Hey guys, I would like to know the difference between a tall deck 427 big block Chev and a regular block 427 Chev. What are the pros and cons of each. I would also appreciate any opinions positive and negative on these engines. I found a good running tall deck engine I am thinking on putting in one of the projects I have going right now. Honestly, I don't know anything about these engines and hope some of you can steer me in the right direction. Thanks in advance. Garey
The tall decks have a taller deck height or it is farther from the crank center to the mateing surface for the heads. They are a low compression engine as in 8:1 low compression and they have peanut port heads. They take a wider intake manifold probably pretty hard to find a performance intake. They do have an upside, you can bolt any big block heads on them that you can find to over come the poor breathing and the have a forged lower end. They are a good foundation if you can find a good one stock for a blower motor. The low deck motor have more in the line of performance parts more redily available, better heads stock and more compression or easier to get more compression if you find a low compression one. But they do not all have forged lower ends if that is a concern for you.
The tall deck engines were used in medium duty trucks. They used four ring piston and a dual thermostat intake manifold that was slightly wider than the standard deck height blocks. If you were putting it into a tow vehicle it would probably make sense. Not so easily adaptable for use in a "hot rod" application. Kind of limited availability for aftermarket performance parts.
Things have really changed over the last few years for the tall deck BBCs. Parts are on the shelf and combos can go big as you want.... almost. Performance intakes have to run spacers and all heads will bolt right onto them. You can go wild or mild but, you may spend a little more for the parts than a standard BBC. Everything is the same from 9.8 deck to a 10.2 deck except pistons and rods!
Good block if you want to swing a big (stroke) crank and some big cubic inches. You can get spacers to use short deck intakes on them. Dont know what you would be putting it in. It would be a heavy engine.
I scored a 427 tall deck this winter for ZERO$$$. The bores look great and the previous owner had the lower end checked out and all was good in bearing land. My buddy is building a bush truck and has hinted he wants it....
I drag raced a tall deck for quite a few years. Took it .060" over with a 4.25" crank and used .250" longer connecting rods and off the shelf .060" over 454 pistons and had a 496 ci. Had it decked about .025" to bring the deck height to zero. Like has been said, regular std deck heads fit. I had an intake that someone made to fit a tall deck and used an adjustable slip collar dist. Like was said before, pushrod length was unique. Nowdays, tall decks are not such ******* pieces like they used to be 10-15 years ago. Lots of off the shelf parts for them today. Not as much as std deck but about anything you want is out there if you look a little.. Just make sure it is a 427 and not a 366.
Summit racing has 10 intakes for talk decks $ 288 & up these engines are great for a big stroker crank, if you want a stock type build another engine may be a better choice
All big block chevys have 6.135 inch long rods. The tall deck truck motors have a taller piston with 4 rings instead of 3 like the short deck ones, thus a .4 inch taller deck. That is where the .4 inch longer rods all the aftermarket makers sell started from, so you couild use a short deck piston in a tall deck block. Also since the deck is .4 inch taller the engine is wider and harder to fit in a small engine bay. The rod to stroke ratio is much more favorable but they are considerably heavier +- 60 lbs.
I think a lot of the "it's a truck motor and no performance parts" theory is old and inaccurate. As stated, the main difference is the deck is 0.400 inch taller. Use std deck pistons with 0.400 longer rods, some good BBC std deck heads, and you have a good performance engine. Sure there are longer pushrods required, a unique intake (or use spacers) and distributor, but any real performance build should check valvetrain geometry and could require custom length pushrods anyway. Great if you want a stroker engine, a 4.25 stroke will fit. Your 427 has 3.75 stock stroke length. Only potential issue is that headers will be further up and out that could create ch***is interference.
For a mechanical pump you probably want one for something like a 68 396 that just has the inlet and outlet and no return line. That fits most 66/71 Big blocks Clean simple and cheap http://www.oreillyauto.com/site/c/detail/PFP0/M16059/02535.oap?year=1968&make=Chevrolet&model=C30+Pickup+RWD&vi=5173625&ck=Search_C0401_5173625_4398&pt=C0401&ppt=C0025#compatibilityTab_
Years ago the truck blocks were very popular in circle track an drag racing. You could get well over 500 cubic inches from these monsters. Everyone used p***enger car heads because of the small restrictive heads
As has been stated, .4" longer rods (6.535" long) and you can use regular car pistons in a tall deck. The longer rods cost no more than the typical aftermarket stock length rod. The 427 block has a bore of 4.25" and a stroke of 3.76". Usually these blocks can go .06" overbore with no issues but can go up to .100" over if it checks out with thick enough cylinder walls. The max stroke is debatable- 4.25" is the norm but some claim 4.375". Plenty of stuff available for these engines- I have one that I plan on boring and putting in something one day. I ran a stock 427 truck engine in my old truck- peanut ports and all- with a short duration high lift cam (Crane, .527" lift I think) and really had a blast. If you are going to use it in a street driven hot rod and don't want to spend much money, I would change the cam and intake (I used a Team G intake) and use a 650 Holley on it. That sounds like too little carb, but with the stock rod bolts and super heavy pistons, you don't want to take it over 5500 RPM unless you like replacing an engine.
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