1500 Xs

[mk55]

Can someone tell me what year this motor was made and is the power rated at the prop or crank.

A friend of mine has one on a yellow and white power cat boat and it runs in the mid 50's which we think should be faster. Any comments on motor and boat would be appreciated.

[Droll]

Can someone tell me what year this motor was made and is the power rated at the prop or crank.


Were made in 1977 and 1978, was rated at the crankshaft ( 155 hp ), prop rating started in 83.
Some earlier engines were almost identical, but weren't XS models .

Arne Kjetil

[largecar91]

They started making them in 76.

[T2x]

Can someone tell me what year this motor was made and is the power rated at the prop or crank.

A friend of mine has one on a yellow and white power cat boat and it runs in the mid 50's which we think should be faster. Any comments on motor and boat would be appreciated.

How big is the Power Cat?

Does it have a wedge?

What prop are you running.

I had a Power Cat 14C years ago with a single 85 inline and it only ran about 50 because it cavitated like nothing you've ever seen. The props back then were nothing like today and the best performance I could get was with a 3 blade aluminum wheel....the two blade nibrals and bronze (race) props didn't work at all.

T2x

[mk55]

It appears to be about 16 to 18 feet long. has two rows of seats. I do not have the boat , that is why I can;t be more specific. Just went for a ride and had to hold on like crazy as it just went around corners flat, no sliding or tipping. The driver of course had his hands on steerwheel and throttle to hold on to, but me nothing but brace myself against the side panels which were quite low. No windsheild on the boat either.

[Mark75H]

Sounds like the boat and set up are at the most primitive brute force configuration.

You are have to bring much more information to the table to get help. "appears to be 16 to 18" feet describes a wide range of catamarans, many models

# 1 is exactly which model this is
# 2 is exactly what prop is on it now
# 3 is what is the rpm at max speed
# 4 is how far below the bottom of the boat is the centerline
of the prop shaft

it goes on from there

[Sunburnt]

I thinks it's this one. It was reported to go into the 70's a couple of years ago... Hmmmmm...:rolleyes:

http://www.powercatboat.com/Group/jh_15t/jh_15t.html

[mk55]

Thats it, the exact one. Gene Church of the twin cities now has it. The speedometer dosent work so we are guessing. some one with a gps said it said around 60 mph but how he could read at the speed it goes is beyond me. Any idea of what something like this sells for?

Did you do the restoration on it being you have the photos. How fast did it go with the driver in the photos 70?

Also how does the boat run with the twin 70's on. You have 10 less horsepower and about twice as much weight with an extra motor. Also are these direct reverse motors so you can use conter rotating props are are they both turing the same direction?

[mk55]

Sounds like the boat and set up are at the most primitive brute force configuration.

You are have to bring much more information to the table to get help. "appears to be 16 to 18" feet describes a wide range of catamarans, many models

# 1 is exactly which model this is
# 2 is exactly what prop is on it now
# 3 is what is the rpm at max speed
# 4 is how far below the bottom of the boat is the centerline
of the prop shaft

it goes on from there

sorry I got you upset but I was just interested in general info but got the whole story. never know when it helps to ask stupid questions. I have learned from it all my life.

[198688]

I have a 1974 Merc 1500 mounted to a 1985 Baja 16ss. Total stock set up with a long shaft and a 21 pitch SS prop. The boat tops out at around 60 MPH at 5900 rpms. Our region in Wisconsin has gone to vitually all reformulated fuel with ethanol and I believe the motor runs like crap since I have been using this fuel even the 93 octane seems to be garbage. I was thinking of running 110 octane racing fuel to see how the motor reacts but maybe I need to adjust timing before I try that-Any Suggestions???

[mk55]

If you use that ethanol crap you will have to change fuel lines make sure you ad something to your fuel tank to keep it from rusting etc. the stuff is bad news for anything but modern fuel injection engines and still will give you less power. why less power, low btu , and you didn;t raise the compression on the motor to compensate. try avation fuel. That is what I use in my old 1948 john deere tractor and it runs great on it. we have many farmers who had to learn the hard way that the stuff may make them rich at 7 bucks a bushell for the corn that they get but can ruin their old tractors in a hurry.

[198688]

Thanks for the suggestion. Any timinig issues or should I leave it at 23 degrees when going with the aviation fuel? Any thoughts on the racing 110 octane option. I do have a nearby source for it.

[Sunburnt]

Thats it, the exact one. Gene Church of the twin cities now has it. The speedometer dosent work so we are guessing. some one with a gps said it said around 60 mph but how he could read at the speed it goes is beyond me. Any idea of what something like this sells for?

Did you do the restoration on it being you have the photos. How fast did it go with the driver in the photos 70?

Also how does the boat run with the twin 70's on. You have 10 less horsepower and about twice as much weight with an extra motor. Also are these direct reverse motors so you can use conter rotating props are are they both turing the same direction?

Hi MK55,

I didn't do the resto of the yellow boat I only knew about it thru our PowerCat group. I can't comment on what was, or wasn't done to it other than paint and interior. here is a link to the PowerCat site, lots of cool things to look at. http://www.powercatboat.com/

Set up and running good I would expect mid 60's, you need a good prop and tach to get it dialed in, there a little tweaks that can bring stuff around, playing with engine height for example. Have Gene call Dick Davis (they know each other very well) I think they've already spoken this week.

Dick and I restored the white one with the 700's, it's a true Cat. Best we got was 55 or so with junk props. We've since installed a pair of 1000's, when they are sorted out we expect to see high 60's low 70's. (we just rebuilt one of the powerheads and should have fire in the holes this weekend.)

Price? If I could get 1/2 of what I have into mine I'd feel lucky, it's not about the money.

I'm running gear shift lowers both right hand..

Jeff

[LightNBug]

sorry I got you upset but I was just interested in general info but got the whole story. never know when it helps to ask stupid questions. I have learned from it all my life.

There's only 2 stupid questions, the one you already know the answer too and the one you don't ask.

[Jeff_G]

198688, do a search on the 150XS and there is a host of information on timing, jetting etc.
Drop your timing to between 19* and 21* at WOT. Change the high speed jets to 82's or 84's.

[Raceman]

1500XS was made 76, 77, 78.

110 octane race fuel won't hurt the engine, but you may experience a slight loss in performance. More octane than the engine needs can hurt, but it will add a safety net against detonation. You can always cut the race gas with pump gas. Half 90 octane and half 110 will work out as expected......... around a hundred. I run super unleaded with 1/3 race gas in my 1500XS just for a little extra safety because I'm too lazy to want to rebuild an inline 6 powerhead. Super unleaded by itself it probably adequate if you could get it without the ethynol.

[specboatops]

198688, do a search on the 150XS and there is a host of information on timing, jetting etc.
Drop your timing to between 19* and 21* at WOT. Change the high speed jets to 82's or 84's.

Thats good info, I believe my 74 1500 J Block is set at 26 degree's btdc

[mk55]

I remember a guy at Tommahawk asked gene if his xs was the j block and gene didn;t know. just what is the j block on an xs and evidently they came either way, j block or not.
Also when the hp was rated at the prop what was the biggest hp inline merc made before they discontinued it. don;t count the twisters and bp, just fishing motors.

[specboatops]

I remember a guy at Tommahawk asked gene if his xs was the j block and gene didn;t know. just what is the j block on an xs and evidently they came either way, j block or not.
Also when the hp was rated at the prop what was the biggest hp inline merc made before they discontinued it. don;t count the twisters and bp, just fishing motors.

I was always told if it was a true XS it would have the " J " stamp on the starboard side of motor, also you could tell by the motor number stamped ....
Raceman will probably know.

[Powercat]

I thinks it's this one. It was reported to go into the 70's a couple of years ago... Hmmmmm...:rolleyes:
......
Speed Secret... This is how you get 70mph from a Power Cat 15t with a 150xs rigged
with carpet and full interior... ( See arrow in photo below)

[T2x]

......
Speed Secret... This is how you get 70mph from a Power Cat 15t with a 150xs rigged
with carpet and full interior... ( See arrow in photo below)

Considering that a 15C (faster hull) ran in the low 70's with 200 hp....... I tend to agree......;)

T2x

[mk55]

How can a speedo be that much different than a gps. 60s on a gps and 70s on a speedo????????????????

[Jeff_G]

Now your catchin on.

[T2x]

Now your catchin on.

exactly......

The standard speedos back then were a joke..... Even the Kellers and Nordskogs were plus or minus 5% at best.

I learned very early that you used a speedometer only to determine comparisons in setup on the same boat (if one prop showed 64 mph and another showed 68- that meant that one was APPROXIMATELY 4 MPH faster)....but never to figure out how fast you were actually going.

T2x

[xskid]

they made them 1974 to 1978,74, 75 were blue striped, louverd cowl, no low water pickup. all xs 150 had the j stamped on block, no j, no xs. just got back from clayton, nice time, but need more outboards.

[Mark75H]

Blue XS must be pretty rare, I haven't seen one in person yet.

[Michael J Giesler]

kellers speedos were close to the real speed of the boat i had someone with a gps on my ally once it said I was doing 107 in a grandsport I say gps are are not 100% because my gs barely hits 100.

[Raceman]

they made them 1974 to 1978,74, 75 were blue striped, louverd cowl, no low water pickup. all xs 150 had the j stamped on block, no j, no xs. just got back from clayton, nice time, but need more outboards.

Not exactly............ The XS didn't come out until '76. The short '75 motor (and apparently some of the '74's) were simply refered to as J engines back then. The '74 Merc brochure doesn't show a louvered cowl on the shortshaft 150, but several people here have said they have original one owner 74's with louvers and J powerheads, so must've been a during the model year change.

As far as the speedometers go, they could pretty much be made to read anything back then. The local Merc dealer in mid 70's called 'em happiness meters and had a airline regulator and panel made up to set em all to run about 15 MPH fast on a 65 MPH bassboat. They used Airguide speedos as their dealer installs and they were easily calibratable.

[rnelems]

Help out my bad memory here. I am looking at an old photo of my Checkmate tunnel boat,photo is dated June 1974. My 1500 is a 1974 short shaft,decals clearly show it to be 1974. It is not an XS,but it does have the louvered wraparound.We rigged this motor in 1974 and made no mods.I guess the short shaft 1500's had the louvered cowl?

[mk55]

did the extra 5 hp of the xs make any difference in speed?

[MN4V]

Help out my bad memory here. I am looking at an old photo of my Checkmate tunnel boat,photo is dated June 1974. My 1500 is a 1974 short shaft,decals clearly show it to be 1974. It is not an XS,but it does have the louvered wraparound.We rigged this motor in 1974 and made no mods.I guess the short shaft 1500's had the louvered cowl?

The louvered cowls were an accessory from Mercury and legal to race. The only stock 1500 motor that came from the factory with a louvered cowl was the 1500XS.
There may have been a time when the louvered cowl was not legal in the stock classes like Sport J and Family J classes.
Mark N

[Raceman]

Help out my bad memory here. I am looking at an old photo of my Checkmate tunnel boat,photo is dated June 1974. My 1500 is a 1974 short shaft,decals clearly show it to be 1974. It is not an XS,but it does have the louvered wraparound.We rigged this motor in 1974 and made no mods.I guess the short shaft 1500's had the louvered cowl?

I'll run through the chronology again: The shortshaft 1500 first came along came along in '73 along with the other 1500's. It did NOT have a louvered cowl or a J block. In '74 the first 1500's did not have louvered cowls or J blocks either, but based on the fact that several people have stated here in the past that they had '74 engines with J blocks AND louvers it must've happened somewhere in the '74 model year. The '74 Merc sales brochure that I have shows a shortshaft 1500 with the '74 stickers and NO louvered cowl. All '75 shortshaft 1500's had J & louvers. The first engine called XS came in '76 and had louvers and red stickers on the cowls, and ALSO low water pickups. NO blue stickered pre '76 engine had low water pickups unless some of the guys the factory helped got em early, and I think I'd have seen em at the APBA/OPC nationals in '75 if this was the case since I was REAL into the JP class back then and had both '73 & '75 stuff myself.


did the extra 5 hp of the xs make any difference in speed?

Yes it did, on a light/fast boat......... probably several if my memory serves. The '73 1500 powerhead on my '71 Allison was upgraded to a new from Merc '75 J powerhead and it picked up about 3 on the speedo. It might've been a tad more than that on a SJ boat. I also put a 1500 J powerhead on my 18' SuperSidewinder and couldn't make it run any faster than the std. powerhead from the '75 model 1500 that it replaced. This was after I'd put the first T3 on my 15 Ally and had the 1500 stuff layin' around.


The louvered cowls were an accessory from Mercury and legal to race. The only stock 1500 motor that came from the factory with a louvered cowl was the 1500XS.
There may have been a time when the louvered cowl was not legal in the stock classes like Sport J and Family J classes.
Mark N

Again, that's not exactly true. ALL '75 shortshaft 1500's came from the factory with louvered cowls, and APPARENTLY part of the '74 production run also. (I base that "apparently" on the fact that at least 2 people here have said in past threads that they OR their family members have '74 engines that they bought new that came with the louvers and the J powerheads from the factory. Until that time I was always under the impression that those two characteristics began in '75) These engines were NOT categorized as XS and did not have the factory low water pickups or red stickers. I also had one of these engines that I bought new. The '75 shortshaft 1500 is also one of the best looking engines Merc ever built with the blue stickers and the BIG 1500 lettering on the sides of the top cowl. First XS's were in '76.

[LightNBug]

If you research the question of the louvered cowls and low water pick ups using Merc's micro fiche you will see that 1974 did have the louvered cowl and that a group of 1500 shorts had low water pick ups before the first XS serial group.

[dale robertson]

I had a 74 with the louvered cowl, that was bought around Feb. or early March. It didn't have low water pick-ups and we didn't know why it was faster. We bought two because the rumor mill said the short shafts with the louvered cowl were faster. I have some close up pictures of the engine somewhere, but here is one on the boat.

[Raceman]

If you research the question of the louvered cowls and low water pick ups using Merc's micro fiche you will see that 1974 did have the louvered cowl and that a group of 1500 shorts had low water pick ups before the first XS serial group.

I just don't believe it. Micro ain't exactly what you'd call a fail safe system of how/when/why and I've seen several inconsistencies when looking up some 850XS stuff on my set. I was at a bunch of APBA races in 75/76/77....... nationals every year, ST. Louis, Eufaula, Miami, etc, etc. and I NEVER saw a blue striped motor with low water pickups until the red striped XS's came out in '76.

Too many people, now including Dale have said they had '74 model engines with louvered cowls to discount it as not accurate, but again, the brochure I have shows the non louvered cowl with '74 stickers. Merc wasn't above making a running change within a year model. The fact that the 1400 was available ONLY in longshaft for the first part of '72 is a prime example. My friend who's father worked for Merc got a short '72 1400 when many of the racers who had raised their transom heights for the 20" 1400 since the new powerhead wouldn't bolt onto their short 1350 mids didn't think they were available when he showed up at a race with one on a pleasure boat.

[dale robertson]

I don't remember any low water pick-ups until the 1500XS (Redstripe). I would liked to have had them.

[mk55]

I asume the lovered cowls were for better breathing of the carbs, but wouldn;t they have worked better with the openings facing forward instead of rear.
I know of a merc dealer, Roger "Tiger" Hanson back in the mid 70's had a switzer with a fishing 135 on it and when he was trying to get 60 mph he always ran it with the front cover off and some window screen inside to stop bugs from getting in. As long as I was still in the area he never did hit the magic 60 mph.
Also, the prop he was using was a hubless made by michigan and made the motor scream until he got up on plane. I always questioned that as the prop was always turning in bubbles from the exhaust. I tried a 13 inch pitch version of it on my 50 merc on a 12 foot jetstreak and if ran no faster that a merc 13 with prop jet exhaust. both went 42 mph by the spedo but the opc michigan prop did not have any hole shot at all.
Did those props ever turn out to be any good?????????

[Raceman]

I suspect that the louvers were more to keep the air around the powerhead from heating up than just for breathing itself. Some of the louvers face foward and some backward.

As far as the Michigan hubless wheels, I had several of them myself in the 70's because they were considerably cheaper than the Mercs. The Michigans that I had were hubless 2 blades in both bronze and stainless. They were thicker than the Mercs and slower. They also didn't have a rubber clutch in them like the Mercs did, and made a terrible clunking sound if you forgot and shifted from neutral into a gear with the engine running. Merc never made over hub bronze, and the Michigans looked awsome if they were polished on a buffer, but looks didn't win races......... not even one on one lake races.

[rnelems]

I still have one of the old 2 blade hubless Michigans,14x 28 I believe.If memory serves,I bought it because the 2 blade Merc stainless props were on backorder.This was maybe 1971 or so?I remember ordering my first 14x28 Merc stainless for my Checkmate MX-14,had it shipped by air freight,outran all of my buddies that weekend cause all they had were the 2 blade bronze hi-perf Merc thru hub props.Funny that I can't remember what I had for lunch yesterday but I can remember driving to the airport for my prop 37 years ago.

[B. Robertson]

Here is a picture of a 74 150 with the louvered cowl. We ran re-hubed D.A.H. 3 blade cleavers. This didn't make Don very happy, but I was running a Johnson on the boat before this engine and already had the props. They worked a lot better than anything else I tried.

[T2x]

I suspect that the louvers were more to keep the air around the powerhead from heating up than just for breathing itself. Some of the louvers face foward and some backward.

As far as the Michigan hubless wheels, I had several of them myself in the 70's because they were considerably cheaper than the Mercs. The Michigans that I had were hubless 2 blades in both bronze and stainless. They were thicker than the Mercs and slower. They also didn't have a rubber clutch in them like the Mercs did, and made a terrible clunking sound if you forgot and shifted from neutral into a gear with the engine running. Merc never made over hub bronze, and the Michigans looked awsome if they were polished on a buffer, but looks didn't win races......... not even one on one lake races.

Michigan also made through hub props...... The 410 was a 25" pitch wheel that ran well on JJ boats in the mid 60's. At that time they were faster than anything Merc had with the exception of John Culver's modified props which took about 2 hours to plane. One day a young engineer named Dick Schneider from Merc walked up to us and handed us a pair of "elephant ears" at the 66 Orange Bowl...and the rest is history. Dick is retired now but he was and is a great guy.

T2x

[AirRide]

Here is a picture of a 74 150 with the louvered cowl. We ran re-hubed D.A.H. 3 blade cleavers. This didn't make Don very happy, but I was running a Johnson on the boat before this engine and already had the props. They worked a lot better than anything else I tried.Welcome to the board B. Robertson.;)

[xskid]

the merc parts catalog calls them xs in 74 as well as 75,76,77,and78. low water pickup came in 76. as well as red decals that said xs . they used louverd cowl also in 74 and 75, but used the standard blue decals. i have an original late 74 j motor. the 73 1500 did have more punch, and mid-range than xs and 74 and up standard 1500s. but not as much top end as xs. i am starting to put another nos j block together to put on 14 ft ally. will be at mt dora. in march. 850xs does not turn speedmaster good. cant find smaller prop. i have a 9 x 15 3 blade cleaver. need more rpms. .... inline-6 will solve that problem!!!

[mk55]

What is the 850xs and I hear there was a 90 hp 3 cylinder. any info on this would be appreciated thanks.

[Raceman]

What is the 850xs and I hear there was a 90 hp 3 cylinder. any info on this would be appreciated thanks.

The 850XS was nothing more than a STD 850 powerhead on a 15" mid section with low water pickups (2.3 gear ratio just like the std 850) and red stickers. Unlike everything else in the XS series there was NO powerhead upgrade in the 850XS.

[Raceman]

the merc parts catalog calls them xs in 74 as well as 75,76,77,and78.

Well, then that means the Merc Parts Catalogue is WRONG. 1976 was the first year of the 1500XS although it was very similar to the previous year's "J engine" as it was commonly called then. It happens when a current crop of employees that weren't even around when an engine was current start upgrading factory literature. One of my big pet peeves is the GM literature that lists the L88 427 Corvette engine as 435 horsepower. The 427/435 Corvette engine was actually a LOT lower horsepower than the L88 and except for the bare block itself shares NO other internal components. Since GM has published that error in their Chev. High Perf parts catalogues for about a decade now, Crane Cams and some other aftermarket manufacturers have started referring to the L88 as 435 horse, and I even had some guy on the tech line at Crane arguing with me about the L88 and L71 (which is the 435) having the same camshaft number.

[Tom Smyth]

RM- your dead right about the 850XS motors.. but theyis still justa purty as the 1500's

[Tom Smyth]

definition of purty =

[SCT]

Tom, that thing is purty! You need to hang it on a boat though....

[BUIZILLA]

how hard is it to find an 850 XS ??

[Tom Smyth]

SCt:

I know i know. Gund deal didnt go and the kitchen remodel has future plans on hold till end of the year. Got a Mark 10 Troll Twin ready to go with all th eparts ( and auto tranny) sitting right here. just no time.

Hope to start seriously looking for a boat fo rthe 850Xs in Jan or Feb

Did you sell your MX-13 yet ?

[bnjackson5]

I have access to a 1500xs that has the vented cowling and looks pretty slick with a 15" mid but needs a lower. I probably can get it pretty cheap. What's it worth?

[Mark75H]

Its hard to say ... the powerhead could be fine or it could have hidden damage from just sitting over time that makes it basically worthless

[bnjackson5]

I know the motor runs fine, my bros an outboard mechanic and he showed me this motor y-day and he asked me to see what you fellas might know about it. Someone left it at the shop he works at awhile back and would probably let it go pretty cheap.

[Tom Smyth]

check the serial number to make sure its a J block.. could be any in line 6 with a louvered cowl

And if he wants to dump it PM me. i am interested in a mate for the 850XS