opinions on sbc block options

[redjmp]

I just pulled my 77 305 mercruiser 898 and need to replace the block.
Just want to get her going with a used block for a few bux while I build something better to drop in next spring.
I am thinking about getting one running in a beat up car or truck rather than trusting one off the garage floor.....
What would be the best thing to get?
I would assume a 86 up truck motor? Would I need to change the cam?
What else besides the frost plugs, carb and electrical?
If I got a 350 block, could I use the 305 heads, intake, carb and electrical?

 

[Rob454]

Re: opinions on sbc block options

You can use the 305 heads on a 350 but it will give you too high a compression and unless you have work done to them it will flow a little less than the 350 heads. thats a trick some street hot rodders use to up the compression. If youre gonna do it personally I woudl sit out the season and get the right motor built for the boat. usually with car motors they dont last. Forget abotu the salt and raw water bla bla bla most car built motors cant sustain the longer higher RPM that is demanded from a boat motor. It will do it for a while but how long could be couple of hours to a year. sort of a shot in the dark if you ask me and I wouldnt want to replace motors every year or less in a boat. PITA
My buddy put a car 460 ford motor in his jet boat and 1 season later he replaced it under warranty. ( took out the crank) again the next year. the shop that built it finally said sorry no more when they found out he was using it in a boat. The moron went there with the boat to show them what the motor was doing. ( took out the crank again)
When I got my reman 5.0 I went to a boat motor after talking to a couple of guys on here. the cost difference was about 300$ if I remember right.
You can find a block thats in good shape and use that to build it

Rob

 

[RCSConstruction]

Re: opinions on sbc block options

No difference between a truck and boat motor, except head gaskets and brass plugs. Newer model motors already have SS fire rings in the head and the only difference there is the brass plugs.
Cam's are virtually the same, heads are the same,crank,bearings,etcccccc

 

[Reel Poor]

Re: opinions on sbc block options

You also have to use an engine built before 1985 because they changed the crankshaft and flywheel. The parts from your engine will not fit the later model engines. Stick with the two piece rear seal engines and save yourself some headaches.

 

[redjmp]

Re: opinions on sbc block options

What year did they start using ss fire rings? Is that the same as hardened seats?
Are there any more desirable pre 1985 engines?
Besides the cam, what makes a truck motor so they last longer than a car engine?
What about the newer vortec heads and manifold?
Will they bolt up to an old small block and use the old marine carb?
Would be nice to run roller rockers and tappets.

 

[RCSConstruction]

Re: opinions on sbc block options

Most of the newer rebuild kits (ie,felpro) have gone to stainless steel rings in their head gaskets. You will have to make sure though.
It used to be a "truck" motor was 4bolt (and "torque'er" camshaft) and passenger car was 2bolt. Not really the case in later years, plenty of trucks with 2 bolt mains. There may be extra webbing in critical areas but not real sure bout that.
If I were you I would find a 4bolt main, pre-85 like RP said. Some vortec heads which will require a vortec manifold and depending on the bolt pattern(square bore/spread bore) your carb you should be ok, may need to re-jet it a little but maybe not (I didn't)
The vortec heads will bolt up fine, along with your exhaust.
Roller rockers,lifters, great! Should put you at around 260-280 hp. (with vortec heads)
Choose a good cam (RV cam) with an overlap of no less than 112*.
HV oil pump (I believe a passenger car has a standard oil pump and the trucks will have the high volume)
Brass freeze plugs, stainless steel/brass oil passage plugs and your golden.
The only thing I can think of as to why rob's buddy was blowing through motors was he was rev'ing the heck out of it. Not supposed to rev these motors past 4900-5000 rpm's. Take that guys 460 and stick it in a 1 ton truck and you can tow a 40' 5th wheel all over the US but not at 6000-6500 rpm's.
Wanna do a quick motor swap? Find a good running used truck motor, change out the head gaskets, freeze plugs, oil passage plugs, timing cover,water pump, stab a HV oil pump in it and go have fun.(of course use all the marine parts from your old motor--dist, carb, etc..)

 

[Flukinicehole]

Re: opinions on sbc block options

I wish you were closer to me I have a complete 305 long block with very low hours that I pulled from my boat last year. If anyone is looking I`ll take $500 for it. Runs great but I had to up the power in my new boat.

 

[Reel Poor]

Re: opinions on sbc block options

You don't need a high volume oil pump it can suck the 5-6 quart oil pan dry at high rpm's. A stock oil pump is more than adequate.

 

[redjmp]

Re: opinions on sbc block options

Ok so I got a line on an old style 350 4 bolt short block from a running truck.
Will I be Ok with putting my 305 heads and carb on for now until I find a set of vortec heads and manifold or will I ruin the motor? I don't need to run it anywhere near WOT.
Is it possible to use my original 898 crank with a newer style 350 2 bolt short block and have everything bolt up?
Can both these blocks take the same kind of roller cam and lifters?
That way I can install the 2 bolt and build the 4 bolt over winter.
Will my type 1 outdrive handle the extra power?

 

[Bondo]

Re: opinions on sbc block options

Will I be Ok with putting my 305 heads and carb on for now

You'll be Fine using the Carb,+ Manifold,....
But,....
Use the 350 Heads,.......
The 305 Heads will boost the Compression Too High,+ the Valves are Tiny....
They Won't Flow Well,... At All.......

Is it possible to use my original 898 crank with a newer style 350 2 bolt short block and have everything bolt up?

Nope,........ The Stroke is Too Short.......

Can both these blocks take the same kind of roller cam and lifters?

Nope,...... They'll need Machine Work for that,.... They're both Pre-Roller Cam blocks......

Will my type 1 outdrive handle the extra power?

Ayuh,.......... If you're Gentle with it...........

 

[MikDee]

Re: opinions on sbc block options

You'll be Fine using the Carb,+ Manifold,....
But,....
Use the 350 Heads,.......
The 305 Heads will boost the Compression Too High,+ the Valves are Tiny....
They Won't Flow Well,... At All.......



Nope,........ The Stroke is Too Short.......



Nope,...... They'll need Machine Work for that,.... They're both Pre-Roller Cam blocks......



Ayuh,.......... If you're Gentle with it...........

Bond-o, On a point here the 350, and the 305 have the same stroke, 3:48" the only difference is the smaller bore.

I agree, the 305 heads won't work, for reasons you stated, I worked on a friends 350 boat motor that was "supposedly" built up, and had issues only to find the problem was, it had 305 heads on it.

 

[Bondo]

Re: opinions on sbc block options

Ayuh,....... You're Right,....... I mis-spoke.......

But,.......
I Still wouldn't try installing a 305 Crankshaft in a 350,......
The internal Balance will be Way Off.......
The larger 350 pistons Weigh more than the 305 pistons....
'course,......
You could drag it all to a Machineshop,+ have it Rebalanced..........

 

[MikDee]

Re: opinions on sbc block options

Ayuh,....... You're Right,....... I mis-spoke.......

But,.......
I Still wouldn't try installing a 305 Crankshaft in a 350,......
The internal Balance will be Way Off.......
The larger 350 pistons Weigh more than the 305 pistons....
'course,......
You could drag it all to a Machineshop,+ have it Rebalanced..........

I totally agree, plus I'm not sure if the crank journels are the same size on a 305, as a 350, I mean it should logically be, it would be cost effective, But? I wouldn't assume so.

 

[redjmp]

Re: opinions on sbc block options

Ok then. Now I have a line on a complete 1990 truck 305. Can I swap out the cranks and have everything from my 898 bolt up? It is a tbi engine and I am also wondering if my intake manifold from my 898 will bolt up?
If I want to build a vortec motor with roller gear, what type and year of block do I need to find?

Thanks to all who have helped. It is muchly appreciated.

 

[MikDee]

Re: opinions on sbc block options

Ok then. Now I have a line on a complete 1990 truck 305. Can I swap out the cranks and have everything from my 898 bolt up? It is a tbi engine and I am also wondering if my intake manifold from my 898 will bolt up?
If I want to build a vortec motor with roller gear, what type and year of block do I need to find?

Thanks to all who have helped. It is muchly appreciated.

Why would you want to swap out the cranks? are you planning on using your 898 block? go with the truck motor complete, no? By the way, out of curiosity, your 898 (198hp) must be a 2bbl carb right?

 

[redjmp]

Re: opinions on sbc block options

No, my 898 block is cracked. The crank is good. Someone replied that:

You also have to use an engine built before 1985 because they changed the crankshaft and flywheel. The parts from your engine will not fit the later model engines.

So I am not sure what will bolt on from my 898.
Yes stock 2 bbl.
Still want to use vortec heads and roller gear. Will they bolt on to this 1990 305?