4 barrell on 70 240Z. Need input

[mulletz]

I have a 70 model that still has the orig. block & head, running strong. I am about to add a new intake & a holley 390CFM Carb.

Also going to do Headers & new exhaust at the same time.

Any input from someone in the know would be appreciated, I'm not that much of a mechanic, but dive into everything headfirst.

I have also yanked all of the smog & AC stuff, any issues concerning that?

Thanks.

[ChrisA]

You may want to go to hybridz.org for 4 barrel info. Most members here run stock carbs or triples.

Chris

[sblake01]

I've really never heard anything good about this setup. The only one I actually seen belonged to a friend a few years back. As I recall, it was a jetting nightmare! He re-jetted that carb so many times and it still didn't run as good as the S.U.'s. The engine was designed for sidedraft carbs and the sharp turn the mixture has to make with a downdraft makes the efficiency suffer. And, by the way, my buddy finally installed a set of Z Therapy S.U.'s and he's been happy ever since. Mind you, that's just my very limited experience with the Clifford intake/Holley carb scenario.

[dattozed]

If you have a V8 in your car.

Stay away from the 4 barrel set up. You will be better off with your su's, and tuning them and you will also get more power.

Headers really wont do anything for the performance of your car with a stock cam.

[Ed]

I haven't heard anything good about the 4bbl set-up either. There was a member here that had this set-up and was very dissapointed with the dyno results. The stock carbs actually produced more HP. I think you would be happier getting rebuilt SU's with your header exhaust combo. And if you have money left over rebuild the top end.

[CrashNBurn]

One thing not mentioned is the throttle linkage. The stock linkage, from the firewall to the carbs, on my 1973 240Z, won't work with the Holley. Some p.o. of my Zed decided to swap the original SU's for the Holley. In the process, the throttle linkage was removed and replaced with a loose, free-hanging cable. I can only assume that the original assembly was removed because it wouldn't fit with the Holley. The jetting and required angle change, as mentioned before, is a problem as well. Personally, I despise the Holley and cannot wait until I have the money to, at the very least, purchase some Z Therapy SU's or, if I find a killer deal, some triple Mikunis or Webbers. Unfortunately, other, more serious and important problems exist on my Zed. :disappoin

Jason Tripp

[jeff1216]

I can tell you first hand.........I did the Holley conversion and it sucked arse.

You have been warned.

Loss of power and you will never get the jetting correct

[Kyle]

I ran it on a 73 and was really happy; I then scored a manifold for my 72, but it came with a 600cfm carb, and I don't think I ever even installed it.

I do have the manifold and linkage available if someone wants to buy it...

[beandip]

Dont Bother

[My260Rocks]

yeah ive heard its better to use the SU's, and the 240 SU's at that. I've then also heard using the spacers from the later 260 SU's with the old 240 SUs will also improve proformance.(?)

On MIKUNIs, there is a problem with taking hard right(left?) turns. This can be fixed by paying NISSAN 300 bucks for each carb to repair, OR by JB Weld-ing up one of the holes linking the bowls to... something else... god what is it, cant remember, dang.

Anyway just remembered that from my Dads racecar build and thought that I had better get that out on the forum, before I forgot it. Dont know if its ever been said.

[hf240z]

I still have my 4 barrel intake. paid $75 for. it is one of those wasted money. any one who want to share my mistake?