best engine mods for stock 260z?

[agnyc1]

i'm thinking of buying a stock 260z that's in very good condition

i'd like to squeeze more performance out of the stock engine

being a novice mechanic, what modifications can i do that will give me

the most provebial "bang for my buck"?

what kind of improvements can i expect from dressing up a stock 260z?

can i get reasonably get the 140hp up to 160 or 170?

can i even improve gas mileage at the same time?

(i know the 2 are usually mutually exclusive.. but hey, i'm dreamin here)

i've tried to do a search of the forums but haven't found any concise answers

would love some of you old pros to make me a list of things you would do

to a stock 260z first to get the most improvement for the least money

just from my limited knowledged about cars in general

i know carburation, air intake, and exhaust are places to start

but would love specifics from you wise shamen 'o the Z

list away!

and thank you!

anthony g

(potential new 260z owner!)

oh.. here's my possible new baby

she's quite a looker eh?

pros:

paint, body, and interior look good

no rust that i can find

engine looks really clean and runs well

original rims

stiffer body & better electrics than 240z

eveything works except for clock

only about 76k miles (if that's accurate)

cons:

automatic

stricter emissions control than 240z (bad carb)

want more power

want better gas mileage

and i'm REALLY gonna miss my t-tops from my old silver 86 300zx

custom 260z t-tops anyone (i'm sure that would be a nightmare undertaking)

the guy wants a little over 3K

what do you think?

does it look good?

should i go for it?

[dat260]

Hi

I have a 260Z early style. I do not know about yours but if its carburated and it has the flat top S.U's get ride of them. My first upgrade was 240Z S.U's, headers and a 2.5" exhaust and a front spoiler. I've reached a top speed of 135MPH. I beleive my engine is stock beside the modification I mentioned above. It's a pretty torkey motor, very good for city driving.

Enjoy, Ari

[boostedz]

I know I will probably get flamed for this but the 240Z carbs are a down grade in all actuallity as the 260Z carbs are larger in bore then the 240Z carbs. Although they are a pain to tune and run, if you get them tuned correctly and get rid of a lot of the emmissions crap, they can be a good carb.

For ease and working with them without going through headaches though, the 240 carbs are the best buy hands down.

Squeezing 20-30 more hp out of the engine isnt going to be possible with bolt ons though, you will need some head, cam and valve work to accomplish this.

[nwcubsman]

Hi

I have a 260Z early style. I do not know about yours but if its carburated and it has the flat top S.U's get ride of them. My first upgrade was 240Z S.U's, headers and a 2.5" exhaust and a front spoiler. I've reached a top speed of 135MPH. I beleive my engine is stock beside the modification I mentioned above. It's a pretty torkey motor, very good for city driving.

Enjoy, Ari

I agree with Ari, but throw in a cam. The exhaust mods will net you almost zero Hp increase on their own. Oh yea, I have 2 '73s and '72 carbs were my first upgrade. 160-170 Hp is really doable (if thats a word).

BTW, nice looking car!!

[jackboxxx]

Im sure those flat top carbs can be tuned with a LOT of effort, but they are known as "boat anchors". they were designed for emmisions not performance. dump them, your Z tuning life will be better for it. as for mods, I used to have a late 73 240, I did

1 1/2" headers, only a 2" exhaust (it was a stock motor internally so it didnt need 2 1/2-3" exhaust...) electronic ignition, new coil, 5 speed, lightened flywheel centerforce clutch and had some properly overhauled early 240 carbs. it ran in the mid to low 15's in the 1/4 mile. (stock is like 17 seconds.) it seemed to really be a lot quicker off the line especially...

Jack

[chickenwafer]

Get some ZTherary early performance SU's, but keep your 260Z N36 intake manifold (it's better than the 240 intake manifold). Then you can add a header and 2.5 inch exhaust with performance muffler (and depending on where you live and your emission laws, you can remove the cat).

But don't overlook the basics. Get new NGK Power spark plugs, new spark plug wires (Taylor Hi-Po or Magnacore wires are good), change ALL the fluids including oil (and get a new oil filter, of course), drain the radiator, everything and refill. Never trust somebody else's matinence schedule.

Horsepower sounds nice, but it isn't everything. New performance tires (depending on how the tires are currently) mounted on lightweight wheels can do wonders for performance, especially handling and off-the-line speed. Also check the brakes and consider replacing brake pads and brake lines. Unless you get a lot more horsepower (like over 190) or plan on racing your car at the track, the stock brakes are fine, but just make sure they're up to s'nuff. Check the u-joints as those are common wear areas, and Z's are known for having bad old bushing on the rear suspension setup (causes a "clunk" when driving).

It's easy to get carried away when getting a new sports car, but don't forget to overlook the little things like matinence and such as I pointed out. You don't know how the PO took care of the car (reguardless of what he told you) and it's always better to be safe than sorry. Remember, this car is over 30 years old! Things wear out, and might need attension.

Dave

[agnyc1]

let's see:

ZTherary early performance SUs (if i were to pull a stock one though what year is best?)

keep the N36 intake manifold

1 1/2 inch headers

2 1/2 inch exhuast

front spoiler (may forego this one for classic appearance)

performance muffler

remove the cat ('75 and older is smog exempt in CA! yeah!)

NKG power spark plugs

THP or Magnacore spark plug wires

drain and refill all fluids & change oil filter

performance tires

lightweight rims (but i really like the look of the stock ones)

check brakes

replace brake pads and lines

check u joints & rear suspension bushings

electronic ignition

new coil

5 speed

lightened flywheel ceterforce clutch

new cam

head valve, and cam work (yikes getting expensive now?)

what else?

anyone else want to change, amend, or add to this list?

keep 'em comin'. i love it.

looks like the first 3 things to focus on

(so i don't get overwhelmed or go broke)

are carbs, headers, and exhaust

(along with all the inspection and tune up stuff of course)

[chickenwafer]

If you were to pull a set of early SU's look for a set from a '70-'71. A '72 is good too, but in '73 is when emissions kicked in. The first '70-'71 Z's had virtually no emissions and were the most powerful of the carbureted Zeds.

It's true if you were to find a set of these early SU's from a 240 in a junkyard, they would be much cheaper than the ZTherapy SU's, but you don't always know what you're getting. And, those Zed's are somewhat rare (but not as much so in CA but still a hard find) and with ZTherapy you're garrenteed a good set of carbs. (Not trying to plug ZTherarpy here: go with whatever company you want, but ZTherapy is the only one I know of that has early performance SU's for a good price). Oh yeah, I think you need a 240Z throttle linkage for the new SU's as well.

As far as swapping a 5-speed, I'd wait. That's a big undertaking- converting a slushbox to a manual. You need the manual gearbox from a 280 (or 280ZX, but a later-year 280 will be easier, i.e. no custom driveshaft), clutch pedal and mounting bracket, master cylinder, clutch hoses, cut the transmission tunnel, a center console from a manual 260, and I know there's more I'm probably forgetting to mention. The slushbox, while frustrating, will do for now unless you are planning to race your Z. If you are, then the first 3 things should be 5-speed manual swap, rollcage (mandaited by SCCA or any other sactioning body for that fact) and other safety stuff like harnesses and sport seats.

Here's a rough price list so far:

-ZTherapy SU's: $850 I think without cores

-Header: $200-350 (MSA has a nice one for about $260)

-Full 2.5 inch exhaust: $300-$600 (Again, MSA has some for under $450)

-Performance Cam: $250-$500 (MSA has a nice one as well, but be aware that changing in a new cam means "refreshing" the valvetrain with new lash pads so they can properly wear in. Some like to replace the valve springs and rocker arms too, but it isn't necessary unless you want serious power)

-NGK plus: $40 for all 6 I think

-spark plug wires go for about $50 at MSA (The Taylor wires)

-a tire and wheel set will set you back about $2500 for good tires/wheels

-front lip spoiler can be inbetween $150-$400

-electronic ignition; whole system can run between $600-$1800

-5-speed manual swap with Centerforce clutch and lightweight flywheel: looking at around $1000

-Performance u-joints from Spicer: $36 each, you need 2 per side or 4 per driveshaft

Okay, as you can see, things are expensive. So pace yourself. With new SU's, header and exhaust you will get more power to keep you satisfied for now and slightly improve fuel mileage. I don't know what your budget is, but that alone will cost around $1500 plus installation if you aren't doing it yourself (some garages charge A LOT for installing new carbs, and some won't do it if the carbs aren't bought through them).

Almost forgot; a lip spoiler will require painting and installing as well, so that's going to add another $250 to the tab. Plus, it would be backtracking a little to have a spoiler painted and installed professionally and not to get the entire car painted (kill two birds with one stone), so that's another $2500-$5500. Or you can not paint it and leave it in primer (or even worse, bare plastic or fiberglass) and cruise around like those ricers do with their unpainted body kit IMO.

Dave

[agnyc1]

i'm down with ztherapy all the way. suprised they're that much though.

i'm not racing it but would love have something of a street rod someday.

thanks for all your time and input dave.

definitely have to give some more thought to whether i want to buy this 260 and dump money into it, or whether i wanna look for a deal on one that's already pimped out.

one from vilidini sold on ebay today for $6700. it was a 73 with an sr20det and all the racing add-ons. wer talking 25mpg, 12-13 sec 1/4 mile, 0-60 in like 6s. it sold for less the entire engine swap and mod. now i'm thinking i should have bought it. doh!

[boostedz]

The flat tops are called boat anchors, and it is a myth, because no one really knows or takes the time on how to tune them properly. I cannot remember exactly the bore of the 70-72 carbs are but if I remember correctly, the stock bore of the 73-74 carbs are 10mm larger.

Note performance gain?

I see a lot of talk about bolt on mods, and well only one person said the right thing about that, it will not do much of anything without engine work to make use of it. Just because it feels faster doesnt make it faster.

Chickenwafer, did make a great suggestion though, first thing you should do is get your car in good tune first. Magnecores and Taylors arent necessary for the wires though, as I am using NGK NE61 wires on my turboed Z at 300HP and have no worries with them at all. Then worry about getting the car going and stopping perfectly and set up your suspension to handle your extra power.

The thing that makes these cars perform is work to the head, you can leave the block stock for the small gains you are looking for and work your head with a cam and larger valves better springs and a bit of port work will get you all you need for what you want.

Good luck with whatever route you choose and I hope you enjoy your car.

[jackboxxx]

Ztherapy offers an upgrade kit for 260Z owners, $700 (core included) gets you a basic setup (you use your 260 balance tube.. and $950 gets you the complete 240 carb setup...including 240 balance tube and linkage.. as a previous customer I can highly recomend them, the work is top notch..everything is completely redone, all new small parts..screws nuts bolts etc..

as for the round top flat top issue, the round tops are 45mm bore...stock. if you bore out round tops, you can get about 50mm max..which comes out to about a increase of 100+cfm per carb. I dont have a flattop carb to measure anymore..so i dont know the bore of those.

as for the exhaust, check with some local shops before buying the pre made msa kit, I have had one of those, and the one i got didnt fit together all that well...and hung kinda too low..at the muffler area, this time around I went to a local muffler shop and got a nice 2 1/2" setup, custom bent aluminized tubing into a stainless magnaflow muffler for $250 (installed price) and its tucked up way better than stock...MSA headers will work good for what your looking for..but if you end up going for high horsepower, youll want a larger diamater tubing than MSA offers..Nissan motorsports has the bigger tubed headers..but up in the $400+ range.

and chickenwafer is so right about doing a detailed once over of everything on the car replacing all fluids, checking brakes, suspension etc etc..

JacK

[agnyc1]

i got the owner to send me some pics of the engine

and sure enough, there are those flat top carbs

damn, i was half hoping to find them already modified

the engine looks stock overall, from what i can tell

i'm torn -- i love the look (body, paint, rims) and good overall condition of this car

but the automatic trans, lack of A/C and stock enigne make me want to hold out for a car that already had engine upgrades that are absorbed by the sell price

like the one i mentioned in my earlier post -- the one vilidini motorsports modified sold that on ebay yesterday for $6700. it was a 73 with an sr20det and all the racing add-ons. wer talking 25mpg, 12-13 sec 1/4 mile, 0-60 in like 6s. it sold for less the entire engine swap and mod cost! now that seems like a great deal! of course the fancier the set up, the more can go wrong, right? though the sr20det is a very fast reliable efficient engine.

if i get this car for 3K and spend 6 or 7K to do that to it at vildini, we're up to 10K. or even if i do the above mods for 5-6K, i'm still getting way up there. i could probably buy a WHOLE LOT more car for 9 or 10K right out of the gate.

the whole idea of buying a Z was to have a fun sports car RELATIVELY on the cheap.

time to break out my old fiat x1/9 -- that thing REALLY has no guts! hahaha.

hmmmm.. torn. torn.

this slow but beautiful stock 260Z for around 3K? is it worth it?