5.7 MerCruiser blown what can I replace it with

[Scott Danforth]

you can get cast-iron take-off intake manifolds if you want.

if you are in fresh water you can get away with the all aluminum intake.

flywheels after 1986 are interchangeable for the 5.7's

you also need a set of brass core plugs (about $11) because the steel ones will rust out.

 

[nola mike]

you also need a set of brass core plugs (about $11) because the steel ones will rust out.

Do we know if/when GM switched over to brass plugs? My '01 had them, and there was another guy on here that had a later model 4.3 as well that were brass from the factory...

 

[Nextelbuddy]

you can get cast-iron take-off intake manifolds if you want.

if you are in fresh water you can get away with the all aluminum intake.

flywheels after 1986 are interchangeable for the 5.7's

you also need a set of brass core plugs (about $11) because the steel ones will rust out.

i will order a set of brass core plugs thanks!

question about spark plugs, on the 99 vortec motor would i still use the AC MR43T plugs gapped to .035 or would i look up the recommended plugs for the 99 vortec engine and use those?

i'm curious if the 99 vortec engine uses the same length spark plugs or the longer reach ones i always see online.

i was too nervous buying used engines form shady people on facebook market place.

i used car-parts.com and found one locally from a 99 suburban with 190k miles but engine is tested and verified good condition no rod knock or blown head gasket and clean oil.

ill probably just pick that one this weekend since the price is right and then order the brass plugs for it.


my old non vortec 350 was rated for 4800 rpms and with the 4bbl carb was apparently rated at 260 hp....

according to several websites. i looked up the specs for the 99 vortec engine in the suburban and it shows:

255hp @ 4500 rpms

so given that fuel injected engines typically make a little more power than carb if anything at least better fuel efficiency.... how much power and i going to lose from that 255 when i slap on a 4bbl carb instead of FI lol.

i thought vortec engines made more power over non vortec engines stock for stock?

 

[Scott Danforth]

vortec heads use the longer plugs

fuel injection does not add HP, it only adds stability for varying atmospheric conditions.

the truck motor is rated 255hp driving all the accessories while meeting emissions and driving a torque converter.

vortec heads are good for 30-40hp over the non-vortec heads

 

[alldodge]

Plugs MR43LTS gap at .045

 

[Nextelbuddy]

Excellent thank you guys I appreciate it.

I'm wondering if now would be a good opportunity to incorporate the Holley EFI kit. I think the hardest part after researching that kit is plumbing the return fuel line into the tank. The only reason I would like to go EFI is that I would like the easier start I'm starting the engine over a carburetor.

 

[nola mike]

That holley kit looks pretty slick. Not too much more expensive really than a new carb and manifold. Haven't heard of anyone here that's done it, would love a guinea pig. Where does the o2 sensor go?

 

[Scott Danforth]

usually I find that a properly maintained carb motor starts easier than EFI. EFI motors require about 2 revolutions for the ECM to know where the motor is. a carb'd motor usually is running in about 1/2 a revolution

and yes, Holley raised the price of their carbs about 50% when they came out with the sniper systems. the carb you could have bought a few years ago for under $500 is now about $800.

 

[alldodge]

. Where does the o2 sensor go?

Good point, they need to be installed to tune it, afterwards they can be removed

 

[Nextelbuddy]

That holley kit looks pretty slick. Not too much more expensive really than a new carb and manifold. Haven't heard of anyone here that's done it, would love a guinea pig. Where does the o2 sensor go?

since most of us have wet exhaust systems, the wideband o2 sensor would need to go into the Riser. there are adapters to drill and tap the adapter bung into the rider or just have an o2 sensor bun welded to the cast riser to keep the o2 sensor away from the wet exhaust in the down pipes where they would normally go.

ideally if i dont go efi then ill most likely get the edelbrock 1409 marine 4bbl carb and some cheaper off brand vortec carb intake manifold. that edelbrock 2516 is just so much more expensive than the auto version.

 

[Nextelbuddy]

usually I find that a properly maintained carb motor starts easier than EFI. EFI motors require about 2 revolutions for the ECM to know where the motor is. a carb'd motor usually is running in about 1/2 a revolution

and yes, Holley raised the price of their carbs about 50% when they came out with the sniper systems. the carb you could have bought a few years ago for under $500 is now about $800.

good to know, i appreciate your knowledge and insight, thanks!

 

[Nextelbuddy]

So curious.. if after all said and done I end up on a 1999 vortec 5.7 350 with a 4BBL carb and the MR43LTS plugs... could i potentially run this Flame arrestor cover? it says Turn key start i guess that means that that specific generation engine had fuel injection for turn key start?

 

[alldodge]

You could put the plastic cover if you like the looks, but TKS is a 2bbl carb which doesn't use a choke, it uses and enrichment module

 

[Nextelbuddy]

You could put the plastic cover if you like the looks, but TKS is a 2bbl carb which doesn't use a choke, it uses and enrichment module

i would honestly like to run the cover that matches my setup as close to possible. im very much a stickler when it comes to being as proper as possible. it reflects in my car builds when i try to get as oem as possible or oem+. i want to have a clean swap that looks great and is as proper as possible.

have any idea which flame arrestor cover would match my setup properly? i know lot of you guys just say dont run one no big deal but it is kind of important to me

thanks!

 

[alldodge]

Have a few issues which will conflict. In 99 the motors either came with a 2bbl (Merc or TKS) or they where EFI. The last 4bbl was in the 97 time fame

 

[Scott Danforth]

the vanity cover is there to put a sticker on that has your plug and timing information. the 5.0's with TKS didnt even have a cover, the decals were stuck directly on the top of the spark arrestor.

I myself like the non-stock look

 

[Nextelbuddy]

wow that's gorgeous! is that sunlight or do you have LEDs to light the engine compartment like that

 

[Nextelbuddy]

Have a few issues which will conflict. In 99 the motors either came with a 2bbl (Merc or TKS) or they where EFI. The last 4bbl was in the 97 time fame

yup ok makes a lot of sense.thanks for schooling me on the mercruiser line up. I can still get that cover and the only difference would be tha tI upgraded from 2BBL to 4BBL then which im sure lots of people do with those specific engines anyways. i like that it has the correct spark plug and gap specs and the firing order etc....

 

[Searay205]

I have seen guys drill holes in the exhaust manifold right where it bolts to the engine for 02 sensor. There isn't a water jacket there. Drill hole tap and screw in. Sure you only getting data from one cylinder but that plenty close enough for a marine engine.

 

[Scott Danforth]

wow that's gorgeous! is that sunlight or do you have LEDs to light the engine compartment like that

LED's. that pic was at night so I could see if they were effective in lighting the bilge should I need it.