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View Full Version : Help me decide on a prop guys........



Moody Blu'
07-07-2002, 05:12 PM
ok, I'm a dumb ass, I always thought the pitch of the prop was on the flat surface behind the cone of the volvo drive.

after grinding the edges to make the prop smooth again(it had wves in it)
I saw the numbers on the side of the prop.

and here it is!!!!

14x23 i think it said 8 or 3 underneath the prop dimensions, anyone know what this means?

ok so...

I run 5300 rpm's with a gps speed of 53 mph(prolly faster now since the prop is smooth but i havent gps'd it)

I am pretty sure I can hit 65 with my motor.
it has gobs of torque.

sooo

do you guys think I should try a 26, 27, 28 even?

14 diameter or 15?

I cant wait to hit 65+ I know my baby will do it!

so what do you guys think I shoudl go for?

prettty good numbers for that motor right?

14x23 5300rpm's 53mph....(shes got 300 more rpms too)

so now I need suggestions........
thanks in advance!!!

Rootsy
07-07-2002, 05:22 PM
14 x 23 in prop jargon refers to diameter x pitch so 14 inches in diameter and 23 inches in pitch. does your sterndrive have adjustable trim like the newer volvos and mercruiser sterndrives? sorry i am not all that familiar with volvos, especially the 250's. without adjustable trim it is difficult to air out the hull which is where you gain your speed really unless you are running HUGE horsepower. i think you can set the drive in different holes but your on plane time and porpoising control will suffer. secondly at what rpm does your motor make peak horsepower (honestly) - you want to try to prop the boat so that it operates in that rpm range @ WOT. knowing sbf valvetrains fairly well i'd try to keep her below 5000 rpm unless you are running some serious valve spring pressures... more pitch and diameter will bring the rpm down but larger diameter is more mass to swing and can put a lot of torque on the hull. There are others here way more knowledgable than me when it comes to volvos... i'm a merc kinda guy...

Moody Blu'
07-07-2002, 05:51 PM
it has no trim and the pin is up as far as it can go

it makes its power from 1000-5000 - thats what the cam specs are I feel it makes tons of power around 4800-5200(peak)

thanks for the info about the sbf valve train, I usually run her at 4500-4800 but it tops out at 5300-5500 with out a skip.....

I do have a set of 351w heads I plan on sending out for all valve train work and larger valves, have any suggestions?
I would like to be able to rev it out and not worry about anything......this motor has like 30 hours on it so its fairly new.....

Rootsy
07-07-2002, 08:04 PM
i'd ditch the stock head rework for aftermarket cylinder heads, especially for some of the prices you can get these days... stock ford castings flow pretty poorly unless you do some SERIOUS port work... you won't see a whole lotta improvement by just popping larger valves in stock castings... but as usual if you are gonna do cylinder heads you need to have adequate induction and carburation as well as exhaust...

just a guess but is that drive trimmed out TOO far? like i said i don't know a whole lot about em.

mattyboy
07-07-2002, 08:32 PM
Moody,
Jamie is right the drive is too high, the volvo without trim always runs better in the middle notch on the drive, the top notch is just too high, I would try a 14 1/2 by 25 I'm doing the same for my boat,you need big hp to turn a 26 or bigger,
good luck Moody

Tony
07-07-2002, 09:38 PM
Roush heads for your sbf. I also run my Volvo AQ200 in the middle pin. I'm running 58mph at 5400rpm's with a 14 x 24 ss Volvo Ultra prop. I'm curious to try a 14 x 26 Ultra, but they are hard to find.

Rootsy
07-07-2002, 09:48 PM
Tony,

i don't have much research into the Rousch heads, how do they flow?

Moody,

if you want to go straight iron which i imagine you do cause of salt water use and you don't want to get into HIGH dollar stuff you might look at the world products windsor and windsor jr cylinder heads.. the Windsors would be what you'd want to lean toward. I am not even sure what SVO offers in a cast iron head anymore... and then there are always TFS, Canfield, edelbrock and a ton of others but mostly aluminum...most sbf's i put together these days are aluminum cylinder heads.... which are no good for salt water... i'd take tonys advice and look into rousch if they are iron... jack turns out some good go-fast stuff...

Tony
07-07-2002, 10:50 PM
Jamie, Roush heads are the same as World Products. They are supposed to be an improved version of the Windsor Jr. I got the Roush 200.
Here is a site describing them:
World Products Roush Heads (http://www.racerwalsh.com/v8_cylinder_heads.htm)

Moody, although I am quite novice, I spent a lot of time gathering opinions. Many felt that, for Fords, Roush is the way to go.
Here is a site comparing some of the other more common heads:
Cylinder Heads Compared (http://www.goautocenter.com/cylinder_heads.htm)

BigGrizzly
07-07-2002, 11:26 PM
I'm gointo throw a wrench into this mess. I am a Ford guy. blue - If you spin that higher than 5200 your in for trouble with the drive as well as the engine. The 351 has big rod bearings, not small ones. I am familiar with all the heads available and for the boat you are ok for now. TFS are the best but you would have to change a ton of stuff to make them work plus they are alumimum. We have gone through all of this before. I have turned the speeds you want and more. My pin was in the middle ( untill I put on a 290)and the prop was a 14 5/8 X 25 michican wheel. I now run a 15/23 Hill at thoes speeds or a 24 Ultra 4 blade (the prop they never made). It doesn't matter what heads you have if you pull 5200, thats great. Try another prop before you do anymore engine work. One other small detail, you can't buy a good exhaust for that motor to make the TFS or world heads work unless you spend over $5000 for a set of exhausts.

Randy

TD
07-08-2002, 07:13 AM
I agree with Grizz, prop it down to a mid 4000 rpm WOT. I have a 280 drive I run in the middle hole and a 14 x 26 ultra and at 4600 rpm I am seeing 57 mph on gps. Oh power is sbc. At this point I feel the only way to get more speed with this set up is more hp, but that will shorten engine life. so for the moment, I'm content.
hope this helps!!!!

turbo2256
07-08-2002, 09:00 AM
My shop is now flowing the SBF cast iron heads up to 225 CFM. The lower lift figures beat the aftermarket aluminum so unless your looking for lighter weight or running over a .6 lift cam. Priced at about $800 more or less. Depending on if we find castings or use yours .. valves .. guide conditions. These heads provide a real kick.

I should add cast iron SBC and CHRY have also been done up in the same way same prices. Also have Brodex Canfield etc available.

Moody Blu'
07-08-2002, 10:47 PM
wow, thanks for all the great replies.

I dont plan on doing any motor work just yet, but I do plan on getting moody up in the 60 mph range witha prop switch.

so are you guys telling me i'll get more speed with my drive down then up?

I highly doubt this.
I could be wrong though.
my boa drives great with the pin all the way up (aside from turning really sharp)

mattyboy
07-09-2002, 10:07 AM
Moody,
the middle notch is nuetral, your boat might run ok now in the top notch but with a different prop and faster speeds it may not handle as well, I have tried all settings on my 16 and the middle is the best the 18 might be a little different,
depending on the lift of the prop the boat might become a handful at wot,
the top notch was way too lose for me, lost top end, but built up my fore arms quite well!

Matt