Short block swap

[magster65]

No I'm not planning to do this but I was just pondering potential issues with replacing a 305 (mpi) short block with a 383 short block. Physically it's a direct bolt it... no exhaust issues, mounting, I'm sure the fuel pumps are good...
I expect the PCM would need a different calibration or maybe a replacement from a 6.2 unit? What about the injectors... do they flow enough if the mapping is rewritten?
I guess I could check and compare part numbers on the different engines. Anyone ever done this sorta' thing?
I imagine a 290 with a 40 mph cruise would be fun though!

 

[Alpheus]

Re: Short block swap

The 5.0 and the 6.2 use the same injector. Part # 885176

 

[Bondo]

Re: Short block swap

Ayuh,... You'll need a Long block, not a short block....
305 heads won't run for Poo on a 383...
The compression will be Way High, 'n the valves are too small to make good power...
And,..
Yes, the 'puter will need to be reburned...

 

[magster65]

Re: Short block swap

Ayuh,... You'll need a Long block, not a short block....
305 heads won't run for Poo on a 383...
The compression will be Way High, 'n the valves are too small to make good power...
And,..
Yes, the 'puter will need to be reburned...

Sorry about the mix-up with my posts here dudes...

Thanks Alpheus.

Bond-o; Long block it is then. I know of only one other similar build where a fella' bored and stroked a 7.4, used the stock fuel & ignition parts and had the ECM fuel curve redone at an Arizona speed shop. It was back and forth (we're on Vancouver island) and I don't think it ever ran to full potential. I definitely wouldn't want to go down that road!
So... both the 5.0 and 6.2 use the ECM 555 with different parameters and the stock Merc 6.2 'program' can be put on my ECM?
What would be the best way to do that without having someone's 'custom' parameters... buy one from Merc? Exchange maybe?
The end goal here is come up with a price.
Thanks,
John

What sort of performance improvement do you think I'd see with the extra 120+ hp? It runs about 45-46 mph at 5000 rpm now.

 

[Bondo]

Re: Short block swap

What would be the best way to do that without having someone's 'custom' parameters... buy one from Merc? Exchange maybe?

Ayuh,... No prob with the postin',... Looks like ya got it figured out now....

To be honest, I can't answer your question on the 'puter,... I don't mess with 'em much...
I've "heard", that only a few Merc. Factory Techs have the programs to reprogram those things...
Arizona Speed is probably your Best bet...

The extra 120hp should put you over the 50 mark, maybe more...

 

[magster65]

Re: Short block swap

Alright.
I'll contact Arizona speed and see what they say.
The 290 is so smooth and responsive at 40 mph... it would be great to cruise at that speed.
Thanks again.