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Need Chevy 427 Info.

22K views 19 replies 11 participants last post by  dmartin1 
#1 ·
Hello Everyone.
I need some help with locating info about my engine.
Recently the old diesel engine in my Suburban "workhorse" threw a rod.I considered replacing or repairing the engine, but costs led me to decide to get a big-block instead. I purchased a running engine for next to nothing. Originally the seller and myself thought the engine was a 454. After getting the engine home I discovered that the engine was actually a 427 tall deck truck motor.I intend to rebuild the engine with some modifications before I put it in the truck.
My problem is that I can't seem to find much info about the engine that would help me decide which modifications that I would like to make. I need to make decisions about compression ratios and camshafts before I put the engine in the truck. Other mods I could make down the road. I would also be intersested in any power tweaks you guys might have about this engine. I don't know the significance of it being a tall deck,either. This is my first big- block, so I have alot to learn.I came up empty when I searched the boards and my internet seaches have turned up little.

Here is what I know about the engine and hopefully some of you guys might be able to help.

Chevy 427T 4-Bolt (casting# 473478)
possibly manufactured in 1980. Heads are oval port open chambered (cating#346236)
 
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#3 ·
You said it was your "work horse", so do you want to keep it that or make it fast? That would make a difference on how you would build the motor. How often do you tow stuff with it? I'm not positive, but the tall deck usually makes for lower compression. Let us know just a little more of your intentions, and you'll get some better tips:) .
 
#4 ·
The tall deck engine is already a very good work horse. They develop lots of torque. Parts are hard to find for them. Good Luck.

Troy,
 
#5 ·
well guys the tall deck 427 is not really the best choice for minor build ups , they are grooped with 366-396-427 truck blocks and it depends on the year as to exact comp. on them but most of them pretty low due to the work they must endure, the block is .400 thousands taller to make room for the extra rings the pistons have, theres 4 sets instead of 3, therefore comp changes via piston are pretty hard to find not to mention the extra friction which makes them less desirable for racing, the engines came with steel cranks same stroke for all 3 sizes 3.75in. and 4.0inch 454 steel cranks are getting scarcer everyday, anyway piston changes require .400 extra long rods to convert to standard big block stuff and or stroke + rod combos to achieve proper deck heights with standard pistons, head changes are possible for compression increases and most big block heads will interchange provided the intake ports will match up, however they had combustion chamber changes as well so the wrong way will really make it sick, also early blocks had b.o.p. bolt patterns on bell housings, not sure about gen. 5 stuff for heads and such but dont think they will fix comp problems, on the positive side the bottom ends are pretty strong, they will usually bore .125 over with moderate wall to spare couple that with longer strokes and rods and you can fix some of the ratio problems the shorter blocks have and end up with some pretty healthy inches and they do have intake adapters for aftermarket stuff, and at least the 427 has the same bore as the 454 making for some pretty good choices for inches. there is other small things about them but nothing worth menthioning at this time.
 
#6 ·
For your intended use you would probably be better off to sell the tall deck to a racer and get a regular passenger block, the pistons in a tall deck are 4-ring tall low compression clunkers, there are no streetable pistons available at a reasonable price for a tall deck it is .400" taller than a regular block, also there is the problem of the two thermostat intake and the governed type carb that it is set up for, and distributor issues, the heads are very small port with small valves and huge chambers, wouldn't make enuf horsepower to pull a fat girl off a tricycle.
 
#7 ·
Thanks for your help guys.
It would seem that my engine may turn into a headache, but it is what I have to work with so I am gonna give it a shot.
As far as my use of the Suburban, it will be a daily driver that will see occasional towing. I use the truck mainly to haul light loads and to haul cars every once in a while. The traffic here in my area has grown heavy and fast, so I will need some "get-up-and-go" if I want to be able to enter traffic without waiting for an eternity. The diesel engine was modified for me by a good friend and it had 365 hp and a truck load of torque. I am hoping to do at least this good with the 427. My hotrod blood just won't let me settle for average, even though it's a big heavy Suburban.
I have gained some more info on this engine that you guys might want to chew on for some more suggestions..

Compression ratio- 8.0:1
hp- 220@ 4000
torque- 390@ 3200

Combustion chambers- 113cc
2.06 intake 1.72 exaust

Thanks Again!
 
#8 ·
Mikey said the 427 truck block is grouped with the 366-396-427 truck blocks. I think just the 366 and 427 were tall decks. Standard deck height is 9.8 and your truck block is 10.2.....
There are parts and spacers to make standartd parts work but the most important thing is your exhaust. With a truck it might not be so bad but, the tall deck moves the heads UP and OUT!
Moving everything bolted to them...UP and OUT!
Supercharger guys like having the extra ring and rail dragster guys don't mind where the headers wind up, so maybe it would be wise to find these types of people to sell your engine to. And in return they might have last season's motor to sell to you!:D
 
#9 ·
My Dad had one of these engines in his big truck.He swapped the cam and intake for a big power-gain.I don't have any numbers but it was noticeable.Could't you have the deck milled at a machine shop to match a passenger block?Seems like that would let you use standard parts.It may not be possible.I don't know.Maybe someone else has some insight on it.
 
#11 ·
nice try guys on decking the block , but no you cannot mill .400 off the deck there would be nothing left of it , it would never hold gaskets and thats if you didn't hit lots of water, however it is possible to mill small amounts off the head and block to raise comp. which would definitly be needed if you intend on camming this puppy, there is more power possible this way as long as you dont get carried away, .020-.025 off the block comes close to half point gain in compression and similar amounts on heads (depending on combustion chamber) about a quarter point, however piston to head clearances become critical when decking blocks, heads are ezier to deal with but do not raise comp as quickly in wedge heads, also yes there is a 396 tall deck truck block, it was there first and had a b.o.p bell housing pattern 366s and 427s came later but did go back to standard chevy patterns.and last thing if your running an automatic trans in that burban better look closely at the stall converter most diesels had way less stalls than gas engines do and will really choke down gas engines let alone camed ones. oh and also thinner head gaskets raise compression as well .
 
#16 · (Edited)
ok i stand corrected on the bop pattern on the big block it had an adapter plate on it that you could not see threw all the dirt oil leaks etc. was looking at pattern on trans, anyway may have also misread numbers anything is possible never found out on engine one way or another about size but the guy said trans was pulled at later date when adapter plate found, probably to make the 400 turbo fit.
 
#17 ·
427 info

Hello drlindz.... I just got done doing a swap like your contemplating.it went very well everything on the exterior of the engin bolts up I did have to mod. the alt bracket slightly and I got a new balencer ...... a little info on the 427 tall deck. these engings run big pistons with 4 rings the weight of the piston is very heavy and will cause problems in a performance aplication this engine was made to make huge torque at low RPM. So either plan on making it a tow monster with about a 4 grand red line or do what I did...... I went with a Eagle rod +.400( as tall decks are .400 taller at the deck highth) this will let you run a stnd. 427 piston( I sed Keith Black but speed pro's would have been good to unless you really want to spend some money) I used the 427 crank( which I have been told is very durable) and had the whole thing balanced. You will have to run a intake manifold spacer if you go with a after market intake ( this is a standard Wieand part and instales with about a half hours work at the maching shop. ) and usualy oval port heads that are 781 or 049 castings make very good power......Thats what I did I am guessing this motor will make around 425 Hpand should rev real easy to 6500rpm's. Do not be discouraged not a lot of people have run this combo but I found a lot of power boat guys do and also some drag racer. the block and lower end are very durable....Also i have had some people tell me that a very good option is taking the 427T lower end and puting it in a 454 wich would bring the CIback down to 427 but would give you a bottom end able to withstand very high RPM's if Ican help in any other way email me ( LinconWells@aol.com)....
 
#19 ·
A Costa-rican mechanic friend of mine swears he has seen 454 tall deck motors in busses!!!!!!!!!!!!
I wanted to slap him but I am pretty sure he was mistaken.
the tall decks I have seen were 427 ,internally balanced, huuuuuge neutral cast iron "flex" plates for the alison auto tranny that had the crossmember bellhousing adapter.
I talked to my engine balancing people and they said , find pistons that weigh the same as the originals (4 ringers) and use the forged crank in my 402 with the 402 balancer and the 402 flexplate and this should give me at least as good of balance as came in the tall block originally.


I wish someone would tell me a kit name and part number that would give me a 427T block rotating assembly, that would give the best all around ( last long ,tons of torque,and rev to at least 5000 rpms without causing a panic) performance with the stock block and some mark IV large oval port open chamber heads.
496,486,509,540,525,blah blah blah
If it were this easy I ,like all other torque freeks, would go for the bigest thing possible, but I don't have a really good grasp on rod ratio -rpm . So I am scared to choose the bigest one.
How many questions are in this post?

Did I read above that these motors stock, make good supercharging candidates with the original 4 ring pistons>?????

I can get ten 427 T motors in less than a week here. They normaly cost around $100 complete, and the big GM superchargers are all over the place in central america as well because the diesel motors are in everything here and the 427's
are well..... cheap!

who in the help wants a 454 that, gets better gas milage than a hyaundai?
We know better.
P
 
#20 · (Edited)
I had 427t in a 1 ton car hauler that would get 8 miles per gallion loaded or empty . I also had a corvette with a 454 got 8 m.p.g.

At todays gas prices forget it drop an inline 6 in it.

I'll bet you can't get them for $100.00 around the midwest very hard to find. you can sell them to motor builders for $250.00 in midwest.I wouldn"t pull it out of truck for $100.00.I get $300.00 for used . have a rebuilt one for $1400.00 no core charge as is +fright

If you want a work horse or a motor for your RV ex. motor. Hot rod motor forget it.

http://www.nastyz28.com/bbcmenu.html
 
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