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I am passively looking at options to replace the L-48 engine in my '79. One came up in my local Facebook Marketplace feed. A rebuilt 87-95 era 350 block, bored .030 over with Vortec heads + a rebuilt 700R4 tranny with a shift kit and corvette servos. I'm keen on the 700R4. The block had a bent pushrod, likely coming from a bad spring or valve guide coming out. But probably a manageable fix. The biggest unknown variable to me is the 87-95 era Gen1 block. I know its a 1 piece rear main, which at the very least means a different flexplate. Are there any gotchas from this type of block that would make me apprehensive about using it as a core for my build? Any other variables I should keep in mind?
Well being a roller cam block it "should" be superior to the older flat tappet cammed engines like you have in the vette now (You do want to make sure it will except a mechanical fuel pump.).. you wont be able to use your old intake with the vortec heads (unlikely your would want to unless its aftermarket now.) and the 700r4 is not an easy swap. I'm not sure about the 79 but my th400 74 is better suited size wise for the 200r4 ive read.
Last edited by augiedoggy; Sep 14, 2020 at 06:40 PM.
sounds nice, how much Each & as a pair ?
true, it's roller-capable, but may not have roller lifters & cam.
OE type roller lifters, lifter guides (dog bones) & spider are available New dirt cheap.
'79 auto more likely than not is THM350 (quite close to 700r4 dimensions).
-add-
Like L48 & L82 heads, OE Vortec's guides are an integral part of head casting; they don't come loose.
Last edited by 71chimera; Sep 14, 2020 at 08:43 PM.
I am passively looking at options to replace the L-48 engine in my '79. One came up in my local Facebook Marketplace feed. A rebuilt 87-95 era 350 block, bored .030 over with Vortec heads + a rebuilt 700R4 tranny with a shift kit and corvette servos. I'm keen on the 700R4. The block had a bent pushrod, likely coming from a bad spring or valve guide coming out. But probably a manageable fix. The biggest unknown variable to me is the 87-95 era Gen1 block. I know its a 1 piece rear main, which at the very least means a different flexplate. Are there any gotchas from this type of block that would make me apprehensive about using it as a core for my build? Any other variables I should keep in mind?
- Ian
An engine you cant hear run and trans you cant drive to verify its good? i would assume they are cores for rebuilding and pay accordingly.
x2 ewouldnt pay much but its a good foundation. The bosses can be drilled and tapped for that hold down for lifters...may have to get your machinist to drill for a mech pump thats easy.
You can run FT or roller nice to have options...With that block hard not to go roller dont need expensive retrofit ones.
I am passively looking at options to replace the L-48 engine in my '79. One came up in my local Facebook Marketplace feed. A rebuilt 87-95 era 350 block, bored .030 over with Vortec heads + a rebuilt 700R4 tranny with a shift kit and corvette servos. I'm keen on the 700R4. The block had a bent pushrod, likely coming from a bad spring or valve guide coming out. But probably a manageable fix. The biggest unknown variable to me is the 87-95 era Gen1 block. I know its a 1 piece rear main, which at the very least means a different flexplate. Are there any gotchas from this type of block that would make me apprehensive about using it as a core for my build? Any other variables I should keep in mind?
- Ian
Originally Posted by igilbert91
I enjoy all the comments that have nothing to do with my actual question 😂
Ive confirmed it was a mechanical fuel pump!
Regardless of what the seller is saying, it’s a core for me as it will need several things just to get ready for Ca Smog.
Its currently listed for $1200. Im sure if I let him keep the intake and carb, I can get this for $1000
If it has as few of miles as he says it does on the rebuild, I should be able to see cross hatching in the cylinders.
AFAIK, No mind-readers or mystics here; you didn't ask about fuel pump. Good luck w/ smog; curious how that pans out.
you'll need a Vortec intake that'll fit under a '79 hood
I've pulled injected sbc apart w/ +100K that still had lotsa Xhatch.
No fuel pump provision......make sure it has the extra bypass hole for water pump or you will have to plug your water pump. If it does have the provision......then it is a 50/50 if someone drilled the bypass port in the Vortec head......but all of this can be done away with by drilling two small holes in your thermostat.
The 2716 Performer EPS is an excellent intake.....fits Vortec.....and your hood.
unless they have NEW blocks (few do) ALL ATK & BP sbc are already Bored +40 over to +60 over & most of those cannot be bored again; ever.
overbore is on their websites; look it up & fact-check it.
very attractive ALL Brand New roller cam Vortec complete long block motors from GM/Chevy. $3K - $4K delivered. Great warranty; locally enforceable.
all 3 have mech fuel pump mount; first 2 have forged steel cranks; producing 250-260 gfwhp depending on intake & exhaust.
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Last edited by 71chimera; Sep 15, 2020 at 12:26 PM.
I would not worry about the block so much but the heads will need to come off to be machined. My money is on the valve guides needing to be cut down. The bent push rod came from some type of valve train interference. Vortec heads are notorious for needing to have the valve guides cut down when a high lift performance cam is used.
If you know that at the front end you can plan accordingly.
JMO
If your valve lift desires do Not exceed .500" - .525", Vortec guides/seats do Not require head machining IF IF you choose the correct spring & retainer.
e.g. a "ghetto grind" on stock retainers coupled with most "Z28 springs" will do it cheaply & reliably; look it up & fact-check it
inadequate clearance between bottom of retainer & top of seal/guide, as well as coil bind, are novice mistakes & have bent lotsa pushrods.
YMMV
Potential Replacement Engine
