Carb spacers
 

I am getting close to getting my engines together and was about to order some carb spacers for my 496's with dart intakes.

Any suggestions regarding the two different types of carb spacers.

*the open type
*or the 4 hole ones

personally I would think the open type considering their going on a open plentum single plane?

Any dyno results as to either of the two???

Thanks,
John

The open spacer is better for top end speed because it inceases fuel / air fogging in the manifold prior to the runners. The 4 hole / individual runners are better for lower speed transition in the same fashion as dual plane manifolds (so I've read and been told). I've got one of each and I plan on figuring out which one works better. The 4 hole style might take up some mid range slack where my single plane manifold might cause hiccups. The open spacer I'll try when the engine is broken in and I want all out speed so I can see if it makes any difference.

I'd love to see if anyone has any dyno results or other flow data.

Another question I'd like to throw into the ring is: is there any bennefit to a 2" spacer instead of a 1" spacer? And is it worth trying both at the same time? (4 hole, then open, then manifold)

Thanks GR... with all the dyno time i had down state years ago i never can recall checking these. Raylar among others probably has this data. Perhaps we can get him to post regarding our discussion. Maybe I'll PM him to see if he can post. It's always good to hear right from the guys who have the knowledge and the data to back it up. As you know I'm sure there are many factors that may apply. I have used them in the past and they were always the open ones and only an inch. Never really expermented much to really give myself as well as anybody else an honest aswer. Of course you'll hear from time to time that it will raise your top RPM by 100 to 200 RPM. Probably doubtful however I don't honestly know. Seems though in a sense it would be like simulating a runnel ram.?

Try a HVH super sucker, you'll like the dyno results, but' try it after testing with-out it first.

Agreed.

All the open spacers will do is move the power into higher rpms. The open ones work better on dual plane intakes.

I use the HVH on my 496. I believe it picked me up 100-200 RPM. According to my "seat of the pants dyno" I dont feel there was any negative impact by using it. I am using an 850 Demon carb and a Victor Jr intake with the 1 inch spacer. The condensation that forms on it when running is pretty interesting too.

I guess a good thing to do would is buy one and run with it and with out it to see if it helps out. The design appears to make good sense (HVH Super Sucker). The results will be another. I'll be sure and post the results. Thanks for the input guys.
John

Please see post #22 here:
http://www.offshoreonly.com/forums/g...-i-need-3.html

Feel free to read my article here:
http://marineperformancetechtalk.com/carb_spacers.htm

If you do an advanced search in OSO's search under 'super sucker' and for author put in 'sb' you'll see much of my ramblings.

Also, feel free to ask questions but you'll need to tell me all engine specs including your top rpm / carb / flame arrestor man and size for me to make a suggestion for you.

Carb spacers are a part of my daily life. I eat, sleep, and drink the stuff.

Thank you for the great info. Much appreciated.
John

I gained 25hp Dyno HP but using a HVH 1" one.800 hp 632.
So they work.

Are all the HVH the same? Is it like the super sucker i have shown in the pic above?

thanks,
John

I was told by the engine and dyno guy that the open type is better.

Or just as good as the reason it increases HP is because it increases plenum volume and alters the carb signal.

like everything , this item is combination specific. for the guy that got 25 hp, i would suggest that that meant his intake combination was seriously wrong to start with. all you can do with this stuff is go to the dyno and make a few dozen tests ( should have been done at build time) or, failing that, go to the lake and run a million back to back tests to find out what your combination wants as far as the element you are testing is.
one mans 25 hp gain with the same bolt on component on someone elses motor will be a 25 hp loss. buy one and try it and try all permutations of it... taller, shorter and be prepared to rejet when you find a direction that the combination wants to go.

there are no magic hp parts except in the catalogs of the people selling them.

there is no one size fits all answer.

Well Steve.My motor is match sorted by a professional not a back yard build.Merlinx intake the best there is.So my way of thinking is if you are chasing serious HP and you are using the best parts available,real HP, single plane intake the super sucker will work.

I have found on the dyno, and not chasing a number, that the 4 hole 1" spacer increased the hp&torque, but it lowered the peak hp rpm along with increasing torque & hp. This was a back to back test. The carb is getting a better signal, thats why fuel had to pulled out. That is very truely stated; adding volume if it's not there to begin with, that wasn't my issue. 548 CID, Pro-filer heads, 4150 dart intake, BG 1025 cfm RS carb.

So just to confirm in general terms the open spacer is better for dual plane manifolds & 4 hole spacer is better for single planes?

To vear off topic a little, I have the perfomer manifold & was considering installing a open spacer to hopefully gain some extra RPMs. My stock ignition only spins up to 4750 so I think I have the best manifold for the lower RPMs. Anybody know @ what RPM the Performer RPM would begin outperform the Performer?

not suggesting otherwise... but think about it ( assuming i understand you correctly) your guy did the absolute best he could do with the best materials and parts that he could find and combined them to the best of his ability. that motor made x power. then, sometime later , with no other changes, you bolt on a carb spacer and make another 25 hp... not an insignificant number. where do you think that power came from ? it came from a massive increase in total flow and a massive increase in inlet tract efficiency. the conclusion has to be that the original inlet tract from the base of the carb to the valve seat was " wrong" to start with and that the addition of the spacer brought that combination much closer to correct. and that is a huge piece of knowledge for you because you have concrete evidence of what direction the inlet tract wants to go.
i think instead of buying into the " magic carb spacer" idea, i might try to figure out what was really happening inside the manifold that was so different and once i knew that actually do a manifold that did that without the carb spacer... THEN bolt the spacer on and see what happens.

the carb spacer is not nitrous oxide. it doesn't possess any energy of its own. what it did was influence something else in ( your case specifically) a very positive way.

i would really want to know why.

Edelbrock says the RPM will go to 6500 rpm but the Performer is good for 6000.

That having been said, with the higher inlet tract profile, slightly wider but most importantly smoother runners and easier breathing (haven't even mentioned colder / denser charge if it's an RPM Air Gap!) then you should be able to see an increase in HP. Whether your ignition can physically power you to the rpm range you need is seperate.

If you're just running out of power and can't get past 4750, the RPM manifold might help, but herein lies a PERFECT opportunity to test the carb spacer! The RPM Manifold is about 2" taller overall than the Performer, if you just put a 1 or 2" OPEN spacer on your Performer and it nets you a gain in RPM, you'll know for certain that the RPM Manifold with it's profile will gain RPM by adding power at revs or just increase power acros the range you have now. My bet? You'll go up a bit.

If you wan't, by the RPM straight up. I run one (now), but it would be interesting to test an open spacer on there first!

Good Luck. :drink:

In dyno test I've seen the open spacer on a single plane intake picks up the midrange with out sacrificing much on the top, so they tent to work great on boats that never see the top RPM range of most all single plane intakes...Rob

Thinking about it.Is the tunnel ram the ultimate carb spacer.

We have seen great results on all types of applications with the HVH super sucker. They are hands down one of the easiest, simplest and least expensive upgrades you can do to an engine. http://www.cpperformance.com/detail.aspx?ID=3354

I've been reading through the post and as most of you probably had some chuckles and perhaps learned some things from what other have experienced. The simple fact is, is that it is an enexpensive test. If you have the room try it. Heck I'm game for anything. There may be pros and cons in every application. Some will work better than others where some may even go backwards. I certainly believe everyones own individual components will determine the end result.

Talked to Dean Gellner yesterday and he mentioned 10 to 12 HP gains as far as dyno results. Personally I took this as it could vary a lot. We all know the true test is on the water.


The one thing "I think" I understand what Stevexm is refering to is if this is so then why don't intake manifold manufactures incororate such design in specific type intakes? I would imagine the R & D along with the mold cost might be pricey. Dificult to say really. Perhaps liminted space in many applications? Then again that's probably why they make tunnel rams.

I just had a crazy idea today while swapping carbs... I had to open up the bores on my 4 hole to fit the butterflys on my new 850 HP D/P.

I have both, a phenolic 2" Open and a 2" 4-hole spacer. I had the 4 hole for the Victor Jr, and the open I got for the RPM Air Gap. During a moment of madness, I took my die-grinder to my 4-hole and made a 'Super Sucker' copy by hand.

I marked out all the port diameters and grind extremeties, then set to work grinding with a stone tapered bit. I know my hands aren't CNC quality, but I like to think I'm okay.

Once sanded smooth and finished, it looked great and even across the bores. Now, if it all falls apart and wrecks my engine, I'll probably cry. But in the mean time, I have a modified spacer to try too!

If it all fails, I suppose I will be the 'Super-Sucker.'

Game On!

there is always the significant added benefit of insulation from the spacer. there was a very restricted catagory of motors that i did where the overall intake dimensions had to remain std but you were allowed to machine the carb flange for the carb... so i whacked 3/4 inch off and made a 3/4 phenolic spacer that replaced in standard form, the al that had come off and those motors ran considerably better on the track than the ones w/out and when you took the decklids off the carbs were always " much cooler" to the touch. so anecdotally it seemed to me that the lack of heat soak was a good deal and i simply figured that it wasn't heating the inlet charge or something. i had no real data but the results were a net gain every time. the dyno said it was the same ( no surprise as nothing had changed in the flow scheme) but on the track there were more revs and better acceleration numbers every time.

some time ago roush and yates started doing something on the floor of the intakes like a fluted pyramid sort of thing... it sat directly under the carb and worked like crazy on the cup motors. i never actually saw one but they were reportedly very effective... has anyone ever done anyting with those outside of nascar ?

I think they marketed them as a 'Turtle' or something. I bought a Holley Strip Dominator for my SBC in my old race boat off ebay and it came with one. He'd drilled the center and tapped it, then screwed it in to the valley beneath the carb. When I asked him about it, he said it was to more evenly distribute the flow down the runners.

Buggers me if it made any difference but that SBC ran happily to about 7500rpm!

I don't know what kind of spacer I have because it came with the previous motors, but we built new 502's this summer with 502/415 longblocks, merlin dual plane intake, 850 holley. We only had one spacer so we used it on the engine powering the power steering. Both motors were set up exactly the same, minus the spacer. One made 419hp at 5000rpm, 498lbs at 3900. The other made 424hp at 4900rpm, 502lbs at 3800. Could have been a coincedence as we were testing two different motors.

:lolhit: My carb spacer came from weiand, its a 177 carb spacer, comes with its own belt. Its a big spacer too, like about 8" and squeals real funny! does add alot more power!
:evilb:

had those, been there - bm 420's. was fun and your right - the noise even gets better when you crack the hatches with three of those bad dogs in there.