5 Petal or 7 Petal Reeds for High RPM on Merc Drag Motor

[CI STV]

I don’t want to provoke any controversy over whose reeds are better. That’s not what this is about, although I’m happy to hear who’s running what brand, etc.
The reason for posting this thread is because I’ve always thought that the ultimate setup was the 7 petal reeds and yet the Diamond Intake on my ported drag motor came with 5 petal cages (Pic below).
I recall Marty telling that they had done some special work with the reeds on that manifold, which is truly a work of art, but I have one (the first one, I think) of the few they made before they closed shop, so, although I trust those brothers and I know they know their stuff, I really don’t know if the 5 petal reeds in my manifold in fact perform better than a ported 7 petal cage setup would at high RPM (10,000+ rpm). Anyone know if anyone else with one of these has tried using the 7-petal reeds?
I have no intention of messing with these now, but suppose I will eventually need to figure out what to do about a set of replacement reeds anyhow.
Thoughts?

[LakeFever]

That’s interesting. Ya know back in the good ol days of car racing the infamous double hump sbc head was a dominant force. They came from the factory with 2.02” intake valves but the porters who REALLY knew what they were doing pulled those valves and stuffed in 1.94” valves to help unshrowd the valve and made more power with the smaller valve than the bigger one. Men like Vizard and the like did this. I wonder what those Diamond fellas figured out here?

[mach351]

I was told cross section airflow was better on the 5’s…..makes sense if you think about. I think the real winner is the fact the 5’s are rubber coated….has to make life easier on the reed….especially at 10k+. I’m sure Chris Carson will chime in…..he’s done a bunch of reed testing.

[CI STV]

That’s interesting. Ya know back in the good ol days of car racing the infamous double hump sbc head was a dominant force. They came from the factory with 2.02” intake valves but the porters who REALLY knew what they were doing pulled those valves and stuffed in 1.94” valves to help unshrowd the valve and made more power with the smaller valve than the bigger one. Men like Vizard and the like did this. I wonder what those Diamond fellas figured out here?

Ha! It’s been a while since I’ve heard anyone talking about double hump heads. Or David Vizard, who was a true engine master. I ported a set of 186 castings myself back in the day, and they had the 1.94” intake. I actually didn’t have a frickin bit of experience with porting, so I just did a port match and cleaned up the short side radius a bit. But they seemed to worked on the 355 that we put them on, until my cousin blew it up on nitrous.
Maybe that was Bill “Grumpy” Jenkins secret with that badass 331 SBC that took out the Sox & Martin Hemi car in…1969?
Coincidently, Joe and Marty used to build race cars for Jenkins in the 70s. I heard a lot of funny stories from them about him last time I was at their shop, just before they closed it down.
I have no doubt that if Joe decides to use 5 petal reeds on their manifold, there was a performance advantage. Those guys know their sh!t.

[CI STV]

I was told cross section airflow was better on the 5’s…..makes sense if you think about. I think the real winner is the fact the 5’s are rubber coated….has to make life easier on the reed….especially at 10k+. I’m sure Chris Carson will chime in…..he’s done a bunch of reed testing.

That’s interesting and makes total sense to me. I would be very grateful if Chris chimed in. One of the reasons I posted this thread is that I was looking at the reeds on his site and I noted that the 5 petal reeds have a max rpm of 10,000 so I’m wondering if the 7 is better up top?

[laser_ED]

What you have are{ 240 sportjet 5 pedal reeds}most likey rubber coated unless joe modified them....9 out of 10 race teams use them because they make good hp and they last the longest....replacement carbon fiber reeds are available from Chris carson in different spec thickness..Now before this post turns into a ford vs chevy deal...I have merc 7 pedal,,,chopper city billet 4 pedal and 5 pedal sets,,,they all work ......P.S do you know the fellow on your island that has an Allison.\???

[Michael J Giesler]

What you have are{ 240 sportjet 5 pedal reeds}most likey rubber coated unless joe modified them....9 out of 10 race teams use them because they make good hp and they last the longest....replacement carbon fiber reeds are available from Chris carson in different spec thickness..Now before this post turns into a ford vs chevy deal...I have merc 7 pedal,,,chopper city billet 4 pedal and 5 pedal sets,,,they all work ......P.S do you know the fellow on your island that has an Allison.\???

There is a very nice 2001 Allison drag on that island that was purchased from baker marine

[laser_ED]

There is a very nice 2001 Allison drag on that island that was purchased from baker marine

That is the fellow I was asking about,,,he is rigging a 260 on it with a horn,,

[CI STV]

That is the fellow I was asking about,,,he is rigging a 260 on it with a horn,,

That would be Denny Connor. Sam Baker sold the hull to another friend of mine about 20 years ago and he brought it down here, but never put it overboard, although he put two different motors on it and painted it over several times, lol. Denny recently bought it and is rigging it now, so it should be overboard soon. It’s painted all black now, which looks better that the previous paint job where it had skulls airbrushed all over it (pic below).

[Michael J Giesler]

That would be Denny Connor. Sam Baker sold the hull to another friend of mine about 20 years ago and he brought I down here never put it overboard, although he put two different motors on it and painted it over several times, lol. It’s painted all black now, which looks better that the previous paint job where it had skulls airbrushed all over it (pic below).

That was the 3rd new bottom drag built Glenn 1st Key Puckett 2nd Sam Baker 3 I believe

[ChrisCarsonMarine]

My opinion,the performance is about the same,the 7's do well all around,and can be a little thinner(better bottom end)than the sport jets.The sport jets originally came in the 240 sport jet motor and were fitted with 020 glass reeds,for 6000 rpm service,too fragile for high rpm.Carbon or thicker glass can work,but the carbon chips and the thicker(heavier) glass is hard on the reed edge and the cage itself.Seen several cages collapse at sustained high rpm.At 9000 rpm they're opening and closing at 300x per second...and they do open and close.
The lighter (smaller)petals on the 7's are easy on the cage,and the seal contact area is loaded less,I perfer them on most motors...Chris

[CI STV]

My opinion,the performance is about the same,the 7's do well all around,and can be a little thinner(better bottom end)than the sport jets.The sport jets originally came in the 240 sport jet motor and were fitted with 020 glass reeds,for 6000 rpm service,too fragile for high rpm.Carbon or thicker glass can work,but the carbon chips and the thicker(heavier) glass is hard on the reed edge and the cage itself.Seen several cages collapse at sustained high rpm.At 9000 rpm they're opening and closing at 300x per second...and they do open and close.
The lighter (smaller)petals on the 7's are easy on the cage,and the seal contact area is loaded less,I perfer them on most motors...Chris

Thanks very much for wading in and sharing your knowledge. That all makes sense to me. I’ve heard of the carbon fiber reeds chipping, so I’ve always stayed away from them. Not a big believer in the carbon fiber hype, whether it’s reeds, driveshafts or hulls, for that matter.
Its hard to imagine those reeds opening and closing at 11,000rpm
After I get my setup dialed in better, I think I’m going to get myself some 7 petal cages and a set of your Drag reeds and try those and see how they compare.
Thanks again.

[HStream1]

Im not going to get into a Pissing match on here with anyone as far as Reeds and cages go. But If anyone would like to PM me as to which Cages and reeds performed the best on the Dyno in a Drag engine Ill be glad to share what I know. But I will say this. The 4 Peddle MAD EFI, Chopper City and 5 Peddle mercury, Chopper City Cages Out performed the Mercury seven peddle in every aspect, it didnt matter whos reeds, what material or thickness was used. Simply put the 4 and 5 Peddle cages flow more air. The Opened up seven peddle's did do a bit better than standard but still didnt out perform the 4 & 5. As far as the 5 Peddle mercury cages there were two styles. The first ones did have cracking issues on the outer edge at high RPM's. But mercury corrected that by adding a Gusset to the outer corners.

[CI STV]

Im not going to get into a Pissing match on here with anyone as far as Reeds and cages go. But If anyone would like to PM me as to which Cages and reeds performed the best on the Dyno in a Drag engine Ill be glad to share what I know. But I will say this. The 4 Peddle MAD EFI, Chopper City and 5 Peddle mercury, Chopper City Cages Out performed the Mercury seven peddle in every aspect, it didnt matter whos reeds, what material or thickness was used. Simply put the 4 and 5 Peddle cages flow more air. As far as the 5 Peddle mercury cages there were two styles. The first ones did have cracking issues on the outer edge at high RPM's. But mercury corrected that by adding a Gusset to the outer corners.

Thanks for your input. That’s good to hear. I’m pretty sure that Diamond wouldn’t have installed them on their intake if it there wasn’t a performance advantage, and I’m sure they wouldn’t use a cage that they knew could collapse at high RPM, since they built this motor specifically for racing.

[Chaz]

If I ever find the need to do another run of billet cages ..



Instead of just bringing the area where the ribs join together .. down a bit and sharpening the hump .



I think it would be smart to "compartmentalize" each section. The columns of air would be given velocity, direction and less likely to tumble away from being split at the last moment by the rib.
The only possible downside would be the room they take up and the added boundry layer of air the extended wall would make.
In this case, the good has to outweigh the bad.



Lake .. a lot has changed since seats were cut with stones .. LOL
The "old" Serdi seat and guide machines could cut a five-angle valve job as well as sweep the wall for a larger valve.
You had to put the head on the block and scribe the bore into the deck , so you could unshroud the valve as much as possible without getting into the gasket ring. But you could only do a straight plunge cut.

My bouyys down the street sold their Serti (thought they were nuts) and now have two Newen CNC seat machines. They can open the throat to a desired diameter percentage, cut as many angles as they can dream up, blend the top cut into the chamber and do a compound sweep that rolls off of the chamber cut, goes wide and then comes back in as to not get into the deck .. unless they want . Really an amazing machine.
Time marches on .. but I'm glad I'm not the only one who remembers turning down the O.D. of a valve head and using it as a template as to how much material to remove from the throat .. shine a light down the port .. Oh-oh .. lil more right there ..





Professor .. I caught that open-close statement .. We'll continue that conversation over a sweet-tea @ the fish house this summer .. good lord willin !