Mercruiser 888

[mauro.]

hey guys I am back again I got a 898 1:65 ratio leg and put it on with the 19 pitch 4 blade prop. i got on plane with top speed of 51 kmh but only to 31 hundred rpms. Do you guys think I am just way over proped or is there something else? Thanks for all the help so far
M.

 

[Scott Danforth]

not sure on how large the boat is, however check your compression. all cylinders should be above 135psi and within 10 psi of each other.

your RPM and speed would indicate either your motor is tired or your boat is really really heavy in which you are way over-pitched.

why did you go with a 4-blade? going to a 19P 4-blade is similar to a 20-21p 3-blade.

 

[Scott06]

hey guys I am back again I got a 898 1:65 ratio leg and put it on with the 19 pitch 4 blade prop. i got on plane with top speed of 51 kmh but only to 31 hundred rpms. Do you guys think I am just way over proped or is there something else? Thanks for all the help so far
M.

verify the tach is accurate first. then yes over propped and or wrong gear ratio. would need to drop at least 4" in pitch if tach is correct.

Were you running it previously with a different ratio leg or is the boat new to you. Agree do some checks as mentioned above including check timing and advance

 

[mauro.]

copression is all up at 150 145, boat is a Reinell 22 ft cuddy cabin glass boat. I have been having truble since i bought it. As i said in previous threads the engine was all rusty so got all cleaned then figured out that it had a 1;32 raito in the leg so that explained why it wouldn't go above 1800 rpm at first with the 19 pitch 4 blade but would get on plane and to 2400 rpm with three blade 17 pitch now that I got the differnent 898 1.65 raitio I get to 3100 rpm with 4blade 19 pitch. Thach should work it is brand new.

 

[Scott06]

copression is all up at 150 145, boat is a Reinell 22 ft cuddy cabin glass boat. I have been having truble since i bought it. As i said in previous threads the engine was all rusty so got all cleaned then figured out that it had a 1;32 raito in the leg so that explained why it wouldn't go above 1800 rpm at first with the 19 pitch 4 blade but would get on plane and to 2400 rpm with three blade 17 pitch now that I got the differnent 898 1.65 raitio I get to 3100 rpm with 4blade 19 pitch. Thach should work it is brand new.

Dont have the previous posts memorized might be good to link them. Yeah 1.32:1 is too tall for the set up. the engine is a 888 - 190 hp 302 ford?

My current boat is a 21 ft bowrider so a head smaller and bit lighter than what you have. it was originally equipped with a 4.3 vortec 2bbl 190 hp with a 1.81 drive ratio. The PO busted the block but it had a 19" 3 blade venence prop on it so I assume that was ok. given your boat is bigger and has similar power would think the 1.65 is still a little tall. Have you tried it with the 17" pitch.

I would think assuming the tach is working and you have good ignition/advance, fuel is getting there that a 15 or 13" prop will get the rpm just over 4000. If I recall the 888 had a fairly low WOT rpm range?

 

[mauro.]

Yes it is the 302 ford has a new comp cam and pertronix dist new coil cables plugs supposed to be putting out around the hp you mentioned.

Havent tried with the 17 pitch due to it having sliped once and i don't want to risk blowing the engine. WOT should be between 3800 and 4200.

So you figure a 15 of even a 13 pitch will get me there? I dont' realy want to search for another legI have atatched the previous posts in the link below. https://forums.iboats.com/threads/m...-in-gear-in-the-water.775000/unread?new=1Copy

 

[Scott06]

Yes it is the 302 ford has a new comp cam and pertronix dist new coil cables plugs supposed to be putting out around the hp you mentioned.

Havent tried with the 17 pitch due to it having sliped once and i don't want to risk blowing the engine. WOT should be between 3800 and 4200.

So you figure a 15 of even a 13 pitch will get me there? I dont' realy want to search for another legI have atatched the previous posts in the link below. https://forums.iboats.com/threads/m...-in-gear-in-the-water.775000/unread?new=1Copy

yes Probably a 15 will do it. Certainly you wont have direct pitch drop to rpm increase if you are bouncing between 3 and 4 blades but you can figure 400 rpm change for every 2” pitch change up or down.

as an example as mentioned I bought a boat in need of a repower. Originally had a 4.3 /190 hp but boat was offered with 5.0 up to 260 hp. i repowered with a 5.0 upgraded with 4 bbl carb in theory was 260 hp, kept the 1.81 drive vs getting a 1.62 that the boat with a 5.0 would have come with. Stepped up in pitch for a 19” 3 blade and found that 21” Revolution 4-4 blade works great as did a 22” 3 blade enertia.
So based on that if you drop 4” pitch or so you should be ok. would be great if you can work with a prop shop to try a few. Personally I prefer 4 blades for loaded watersports but depends on how you use your boat

 

[Bondo]

Yes it is the 302 ford has a new comp cam and pertronix dist new coil cables plugs supposed to be putting out around the hp you mentioned.

Havent tried with the 17 pitch due to it having sliped once and i don't want to risk blowing the engine. WOT should be between 3800 and 4200.

So you figure a 15 of even a 13 pitch will get me there? I dont' realy want to search for another legI have atatched the previous posts in the link below. https://forums.iboats.com/threads/m...-in-gear-in-the-water.775000/unread?new=1Copy

Ayuh,...... Have you cross-checked the tach against a known good shop tach,..?? yer numbers don't sound right,.....
That motor should be happiest at 4400/ 4800 rpms @ Wot,.....
And, yer not gonna find a 13" prop,..... 15" is as small as they go from an I/O,.....

 

[Scott06]

I know some of the older engines had really low WOT ratings but would think a ford 302 would be happier mid 4000's as well.

I think some are available in 13"s like this black max, but you will definitely find less options below 15" pitch

Black Max (16 x 13") MERCURY RH Propeller, 48-78114A45

www.boatpropellerwarehouse.com

 

[mauro.]

According to the service manual WOT is suposed to be around 3800-4200 rpm, you figure that it is too low?
from what I can tell the boat originaly was equiped with the 1.65 ratio cause the original leg had the letter C stamped which acording to Don's chart is the 1.65 raito. On mine somehow the previous owner who supposedly rebuilt it ordered the wrong gear set.
tach should be ok as it is brand new and on the 8 cylinder mode.

Do you guys figure I should just order the 13 pitch or should I first trie a 15 or even a 17 from the shop in town?

Oh and also I should probably add that it takes about 30 seconds or so to get on plane if you open it wide it will go to about 2800 then slowly edge onto plane and then when all trimed out will have the WOT of 3100 and top speed of 51 kmh. It has good power the 2800 rpms are instant and you can feel the push it just has a while to get out of the hole.

 

[Scott06]

According to the service manual WOT is suposed to be around 3800-4200 rpm, you figure that it is too low?
from what I can tell the boat originaly was equiped with the 1.65 ratio cause the original leg had the letter C stamped which acording to Don's chart is the 1.65 raito. On mine somehow the previous owner who supposedly rebuilt it ordered the wrong gear set.
tach should be ok as it is brand new and on the 8 cylinder mode.

Do you guys figure I should just order the 13 pitch or should I first trie a 15 or even a 17 from the shop in town?

Oh and also I should probably add that it takes about 30 seconds or so to get on plane if you open it wide it will go to about 2800 then slowly edge onto plane and then when all trimed out will have the WOT of 3100 and top speed of 51 kmh. It has good power the 2800 rpms are instant and you can feel the push it just has a while to get out of the hole.

First verify the tach is correct vs a shop tach as a sanity check. Dont care if the tach is new, easy to do rev it up in neutral see what shop tach says vs dash tach.

IF you have a prop shop that will let you try before you buy that is the best way to go. I would start with a 15 based on what you have given, 17 will be too tall unless your tach is wrong.

 

[mauro.]

Alright I wil have a look if they stock a 15 an then see what happens will check with shop tach.
Thanks a lot for the help
Mauro

 

[Bondo]

According to the service manual WOT is suposed to be around 3800-4200 rpm,

Ayuh,...... What manual is that,..??

The 1.32:1 ratio was only offered for a short time, with the 351 Ford Windsor motors,....
The original 302s ran the 1.50:1 ratio,....

 

[mauro.]

it is the original 2 volume mercury marine maunal in orange covers it covers all alpha one and pre alpha as far as I can tell.In the prop recomendation chart they say for a 21-24 foot boat they recomend a 17 pitch with the 1.50:1 ratio and WOT rpm of as said 3800-4200 rpms But you figure it is too low?

 

[Bondo]

Yes it is the 302 ford has a new comp cam

Ayuh,....... Which comp cam,..?? What are it's spec.s,..??

 

[mauro.]

cams part no is 31-213-4 it is the marine cam makes power between 800 and 4800 rpm it was the only one left they don't make it anymore.

 

[mauro.]

specs can be found on sumit racing when you put in the part no easier than listing on here but just isn't awailable any more

 

[Scott Danforth]

Camshaft, Hydraulic Flat Tappet, Duration 252 Int./252 Exh., Lift 0.432 Int./0.432 Exh., Lobe Separation 112, Ford, SBW, 221-302, Each

Really a mild cam

 

[mauro.]

Do you think that is part of the issue?

 

[Scott Danforth]

Most of the Ford marine cams I found are in the 260 degree, 0.445" lift range

At a minimum, go up in rocker ratio

It may be part of your issue, but not all of it