400 sbc performance rebuild
Le Mans Master
Joined: May 2007
Posts: 5,028
Likes: 1,120
From: North tonawanda NY
the blocks vary and some pistons are known to sit up to .020 further down than others.... yes it caused me to use .027 gaskets... would have used the 015 gaskets I have but I'm already on the verge of detonation zone with iron heads and pump gas...it was a good thing my dart 64cc heads actually measured 68cc and the 7cc speedpro flat tops took a few cc's more liquid before leveling off as well...many manufactures inflate or round down the numbers in this case..
Racer
Joined: Feb 2013
Posts: 386
Likes: 3
From: Clifton Virginia
Got 400 sbc, no price limit but don't want to go
Overboard, want best performance parts for cost
-run premium or regular, 10 to 1 or 10.5 to 1
- naturally aspirated
-taking suggestions for pistons, rods, aftermarket heads,
Intake, taking in consideration it has to fit under stock hood
Of 76 sting ray.
Would like to hear your ideas, thanks.
Overboard, want best performance parts for cost
-run premium or regular, 10 to 1 or 10.5 to 1
- naturally aspirated
-taking suggestions for pistons, rods, aftermarket heads,
Intake, taking in consideration it has to fit under stock hood
Of 76 sting ray.
Would like to hear your ideas, thanks.
Melting Slicks
Joined: Jul 2006
Posts: 2,291
Likes: 493
From: Salmon Arm, BC
To make it right, I'd send it to the machine shop and go .030" over. Do a plate hone for final cleanup for the best ring seal. Don't cheap out at this point, you'll regret it if you get lots of blowby.
Dress out that casting flaw with a carbide burr....it's nothing major. Your on your own with the other debacle...
Dress out that casting flaw with a carbide burr....it's nothing major. Your on your own with the other debacle...
Racer
Joined: Feb 2013
Posts: 386
Likes: 3
From: Clifton Virginia
To make it right, I'd send it to the machine shop and go .030" over. Do a plate hone for final cleanup for the best ring seal. Don't cheap out at this point, you'll regret it if you get lots of blowby.
Dress out that casting flaw with a carbide burr....it's nothing major. Your on your own with the other debacle...
Dress out that casting flaw with a carbide burr....it's nothing major. Your on your own with the other debacle...
go three over with nice set of runners and roller cam, you could end up with one mean 406 where you be doing the blowbys.
PM me and I will give you the exact list of what I did to my 400 sbc to push over 500HP.
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
Example: 1/2 of stroke + rod length + piston comp height = deck height to shoot for.
400 with 6" rods 1.875" + 6" + 1.125" = 9.00"
Machine the deck to 9.00" and you have a zero deck or very close. I like to stick the piston out of the hole a little to run thicker head gaskets and still get my desired squish.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
If you know your stroke, rod length and piston compression height, you then have a spec to shoot for when you deck the block.
Example: 1/2 of stroke + rod length + piston comp height = deck height to shoot for.
400 with 6" rods 1.875" + 6" + 1.125" = 9.00"
Machine the deck to 9.00" and you have a zero deck or very close. I like to stick the piston out of the hole a little to run thicker head gaskets and still get my desired squish.
Example: 1/2 of stroke + rod length + piston comp height = deck height to shoot for.
400 with 6" rods 1.875" + 6" + 1.125" = 9.00"
Machine the deck to 9.00" and you have a zero deck or very close. I like to stick the piston out of the hole a little to run thicker head gaskets and still get my desired squish.
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
The closer you run the piston to the head, without actually hitting, the crisper the engine will be and it will be less sensitive to detonation. As the piston approaches the head, the air/fuel charge is squeezed out of the quench (squish) area into the chamber. This creates a more homogenous mixture in the chamber, meaning less lean or rich areas, resulting in a better burn and less tendency to have detonation (pinging). Usually with a tight squish and a modern efficient combustion chamber, you need less total ignition timing, especially if combined with high compression.
My pistons are out of the hole .005". With a .039" head gasket, I have .034" squish. Back when I was building a lot of race motors, I would tighten the squish until the pistons and heads would just start getting acquainted with each other and then back off a couple thousandths.
My pistons are out of the hole .005". With a .039" head gasket, I have .034" squish. Back when I was building a lot of race motors, I would tighten the squish until the pistons and heads would just start getting acquainted with each other and then back off a couple thousandths.
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Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
Would it be the same as being .005" in the hole and using a .029" gasket? I get quench, but am curious about having the pistons stick out the top as to the benefit to that as opposed to the other way.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
As things wear heat up and stretch over time that piston can kiss the head when it starts to rock or god forbid stretch a rod bolt
Floating valves, hit.
Im not negating what is said above just pointing a thing out or two.
Piston to valve clearance may mean cutting the pistons and poss. rebalance. For a race engine pushing the limit on something that gets torn down periodically so far out of the hole is common. Wouldnt get too hung up over # perfect quench on a street strip motor. A few thou either way wont make any difference imo. Leave room for error ie idiotproofing
Floating valves, hit.
Im not negating what is said above just pointing a thing out or two.
Piston to valve clearance may mean cutting the pistons and poss. rebalance. For a race engine pushing the limit on something that gets torn down periodically so far out of the hole is common. Wouldnt get too hung up over # perfect quench on a street strip motor. A few thou either way wont make any difference imo. Leave room for error ie idiotproofing
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
As far as having a tight squish on the street, I've run .034",.036" for decades on small blocks and never hit anything. I also feel the squish is even more important in these days of poor quality gas, especially if you are pushing the compression ratio envelope like I am. Don't under estimate the ability of a tight squish to help prevent detonation.
Although I am a believer in tight squish, it is nothing new. Smokey Unich was touting the benefits of a tight squish before our C3's even existed.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
The notch looks like a casting flaw but its nothing to worry about.... You may want to take a die grinder and just gring the notch out (grinding up into the cylinder towards the head.) and round out so there's no sharp edges
The starter bolt may turn into a headache???
I would lay the crank in with the flywheel. Then bolt your starter in. You can check the alignment of the gears and maybe even put power to it. I've seen people eat flywheels and starters just because a starter bolt was a tiny bit bent.
So I caution you before you attempt to rebuild the entire motor. Make sure that starter isn't an issue or you'll be miserable
The starter bolt may turn into a headache???
I would lay the crank in with the flywheel. Then bolt your starter in. You can check the alignment of the gears and maybe even put power to it. I've seen people eat flywheels and starters just because a starter bolt was a tiny bit bent.
So I caution you before you attempt to rebuild the entire motor. Make sure that starter isn't an issue or you'll be miserable
Last edited by hugie82; Jun 28, 2013 at 10:41 AM. Reason: Spelling
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
Are you going to have the block fully machined, as in; cook the block out, line hone the mains, bore with torque plates off the mains, deck the block, install new cam bearings, etc...? Have you checked on the cost for fully machining the block? Do you have a crank? Is it the stock cast crank if you do? The stock cranks are prone to cracking.
It can get quite expensive. You may want to look at a new block, crank and rods. Nothing worse than building a new motor and it failing soon after, or ending up with as much money in it as the good stuff would have cost you. That starter bolt would scare me too!
It can get quite expensive. You may want to look at a new block, crank and rods. Nothing worse than building a new motor and it failing soon after, or ending up with as much money in it as the good stuff would have cost you. That starter bolt would scare me too!
Burning Brakes
Joined: Jun 2010
Posts: 1,165
Likes: 93
From: Bellmore NY
Back in the 90's, 400 sbc's were all the rage. A friend of mine bought this book [pamphlet really] from the back of a magazine on "How to 11 second your late model F body". His first rendition of this motor sailed into the low 12s, and eventually the high 11's in a full weight G-body [86 monte SS with additional weight of roll bar].
His next rebuild eventually saw 11.4s on motor by changing up the combo a bit. Im pretty sure he went 10.60's on a 100 shot.
This particular combo probably wouldn't be great for you based on your gear choice, and subsequent choice of converter based on that gear, but the point is that its real easy to go fast with a 400
His next rebuild eventually saw 11.4s on motor by changing up the combo a bit. Im pretty sure he went 10.60's on a 100 shot.
This particular combo probably wouldn't be great for you based on your gear choice, and subsequent choice of converter based on that gear, but the point is that its real easy to go fast with a 400
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
As things wear heat up and stretch over time that piston can kiss the head when it starts to rock or god forbid stretch a rod bolt
Floating valves, hit.
Im not negating what is said above just pointing a thing out or two.
Piston to valve clearance may mean cutting the pistons and poss. rebalance. For a race engine pushing the limit on something that gets torn down periodically so far out of the hole is common. Wouldnt get too hung up over # perfect quench on a street strip motor. A few thou either way wont make any difference imo. Leave room for error ie idiotproofing
Floating valves, hit.
Im not negating what is said above just pointing a thing out or two.
Piston to valve clearance may mean cutting the pistons and poss. rebalance. For a race engine pushing the limit on something that gets torn down periodically so far out of the hole is common. Wouldnt get too hung up over # perfect quench on a street strip motor. A few thou either way wont make any difference imo. Leave room for error ie idiotproofing
Thread Starter
Intermediate
Joined: Jul 2011
Posts: 25
Likes: 0
Hey guys I'm done, complete, turnkey engine on the
Stand, KB hypereutetic pistons, 10.5 - 1, punched into
A 406, complete edelbrock performer rpm top end, roller
Rockers, mild street strip cam,
My question now is will i be able to fit a deep sump
Moroso oil pan into my 76 vette and also what ways
Have people made a Holley carb and a high rise intake
Fit under a stock hood?
Stand, KB hypereutetic pistons, 10.5 - 1, punched into
A 406, complete edelbrock performer rpm top end, roller
Rockers, mild street strip cam,
My question now is will i be able to fit a deep sump
Moroso oil pan into my 76 vette and also what ways
Have people made a Holley carb and a high rise intake
Fit under a stock hood?
Drifting
Joined: Jun 2012
Posts: 1,990
Likes: 183
From: Port St. Lucie Fl
Le Mans Master
Joined: May 2002
Posts: 5,086
Likes: 786
From: Lebanon Township New Jersey
As for the deep sump pan, there is no way around it, every inch deeper puts it an inch closer to the pavement. Not worth the risk on a relatively mild engine.
You can fit just about any carb and manifold under the hood of a 76. You need a 2" drop base air cleaner with a 3" x 14" element. The problem you might have is if your carb has vacuum secondaries, and with an automatic it should, the vacuum attachment on the side of your Holley might interfere with the drop base.
You can fit just about any carb and manifold under the hood of a 76. You need a 2" drop base air cleaner with a 3" x 14" element. The problem you might have is if your carb has vacuum secondaries, and with an automatic it should, the vacuum attachment on the side of your Holley might interfere with the drop base.