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Single Plane vs Dual Plane + Carb Choice


Guest flapjack

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Guest flapjack

Hey everyone. As far as my swap goes, I'm still it the "collecting the parts" stage. My Z is running pretty well, with the exception of the usual clunking rear and some minor electrical problems.

 

So far, I've collected the following:

 

- 350 V8, with stock heads, rebuilt, missing cam shaft ($150, from a 68 Chevelle)

- An older 700-R4 that is supposed to be in good running shape ($125)

- Torker II manifold (traded for 40GB hard drive I had laying around)

 

I'm kinda stuck at the carb/manifold/cam shaft decision. I've been told the most radical cam I can use would be a 270, or else I'd need to change my torque converter, which I may do anyway. Also I've been told that a single-plane manifold is only good for high RPM applications, and that I should swap it for a dual-plane.

 

I've never done an engine swap, but I am pretty knowlegeable on auto mechanics, and have torn engines down to the pistons before. I know it'll be a learning experience, but I'd like to call on your expertise.

 

The victim is a 1975 280Z with a 3-speed auto. I have the R200 rearend, and I've already pulled that and inspected it when I changed the rear wheel bearings. All looks well.

 

Any suggestions???

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Guest flapjack

Yeah, I've been searching and reading through all the old posts (currently on page #5).

 

I guess I'm a bit hesitant because of the "what went wrong" stories.

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yeah...

 

GrumpyVette is the man!

 

 

just do a search for his posts and you will find more information than you could ever hope to retain.

 

here is what I think I know about single planes vs dual planes:

 

Dual planes usually produce higher torque in the lower rpm range. Single planes usually produce better top end horses.

 

Single planes mix well with the Z car. you have a light car, so losing a bit of torque in the low rpm range isnt a big deal, it will most likely help you keep traction ( a little). and once your hooked up and running high RPMs you have more power to use.

 

but I havent done any testing of this on my own. so i cant say anything for sure.

 

I think I picked up those ideas from one of grumpyvette's posts.

 

Joe

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Two weeks ago I put a super victor-style single plane manifold on my 327 in place of a performer rpm, and personally I'll never go back to a dual plane on a Z. Grumpy's posts that Joe mentioned are right on the money about single planes and Z's. As for a carb I'd go with a 650 Demon or Holley DP.

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Guest flapjack

At first, I was a little bummed to hear about the single plane manifold not doing as good at low RPMs, but when you think about the high-revving nature of imports, I guess it fits. I'm glad to know that there are some people that really enjoy the single-plane manifolds. I think I'll just stick with it and learn from your experiences.

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My friend Mike D is running a single plane (Weiand Team G) on his 355, but he also has 11:1 compression and some very trick, ported Corvette heads that flow something silly high number. Keep in mind that your heads are the biggest sticking point.

 

Ideally you should have matched components for your engine, but I know what it is like getting 'stuck' with what you have due to budget, etc. That said, yeah, I'd keep the cam to what was suggested to you. I bought a Stealth manifold (dual plane but acts like a single up in the revs) with a camshaft that works for it (good to about 5500-6000 rpm.). I was able to get some aluminum heads for cheap and the compression will go from about 8.5:1 to 10:1---this will only help the horsepower numbers!!! The torque might be a bit much, but I think the engine will rock.

 

Hopefully others will chime in with their combos too.

 

Davy

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just some info

look over these engine combos and find which is the closer match to your combo!

theres lots of factors that effect the results but in general

if your cam is under 235 dur.@.050 lift and uses hydrolic lifters

if your engine spends most of its time under 4500rpm

if your not running a free flow exhaust and headers

if your compression is under 10:1

if your cylinder heads flow less than 240cfm @.500 lift

if you running a 2.57 to 3.55 rear gear

if your car weights over 3400lbs

youll be more than likely in the combo where a dual plane intake works better

 

your cam is over 235 dur.@.050 lift and use solid lifters

if your engine spends most of its time over 3500rpm

if your running a free flow exhaust and headers

if your compression is over 10:1

if your cylinder heads flow more than 240cfm @.500 lift

if your running a 373-5.13 rear gear

if your car weights under 3200 lbs

youll be more than likely in the combo where a single plane intake works better

 

you should read this

 

http://victorylibrary.com/mopar/intake-tech-c.htm

 

BTW

5416.jpglow raise runners that hit the heads at an angle don,t tend to work well

 

2925.jpg

 

runners that enter at a high angle in line with the ports tend to work better

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I am also running a Weiand stealth dual plain and love it. It gives you torque on the low end but really keeps up on the big end. 224/230-502/510 roller cam on a 10.3 to 1 355 sbc.

 

Only part I think I missed on are Edelbrock rpm heads..wished I had gone AFR 190-195's. That's next :D !!!!

 

Mike

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I'm running an Edelbrock Victor single-plane on a 327. About 9.5:1, worked-over vortecs, Holley TBI-type injection, roller everything. I must say, everything the guys above (especially grumpy) had to say about single-planes is true. In practice, the thing is fairly flat below about 4500 or so. At that point, though, it lights like a Solid Rocket Booster, and you're in for a real ride. I have to be very, very careful about redline, it doesn't get "flat" as it approaches the top, there's no sense of "that's enough", it just keeps on wanting to go - I imagine all the way to self-destruction. It's rather like the big Kawasaki two-strokes I rode back in the day (nicknamed "flexy flyers"), nothing much down below, open the throttle at low RPM and nothing happens: but when you hit about 5000 it was like somebody flicked the power switch.

 

At very low RPM, thought, it's great for my Z. The torque is greater than the stock motor, but not radically so, so it's very "streetable". In the rain last week (and wasn't *that* weird?), I had no trouble controlling it, which I have in other light, high-powered cars.

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Guest flapjack

Thanks everyone, especially Grumpy! That was some awesome info, for a guy that is still learning the basics on engine building.

 

Of course I love the idea of that low RPM "whomp", but in reality the single-plane is starting to make more sense.

 

I've always worried a bit about having a built-up engine that creates tire slippage at low-RPMs. This is a car I want my wife to be able to drive if she wants.

 

Another thing that sounds like it may benefit is the gas mileage. If I'm just doing normal cruising to work and back stuff, the lack of power at cruising speed should get me a better MPG, right?

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