, other wise, it doesn’t matter. Just one more question needs answering before we can recommend the ideal head for this application. Does this ‘81’ short block have the later Flat top pistons or the earlier Dished pistons? 1) Flat top piston choices. If this short block has the flat tops, that is great news. The P-79 or P-90 head would be ideal. With the flat top pistons on pump gas, I would stay away from the older open chamber heads, (E-88, N-42 and N-47), as they will detonate audibly even at a paltry 9.5:1 compression ratio. As cast, those open chamber heads are a very inefficient design from the standpoint of the actual combustion process. They work just fine with dished pistons and the sedate 8.3:1 comp ratio, and in fact will perform surprising well for only 8.3:1, but as cast, they do no like flat top pistons in an L-28, even with super unleaded. They will still rattle audibly. Now if you weld up the combustion chambers and reshape those chambers similar to the MN-47 chamber, they will handle upwards of 10:1 compression ratio on pump gas, (with flat tops or custom dished pistons keeping the dish under the chamber only), but that falls into the exotic custom cylinder head arena, read $$$$.$$. As a side note, there is another cylinder head massager on this forum located in AZ that states the MN-47 when used on a flat top L-28 bottom end doesn’t detonate, even at a staggering 11.3:1+ compression ratio. I haven’t personally tried that combo on pump gas, (our F-prepared race car is powered by a flat top L-28, MN-47 head that runs on Av gas), but he does sound very convinced that there is no issues with this combo on pump gas. 2) Dished piston choices. If this ’81 block has dished pistons, then I would stick with the older open chamber E-88, N-42, or N-47 head. As mentioned above, the open chamber heads work just fine with the dished pistons. The MN-47 would be nice but with the dish in these pistons being so large, this essentially negates all of the free bonuses the tight squish chamber that the MN-47 offers, i.e. detonation resistance, shorter burn process due to the more efficient confined chamber etc. Hope this helps. Quote Link to comment Share on other sites More sharing options...
Mack Posted April 2, 2006 Share Posted April 2, 2006 Ill toss in my 2 cents..... being one of the only members on here running an MN47 on a flat top block and daily driving the piss out of it. My set-up does detonate. I plan on curing that soon tho. I am getting megasquirt. I feel that my detonation is due to the increased flow capacity of my engine coupled to the fact that the stock EFI just plain sucks. The stock EFI (on an NA car) goes into a linear mode at about 3500rpms at which point the "flapper door" on the AFM is wide open and no longer actually measuring the air coming into the engine, and the computer just geusses how much fuel to inject based on engine RPM. while this is all fine and dandy for a stock car, it sucks wehn you ahve modified yours. Im running about 3.5 points over stock compression for my car (I have an 80, which has 8.3:1 compression, and Im running 11.7:1) I have mildly ported my head, intake manifold, and throttle body as well as a high flow intake. plus a bit of a bump in the cam dept, not a lot, but every littel bit helps (or in this case, hurts) so, its safe to say theat my engine flows a bit more than a stock head. which exacerbates teh problem. the original EFi was set up for economy and emissions, NOT performance. With an MN47 on flat tops, with a lumpy cam and a set of 45mm webers, I *think* it would run FINE. You'lll have PLENTY of gas and air to feed that engine (I did see a stock EFI dyno chart and the air to fuel ratio was hovering around mid 14's:1, not good for performance). I'll know for sure in a few weeks or so once megasquirt shows up and I can tune it to run a proper 13:1 air/fuel ratio under WOT. Quote Link to comment Share on other sites More sharing options...
phantaz Posted April 3, 2006 Author Share Posted April 3, 2006 THnx for the quick responses guys... =) Umm Paul quick explanation on one of my statements.. the only reason i was curious about the EFI vs Carbs was because ... 1) im pretty sure both my dad and i are running the same head.. i have stock FI on my 77 and his is carbed.. was curious if that was hurting him. 2) im not quit sure if he used the head on the 81 engine or if he pulled the head off his wrecked z and stuck it on this block..i will find out for sure adn post the answers along with verified block casting number and head numbers monday nite. im hoping that will clarify things even further. his car really does boogy when its throttled right but as i said it sometimes feels as though its not flowing right compared to his original set up.. now im wondering about the flattop/dished pistons you mentioned..once again something i would have not thought aobut until smacked upside the head like just now =0). Maybe if he did switch heads the blocks had diff piston set up.. he was a import machanic for several years before teaching so im hoping he didnt miss that but he was in a hurry as it was his daily driver and had to get it back on the road asap. Mack... does your MN47 have any port work done on it or is it stock besides the top (cam,springs and lashpads)? once again.. thanks for the replies. Quote Link to comment Share on other sites More sharing options...
phantaz Posted April 3, 2006 Author Share Posted April 3, 2006 and here is the only picture i could find of his car that was digital...i hope teh link is clickable..sorry if it isnt. i havnt figured out how to post pics to show up yet. this was taken in 91, about 2 years after he painted it. Has a MSA kit all glassed in except teh airdam..which he goes through about every 5 years lol. and a glassed in fender flare kit. the hood scoop he did him self. i have a second pic im trying to get resized and will post that when i can. sorry if they are big images. and a scary pic of me with a great combover LOLOL omg some one shoot me. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted April 3, 2006 Administrators Share Posted April 3, 2006 Hmmm.. His triple carbs won’t hurt him one bit, in fact, his induction system is ideal from a pure “performance only” stand point when it comes to carbs. The trick is getting them dialed in properly. There are a lot of guys out there that claim to be good at tuning those carbs, but in all reality, there are only a handful of real super tuners in this country that can actually extract their maximum potential on an engine. Once tuned properly, they will hands down, out perform the OE EFI, all else being equal. Even the early SU carbs will out perform the OE EFI when set up properly. Stormin Norms 12 second N/A Z car is testament to that as there are NO naturally aspirated Z cars running 12’s with the OE EFI system, let alone many in the 13’s, if any. There are plenty of carbed and aftermarket EFI Z’s in the 13’s and a few in the 12’s. Hope that helped… Paul Ruschman Quote Link to comment Share on other sites More sharing options...
phantaz Posted April 5, 2006 Author Share Posted April 5, 2006 well mostly narrowed down... =) he has the P-79 head from his original motor but put it on a stock 74 later 260z block... Yeah i thought it was an 81...but apperently the only thing left of the 81 in this car is the 5 speed and rear end... he removed all the efi stuff and put head and carbs on this one.. i couldnt find a block number partly because we didnt have a flash light and it was buried in his garage and also becuase he put airconditioning in it he made his own bracket and it covers where i think the block code is at =/, but it is the stock 74 1/2 260 block so hopefully that narrows it down with regards to flat top or dished pistons. and regards to properly tuned carbs.. he was nodding his head up and down in a vigourous fashion when i started talking about what a few people said about teh difficulty LOL he wishes he had stuck with his duals he had before becuase it took him so long to "tune" these.. they run fine but properly tuned... he just laughed and said they get the job done =) Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted April 5, 2006 Share Posted April 5, 2006 If you want to know what's the best stock head for your application, I'd say a 280Z N42 or N47. Your motor *should* have flat-top pistons, with the 280Z head you'll get 9.8:1 CR. No problemo on high-octane pump gas. The N47 has the same round ports as your '81 P79, so with that one you can keep the same exhaust manifold. My .02 only! Quote Link to comment Share on other sites More sharing options...
hoov100 Posted April 6, 2006 Share Posted April 6, 2006 screw it, from what i am hearing, im just gonna get a p90 or an n42 and port them out. Quote Link to comment Share on other sites More sharing options...
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