V-P 5.7 Gxi intake on 383 stroker?

[686SPORT]

Yes, I know all about V-P systematic issues. Missed the 2023 season finding a mechanic who would take on the overheating issue on the 290 Chap with 5.0's; didn't get back on the water until late '24. Since the admiral is no longer here [accident, not her fault], I don't need a cruiser and could do nicely with a 24-26' cuddy. We sold the last 265 when the younger child left home and moved 2000 miles away. Now he's back in the East and his kids all love watersports - ages 5 to 13. Our older child is covered by an in-law who has a Mako, and sonny boy loves the 265 - or any other similar inboard. Sterndrives are so much better for anything other than fishing. Plus a 265 can live on a trailer, unlike the 290.

Other factors to consider: age, money, and distance. I'm 74, just bought a condo near the boat, but still reside 200 miles away. The marina owner who has this 265 is a good guy, but he is covered up in his own projects in addition to all the work he does for us paying customers. I once had a Duramax - can't even imagine how much trouble that swap could create. Going BBC would at the least entail swapping out the sterndrive for one with the right ratio, and then there's engine management to consider. Using a 4-barrel seems the most attractive option, but then the major purpose of the ECM is to protect from detonation. Can you marry the ignition retard control to an engine that doesn't use the ECM for fuel management?

 

[Lou C]

What you need to do as far as detonation is:
carefully check and verify total timing advance to make sure it isn't too advanced for your engine....
verify that your fuel mixture is not too lean...
make sure that the boat is not over-propped, better to prop it to the top end of the manufacturers specs or 4800-5000 rpm...
no matter what anyone says use at least 89 octane gas or higher, during the season when my boat lives in the water, the gas docks I use sell only 93 octane and I have never had pinging or detonation problems with this engine (original 1988 short block, reman cyl heads in 2017)

thousands of classic muscle cars lived a decently long life engine wise with no knock sensors but an owner who knows what the engine needs to survive.

My boat is a heavy 20' to be running a little 4.3 so I have checked the total timing advance (these run a good bit less than a 5.7, total is only 18*), and have always run premium gas and have it propped so it hits close to 5,000 with a light load. I think that's why it has lasted as long as it has.

 

[686SPORT]

Back in the day we tuned race engines using exhaust gas temperature gauges and set up the MSD with a little retard at the top end. Never burned a piston, and if a rod let go it was at the big end from too many revs. Any way to get EGT reading from a marine exhaust stream?
btw, I've had lots of engines with manual chokes - even 2-stroke power tools.

 

[alldodge]

Any way to get EGT reading from a marine exhaust stream?

AFR Blocks

 

[Scott Danforth]

- . Going BBC would at the least entail swapping out the sterndrive for one with the right ratio, and then there's engine management to consider. Using a 4-barrel seems the most attractive option, but then the major purpose of the ECM is to protect from detonation. Can you marry the ignition retard control to an engine that doesn't use the ECM for fuel management?

I put my BBC in front of the DP290 drive with 1.95:1 gears. I just jumped from B5 / B6 props to B7 / B8s no need to change drive

The EFI and ECM is there because GM switched from Carb to EFI on the trucks.

You can add knock control if you want, however detonation isn't really an issue. The 4.3 V6 is at the edge of detonation, but that has to do with it being a V6

Keep base timing below 8 degrees for reversion issues, run 24-26 degrees of advance. Your just a few degrees from optimal, however to get to all-in at 36 degrees, means you risk reversion at idle with stock wet exhaust

 

[686SPORT]

My old racing buddy found this guy in Herndon, VA.\:
https://www.maicsalazardiagnostics.com/
Anybody know anything about him?

re: fitting BBC 8.1: assume there are adapters where needed to attach motor mounts and exhaust y-pipe. Can you use the sbc coupler and transom assembly? How about fuel pumps for carb setup - mechanical, electric?

iirc, Detroit V-8's in my lifetime all had automatic chokes. Only ever had two V8's with 4 barrel: 1970 LT-1 and 1988 Mercruiser 260. Wouldn't this work?
https://www.ebay.com/itm/282734026901

Signing off for the week. You guys have a good one.
686SPORT

 

[Scott Danforth]

You need the Y pipe for a big block as the width and height of the engine is bigger than the small block

You can use the drive plate on the 5.7

You set up the electric fuel pump using an oil pressure switch and relay or you can use the diodes

Regarding the divorced choke you posted. Has not been used for over 40 years. Additionally, Volvo used Holley carbs on all V8's except 2 lower HP variants back in the early 80s

 

[Lou C]

That divorced choke will only work on a Pre Vortec with the internal exhaust crossover in the intake manifold. Modern Holley and Edelbrock carbs come with electric chokes.