For what you are doing, I would use Felpro Marine head gaskets.
Valve Springs depend on cam. If you are going to use a 731, then I'd prob use Isky 8005A's or Comp Cam 929's.

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Yes I have been told that cam will work fine in a blower application so yes ill use it and I'll look into the valve springs you suggested any special rings for my pistons

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https://cimg8.ibsrv.net/gimg/www.off...14b402d28e.jpg
Im guessing this one is stock i can't find much on these numbers anyone recognize

Your 454 Mag came with forged TRW pistons.
The .030 over SpeedPros that are in it now are the correct "cross reference" piston (similar dome, etc to the originals).

I do see that somebody has bore-notched your block (this is good) to unshroud the valves. That's good for 5 free hp (more on a high rom motor).

Here's what you need to focus on for a good outcome..
Check your rod bolts. If they are already replaced with aftermarket (SPS or ARP), then just check the big ends for roundness. If ok, then just match the bearing size properly. If they are still running stock bolts, then press in new ARP's and have the big ends resized (due to the press-fit, you have to rework the big end anytime rod bolts are replaced.
Next - before you disassemble, check to see where the piston sits below/above the block deck at TDC (piston quench pad to block surface).
It may be .020" "down" in the hole, or .005 "up" out of the hole. You need to know this to select your head gasket.
You WANT 0.036-0.045" quench clearance (between the quench pad on the piston and the flat portion of the head).
For example, if you plan to use the FelPro .039" thick (compressed) gasket, then your piston can not be more than 0.006" IN THE HOLE, nor more than 0.003" OUT OF THE HOLE. If you are OUT more than that, you'll need to use a thicker gasket. If you are IN more than that, you'll either need to use a thinner gasket OR deck the block to get the distance where you want it. All of this is important. Especially if you plan to add 5 psi of boost. The tight quench clearance improves "burn" in the combustion chamber AND creates turbulence that prevents charge detonation. Very important.
If you set up your motor as described above, with UNCUT 118cc heads, at 030 over, you will be at a compression ratio of 9.1:1 (stock block usually has the pistons down 035 or so in the hole, netting a 8.75:1 CR).
At 9.1 CR, 5psi of boost will be the limit with a Crane 731 cam or similar. If you want more boost, you should plan on running flat-top pistons.
If you do NOT plan on supercharging, you can cut your heads to 115cc - .003" per cc on GM 088 heads - to 9.4:1 CR.
Back to the cam - a Crane 731 will require a thrust button against your timing cover, and hydraulic roller lifters. Also, make sure the cam gear and distributor gear are compatible. Some roller cams have a drive gear that works with the regular distributor gear. Billet cams require a bronze distributor gear. For lifters you have 2 choices ... run "tie bar" retrofit hydraulic roller lifters or machine your block for Gen 6 dogbone lifter locator plates. Using dogbones allows you to use the lighter and less expensive GM Gen 6 lifters on your MkIV block.
For rockers, don't buy Chinese rockers. Repeat that sentence 40 times. You are better served with 1960's style stamped steel L88 rockers than Chinese aluminum needle bearing roller rockers. But, you can't go wrong with Crane gold or any if the Comp rockers that fit your budget. Don't buy used ones, unless you plan to send them in for refurb.
Wait until all head/block machining is done before you measure for pushrod length.
Match the valve springs to the cam, shim the springs to the correct installed height.. Check to see if you have any interference issues between the valve locks and the top of the stem seals. Sometimes, you may need to have the tops of the guides machined deeper to lower the seals for clearance (use Viton seals). Keep in mind you are going from .480 ish lift to around .600
Valve prep is typical. Undercut the exhausts.
A little bowl blending on the heads, a standard 3 angle job on the seats. Don't mess with the floors or shortsighted radius on the ports. Just don't touch em.
Use a piston stop to properly locate the timing pointer and use timing tape on the balancer for future easy TDC reference. Do not trust the timing set to degree your cam. Use a degree wheel and set it up +4 advanced just like Crane recommends.
The factory GM aluminum dual plane intake is surprisingly good. But if you're planning on a new intake, the Edelbrock RPM AirGap is the one to beat. If you plan on running in salt water, you MUST use an intake with a bronze lined water crossover or at least one that is hard anodized.
Be sure to mock up your intake with USED intake intakes to see if you need to do anything weird to mate up w the heads properly - run a camera in the ports to see how you transition from the runner into the heads. This is because you may have a decked block and decked heads and may also need to shave some off the intake flanges to get the correct gasket crush..
Port matching from intake to heads is a bit overrated, but you should fix any major mismatches. Try not to cut anything off the floors of your intake ports on the heads.
Stock 454 Mag exhaust manifolds start spring the fun at 450hp. If you stay below 450hp, you can use em. If you want more, you'll need something better - GIL, CMI, Lightning, etc.
An 800 or 850 Holley will be great. Vacuum secondary is fine, mech is not necessary. Both can be tuned to perform properly.
​Timing curve for ignition will need tweaked some. Basically, wide open throttle you need 36 degrees total timing. Idle, you need around 12 to 14. Bring it in however quick you can without pinging on a hot day.
You'll want to make sure your engine can get plenty of air to the carb. Boats are notorious for HOT engine compartments, which is your enemy for getting plenty if cool air to the carb. Sometimes extra vents/plumbing may be necessary. Best way to know is to do all your tuning/jetting with the hatch off or at least closed down on spacers to create a 4" air slot to feed the motor. Then when you have a speed/rpm baseline, shut the hatches tight and try again. If you lose ANY rpm, you need to figure out how to get more cool air to it.
Factory fuel line sizing may not be adequate for 500hp. Always run a mechanical fuel pressure gage from a pressure tap right up at the carb inlet. While tuning, keep an eye on it, and while wide open throttle, your pressure should remain steady and never drop any. If it weakens with additional rpm, then you need to find and address your restriction.

Ill probably come back and add more later.

Lots of really good advice ^^^^^^^^^^^

I don't think you need to run a cam thrust button though. The 168731 cam is a Gen VI cam so pretty sure you just need to run the correct Gen VI timing chain set with retainer plate....I think...mccollinstn????

That 168731 cam also has a pressed on cast iron cam gear so you can run a stock distributor gear. I ran almost 8# of boost with that cam, but I had a 7.5 CR.

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Ok mcollinstn I am going to put a wieand 177 charger on it for sure I just bought it it is setup for 5psi, to check quench on these pistons properly do u check beside or on top of the dome there are 2 flat spots ?

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https://cimg5.ibsrv.net/gimg/www.off...15768073e9.jpg
In my diesel world its the highest spot but all my pistons have a flat ring around them

Left (not the dome)

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Thank u sailtexas

Yep. The 731 (168731) is a GenVI. Most guys reference the "731" and "741" cam grinds, and I guess I do as we'll, sort of like all cola is Coke. To run a 168731 in a MkIV you have to machine the front of the block for the thrust plate. The 139011 is actually the part number for a MkIV. And a needle bearing button will suffice for it AND you can still fit a legitimate double roller chain. And, really, Comp makes a similar cam in the XM284HR, albeit with slower ramps and less lift. I prefer the Crane, unless you go custom.

Seems a 177 blower is on the plate now, and I stick with the "731" style cam for a decent choice unless he wants to go custom grind.

The choice to machine the block for a GenVI cam thrust plate OR run a MkIV setup with cam button is your choice. I can't recall whether the 139011 cam has a steel gear or a pressed on cast gear. If you run this cam you'll need to double check..

Running a 5psi 177 blower, there are carb setup tips you'll need. If you run a Holley, don't run a power valve in the secondary metering plate, or block it off if it has one. You'll need to upsize the secondary mains if you block off the PV. If your Weiand 177 is from a Merc 525SC with the 1050 Holley then just jet it to baseline Merc specs, although they run rich at no-wake speeds and drilling a .060 hole in the primary throttle plates helps that.. You will also want to make sure you run electronic timing advance and NOT a mechanical advance in the distributor to minimize surging around the docks. Blower surge sounds cool, but is a hassle. Thunderbolt IV distributor doesn't have mechanical advance, so if you're using what came on your 454 Mag, then you're good there.

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Ok so back to measurements for head gasket
https://cimg2.ibsrv.net/gimg/www.off...cf41b2c84e.jpg
It shows between 30k and 31k

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https://cimg2.ibsrv.net/gimg/www.off...182910876d.jpg
This is what I'm installing

did you rock the piston back and forth and take an average?

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Yes 30 - 34

Cut .034 off the block (zero deck). Then run .036-.039 gaskets.
Yes, it will increase compression, but the added turbulence from the "squish" benefits you MORE in both WIN/WIN categories. Power production AND detonation prevention.

Then, do some bowl work on the heads to unshroud the valves and add a few cc's to the chambers. Don't cut the heads unless they arent straight/flat.

I can't tell what carb that is.
Since you're running an aftermarket distributor, figure out your electronic advance and lock out the mechanical advance.
What ignition box/amp are you gonna run?

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So I couldn't run a smaller gasket with the way the block is now and ignition is just factory setup still

I can't speak for the ignition. But Cometic makes gaskets in about any thickness down to .027". They are the best on the market bar none. Using thinner gasket achieves same as cutting the block.

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Thank u smitty that's what I thought but wasn't positive

Only issue with the .027" gasket is your still going to be above recommended max "quench" distance of .045". Unless you're going for every last ounce of performance in a timed racing situation I doubt you'll ever be able to measure the difference it power.

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I'm not at all I just want it to be right no issues all season

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Or I should say id like to put another 700hrs on it myself

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Mcollinstn its a 1050 holley carb but ignition is all stock

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So is there not a good cam out there that I can install with out doing any machine work or is there no way around this

You can use the Gen VI cam in your Mk IV. Just need to get the retainer plate thru GM. The block "should" already be machined for it. I'd be surprised if it isn't already. Use the Gen VI chain set.

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https://cimg4.ibsrv.net/gimg/www.off...9e11acbdf3.jpg

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https://cimg6.ibsrv.net/gimg/www.off...1d38525c88.jpg

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https://cimg6.ibsrv.net/gimg/www.off...746c7ed4f2.jpg

http://www.summitracing.com/parts/na...1053/overview/

That's the link to the GM chain set and includes the retainer plate. Some have said they needed to elongate one of the bolt holes in the plate to use it on the MK4. Some will complain it's a single roller but it's plenty strong and durable.

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So there isn't a direct replacement performance cam for this engine

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So there isn't a direct replacement performance cam for this engine
or is this my easiest option for a mark 4

I would buy the Cloyes set for a few dollars more. I have found it to be much tighter on initial install. And it’s adjustable, not that you will need that. Sorry No part number

It'll be much much easier to find a used Merc or Crane factory roller grind for the Gen V/VI than to find a used equivalent for the MK4. And a heck of a lot cheaper than buying new.

It's your motor, and it's your dollars. .050" is pretty much the line in the sand.
Under .045" quench clearance is a "SQUISH MOTOR". Above .055" is not.
A motor with tight quench clearance is more responsive, has better throttle response, can accept optimal ignition advance curves on lower octane, is much more detonation resistant and can handle more boost than a "non squish" motor of the same compression ratio.

In the 70's everybody put pop-up 11.5:1 pistons in our 350 small smallblocks with open chamber heads. The piston pads were 040 to 060 in the hole and we ran 039 gaskets The. actual CR was usually in the neighborhood of 10.5 to 10.8:1. And on pump gas they rattled like a snare drum, and we had to pull so much timing out that they ran like total crap. When we went to the grudge drags, we cranked the timing up, dumped in race gas, and went fast. Then, we pulled the timing back out and ran a sick rattling pump gas motor til the next weekend. We didn't understand the concept of squish turbulence.

If you build the same motor with zero deck, 039 gaskets, and flat-top pistons, and cut the heads to give you the same 10.5 to 10.8:1 compression, then you will be rewarded with a motor that you can't make rattle on pump gas running full timing advance. It will rev quicker, and go faster on pump gas than the other motor would run on race gas.

We've got a 440 Mopar RB running 11.3:1 with aluminum closed chamber heads (TFS 240s) on 91 octane with 18 degrees initial, and 38 degrees all in at 2900 with 56 degrees with vacuum advance. We can't make it rattle. Runs stronger and harder than any of the motors we built the "old way". The biggest example is the Coronet we ran years ago with a solid roller cam and 11:1 pistons that needed race gas to keep from rattling. The new motor runs more compression, has less duration and overlap (hydraulic flat tappet, no less), runs on pump gas, and is 2 tenths faster in the 1/8th and is a blast to drive.

So, do you NEED to make sure you end up 036-040 squish? No. People run motors every day that dont operate "in squish". In fact, chevy big blocks never came in cars and trucks with tight squish. That was a secret engine-builder trick until the late 1980's.

Now you have 2007 6.2L Yukons and Tahoe with 10.6:1 CR and 410hp running on 91 octane and getting better fuel economy than a 165hp Chevy 305 from 1982. These are not the "direct injected LT motors". They are normal port-injected motors with TIGHT SQUISH CLEARANCE.

But yes, to cut the block you'll have to strip it bare and pay $175 or so.

I won't think less of you if you don't.
But its my position that I would be doing you a disservice by not explaining the benefits..

Run the retrofit cam which is the same specs as the 731 except made for MarkIV/Gen V. https://www.summitracing.com/parts/crn-139011
Then use this timing chain set up or similar. It has a thin bearing on the block side of the upper sprocket. https://www.summitracing.com/parts/crn-13977-1
Then use a cam button like this or similar. https://www.summitracing.com/parts/crn-99165-1

I'm pretty sure these are the exact parts I used when I swapped to roller cam in my 525SC.

supercharged and n/a react very different to quench clearance.
ever had the heads off a 1075? Flat top pistons are .120 in the hole.

My cam in the swap shop that you inquired about would work just fine and is a direct replacement.

No, SC an NA behave the same in regards to squish. There are plenty of cases where the trade-offs in getting the numbers just aren't worth it, but they do both benefit similarly to a tight chamber.

And, no. I've not had heads off a 1075sci. I've had bore scopes in them and they do run flat-tops. And while I don't doubt what you say, the Diamond piston website shows the 1075sci stack up with stroke, rod length, and piston compression height to be
(4.375 ÷ 2) = 2.187 (stroke by half)
+ 6.635 (rod length)
+ 1.380 (piston compression ht)
= 10.202"
That's on a GM tall deck, which is a 10.200" block. For the pistons to be down 120 the deck ht would have to be 10.320

Take a look at the Daytona Sensors ignition. I swapped from the MSD 6M to Daytona Sensors. The difference is incredible, very useful feature set as well. I run 93 octane, but when I can't, I can flip a switch and pull 4 degrees out to run 90 octane marina gas. Idle control with timing is amazing.

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Ok so we got cam and gear train figured out now do do i buy flat top or keep what I have and build from them secondly if u guys do say flat top do I install 1 in the same hole and remeasure the piston height then have cut ???????

Whatever piston you choose, mock one up in all 4 corners of the block and measure. Write the # right on the deck and the machine shop will handle it from there