Intake spacer

[Merc 2.5]

I'm runnin a mild build 2.5 ff block, runs real good , I had noticed a intake leak behind spacer(carb motor) while i had a extra gasket i thought I'd take spacer off a see if theres a difference runnin without it. Now some may call bull but I'm goin with what I felt in the seat .. I lost 300rpm out of the hole , noticable mid range punch difference, and also (wasnt expecting this) lost 2 or 300 rpm up top (could had been me and jack plate) , give or take a little, now this maybe just be how my motor is ported etc,etc. But my boat is on the heavy side and seems to me it b alot more noticable on lite boat. Either way its definitely goin back on for bottom and mid range , noting else changed , also as I was doin a wot run this happen457823

[kellytheaker]

Intetesting - i thought the reason for the spacer was for just that - improvement . Sorry to see the prop but more important how is the area around it from the slung blade . Its not till you have this happen and more - that you start paying more attention looking for visual clues - cracks - in props and blades .

[Motv18]

Yep,

you could spend some tune time with it off, and maybe get it closer.

Normally these type things improve all around and move the peak higher.

Something like without its 200hp/200ftlb at 5280 and 175/180 at 600 and with its 210/210 and still 230/230 at 6000 (no math just hp/torque equal at 5280 or something)

[Merc 2.5]

I did do launch after launch to try hit target rpm , I can hit 6100 out of the hole ,with that 4 blade , and when I took spacer off it stopped at 5700 5800, but yes the spacer definitely helps , I've heard sum say they see no improvement but I can feel difference and see it in tach,,, since I throwed a blade (every thing else is fine) I had put on a 28 chopper , so I will kinda redo my "test of sort" with the 28 ,

When I built the mota. I put everything on it at once , so I figured it b good time.to c exactly what it does for em

[ChrisCarsonMarine]

Intetesting - i thought the reason for the spacer was for just that - improvement . Sorry to see the prop but more important how is the area around it from the slung blade . Its not till you have this happen and more - that you start paying more attention looking for visual clues - cracks - in props and blades .
He's saying he lost performance when he removed the spacer,not added it...

[Merc 2.5]

He's saying he lost performance when he removed the spacer,not added it...

Ya maybe I cobbled few words. Yes I LOST 300rpm atleast out of the hole, lost midrange, noticable difference,, and like I said maybe it was my jackplate setting , idk and I'll never know with that prop , but I lost rpm up top prob 200 or better

In other words. I lost power through out the rpm band

[InjectorService]

Thats a pretty big difference in RPM and feel for nothing more than a spacer. Good test!

[KIRCHNER]

I HAVE a replacement propco 24 like new if you need it. they do have thin blades.

[Merc 2.5]

I HAVE a replacement propco 24 like new if you need it. they do have thin blades.

It was a good decent prop for my set up, but I was gettin ready to get it worked for little more lift , so now I think I'm gonna look at sumthin diffrent ,and I need get hydraulic steering b4 I get another prop neway. I still have 2 28 choppers and one has a offshore cut , just lots and lots steer torque and take forever to get on pad , need stern lift , need get lighter bass bote really lol

[Merc 2.5]

Thats a pretty big difference in RPM and feel for nothing more than a spacer. Good test!

I had planned on putting it back on and testing again with same prop but now that not gonna happen , I did run my 28 without spacer ,and now have spacer back on and gonna see what difference I can tell with 28. I wouldnt nessicarly call it a test but I can see a difference in the tach and mid range punch about 3k

I wanna add if you have a bone stock motor u may or may not see the same gains I did . But I'm positive there will be gains , just dont want people to think it's a guaranteed amount of rpm etc. my motor been modified from flywheel to prop in one way or another

[KIRCHNER]

Over hubs-- all have poor holeshots and high steering torque IMO. I bought a solas scorpion. great lift all around and killler top end. 15.25 dia,thru hub. there really for bass boats. flo-tork hub. all reviews are great . huge rake & cup. my chopper is on the shelf. best of all.there not expensive. there 2'' 2.5'' stiff. half the torque of a chopper.

[Chaz]

2.5 .. there are two very good reasons for what happened.

#1 Increased "plenum" (storage) area between the reed block and carburetor venturi.

#2



I know you looked down the hole as you were putting it back together .. :thumbsup:
Tell us what you saw ... :smiletest:

[Merc 2.5]

"Down the hole" meaning front of intake ? I see a "tunnel" to reeds. Longer tunnel with spacer , like the gud ole weiden tunnel ram. Kinda

[tcrabtree]

Ran em both with & without spacers . Never saw any difference in performance

[Chaz]

"Down the hole" meaning front of intake ? I see a "tunnel" to reeds. Longer tunnel with spacer , like the gud ole weiden tunnel ram. Kinda

Thru the carb bore or at the manifold flange. With the spacer if nothing else, it provides a better line of sight to the reed block area. Going from a circle that is the carb bore to a short by wide reed block is never a good transition. Moving the "manifold lid" farther back will slow the air column a little, but will tend to unking the path, which is usually a net gain in airflow.
Air does funny things. It wouldn't surprise me one bit if some reeds opened sooner, wider and closed later than others. Anything you can do to make all the reeds "see" the same volume, speed and duration of the column from one end of the block to the other will be a step in the right direction.

[Merc 2.5]

Ran em both with & without spacers . Never saw any difference in performance

Damn. I hate it for ya. What u runnin ? Cause I can clearly see the difference, again the spacer mite just jive with my port work

[tcrabtree]

Damn. I hate it for ya. What u runnin ? Cause I can clearly see the difference, again the spacer mite just jive with my port work
Everything from carbed fishing motas to Laser & HP EFI race motors 260/280/300 (tel:260/280/300). We get a smoother idle without the spacers on our EFI motors . Helps during staging

[Chaz]

And what does that tell you .... ?

[Merc 2.5]

Everything from carbed fishing motas to Laser & HP EFI race motors 260/280/300 (tel:260/280/300). We get a smoother idle without the spacers on our EFI motors . Helps during staging

Even mother merc dont invest in many bolt.ons but they seem to think the spacer helps since putting em on from factory , I'm no drag racer tho,

[FORBESAUTO]

I’ve always experienced significant gains on carbed and laser style injected motors due to the fact of smoother transition as Chaz stated and straightening the flow from the left, right, up and down turns from intake into reeds. Not so much on horn, plenum, and slide style setups that by design already has smooth straight shot to reeds with no dead spots