4 barrel intake?

[lowrider]

I just bought a 74 260z, to my supprise has a 4 barrel intake. I have never seen anything like this on any other Z. Im kinda wondering if its custom or part of a small run? on to the pics.

 

 

 

[Six_Shooter]

It's definatly an interesting looking piece.

[woldson]

That totally looks like a custom job! Kinda cool.

 

Do some searching for 4barrel intake to help you figure out what size carb might suit your needs. ArazonaZ makes one, bit different though.

[J Taylor]

I picked up 2 240z's recently. One came with some crappy intake with a 2 bbl carb and one came with an intake indentical to yours with a holley 390 cfm carb. I came across an auction a little while back where a guy was selling one just like this and said it was made by Turbo Tom. I haven't been able to find anything else about it. If I get more info I'll let you know.

 

JT

[lowrider]

im kinda weiry of this intake manifold, you would think that the carb being lower than the actual intake ports on the motor would effect performance.

 

J Taylor, did you ever run that car with the 390? Im wondering if it wouldnt be better to get a better intake set up before i spend the money buying a new 390 just to have it perform poorly.

[J Taylor]

Well, I bought the car not running. Put a battery in it and it fired right up just didn't run very well. After playing with the idle mixture screws I got it to where it fires up and idles good but it doesn't run very well down the road. Thats as far as I've had time to get with it. I'll let you know as I progress......I may end up putting some early SU's on it at some point and ditching the 4 bbl.

 

JT

[Daeron]

I think the Turbo Tom is a drawthrough system, putting the carb before the turbo....

 

That particular piece looks like a hack job that belongs in the garbage. I just said this in another thread and I MAY be wrong... but from the pics posted it looks like junque to me. Ditch it for some SUs; I won't knock the 4 barrel on a proper intake manifold, but that thing looks like a couple teenagers welded it up thinking they could slap a four barrel on the japcar.. Good idea, poor execution. If anything, the carb ought to be on a ramp ABOVE the intakes of the SU manifolds, and have a hole cut in the hood to snag some positive air pressure from up above the hood.

[ozconnection]

Yeah I agree, this manifold is far from perfect!

 

I've seen these things pop up on ebay from time to time and some of them are not too bad, with the base of the manifold water heated (like the one you have) and what appears to be 'cast'. Also of note is that the plenum chamber is quite large on yours, so gas velocity will drop off quite a bit after exiting the carb, undoing all the good work done by the small venturi's in the Holley.

 

Some of the better versions I've seen have a divider in it to separate the front three cylinders from the rear three. This really wakes up the bottom end of the rev range and is akin to the V8 boys' term "dual plane" manifold. So if you're keen, you could fabricate a simple divider and have a go. However, the carb will require tuning though, as the pulses that effect flow through the carb will alter the fuel curve requirements significantly. Jetting will get you close but often a Holley needs more work than this and it revolves around boosters, emulsion tubes and transition circuits. Not impossible, but I've had to make these changes to get my engine running exactly how I wanted it. This is often why guys who try and run Holleys throw them out....they fail to get the tune spot on by really understanding what's required, the problem with attempting to adapt a V8 carb to a small capacity six.

 

Still, have a play with what you've got mate. I hope I didn't put you off though.