5.8 Merc

[marquis_82_withneons]

so im thinking about doing a 5.8 swap in my Merc when the 4.2 dies. i dont know what ill do with the 4.2 as i cant imagine anyone wanting it.. but anyway. seeing as how 80s mercs came with a 5.8 option, is it a good idea to swap mine? id like to keep the same mileage i have now 18-20, is this possible with a 5.8?

side note: my LTD has the 351W and i believe gets around 15, but shes also VERY tired too.

[Mainemantom]

In my opinion, I would rebuild the 4.2 or get a 302 with FI from a mark 7. The 351s that I have had in that era were junk. I got excellent mileage on both the 255 the 302. 18-22 mpg 351s that I have had, did not get good gas mileage averaged 15-17 mpg.

[marquis_82_withneons]

i like my carbs. my 4.2 is carbed atm. previous owner did a swap from the CFI. so ill stick with n/a. but ill got with a 302 then. just curious

[Lincolnmania]

if you do a 351 and your on a budget, i would get a 94-97 truck roller shortblock and a pr of gt40 heads from a 96 exploder and the bbk 351 swap headers and carb and intake and roller cam of choice.......real good combination and no worry about having to find special oil for the flat tappet cam in the earlier motors.

[marquis_82_withneons]

if you do a 351 and your on a budget, i would get a 94-97 truck roller shortblock and a pr of gt40 heads from a 96 exploder and the bbk 351 swap headers and carb and intake and roller cam of choice.......real good combination and no worry about having to find special oil for the flat tappet cam in the earlier motors.

as complicated as that sounded, im sure its very simple. being 90's im sure its be EFI, so thats a drawback for me. i know i know, efi IS better. but simplicity is my best friend and an engine bay full of wires is not a friend of mine. (more wires than carb anyway) and i am very familiar with a carbed 351w as thats what the LTD has.

my thought was to find a used 70s engine, maybe if lucky one with less than 100k. freshen it, drop it in, call it done.

[miamibob]

if you do a 351 and your on a budget, i would get a 94-97 truck roller shortblock and a pr of gt40 heads from a 96 exploder and the bbk 351 swap headers and carb and intake and roller cam of choice.......real good combination and no worry about having to find special oil for the flat tappet cam in the earlier motors.

If need be can't he simply add some ZDDP (zinc) at every oil change to bring it back to SF and call it a day??

[mrltd]

as complicated as that sounded, im sure its very simple. being 90's im sure its be EFI, so thats a drawback for me. i know i know, efi IS better. but simplicity is my best friend and an engine bay full of wires is not a friend of mine. (more wires than carb anyway) and i am very familiar with a carbed 351w as thats what the LTD has.

my thought was to find a used 70s engine, maybe if lucky one with less than 100k. freshen it, drop it in, call it done.

There is nothing about that post about putting EFI on the 351... Get a roller motor, can use a nicer cam. Still can use a carb. The explorer heads are a great upgrade.

[marquis_82_withneons]

i know he didnt say specifically about efi.. i was just assuming since its a 90s engine that it WOULD be efi, if a got a stock one that is

[1980c10]

Yes, it would be efi. But your missing the part where he said to put a carb'd intake on it.

Purchase a roller 351w
Get a set of gt40 heads
Carb'd intake of your choice
Carb of your choice (Holley) lol
A set of headers

And even with the stock H.O. cam you'd have a great running combo.

[zoomie]

you have to be careful with buying f4te blocks just a thought

[88Vic]

You'd be very lucky to get 18mpg from a carbed 351, on the highway sure but in the city I doubt it. My 86 C10 with a Q-Jet 305 couldn't get close to 18mpg city.

[marquis_82_withneons]

i have 2bbl on my 351w and im a conservative driver.. got decent mileage there.. idk i dont really give a shit.. ill probably just get a 5.0... im not building a damn racecar. i wont need a 351

[fmansfield444]

Put a 4.6 in there lol. I get 25-30 mpg outta mine. I get a steady 20 outta my 302.

Could go with a Chevy 350 ha JK please don't.

[marquis_82_withneons]

Could go with a Chevy 350

you.... GTFO now.... lol.. speaking of 350's a friend of mine has 3k in his 84 Sierra engine rebuild and he broke the timing chain xD

[84GrandMarquis]

If you do pull the motor, hold on to it if you have the space for it. The 4.2 is pretty rare, and while slow and not very desired, I can assure you that years down the road, a numbers matching 4.2 Marquis will be quite the oddity. Probably not too valuable, but certainly rare and by that point in time, I bet people will want to get their hands on one unique car. My dad had a super rare Buick Regal 4.3 Diesel that he swapped out for an Olds 307, and not a day went by where he didn't wish he kept the seized diesel motor!