427 ci tall deck motor

[CR10]

Hey guys, i know some of you out there should have an answer for me, this is my situation...... a couple of years ago someone gave me a 427 chevy motor, and i was so happy until the day i found out that it was a tall deck motor, and as many of you know this is one hard project to do, specially if you want to do some performance upgrade to it.
The casting number on the motor is 473478, has 4 bolt main, but the heads are open chamber, 122 cc (way too big for my desires), and has 4 ring pistons.
I know in order to get some nice torque (@ least 400 foot/lbs) I should change the heads for something with smaller chambers, but what about those pistons? If i want to replace them for the regular 427 car pistons, what should i do connecting rod wise? I had read a couple of guys that has done the conversion but they don´t tell how....
And i really want to keep this motor for my little C10.....

Someone please help   

[cubicdollars]

I am building a 505 Tall Deck right now, My combination is for an f2 Procharger that will spin into the 7000+ RPM Range. I chose the tall deck so I could get a better rod to stroke ratio.

My combo is a Callies 4.250 Stroke Crank, CompStar 6.800 Rods, and SRP 4.350 pistons with a pin height of 1.27 (the same as a stroker piston) I run that same piston in my 489 stroker.

The Tall deck is .400 taller than the standard deck, you have to run a talldeck intake or a standard deck intake with spacers and a slip coller distributor. I chose to run a T/D intake the Dart that I bought has the distributor hold down recessed so I could use my S/D MSD with no slip Coller.

Hope this helps, Check out my webshots there is photos of the engine under my Stepside picts

[CR10]

Wow, that is the answer that I was looking for , thank you so very much....
One last thing.. I can tell you got some experience with this motors, how many "cc" should I be looking for, whenever I get the chance to buy the heads, I just want some street performance, not for towing 16 wheelers or anything like that!
By the way sweet pics!!

[VileZambonie]

What's the casting # on the heads you have? Open chamber heads actually flow pretty good. There are some nice dome piston designs to go along with them. So if you're planning a N/A 427 look into better piston options before you junk the heads.

[cubicdollars]

I agree a good Oval port head would be great to use on your combo. a 781 head or an 049 head are realitvly easy and cheap to find.

Here is a pretty good post with alot of info on the tall decks http://forums.hybridz.org/index.php?showtopic=37175

Hope this helps

[CR10]

mine are 343772, oval port........ what do you think?

[cubicdollars]

Not too much information on www.Mortec.com on these heads

Anyone else?


330864.....68-84...oval...OPEN...396, 402, 366T,
                                 427T, 454 Truck
330865.....68-84...oval...OPEN...396, 402, 366T,
                                 427T, 454 Truck
330866.....68-78...oval...OPEN...366T, 427T
330867.....68-73...oval...OPEN...427T
336765.....68-78...oval...OPEN...427T
336768.....73-76...oval...OPEN...427T
336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports
343771.....68-86...oval...OPEN...366T, 427T, 454
343772.....68-86...oval...OPEN...366T, 427T, 454
343783.....70-76...oval...OPEN...454 Truck
346236.....75-87...oval...OPEN...454, 120cc chamber, 225/116cc ports
352625.....70-76...oval...OPEN...454 Truck
353049.....73-84...oval...OPEN...454, 122cc chamber, 255/119cc ports
366765.....74-78...oval...OPEN...427T
473328.....68-69...oval...OPEN...366T
3856206....65-66...oval..CLOSED..396, 97cc chamber
3856208....65......rect..CLOSED..396/425hp, 109cc chamber
                                 396/375hp "Z-16" Chevelle
3856213....66-82...oval..CLOSED..366T, 427T
3856260....68......oval..CLOSED..396 Truck
3872702....65-66...oval..CLOSED..396, 427, 98cc chamber
3873858....65-67...rect..CLOSED..396, 427, 109cc chamber
3876875....77-85...oval...OPEN...427T
3904390....67......oval..CLOSED..396, 427, 98cc chamber
3904391....67......rect..CLOSED..396, 427, 107cc chamber
3904392....67......rect..CLOSED..427, Aluminum, L88, L89, 107cc chamber
3904393....68-76...oval...OPEN...366T
3908952....67......oval...OPEN...427, "M.Truck", Marine
3909802....67......oval..CLOSED..396, 427, 101cc chamber
3917215....67-68...oval..CLOSED..396, 427, 101cc chamber
3917219....68-85...oval...OPEN...366T, 427T
3919840....67-69...rect..CLOSED..396, 427, 107cc chamber
3919842....68-69...rect..CLOSED..396, 427, Aluminum L88, L89, 107cc chamber
3931063....68-69...oval..CLOSED..396, 402, 427, 101cc chamber
3933148....69-84...oval...OPEN...'69 396/265hp, 366T, 427T, 112cc chamber
3933149....68-76...oval...OPEN...427T, 122cc chamber
3935401....68-76...oval...OPEN...427T
3946074....69&71...rect...OPEN...'69 427 L88, ZL1, Aluminum, 118cc chamber
                                 '71 454 LS6, "round exhaust port"
3964290....69-70...oval..CLOSED..396, 402, 427, 454, 101cc chamber
                                 Large or small hex spark
                                 plugs used
3964291....69-72...rect..CLOSED..396, 402, 427, 454, 109cc chamber, Large or small hex spark plugs used, crate motor usage in years after 1970.
3965198....68-69...oval..CLOSED..396 Truck
3975950....68-70...oval...OPEN...396, 402 Truck, 366T, 427T
3986133....68-85...oval...OPEN...366T, 427T, 454 Truck
3986135....69-73...oval...OPEN...366T, 427T
3986136....68-84...oval...OPEN...366T, 427T, 454 Truck
3993820....71......oval...OPEN...402, 113cc chamber, 255/114 ports
3993820....71-84...oval...OPEN...454 Passenger and Trucks, 113cc chamber, 255/114 ports
3994026....71......rect...OPEN...454 LS6, 118cc chamber
3999241....72......oval...OPEN...402, 454, 113cc chamber

6272292....70-78...oval...OPEN...402, 454
6272990....70-up...rect...OPEN...454 service replacement, used on some MKIV crate engines, 118cc chamber
10045427...........rect..........Pontiac/Chevy Aluminum, 91cc chamber
                                 Large Port, race
10049875...........rect..........Pontiac/Chevy Aluminum
                                 Small port, race
10051128...........rect..........Bowtie, Aluminum 72cc chambers
                                 Symmetrical ports
10051129...........rect..........Bowtie, Aluminum "raw"
                                 casting, Symmetrical ports
10052902...........oval...OPEN...MkIV, 427T
10101140...91-up...oval..CLOSED..Gen.V 366T, 427T
10114156...91-up...oval...OPEN...Gen.V & VI 454, 118cc chamber
10141279...96-up...oval..CLOSED.."Vortec 7400", 100cc chambers
10487052...77-90...oval...OPEN...366T
12363391...96-up...oval...OPEN...Bowtie, Aluminum, Signature
                                 Series, fits MKIV, Gen.V, Gen.VI, 110cc chamber
12363401...96-up...rect...OPEN...Bowtie, Aluminum, Signature
                                 Series, fits MKIV, Gen.V, Gen.VI, 118cc chamber
12558162...01-up...oval..CLOSED..Gen.VII,"Vortec 8100", 8.1L, 496, truck
12560241...98-up...oval..CLOSED.."Vortec 7400", 100cc chambers
12562932...91-95...oval...OPEN...Gen.V, truck crate motor, 118cc chambers
12562933...91-95...oval...OPEN...Gen.V, 118cc chambers
12562934...00-up...rect...OPEN...Gen.VI 502 Marine
14011077...69-up...rect...OPEN...Aluminum, fits MKIV, "C-port"
                                 118cc chamber, also sold as a "solid" head
14044861...84-96...rect..........Bowtie, Aluminum, MkIV,
                                 "raised runners", 1st design, 105cc chamber
14044861...96-up...rect..........Bowtie, Aluminum, Signature
                                 Series, fits MKIV, Gen.V, Gen.VI
                                 "raised runners", 2nd design, 115cc chamber
14044861...84-96...rect..........Bowtie, Aluminum, MkIV
                                 "raw" casting of "861" MKIV
                                 1st design
14081045...78-87...oval...OPEN...454
14081052...85-87...oval...OPEN...366T, 427T, 454 Truck, Marked "HiPerf"
14092359...86-90...oval...OPEN...366T, 427T, Marked "HiPerf"
14092360...86-90...oval...OPEN...454 Truck, "peanut" round ports
14096188...70-71...rect...OPEN...454 service replacement, also used on later Mark IV LS-6, LS-7 and 454 HO crate motors, 116cc chamber
14097088...91-up...rect...OPEN...Gen.V 454/502 HO, 118cc chamber
24502585...97......rect..........Olds/Chevy, DRCE 2,
                                 Pro Stock aluminum, for blocks w/4.900" bore spacing
25534404...04......rect..........Olds/Chevy, DRCE 3, Pro Stock, aluminum, for blocks with 4.900" bore spacing

T = Tall deck
Oval includes both "peanut" (also called "round") ports and large oval ports

[VileZambonie]

They're not the big valve heads but they are easily workable. If they have rotators, get rotator eliminators and do some porting. Port matching is worth it's time if you're so inclined. Get springs to match your cam and make sure you install the springs at installed height spec and you'll save a lot of $$$

[CR10]

Okay, I may not have the accurate measurements but so far I got this numbers from those (in my own lab), 123 cc chambers, 230 cc intake runners, 80 cc exhaust runners, 1,85" intake valves, 1,65" exhaust, oval ports, and heavy as heck!!

Thanx for the feedback..

[Engineer]

If you can find "049"s or "781"s you will be much better off. The oval ports are much bigger on these heads.

I was at a swap meet recently and passed on a set of virgin "049"s. Guy wanted $150.00 for them. When I went back to get them they were gone after only 1 hour. I didn't need them, but I knew that $150.00 was a steal. And apparantly so did someone else.  

As far as the 427TD, that is an awesome engine block to start a ground up build. Put the longest rod possible in it, keep the O.E. steel crank, and balance it, and it will make you a good foundation.

A good matched roller valvetrain, and that long rod 427 will spin 7,000RPM all day long.

Also, don't discount the open chamber heads. They flow better than closed chamber heads because the intake valve isn't shrouded by the chamber wall.

[CR10]

once again, thanx for the info, it is very much appreciated....
I recently wrote a letter to summit racing, and they say that i could fit any 427 car piston in it, but i should need 6,535 " conn rods, so as I see this, there are many ways to do this, you can go as crazy as you want.
I just got one more question.....
What will happen if i just go cheap on this project, and fit the oem 4 grooved pistons??.... I know I am NOT gonna take this road, but one can wonder...... what will happen if i go oem on pistons and try to fit an hot cam???

[cubicdollars]

I used SRP # 142982  it's 4.350 bore and a pin hieght of 1.270, set of 6.800 Compstar Rods and a 4.250 crankshaft.

This is a quote fro the HybredZ Site "1.27"piston pin height, + 6.8" rod length + 1/2 of 4.25" stroke(thats 2.125") equals 10.195" or .005 below the 10.2" deck on a tall deck block
thats a 1.6:1 rod/stroke ratio, or close to the 1.63:1 a 350 chevy has and better than the original 454s 1.53:1 ratio, even thought the strokes been increased"

 and a link to the SRP Site.
 http://www.jepistons.com/Catalogs/SRP/Chevy_BB/flat_top_inv.aspx.

Hope this helps