Just bore the block??????
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 7,186
Likes: 45
From: detroit area
Just bore the block??????
Been on the fence about a crate engine since everything on my current SB is new.. 650 holley DP, performer intake, plugs/wire/, cog drive belt system/etc, heads rebuilt/ported... Only thing that I haven't touched is the block/pistons. I'm looking to possible just have a engine shop pull it and bore it out or just get a new block/pistons. With what I currently have, I would like to get 400hp or more if possible... I have no getup right now and ready to pull the trigger on just dropping it off to have done.
Last edited by onaqwst; Oct 8, 2021 at 08:51 PM.
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Buy a new short block then. Although the old block may be perfectly serviceable. You'd want the block sonic tested to verify that it will take the overbore but if it's never been out it should. With a short block you could get a roller block & 1 piece seals
Thread Starter
Le Mans Master
Joined: Nov 2004
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From: detroit area
Yeah, I think the block might be the issue, hence why I want to just swap it out. I will look into that, thanks
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For a shortblock to kill the power....it would have to be severely hurt. Even a smoking engine will run hard if the rest of the parts are right. It probably is a low compression engine...so certainly kicking it up a couple of points will help...but power is in the heads/cam and tune.
You said the heads are ported. What heads? Any flow numbers? What cam is in it?
If you're going to go into the shortblock...no reason to not at least make it a 383.
JIM
You said the heads are ported. What heads? Any flow numbers? What cam is in it?
If you're going to go into the shortblock...no reason to not at least make it a 383.
JIM
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On mine when I did a refresh a couple years ago. I found the bores all well within spec's. I honed the cylinders and fitted them with new hyperunetic pistons and rings of the same (Std) size, some new crank and rod bearings and reassembled. 5 thousand miles later. Running great, no oil consumption and a fraction of the cost of a new short block.
Just my 2 cents.
Just my 2 cents.
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You want a 50%+ increase in h.p. From what I've read on the Forums your original engine may be pushing it's limit if you modify it that much.
Maybe a new short block (and possibly U.S. made aluminum heads/if the original heads aren't built for power) would be your best bet.
Maybe a new short block (and possibly U.S. made aluminum heads/if the original heads aren't built for power) would be your best bet.
Dr. Detroit
Joined: Mar 2012
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From: New Braunfels Texas
Hello fellow Michigander.....
Being from the D, you are in probably the best place in the world to have your block machined. How much do you want to do? If you can build it yourself.....have the block machined and buy a balanced rotating assembly from Scat, Eagle or others.....if not, then as mentioned, get a short block from a reputable shop.
If you have a fresh top end....the short block is the best way value and timewise.....
Jebby
Being from the D, you are in probably the best place in the world to have your block machined. How much do you want to do? If you can build it yourself.....have the block machined and buy a balanced rotating assembly from Scat, Eagle or others.....if not, then as mentioned, get a short block from a reputable shop.
If you have a fresh top end....the short block is the best way value and timewise.....
Jebby
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 7,186
Likes: 45
From: detroit area
For a shortblock to kill the power....it would have to be severely hurt. Even a smoking engine will run hard if the rest of the parts are right. It probably is a low compression engine...so certainly kicking it up a couple of points will help...but power is in the heads/cam and tune.
You said the heads are ported. What heads? Any flow numbers? What cam is in it?
If you're going to go into the shortblock...no reason to not at least make it a 383.
JIM
You said the heads are ported. What heads? Any flow numbers? What cam is in it?
If you're going to go into the shortblock...no reason to not at least make it a 383.
JIM
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Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 7,186
Likes: 45
From: detroit area
Hello fellow Michigander.....
Being from the D, you are in probably the best place in the world to have your block machined. How much do you want to do? If you can build it yourself.....have the block machined and buy a balanced rotating assembly from Scat, Eagle or others.....if not, then as mentioned, get a short block from a reputable shop.
If you have a fresh top end....the short block is the best way value and timewise.....
Jebby
Being from the D, you are in probably the best place in the world to have your block machined. How much do you want to do? If you can build it yourself.....have the block machined and buy a balanced rotating assembly from Scat, Eagle or others.....if not, then as mentioned, get a short block from a reputable shop.
If you have a fresh top end....the short block is the best way value and timewise.....
Jebby
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 7,186
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From: detroit area
Found a shop close so will take it up there next week and they can pull the engine/etc... This should give me some time to research and see what my options are. Might be a good time to upgrade to a MSD ignition setup too. Should probably change out the fuel pump while I'm at it.
Safety Car
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From: Orange County Ca
I've known a few people who have done similar projects and were pretty much disappointed.
You need to research some more, and then, realistically, think about what you expect to gain.
As said above, just refreshing your short block may not be gaining you much, while costing $$$.
You need to research some more, and then, realistically, think about what you expect to gain.
As said above, just refreshing your short block may not be gaining you much, while costing $$$.
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 7,186
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From: detroit area
Just spoke to my dad when he came over last to help me figure it out (he's an OG mechanic so has helped over the years, but getting up in his age so can only do so much)
My heads are 202 and opened up on 3 sides(think that typical). compression is around 125...
could just be a timing/.spark issue....
I'm still thinking a 383-400 upgrade, but will see. with what ever works with what I have on the top end/components ...
My heads are 202 and opened up on 3 sides(think that typical). compression is around 125...
could just be a timing/.spark issue....
I'm still thinking a 383-400 upgrade, but will see. with what ever works with what I have on the top end/components ...
Pro
Joined: Jul 2021
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OP
If yours still has its original pistons & heads; it had Very Low compression when new & it's a near certainty it still has very low compression ... porting & rebuilding heads don't raise compression. Dunno which year or model yours is but (judging by your profile pic) it came w/ low compression large chamber (~76cc) heads and (unless L82) came with low compression dished pistons.
JMO, I suggest a new GM crate motor w/ modern GM Vortec heads; otherwise it'll cost more to rebuild & upgrade yours. GM crate motors have THE best warranty. YMMV
Thread Starter
Le Mans Master
Joined: Nov 2004
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From: detroit area
Yup!
OP
If yours still has its original pistons & heads; it had Very Low compression when new & it's a near certainty it still has very low compression ... porting & rebuilding heads don't raise compression. Dunno which year or model yours is but (judging by your profile pic) it came w/ low compression large chamber (~76cc) heads and (unless L82) came with low compression dished pistons.
JMO, I suggest a new GM crate motor w/ modern GM Vortec heads; otherwise it'll cost more to rebuild & upgrade yours. GM crate motors have THE best warranty. YMMV
OP
If yours still has its original pistons & heads; it had Very Low compression when new & it's a near certainty it still has very low compression ... porting & rebuilding heads don't raise compression. Dunno which year or model yours is but (judging by your profile pic) it came w/ low compression large chamber (~76cc) heads and (unless L82) came with low compression dished pistons.
JMO, I suggest a new GM crate motor w/ modern GM Vortec heads; otherwise it'll cost more to rebuild & upgrade yours. GM crate motors have THE best warranty. YMMV
If I can stay under 5-6k for the short block/upgrades/etc, that would be great. I wont really know until I have it looked at. trying to avoid buying everything twice if I don't have to.
https://www.jegs.com/i/Chevrolet-Per...55719/10002/-1 just an idea
Last edited by onaqwst; Oct 4, 2021 at 02:44 PM.
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The original heads may have been "ported" and be in great shape as far as a valve job.....but I can guarantee you there is a LOT of power available with a decent set of good aftermarket heads matched with a good cam. OEM heads just aren't that great as compared to anything you can buy these days. A basic 383 shortblock or complete engine will make you happy with good heads and cam.
JIM
JIM
Thread Starter
Le Mans Master
Joined: Nov 2004
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From: detroit area
Some ideas...might have to just ditch the reuse what I have idea.... sell off the parts and hope to cover some expenses
https://www.jegs.com/i/ATK-Engines/0...model=CORVETTE
https://www.summitracing.com/parts/m...ette/year/1977
Might be easier to just pull/swap then try to rebuild/etc......
https://www.jegs.com/i/ATK-Engines/0...model=CORVETTE
https://www.summitracing.com/parts/m...ette/year/1977
Might be easier to just pull/swap then try to rebuild/etc......
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What is your compression ratio, you can throw alot of speed parts at it but if you have stock low compression pistons and heads your losing HP right there. I would just get the block bored, new high compression pistons and decent aluminum heads. A 355 will make great power with the right combo
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 7,186
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From: detroit area
What is your compression ratio, you can throw alot of speed parts at it but if you have stock low compression pistons and heads your losing HP right there. I would just get the block bored, new high compression pistons and decent aluminum heads. A 355 will make great power with the right combo
Will see what they say when I swing by next week....
Pro
Joined: Jul 2021
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more brain fodder
Some ideas...might have to just ditch the reuse what I have idea.... sell off the parts and hope to cover some expenses
https://www.jegs.com/i/ATK-Engines/0...model=CORVETTE
https://www.summitracing.com/parts/m...ette/year/1977
Might be easier to just pull/swap then try to rebuild/etc......
https://www.jegs.com/i/ATK-Engines/0...model=CORVETTE
https://www.summitracing.com/parts/m...ette/year/1977
Might be easier to just pull/swap then try to rebuild/etc......
Be advised. All GM sbc crates are completely brand new top to bottom. And have the best warranty in the business with No Restriction on where you Must file any claim (sue) if you can't resolve a warranty issue.
Be advised. Crates from either ATK (aka Vege) and BPE have a warranty which Restricts user to file (sue) in Company's State of choice; ATK/Vege = Illinois while BPE = Nebraska. Suggest read the fine print and/or consult Your counselor Before writing the check; because, sadly, sometimes stuff happens.
The BPE motor referenced above has a New block but many (if not most) BPE crates use a remanufactured block which has been bored out to (or beyond) blocks' intended/practical limit.
ATK/Vege crates are similar; some have new blocks while some use a remanufactured block which has been bored out to (or beyond) blocks' intended/practical limit.
When it comes to cranks: Cast Steel is Not Forged Steel. Cast is Cast. Forged is Forged; and is more robust than Cast.
FWIW, GM sells a True 383" (the one you reference) with standard 4 inch bore & 3.800" stroke forged crank.
This $3600 motor: from GM
https://www.gmperformancemotor.com/parts/12691673.html
This roller motor will easily make 300-315 Gross SAE HP on an engine dyno with a good carb & distributor & headers
With a drop-in spring & retainer swap ($140),bigger roller cam swap ($250) it'll easily make ~ 425 Gross SAE HP on an engine dyno; and do it reliably.
Freshen your carb & dist, a new Vortec intake $175 ...DIY I'm seeing under $5K. Cam & spring swap rather easy.
four USA-made billet steel roller cams for sbc
https://www.summitracing.com/search/...rder=Ascending
think long & hard