Considerations for engine swap

[Scott Danforth]

all small block motors share the same exhaust mounting pattern. so your exhaust will be fine

intakes on vortec heads are different

vortec heads have all the mounting points as the 1991-1995 heads have.

roller blocks came out in 1988 (castings were changed in 1985 for the 1986 model year, however first vehicles being the 1987 corvette and 1988 F-bodies from the Romulus engine plant). however only a few truck blocks from the Tonawanda engine plant actually had the roller keeper bosses machined as the Trucks did not get roller cams until later (about 1991, with boats following about 1995 or 1996). after 1996, all factory small blocks have roller cams.

with a 5-axis machining center, the bosses can be machined, however why grab a motor that doesnt have them machined when there are so many core motors with roller cams and all new blocks are properly machined.

since you are up there in Newfoundland, here is what I would do. take a week off of work, drive down with a 1996 or so pickup truck on its last leg, drop in a new stroker crate motor into the truck, and drive back...... then shoot the truck and put the motor in your boat. it would save you thousands

 

[Century Arabian]

Scott, thanks for the lesson, I knew there were changes to the 350 around '86 and also the '95 change to the vortex, but how it all came about I wasn't sure. I do appreciate taking the time to explain it too me and now i do believe i have what information i need. Something from a truck between '91 and '95 if I want to avoid the Vortec head and having to change intakes.
I can also pick up something, from a truck, '96 or later and purchase an aftermarket Vortec intake to take the quadrajet. Now this option looks a little tricky. Do the '96 to 2002 Vortec blocks have a mechanical fuel pump boss and drilled for the fuel pump rod. I was looking at some crate engines from Summit and most of the vortec motors state that they are not equipped for manual fuel pump. Is this the rule of thumb for the vortec 5.7ltr?

By the way, I do like the idea about driving down there in an old clunker, but finding something up here from that era that still has body panels intac could be a problem. lol.

Thanks again
Clyde

 

[Scott Danforth]

keep in mind the vortec heads are worth 30hp alone, so for the cost of an intake, probably the best thing you can do for your motor. I did ported vortec heads, a cam swap and intake with a phenolic spacer for my small block prior to going big block

no, there is no fuel pump pad on the 96 and later production blocks however the aftermarket dart blocks do have them. just run a $87 carter marine fuel pump with a relay and a $15 oil pressure switch.

 

[Century Arabian]

Thanks Scott. I used 200cc Edelbrock E-tech Vertec heads and intake combo on the 383 we did for the '79 vette a few years back. Great heads but may have went a little large for the engine. Not a lot of intake velocity at the low end of the torque curve but once she gets her heart rate up she really roars.
Thanks again. Think we have a plan. I will keep you posted when this starts to move forward.
C

 

[porscheguy]

all small block motors share the same exhaust mounting pattern. so your exhaust will be fine

intakes on vortec heads are different

vortec heads have all the mounting points as the 1991-1995 heads have.

roller blocks came out in 1988 (castings were changed in 1985 for the 1986 model year, however first vehicles being the 1987 corvette and 1988 F-bodies from the Romulus engine plant). however only a few truck blocks from the Tonawanda engine plant actually had the roller keeper bosses machined as the Trucks did not get roller cams until later (about 1991, with boats following about 1995 or 1996). after 1996, all factory small blocks have roller cams.

with a 5-axis machining center, the bosses can be machined, however why grab a motor that doesnt have them machined when there are so many core motors with roller cams and all new blocks are properly machined.

since you are up there in Newfoundland, here is what I would do. take a week off of work, drive down with a 1996 or so pickup truck on its last leg, drop in a new stroker crate motor into the truck, and drive back...... then shoot the truck and put the motor in your boat. it would save you thousands

Actually, trucks didn’t get roller cams until ‘96 when they got vortec heads. I’ve got a ‘95. No roller. It has the bosses, but I don’t think they’ve been machined. For some reason, even the cars in the early 90s with the tbi injection had roller cams, but on the trucks they held off as long as possible. I’m guessing it had to do with stretching the high profit margins a bit further.

Beat bet is just start with a ‘96 block and heads as all the pieces are there and no guesswork.

 

[Scott Danforth]

Thanks Scott. I used 200cc Edelbrock E-tech Vertec heads and intake combo on the 383 we did for the '79 vette a few years back. Great heads but may have went a little large for the engine. Not a lot of intake velocity at the low end of the torque curve but once she gets her heart rate up she really roars.
Thanks again. Think we have a plan. I will keep you posted when this starts to move forward.
C

the heads on my 468cube big block are only 169cc intake runners with a 119cc combustion volume. 200cc heads on a small block means there is no low end or mid range.

 

[zealer]

I recently completed a non-vortec to vortex upgrade. My 96’ non-vortec was scrap so I bought a vortec longblock. Had to swap the mechanical fuel pump for an electric one (a carter, wired with a oil pressure switch and relay) and get a new intake. The latter was the most difficult part. Hard to find a mercruiser original vortec intake without spending an arm and a leg, so instead I put a weiand aluminum version on. I don’t expect any issues with fresh water use but not sure what the lifespan would be in a salt water environment.

the longblock I got must be a late 90’s because all the threads are still SAE and thus I didn’t have to get any new bolts. Around the change of the millennium GM started doing metric threads.

 

[achris]

Metric blocks have an "M" as the last character in the casting number...

 

[Lou C]

Do you have any local hot rod shops that also do machine shop work? I picked up a set of reman marine pre vortec heads for my 4.3 from this place in Long Island...for approx. $550.

https://www.skspeed.com/