Jump to content

Big Block Deck Height


Recommended Posts

I've been looking at blocks for my build.

 

I've got some questions about big block and the deck heights.

 

How is this actually measured? How do you determine deck height?

 

What is the differences in a tall (10.2 inches) vs the shorter OEM

Does one pose an advantage over the other strength wise? I'm assuming the taller deck offers more strength?

 

Are there any members running a taller deck and if so did you have clearance problems with things like the master cylinder firewall etc.

 

Thanks!

 

 

 

 

Link to comment
Share on other sites

I am sure Sam will chime in on this, but I think the headers will fit differently, you need a distributor with an adjustable collar, and the heads / valve covers will stick up more...

 

Ian

Link to comment
Share on other sites

a short deck is 9.8" from the crank centerline to the deck surface, a tall one is 10.2"

 

you would have brake booster issues, header issues, distributor, intakes are different

 

I had trouble with my headers, cause my heads have raised exhaust ports, and I'm using a short deck block

 

I would recommend staying with a short deck

 

OH!!! I forgot hood clearance too

Link to comment
Share on other sites

Sam is right on with what he is saying.

Tall blocks are nice for big stroker motors because you can run longer rods. If you are considering tall 427 truck block you are limited by bore size. And the oil galley that runs at the bottom of the drivers side of the block limits how much you can grind for crank and rod clearance. Aftermarket blocks correct most of these issues but there is the increase in cost.

You can get spacers to install any intake manifold but you must port macth them to your heads and intake.

I would think that custom headers would be required they will be at least .400 higher maybe more depending on head selection,

 

I love big inch motors but for a monte I would stay with a standard height block you can build a 496 with .250 long rods real easy it is a great motor as long as you don't spin it to the moon.

Link to comment
Share on other sites

Thanks guys that helps.

 

I have just picked up the rods, pistons, crank, harmonic balancer, and flex plate these are a 496 Stroker kit with .060 over pistons...and I am now looking at a Dart Cast Iron block standard height of 9.8 inches.

 

I'm am not sure what my 454 has on the lower half, but if it is a 2 bolt main I most likely will go with a new block with 4 bolt mains.

 

There are several Dart blocks on summit with varying bore diameters bringing me to my next question, why the variance in the bore diameters? Is this something that the manufacturers do as a matter of course for oversize pistons and rings? ?

 

Forgive my ceaseless questions here, I have never done anything other than a stock rebuild so I'm not familiar with why they would offer various bore diameters.

 

Assuming that I end up buying a new block, What bore diameter should I choose with that .060 piston?

 

Link to comment
Share on other sites

Bones, sorry I don't have it as I wrote it down and left it behind in TN and now the wife can't seem to locate that "scrap of paper you left laying around" DOH!

 

According to the previous owner the block is from a 1978 truck, any casting numbers that match a 1978 from what I found say "either 2 or 4 bolt mains" ..so that's not much help at all. I'm erring on the side of caution and saying the block is a 2 bolt.

 

If it is I was pretty much set on replacing it with a 4 bolt for durability.

Link to comment
Share on other sites

Greg, mine is only a two bolt, are you thinking of going as far as mine?

 

everybody has this thing about having to have a "4 bolt" and most of the time IT IS NOT NECESSARY

Link to comment
Share on other sites

I ran a 72 truck block 2 bolt, cast crank, stock rods in my previous motor (454) pushing around 525 hp with never an issue with the short block. However, if everythings apart it never hurts to upgrade and have the added insurance.

 

Someone once told me and I agree - there was a reason the General used 4 bolts and forged internals in their high performance motors grin

Link to comment
Share on other sites

DO they may a conversion kit for Big Blocks to go to 4 bolt mains. One engine builder I used in the past said the on the small blocks the 2 bolt blocks were usually sturdier and better cores. He would put the after market splayed kits in them if you really wanted 4 bolt mains...

 

Ian

Link to comment
Share on other sites

Supercharging or turbo is not in the future but I might run a 75-100 HP shot of Nitrous for passes at the track.

 

I guess it would help if the end goal was stated, I'm looking to break into the 12's on the track but still keep the car street friendly enough to drive to a show, or local cruise in. I don't street race, I might blip the throttle here and there but street racing is not worth the huge fines and risks of an accident.

 

Right now I have:

 

The lower half consisting of a 496 Stroker kit, with domed pistons, and Scat I-Beam rods @ 6.135

Scat 4.25 stroke cast crank

Sealed Power domed Pistons, these are .060 over.

Fluid damper Harmonic balancer

Hayes Flexplate

 

The heads are cast iron rectangular port casting number 14096188 These come back as a "service replacement head LS6" 119 CC 2.19 Intake / 1.88 Exhaust. Other than porting and polishing I don't expect to heavily modify these. Valves will be Manley stainless heavy duties, with roller rockers. Heads are brand new and not built yet.

 

I have not selected a cam yet but am leaning towards a hydraulic roller with advertised duration of around 270 and lift in the area of .510. Next to the choice of keeping my current block or replacing it this is my next biggest concern, this cam might be a bit much for running on the street, and the vacuum / heat problems might be an issue with it, although I've already got those monster flex-a-lite electric fans in there and I will replace the stock radiator with a aluminum unit and I can always run a vacum canister / pump if needed.

 

Pete Jackson Gear drive.

 

The Hedman shortie headers will be replaced by a set of long tubes.

 

Intake will be a single plane aluminum with a 850 CFM Demon.

 

Rear gear will be a Eaton Posi 3.73 and I'm really set on doing away with the automatic trans and installing a 4 speed Muncie.

 

That my 72 was originally a 350 4bbl car, and the motor was replaced with the 454 out of a truck, among other mods done in it's history, it already sort of took me out of "factory original", so I've opted to make it more of a street / strip car.

 

I'm figuring the above set up should yield around 11.5 / 1 compression and 500 HP, off the bottle at the flywheel.

 

Okay, 4 bolt or 2 bolt block? I'm not opposed to machining my current block considering it comes back with no cracks or problems from the shop inspection, let 'er rip and tell me where I'm "stuck on stoopid" here...LOL Thanks.

 

 

Link to comment
Share on other sites

2 bolt block

 

Weiand stealth dual plane intake (you won't like the single plane, and not enough RPM for the single plane)

 

I would go with a timing chain, drop the compression back to 10:1, and go with a bigger cam (esp w/ a 496)

 

with 11.5 comp and that small of a cam, you will need race fuel to run it, (that is a pretty small cam for a 496 w/ that much compression)look at some of the Lunati Vodoo Hyd Rollers

 

I have a Milodon gear drive set for sale, if you really must use a gear drive

 

you can buy the 4 bolt main caps, have your block drilled for the extra bolt, then line-hone the block, it is not needed for what you are planning, my should going into the 10's, and I'm running a 2-bolt w/a ARP stud kit, I have no concerns about it staying together pumpimg 11.9:1 compression wink

Link to comment
Share on other sites

Quote:
My changes would include:

Forged Flat Top Pistons

Lose the FluidDampr, they have a terrible rap since they were bought. There are plenty of options.

I would also agree that that is a mild cam.

 

Well since I bought the entire lower end as a balanced assembly I'm a little hard pressed to change to a flat top vs Dome. I'd have to sell this entire set up and start over.

 

270 is too mild???!? Aieeee...I guess I never took into account the 50 extra cubes on a stroker and the better heads I will be running this time around.

 

Like I said this is the first serious no sh*t motor build for me,

 

I built a 455 in my 72 Cutlass waaaaay back when but I really didn't have a lot of cash being a military sort back then and like most inexperienced, I stuck a rather large Crane fireball 292 Duration cam in the block with...stock heads, stock springs, tiny valves, and dish pistons...you can guess the rest.

 

While it did run okay, it had a lot of problems with vacuum and running hot. I was also in Rhode Island, and the cam was killing me on a smog check. So that all came into mind when I started looking at Cams.

 

Guess we will see what the block looks like when it comes out, I am looking at having it pulled here soon and starting the machine work. My mechanic is chomping at the bit to get started...LOL.

Link to comment
Share on other sites

2 bolt block

 

Weiand stealth dual plane intake (you won't like the single plane, and not enough RPM for the single plane)

 

I would go with a timing chain, drop the compression back to 10:1, and go with a bigger cam (esp w/ a 496)

 

with 11.5 comp and that small of a cam, you will need race fuel to run it, (that is a pretty small cam for a 496 w/ that much compression)look at some of the Lunati Vodoo Hyd Rollers

 

I have a Milodon gear drive set for sale, if you really must use a gear drive

 

you can buy the 4 bolt main caps, have your block drilled for the extra bolt, then line-hone the block, it is not needed for what you are planning, my should going into the 10's, and I'm running a 2-bolt w/a ARP stud kit, I have no concerns about it staying together pumpimg 11.9:1 compression wink

 

 

Thanks Bones! I guess I got some learning to do here on this stroker build. I'll look into the 4 bolt and machining the block.

 

On the manifold, I kinda figured it would help not so much on the street, but on the strip as I hit the 1/8 mark and pulled through the traps ...No?

 

Let me know what you want for the gear drive, yeah.. I know its not NEEDED..but I WANT one...nothing sounds as cool as a gear drive whining ...Bwhahahaha. nutz Email's in signature block or PM me.

 

Link to comment
Share on other sites

with that intake I can almost guarantee it will be slower

 

you could have you piston domes shaved to lower compression, then balance it

 

my gear drive won't be as noisey as a Pete Jackson

 

this is the one I have http://www.jegs.com/i/Milodon/697/12600/10002/-1#

 

don't pick a cam until you have all the rest set, I'll have you talk with Chris Straub...he designed my cam, and was a BIG asset with helping me put mine together

Link to comment
Share on other sites

How big is the dome on the pistons? You will need a bigger cam to go with those heads.

I agree with Sam that Chris Straub would be the guy to call for a cam. Actually save yourself some research and call Chris and tell him what you have and what your plans are and he will help you out. There is no need for you to reinvent the wheel, these guys have put many combo's together.

Link to comment
Share on other sites

 

270 is too mild???!? Aieeee...I guess I never took into account the 50 extra cubes on a stroker and the better heads I will be running this time around.

 

 

Trust me, the 270 cam would be on the mild side for a 454

Link to comment
Share on other sites

Guest cstraub

TN454,

For what you are wanting to do a good solid 550HP should get you there. An OEM 2bolt block is maxed at around 600HP with bolts and around 650HP with studs. Over this the engine will see cap walk and she will consistanlty eat bearings.

 

One thing you need to get rid of is the fluid damper. You can read on Scats website the owner of the company has had more crank failures due to that damper then any other. Fluid dampers need to be frequency tuned to the rpm range that a crank is going to run. Fine for narrow rpm race engines or diesel engines running 2500 rpm.

 

Camshaft wise I would recommend a good hyd roller set up based on the rpm and the combo. Be more then happy to assist you in this selection or any other parts you may need for the build. If you want to consider a Dart block I stock those as well.

Link to comment
Share on other sites

TN454,

For what you are wanting to do a good solid 550HP should get you there. An OEM 2bolt block is maxed at around 600HP with bolts and around 650HP with studs. Over this the engine will see cap walk and she will consistanlty eat bearings.

 

One thing you need to get rid of is the fluid damper. You can read on Scats website the owner of the company has had more crank failures due to that damper then any other. Fluid dampers need to be frequency tuned to the rpm range that a crank is going to run. Fine for narrow rpm race engines or diesel engines running 2500 rpm.

 

Camshaft wise I would recommend a good hyd roller set up based on the rpm and the combo. Be more then happy to assist you in this selection or any other parts you may need for the build. If you want to consider a Dart block I stock those as well.

 

Hey Cstraub Thanks When the cam time comes I'll make sure I give you a call. I visited your website, & I noticed the 423 area code, where are you in TN?

Also, since you've been in the business in that area do you know of a reputable machine shop, I'm looking at a place over in Kingsport that deals on E-bay called Whitehead Automotive.

Link to comment
Share on other sites

Guest cstraub

I've been in NE TN since '01. I live in Boones Creek.

 

Fred White sold the parts store to his nephew, he does the ebay stuff. Fred White still does machine work but not the same people. Fred does do good work. There is another shop in Bloomingdale called J&J Machine. Both Jeff's are good machinest and could handle the block work.

Link to comment
Share on other sites

Hey all, Here's some more information on that lower half I bought, it just arrived today.

 

Pistons are Sealed Power Part Number H603CP .280 Dome.

 

With my 119 CC heads I'm showing that to come out to a compression ratio of 10.07:1 did I figure this right? I thought I'd be closer to 11?

 

 

 

 

 

 

Link to comment
Share on other sites

×
×
  • Create New...