single or dual plane manifold?

[kachina_labala]

I have a 22' Kachina Lake boat with a 454. The previous owner put dual edelbrock quads and a small cam 510 lift 265 duration. The motor has the 325cc rectangle port heads but is otherwise stock. I have added lightning headers and had the pump done by mpd. I was going to add a small nitrous kit this year but dont have the time. To put the nitrous on I had to get a different manifold. The boat had a dual plane edelbrock dual quad manifold but the carbs were too close together for the nos plates. I ebayed a offy dual quad manifold that is a single plane that the carbs are further apart so I could put the plates on. I would like to use the offy so I can add the nitrous later. What issues can I expect changing from a split plane to a single plane? What carb tuning will I have to do? Should I just go back to the dual plane?
Thanks
Matthew

[napabob]

Try:
http://popularhotrodding.com/enginemasters/articles/hardcore/0601em_intake/index.html
I have an Edelbrock Performer RPM 2-O (for oval port heads) dual plane and it fits into my RPM range (idel - 5500 RPM)

[IMPATIENT 1]

I Had A 79 21ft. Taylor Sc Jet And It Liked The Rpm Intake Better, Ya Know Summit Racing Makes Rpm Air Gap Knock Offs Now That Are Cheaper Than Edelbrock.i Go With A Summit "rpm Air Gap" Style Intake For 200 Bucks, It'll Work Well For Ya.

[kachina_labala]

Thanks for the info but the real question is can I run the offy without too much hastle and loss of driveability (able to add the nitro kit later) or should I go back to the edelbrock dual plane? I already own 3 dual quad manifolds and dont want to buy another. (third is a dual quad tunnel ram thats too tall to fit

[bigblockbill]

All the software dyno programs I have ever ran tend to like a single plane over the dual plane at all rpm ranges for a single 4 bbl. I have switched all my boats to singles and picked up ~100 rpm. Never tried a dual carb setup however.

[IMPATIENT 1]

All the software dyno programs I have ever ran tend to like a single plane over the dual plane at all rpm ranges for a single 4 bbl. I have switched all my boats to singles and picked up ~100 rpm. Never tried a dual carb setup however.
YOUR RITE, I'VE DONE THE SAME.ON THE SC I HAD, IT CAME WITH A VICTOR INTAKE THAT HAD SOME YRS. ON IT, I HAD A NEW RPM SETTING THAT I TRADED FOR SO I TRIED IT OUT. THE BOAT HAD MORE BALLS TO GET MOVING AND RAN BETTER ON TOP WITH THE RPM THAN THE VICTOR.IT GPS'D 62MPH ON THE VICTOR AND 65.3MPH ON THE RPM, BUT THAT COULD HAVE BEEN LAKE CONDITIONS TOO.JUST FROM THE "SEAT-O-PANTS" THE RPM FELT BETTER.

[TopCat]

single plane hav a better performance curve & top end/// dual plane work better at idle and at low to mid range rpm. It depends on what you're going to use your boat forundefined

[rerfert]

I was always told the single plane intakes were more for higher rpm ranges rather than idle conditions...You use your nitrous shot on the upper rpm range,SO the single plane intake would have less air restriction to the heads...well that is the way I see it.
With nitrous I would run a single plane manifold.

[kachina_labala]

I was also reading that the single plane was more for high rmp. My concern is how much trouble will i have in everyday lake situations?

[kachina_labala]

Well, After changing the intake I gained 400 rpm at the top but I now have a over heating / water flow problem. Since its the first time out this year im not sure where the problem is coming from. I added roller rockers, a new intake and had the pump refreshed from a little rock damage. now im melting exhaust hoses. The temp guage on the motor doesnt show the motor as hot (maybe a bad sending unit ?) but the intake manifold by the exhaust crossover (blocked off by the gasgets) is hot as hell and the exhaust hoses are melting. P U it stinks.

[IMPATIENT 1]

wonder if its runnin lean?? that'd melt tubes and not show up to much on the temp gauge

[SmokinLowriderSS]

Just lean shouldn't melt the water cooled exhaust hoses. Water flow problem. How did you plumb the headers? I switched from logs to Lightnings this past winter, zero trouble this year, exc engine running about 20 deg COOLER now.

[kachina_labala]

same setup as last year. I didnt have any issues last year. Im pretty sure its a water flow thing too. My thoughts are somthing plugiging the headers (possibly scaling) or header feed lines. Im a bit sick of the rubber tubes though. I think im going to have some steel tubes fabricated to replace most of the hose.

[kachina_labala]

Does anyone have a picture of or a link to the waterflow through a BBC? Whats the easiest way to get the freeze plugs out without a slide hammer? I think I may be full of sand which is limiting the water flow through the motor and not cooling. It seems like the oil gets hot but not the cooling water. Any Ideas would be helpful.
On another note ..For the short time that I did get to run the boat I went from 4600 rpm to 5000 rpm by changing the manifold and rockers. Acording to the JPC thats a big jump in Horse power. Last year was dominator A impeller 53mph @ 4600rpm. this year I pulled 5000rpm. Didnt get a top speed. Thats like 90 horse gain. Does that seem possible?

[kachina_labala]

Well, Ive had the boat out twice this year. On the first run I had overheating / water flow issues. I found the block was stuffed with mud and the header water manifolds had plugging from scaling. During the short time I ran the boat I thought I gained RMP (misread the guage) but in fact I lost RPM at the top end. At least 200 to 400 rpm from the changes I made (intake and rockers). The second time I went out, after I got all of the mud out and replaced the exhaust hoses, I noticed some strange happenings. When I would accelerate to full speed, if the engine was cool , I could get 4300rmp but the longer I stayed at full throttle the rpm would drop to 4000. If I would drop back to cruse at 3500-3800 for a while I would only be able to accelerate to 4000rmp. If I stop for a few minutes , idle, I can then get back to 4300. Oil pressure is 25psi at Idle when warm. Engine water temp stays below 150 the whole time Any thoughts what would cause the loss of power? This didn’t happen last year.

[Squirtcha?]

What kinda (make and model) of carbs are you running?

[kachina_labala]

edelbrock i belive 625 (not sure) vacume secondaries

[Allan Gorneault]

I would like to add my 2 cents based on my experience. If you look at any torque curves on an engine running a dual plane you will find that they drop off at around 2500-3000 rpm. They are very strong from idle but are useless at anything over 3000 rpm. I fell into the trap because the RPM range is idle to 5500 and sounded like it would work. A single plane manifold will make max torque in the 4500-5000 range , right were we drive our boat. I gained about 200-300 rpm going to a single plane manifold.

[Squirtcha?]

If I'm reading everything correctly, he is running a single plane now (used to have a dual plane).
Reason I asked about the carbs is just a theory. I wonder if since they're vacuum secondaries that maybe while under acceleration/load the secondaries are opening. Once max speed rpm is reached the secondaries are closing slightly due to less demand/load/vacuum on them?
Just a thought.

[kachina_labala]

Now thats an interesting thought :idea:

[396_WAYS_TO_SPIT]

blown and injected is the ONLY way to go;);)
I would say single plane in most applications. On a low rpm motor I would run a dual....

[TopCat]

and the single plane will perform even better with a spacer but don't believe it helps dual plane as much

[kachina_labala]

yes that is what I would have expected too. but... I lost Rpm with the single plane with 2" spacers. For my next trick im going to remove the spacers. The manifold has a divider. between the left and right sides of the manifold (no its not a dual plane).Open spacers negate the divider. By removing them I may improve the vacume by only pulling from 1/2 the carb per side. I guess its worth a try.