5.7 Engine swap

[Flyinb]

After determining i need a new engine and manifolds for my 1984 Sea Ray 260 engine#6872480 i just found a deal on a later 80's 350 magnum engine#B779915 with low hours, good compression complete minus carb and coupler. Would everything be compatible? The manifolds look different but seem to have the same angle and dimensions as my old ones and not sure if my engine coupler would bolt on to the fly wheel? Looks like my quadrajet will work on the intake manifold.

 

[Bondo]

Re: 5.7 Engine swap

Ayuh,.... Not sayin' there Won't be any Gotchas, but it's a reasonbly straight forward swap...

If yer coupler bolts to the flywheel, it'll work...
If it bolts to the crankshaft, it Won't fit, the bolt pattern is different, startin' in 86/87...
Ditto the carb, which mighta been a quadrajet, or possibly a Merc/ Weber...

 

[Flyinb]

Re: 5.7 Engine swap

Well got the engine and found my first "Gotcha" the new engine's flywheel is about 1 inch larger than my old engines and the coupler bolts to the flywheel verses the crankshaft on the old engine. No problem as i will get a new coupler anyway, the real problem is my rear flywheel cover/engine mount wont work on the new engine as it don't seem to have enough clearance for the bolts that hold the coupler on and the fella i got the engine from diden't have the mount handy so i hope he can find it.

 

[Bondo]

Re: 5.7 Engine swap

Well got the engine and found my first "Gotcha" the new engine's flywheel is about 1 inch larger than my old engines and the coupler bolts to the flywheel verses the crankshaft on the old engine. No problem as i will get a new coupler anyway, the real problem is my rear flywheel cover/engine mount wont work on the new engine as it don't seem to have enough clearance for the bolts that hold the coupler on and the fella i got the engine from diden't have the mount handy so i hope he can find it.

Ayuh,.... If ya search iboats, I believe Sierra sells a conversion coupler that'll work, but you'd need the smaller flywheel to fit yer motor,...

Does the new block have 2 starter bolt holes, or 3,..?? If 3, you can run the small wheel...

 

[Scott Danforth]

Re: 5.7 Engine swap

Well got the engine and found my first "Gotcha" the new engine's flywheel is about 1 inch larger than my old engines and the coupler bolts to the flywheel verses the crankshaft on the old engine. No problem as i will get a new coupler anyway, the real problem is my rear flywheel cover/engine mount wont work on the new engine as it don't seem to have enough clearance for the bolts that hold the coupler on and the fella i got the engine from diden't have the mount handy so i hope he can find it.

I would also start searching craigslist and ebay for the parts if the PO cant find them

 

[Pete104]

Re: 5.7 Engine swap

Yea, this could be a puzzle! The exhaust risers at that time came both 3 & 4", as well as different down angles. 7 degree & 15 degree

 

[Flyinb]

Re: 5.7 Engine swap

Ayuh,.... If ya search iboats, I believe Sierra sells a conversion coupler that'll work, but you'd need the smaller flywheel to fit yer motor,...

Does the new block have 2 starter bolt holes, or 3,..?? If 3, you can run the small wheel...

From what i make of the conversion coupler is that it has a smaller dia bolt pattern to fit to the newer flywheel with one piece rear main seal (that i assume is what i got). If so all i need is the coupler and my older bell housing/engine mount will work with the newer engine??

I haven't checked the started bolts yet. Would both engines use the same starter with different mounting holes to allow for flywheel size or are the starters totally different models??

 

[Flyinb]

Re: 5.7 Engine swap

Yea, this could be a puzzle! The exhaust risers at that time came both 3 & 4", as well as different down angles. 7 degree & 15 degree

I did take one of my old risers with me and they are the same angle and dia.

 

[Bondo]

Re: 5.7 Engine swap

I haven't checked the started bolts yet. Would both engines use the same starter with different mounting holes to allow for flywheel size or are the starters totally different models??

Ayuh,... The starter mountin' holes determines which flywheel can be used....

A straight across pattern is for the 12" flywheel...
The Staggered pattern is for the 14" flywheel....
If yer block has all 3 holes, you can run Either flywheel...

They just have to Match...

 

[Flyinb]

Re: 5.7 Engine swap

Both blocks only have 2 holes for starter. Looks like the starter from the pre 86 block is different than the 86 and newer block as well. Was hoping i would have a spare starter, will still have plenty of spare parts from old motor. I think i will go with the Sierra #18-2172 coupler and use the bell housing/engine mount from my old engine, i hope

 

[Flyinb]

Re: 5.7 Engine swap

OK...Finally got the engine in the boat....To got from an 84 to a 88 engine the only things i had to do was (1) Use the Sierra conversion coupler (2) Modify the dust cover on the front of the bell housing a bit (3) Find longer 3" exhaust tubes that connect the riser elbow to the Y tube on transom, i need to find some. Now if it runs well i will be very happy