4-barrel intake: THE FACTS

[Daeron]

Well, I have to ask (since we stumbled on a box of like, either 7 or 9 of the aluminum adapters a few months ago)

 

What about putting twin DGV webers on in place of the SU's?

 

My Dad forced me to shut my mouth and quit whining about four barrels on Z-cars a long time ago; it goes against my natural grain but I grudgingly admit power can be made and any complaints I may have are, in the face of a well built engine all around it, superfluous.

 

Despite that, I *still* feel that 1 and 6 get the short end of the stick with just about any 4 barrel manifold I have seen, and the twin Weber downdraft seems to me the best of both worlds (except for the fact that you have two carbs instead of one.) Obviously the big, heat absorbing J that the adapter makes is a drawback.. but I know many people have used them as "big power" SU replacements on many cars equipped with SUs. why not throw them on instead of a holley?

Edited February 23, 2010 by Daeron

[T-Bone028]

I believe the main theory on why the DGV webers arent a good option is that the DGV webers have a sharp angle in which fuel/air has to flow. If you have the ztherapy video, it explains it quite well.

 

In short, its almost abrupt the way it is designed. Imagine a "J" where the top of the J is where the carb sits, and the other end goes to the head. The curve downwards at the bottom of the J and then back upwards again is what makes it a poor choice. Your fuel mixture hits a "wall" at the bottom, then has to flow upwards to feed the engine...kind of like going uphill. Its not a smooth path. I hope that makes sense.

[sticky280zx]

 

Despite that, I *still* feel that 1 and 6 get the short end of the stick with just about any 4 barrel manifold I have seen, and the twin Weber downdraft seems to me the best of both worlds (except for the fact that you have two carbs instead of one.) Obviously the big, heat absorbing J that the adapter makes is a drawback.. but I know many people have used them as "big power" SU replacements on many cars equipped with SUs. why not throw them on instead of a holley?

 

Here is a pic of "my" manifold.....notice the sneaky sneakiness i did and ill explain it more after i hear what ya'll think....

 

[Daeron]

Here is a pic of "my" manifold.....notice the sneaky sneakiness i did and ill explain it more after i hear what ya'll think....

 

I think you're a freakin hoser, but a brilliant hoser Awesome, I can't wait to see that adapter.

 

It's nothing I could ever see myself using, but any four barrel fits that category. I still think its the bee's knees though.

[Tony D]

Just remember, there was a 4V Datsun/Nissan Manifold.

 

 

YEAH, it's a FOUR barrel, here's the comparison:

 

There were dual two barrel inline Mercedes Manifolds.

 

Guys argue about Corvair carburetor placement, too!

 

 

<EDIT> That bastard yetterben just sent me a link last night to YahooJapan Auctions for an HA30 Cedric four-barrel intake setup complete with original Nissan Supplied Four Barrel on it! Only about $1200.....any takers?

Edited March 12, 2010 by Tony D

[Datsun#1]

Just from my own personal experience.My first set up on my L2(9) stroker was two Side draft roundtop SU carbs vary clean and in new condition running modded SM needles with a mild cam 274dur-480lift. The proformance was great.decent mialage aswell.remind you this is a fully restored engine with no miles on it in the begining.The cam came on decent but still not enought.Seeing how the SU carbs bring in around 152cfm each (304cfm) toatal, I decided to go ahead and buy the holley setup.I removed the choke plate to start with because i live in florida and theres really no need for one here.My buddy who was a machanic for 50 years tuned and jetted the holley for me to sute my power band.The car never pulled so hard.BIG improvment over my SU set up.I have since Installed a much larger Isky cam 308dur-560 lift and the carb handles every bit of it.had to retune it for my new cam but as far as profomance engines goes,the holley is by far a much better set up.it really wakes the car up.a friend of mine is running the arazona manifold with a holley 540cfm carb and a HUGE cam at least 2 steps up from mine.it pulls like a bat out of hell all the way to 8000rpm (his is race only).But as stated,Crisp response,decent economy (who cares,its a Z) and works way better than SU carbs when it comes to a Cam that is much larger than a mild street cam.My cam is rated to be used off road but with the holley it is vary streetable.Dynos will be posted soon.

 

              Datsun#1

[zacward]

Ive had the AZ car 4bbl intake mani for a year or 2 now. The holley 390 (bought mine at: http://www.summitracing.com/parts/hly-0-8007) has fuel slosh issues around high-G turns (sputters and can flood). Out of the box the primaries were jetted too lean and the secondaries too rich. Transition between cruise and "getting on it" can be a bit laggy, but I attribute it to my crankcase venting system( low vaccuum).  Maybe different in other expirience. My car is a 1978, block bored 0.030" over, late 260z head and l28block, stock dished pistons; did a little port smoothing, but no real porting done, stock injection cam, custom cold air intake using http://www.summitracing.com/parts/spe-98499 . Carter 45 gph fuel pump 6-8 psi, deadhead style, fuel filter before the pump (rusty fueltank) and another in oem location.

I decided to convert to the 4bbl setup because I couldnt get my fuel pump to stay running. Went through many parts and diag procedures but couldnt get the relays i needed from the dealer or aftermarket. Saved up my $800 and installed the AZ Car mani and holley 390.
Final impressions:
It'll start up and run every day for you and "convenient" trips. Here in TX sitting at idle for extended periods (traffic jams/consecutive stoplights), my Hooker header will boil the fuel out of the secondary bowl in certain conditions. (Fuel bowls are setup correctly, header primaries wrapped under carb and adjoining 2 cylinders)

My honest recommendation is to use the edelbrock 500 thunder avs with a full jet kit, wideband, and vacuum guage kit (for tuning idle), for the 4bbl induction systems. Cheaper than the holley with no fuel slosh!

Edit: forgot to say, the holley 390 will not fit on the AZCar intake mani without a carb spacer unless you clearance where the primary butterflies run into the manifold. You should be running some kind of spacer/ heat shield with the 4 bbl anyway as it get heatsoaked easily. The reason behind that? Look at how far the stock sidedraft carbs are from the exhaust mani on a stock setup; Now look at the 4bbl setup. Secondaries sit right above exhaust manifold.... But with a ceramic header, I would hope for better results and less heat soak issues.

Edited December 27, 2014 by zacward

[Tony D]

I'd trash the carb and put a TBI injection unit on there and forget the headaches of 30's technology.

There is a necroposting penchant of late, so we wanna talk EFI vs 4 bbl, the 4 bbl we used was idling at 2,200 rpm, the 45 DCOE's at 1,700, and 45 mm ITBs at 500 if we wanted it to. Lightning fast, crisp throttle response from as low as 400 rpm idle, but we moved it to 900 just because. Started right up on 35 degree mornings, fast idled and etc just like a factory car.

 

Horsepower gain on the ITB's over Webers was 40Hp at 8,250 rpm, and 45DCOE's were at least 20HP more over the Four Barrel at 7,500.

 

NASCAR went EFI, time you did so too.

 

I got a four barrel intake on my 72, it's been running an EFI setup now going on 23 years.

 

23 years.

Edited December 27, 2014 by Tony D

[michael wales]

I'd trash the carb and put a TBI injection unit on there and forget the headaches of 30's technology.

There is a necroposting penchant of late, so we wanna talk EFI vs 4 bbl, the 4 bbl we used was idling at 2,200 rpm, the 45 DCOE's at 1,700, and 45 mm ITBs at 500 if we wanted it to. Lightning fast, crisp throttle response from as low as 400 rpm idle, but we moved it to 900 just because. Started right up on 35 degree mornings, fast idled and etc just like a factory car.

 

Horsepower gain on the ITB's over Webers was 40Hp at 8,250 rpm, and 45DCOE's were at least 20HP more over the Four Barrel at 7,500.

 

NASCAR went EFI, time you did so too.

 

I got a four barrel intake on my 72, it's been running an EFI setup now going on 23 years.

 

23 years.

I've been looking at doing this recently but have been unsuccessful in finding any threads or builds with a TBI setup on a ArizonaZcar intake. Any one have any good links I might of missed? If not, I might guinea pig myself, it seems like least expensive non-stock EFI setup you could build. Lots of future potential for tuning, FI, nitrous etc...

[Tony D]

It's not "Guinea Pig", it's been done. It just predates the Civilian Internet. Retroactively dissecting a working system for the purpose of documentation is more work than its worth.

Guy goes and takes apart a perfectly functioning system that's been daily driven for 20+ years, only to have idiots on the internet pick apart the work (by people too stupid to acknowledge a functioning system, and bent on bench-racing in mommy's basement.)

 

There really is no upside for someone who's done it, to go back and explain it in public after the fact.

 

The least expensive EFI system you will have is a Megasquirt on the stock EFI manifold, or a Megasquirt driving Patton Machine TBI Drop-In Adapters. Hell, with the Patton Machine conversion, you keep all your stock air cleaners and linkages, no hack job crap with bad filtration and hood clearance issues.

[michael wales]

I understand you views on the builder not seeing an upside but this site has a wealth of knowledge on so many subjects applied to the Z car format that i was surprised to seemingly find a subject that hadn't been discussed to death (4bbl TBI). I was kind of hoping to guinea pig more then anything. I for one am not nearly as experienced as your self or so many others here so doing a build thread is as much out of necessity and for the upside of getting the constructive criticism and not having to learn the hard way as it is to log the progression of my own builds.

The Patton Machine kit looks extremely interesting especially if i can keep my current cannon manifold. I was referring to a complete setup like this http://www.quickfueltechnology.com/quick-fuel-injection/qfi-master-kit-black-diamond.html which seems very similar but is probably to big for a N/A Z motor running the Arizona Z car manifold. I appreciate the links and i think I'm going to contact Patton as they seem to have experience with smaller triple L6's instead of single carb v8s. looks like i may also need to get some information on Mega-squirt as the Patton kit uses a GM ECU and I'm not sure if that will play nice if i decide to go forced induction later on.
 

[Tony D]

There was a system being niche marketed and private branded out of Corona CA called "boss EFI" it was based around a self tuning ECU, with PWM controlled fuel pump good to 500 hp.

 

The delivery and what engine it's on is really irrelevant. GM TBI was used on Turbo VW's for years. Same goes for Holley Commanders ... If the manifold flanges to the air door, the EFI works.

 

EFI doesn't care what engine it's on.

 

Going forced induction later on negates using SU's.... And a bonnet Four Batrel? Well that's surely been done to death.

 

If you limit your searches to L-Specific installs you limit your knowledge. Period.

 

The reason most of these projects fail is precisely because people put blinders on thinking a Chevy Blow Through reacts differently than a Datsun Blow Through.

 

You need to decide on the project you want to do. If you do all this long range bench racing "what if" contingency planning it never gets started.i know guys talking about their ideal build since 1985. To this day their rattle trap pos sits with Bondo zits and a bunch of half-assed attempts at interim steps, but never clarity of vision and focus to complete anything. Always holding up waiting for the next magic bullet.

 

Pick a route, see it through. Then see where you're at and see if it's a place you like. If not, change it.

 

At least you will have done something!

 

 

As for "discussing to death" four barrel EFI on an L-Series, there really isn't much to discuss. People wanting EFI generally go for port injection, not TBI. Those that are TBI satiated generally are of the "it works I'm happy" mindset and that's the end of it.

 

It's not a combination that shines in any particular way. It's just something you do to get a roller rolling. There are better alternatives for high performance and for near-stock performance. I mean, Patton's adapters are less than a new Holley, fit in the SUs most have on the car, and the rest of the EFI can be Bodged from stock nissan cast off parts and a Megasquirt.

[GeeZ]

I've had a Cartech carb adapter back in 1979 on my 260Z that had the problematic Hitachi SU's. While the Holley 4 barrel (later Turbo Tom's kit) was way better than the Hitachis it doesn't hold a candle to FI. Using the Turbo Tom built engine, Megasquirt and Holset turbo, my 260 put 435 rwhp. Amazing performance.

Go FI.