Small Block 400 swap

[WestCoastPete]

I am doing and engine swap from a small block GM 350 to a small block 400. You would think this would be simple enough. The boat is a 28.5 footer Bayliner with Flybridge weighing around 6000lbs with a single screw. The drive is Volvo 280. Since these engines are externaly balanced the machine shop installed a counterweight for the flywheel. I have all brand new marine parts including the brass freeze plugs. Everything was going in smoothly until I ran into this problem which I hope someone out there with more experience has ran into the same situation and can help me get back on track. The starter I had for the 350 had bolt holes that were straight across. The small block 400 has boltholes for the starter which are offset. Since my 350 starter did not line up on my 400, I bought a new starter that has offset boltholes made for my 400 block (GM casting block of 330817). Which came originally on '75 to '80 heavy duty truck from what I gathered that the 400's used the larger diameter flywheel. The Volvo 280 Bellhousing can only accept the smaller flywheel which came on the 350ci. Other than drilling and tapping threads on the block, does anyone out there know what starter I can use. The offset bolthole starter I bought made for the 400 block did not line up properly due to the smaller diameter flywheel that is installed on it now. If I was to change the flywheel to the larger diameter one, it won't fit inside the bellhousing.

 

[Lyle29464]

Re: Small Block 400 swap

some one will be along that knows the starter problem. The 400 has not worked out well in marine use. It gets by if you have FWC.

 

[Bondo]

Re: Small Block 400 swap

Ayuh,... I donno's that the 400 ever used the 12" flywheel, 'n the flywheel has to match the starter drillings in the block....

I know of no way to make work, what you're trying to do...
Possibly, a hi-torque mini-starter with the multi-fit adaptable housing,..?? Donno...

 

[series60]

Re: Small Block 400 swap

As mentioned before the sbc400 does not make a good boat engine because of the steam holes in the block to head castings. These small holes will plug up very easy if sea water cooled. Not so much with FWC.

 

[TilliamWe]

Re: Small Block 400 swap

BTW, FWC is a common (somewhat) misnomer for "CLOSED COOLING".

 

[float2]

Re: Small Block 400 swap

I can't offer any help but thanks for bringing this up. I have a good sbc 400 out of a Suburban that I was going marinize and swap out in place of my 305. Hmmmmm.......

 

[TilliamWe]

Re: Small Block 400 swap

I can't offer any help but thanks for bringing this up. I have a good sbc 400 out of a Suburban that I was going marinize and swap out in place of my 305. Hmmmmm.......

Okay not to veer off topic, but *IF* you had a 5.0 or 5.7 from before 1987, with a 2 piece rear main seal (like ALL 400s have), would this 400 swap work easier? I thought the smaller flywheel on the 5.0s and the 5.7s came about with the switch in 1987 to a 1 piece rear main seal. Is that accurate?

 

[Bondo]

Re: Small Block 400 swap

I thought the smaller flywheel on the 5.0s and the 5.7s came about with the switch in 1987 to a 1 piece rear main seal. Is that accurate?

Naw,... Not really...
Chevy has Always used both the 12", 'n the 14" flywheels....
Most, or many of the later model blocks are drilled for Both starters, so either size flywheel can be used....

 

[TilliamWe]

Re: Small Block 400 swap

Naw,... Not really...
Chevy has Always used both the 12", 'n the 14" flywheels....
Most, or many of the later model blocks are drilled for Both starters, so either size flywheel can be used....

Okay, thanks! So this is simply an "older" block issue?

(Bubba, so if the 400 *can* be internally balanced, why did GM choose to make them externally balanced?)

Is it too late for Pete? Can he take the motor back to be internally balanced and then just use "any 'ol" small diameter, 2 piece rear main seal, flywheel?

 

[Bondo]

Re: Small Block 400 swap

Okay, thanks! So this is simply an "older" block issue?

(Bubba, so if the 400 *can* be internally balanced, why did GM choose to make them externally balanced?)

Is it too late for Pete? Can he take the motor back to be internally balanced and then just use "any 'ol" small diameter, 2 piece rear main seal, flywheel?

Ayuh,... Manufacturing Co$t$...

It has to be "Thought of" at the time of engine Planning....
The Bare crankshaft would need machinin', balancing, drilling, 'n additions of babit metals...
Way, Waay to late for that....

 

[WestCoastPete]

Re: Small Block 400 swap

I recd a lot of suggestions locally regarding the the Hi-Torque mini Starter and a local gearhead gave this info on a GM Performance parts mini Hi Torque starter. Which may work but it's worth a try. I know have a stack of starters I've tried and nothing have worked. Because this one is adjustable it may just be the ticket. I will purchase it on Monday and give everyone an update once I get it in. The other dilemna I know face is how can I convert this automotive starter into a marine starter? It may be another topic. Ahhhh, the joys of owning a boat! Thank you all for your inputs. I can't wait to try this starter out.

https://store.gmperformanceparts.com/store/SelectProd.do?prodId=7506&redir=true&manufacturer=GM&category=Electrical%20/%20Ignition%20Systems&name=High-torque%20mini-starter%20&model=<!--12361146-->

Part # 12361146
High-torque mini-starter
Gear reduction starter is designed for 1958-1996 V-8 and all 90' V-6 engines
Compact design provides increased clearance
Weighs only 10.5 pounds and has a gear reduction of 3.75:1
Equipped with a dual bolt pattern for 12.75 (153-tooth) and 14 (168-tooth) flywheels
Housing can be rotated to clear exhaust systems
Includes starter, mounting bolts, shims, gaskets, and electrical connectors
NOTE: Not recommended for competition use.

 

[Bondo]

Re: Small Block 400 swap

The other dilemna I know face is how can I convert this automotive starter into a marine starter?

Ayuh,... I just looked at yer link,...
That starter, By Design, is igntion protected, 'n is Safe....

It may not have a CG rating, but it Is Safe....

 

[WestCoastPete]

Re: Small Block 400 swap

Okay not to veer off topic, but *IF* you had a 5.0 or 5.7 from before 1987, with a 2 piece rear main seal (like ALL 400s have), would this 400 swap work easier? I thought the smaller flywheel on the 5.0s and the 5.7s came about with the switch in 1987 to a 1 piece rear main seal. Is that accurate?

The problem I have is that my small block 400 has mounting bolt pattern specifically for the 168 tooth flywheel starter. The flywheel size my Volvo Penta 280 can only accept is the 153 tooth flywheel. My big mistake is I dropped the small block 400 in the boat already and expected my old starter for the 350 to bolt right in. My machine shop has an automotive mindset and has never heard of this problem. "Lucky me!" If I can't find a starter with the offset mounting bolt pattern that mesh with the 153 tooth flywheel, my only other option is to pull the 400 back out and take it back to machine shop to have the block tapped for the 153 tooth starter set up. Getting the engines in out of the boat was a challenge in itself since the gunwhales are 10 feet off the ground. It looks like I might may have to do it again.:facepalm: I've added a shot of the 350 coming out with scaffolding set up.

 

[Bondo]

Re: Small Block 400 swap

my only other option is to pull the 400 back out and take it back to machine shop to have the block tapped for the 153 tooth starter set up.

Ayuh,... It's entirely Possible, that that Can't be done...
Chevy rarely adds the extra iron, where it don't need to be, for their original purposes....

Your Problem is with the Volvo drive, not so much the motor, other than it being the wrong choice of power...

 

[Howard Sterndrive]

Re: Small Block 400 swap

Possibly, a hi-torque mini-starter with the multi-fit adaptable housing,..?? Donno...

I'd be off investigating that, if I were you

I have a mini starter in my car with the 400 - so they definitely make them for the 400 mounting boss- just not sure if the nose can be changed or relocated to accommodate the smaller ring gear

This machine shop that you paid to externally balance the flywheel and all that jazz... they should know if they do that sort of work

 

[Howard Sterndrive]

Re: Small Block 400 swap

Other than drilling and tapping threads on the block, does anyone out there know what starter I can use.

hmmm..looks like drilling is the fix

google is saying everyone that has a 153T f/w on a 400 drilled the block to accept a 350 starter
and a couple guys drilled it wrong and are chewing up starters and ring gears, so drilling needs to be spot on.

 

[gilby246]

Re: Small Block 400 swap

I have had a 400 (bored to 402) in my boat for a few years now and runs 150 degrees all day long. Oh, I used vortec heads and had steam holes drilled
and yes, its raw water cooled

you might be able to get a starter with the correct bolt holes and have a shop put the correct bendix on to mesh with your flywheel teeth. A bendix gear is only about 20 bucks

 

[dan t.]

Re: Small Block 400 swap

OK I notice that no one has mentioned if you got the 153 tooth flywheel re ballanced to match the externaly ballanced 400, if you havent it will shake something terrible. You can get a ballance plate that bolts between the flywheel and crank, I havent used one but see them in performance mags all the time. As for the starter bolt holes, pull it out and get it drilled and tapped.

 

[WestCoastPete]

Re: Small Block 400 swap

Thanks for all the reponse. So far the only thing that looks promising other than pulling the motor back out is this starter from CSR performance. I called the starter company and explained to the engineers my situaton and they stated this starter will do the trick. This is what they designed it for. The small block 400 Staggerred Bolt Pattern with the ability to mount for 153 or 168 teeth Flywheel. Here's the kicker! They're back ordered for weeks on out! Ouch!

http://www.summitracing.com/parts/CSI-100SBP

 

[Bondo]

Re: Small Block 400 swap

Ayuh,... Hopefully, that counter-balance plate don't screw things up....

On my 400, I went with a flywheel balanced FOR the 400....