help!!! i need to know what it is that my fater bought me??

[Bondo]

Re: help!!! i need to know what it is that my fater bought me??

----bore----
181 cid-----4.00
153 cid-----3.875

Ayuh,... That's .125".....
I seriously doubt there's enough Iron in that block to withstand that overbore, 'n still have cylinder walls...

 

[alilley]

Re: help!!! i need to know what it is that my fater bought me??

some more information:

the crank jernals 3.0
main- 2.2983 - 2.2993
rods - 2.099 - 2.001

the 153
main - 2.298 - 2.299
rod - 1.999 - 2.000

so according to that then the rods will interchange on the crank. now i have 2 set of rods to off. swo now it would be a matter of wither finding out if either set of rods and pistons will work in the 153 block due to deck heigth. the only way i can think of is to pull the motor out of the boat and tear it down, and tear the 153 down and see what fits. i will be getting a hold of "effingahm regrind" (they are very reputable in this field) to find out the length of the 2 differant rods to see if they will work

now some one please give me an insight here or should i say clear my thinking a little. since going to a longer stroke using the same piston/rod combo (ie the 153 set) the longer stroke will push the piston up further and pull it down more (3.6-3.25=0.35 longer stroke 0.35/2=0.175 is the distance further the piston will travel in both direction) so if the rod is 0.175 shorter then the other then in theory that would put the piston in the same spot and not push it out the top of the deck. now i know we are not talking a hole here but i also know that when builkding a motor ever .0001 of an inch counts. i will keep you all posted as i find out more info on the build as i know there are a bunch of 3.0 out there with the same issue

 

[fishrdan]

Re: help!!! i need to know what it is that my fater bought me??

I would continue to look for a 181CI block and forget the 153CI block as you will be loosing too much HP in (as you said) a marginal HP boat.

I had a 140HP Mercruiser in an ol' SeaSwirl tri-hull. At sea level it hauled azz, but at 6-7000' elevation (where it was loosing about 20HP due to thin air) it was a dog. To get marginal performance (slow planing) out of the boat I had to rejet the carb and re-prop the boat, but it was still a dog. This was expected up at that elevation,,, but I wouldn't want to have the boat running like that all the time.

 

[Howard Sterndrive]

Re: help!!! i need to know what it is that my fater bought me??

Dad found you a 2.5 for $65!

You can sell it (running) for 10 times that.

Take the $650, give it to dad and tell him to come back with a 3.0
and tell him keep the change.... sounds like he's a good bargain hunter.

 

[alilley]

Re: help!!! i need to know what it is that my fater bought me??

as long as i own this boat it will not see no 6 - 7000 elevation i live in central illinois and only there is only about 4 lake that i like to visit

if i am calculating correctly even if i use teh standard bore from the 2.5 i will only loosing 10 cubic inches of displacements and that should not be that much of a hp loss. if i have to slightly bore the 2.5 and not use the 3.0 set then i would regain a little of it back

as far as have dad look for a 3.0 well that is what he though he found for me and we very highly dought it if this motor runs we nabbed it for the block with the hopes to get a motor back in my boat.

i have a call in to a reputable shop that works with connecting rods to find out if both botors use the same rods i will post what i find out when io find it out