Thread: Motor selection

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I will soon be searching for a Chevy muscle car. I want a hi po 350 or a big block suitable for street cruising with emphasis on practicality. That is, not extreme high h.p., not too heavy, easy to work on, practical for any size car from a Corvette to a Chevelle. What do you suggest?

Are there many differences between big blocks in size, weight, motor mounts, transmission mounting, etc? I am thinking mainly 396, 427, and 454. Thanks for your help.

All the big block engines will be with in a few pounds of each other in weight, all have the same external dimensions, and mounting holes for the engine and trans. There are way more 454 cores around, so you get a bigger engine cheaper as for a core and it will not cost any more to build, and some parts are actually cheaper because of the volume. Now, there are some raised deck truck and marine engines, but I am assuming you would find and build the more common standard deck block.

any bbc will fit that bill long as you stay with the 396-502 9.800 deck moving up to the 366to 427 tall deck 10.200 blocks will take abit more money and more work to make things fit. the 366 is not the block to use you can get more out of a 427 tall deck by using a 4.250or 4.500 crank to get more CID and other things can be done crank rods pistons to the 396to502 blocks for more cid as well as other blocks that are made but i will not get in to all that .a 396 pistons are abit more then lets say a 454 but they all take the same gaskets cam rod main bearings .cam lifters .oil pump rods .oil pans tin if there all mark 4s the older 65/67 396 /427 took a grooved cam and dif cam bearings

Thanks for the feedback on BBC comparison. It is just what I wanted to know.
That prompts one more question: Is there an easy way to identify which engine is in a vehicle?

If you get a Chevelle, Go with a big block. 396, 402, 427, 454, 502. Chevelle just looks better with a big block. My 70 Chevelle SS has a 402. With a 5 speed tremix and 3.73 gears it will get 15 to 17 mpg.

Originally Posted by WurlitzBurg

Thanks for the feedback on BBC comparison. It is just what I wanted to know.
That prompts one more question: Is there an easy way to identify which engine is in a vehicle?

i can look at a bbc and tell what it is after 30 years of building them you can get a book or mortec as block/head casting numbers that s the best way for someone new at the game

Originally Posted by rsluggoboy

If you get a Chevelle, Go with a big block. 396, 402, 427, 454, 502. Chevelle just looks better with a big block. My 70 Chevelle SS has a 402. With a 5 speed tremix and 3.73 gears it will get 15 to 17 mpg.

yep did a 496 mild 10.3cr merlin iron head roller engine for a 70 chevelle .going to put the needed parts on the rear suspension to make it some what..... hook up

All so, if you get into the Gen V or Gen VI big blocks you wil have a few differences. Gen V does not have the mechanical fuel pump boss on the block, and Mark IV production heads most of the time leak at the deck coolant holes.(The Gen V deck coolant holes are shaped much different than Mark IV), and the Gen V production blocks do not have a boss for the clutch pivot ball, to hold the z shaft for the clutch. The Gen V and Gen IV also went to the one piece rear main seal with its' attending oil pan,crank and seal. There are some features that get mixed and matched when you go to a GM bowtie block so be aware of what you want in a block. Some good features of the newer blocks are the ready to go hydraulic roller cam design built into the block and all are 4 bolts mains. A net lash valve train and having the right flex plate or flywheel are just a few of the little things to keep in mind when building the new engines, but the net lash valve train is easily converted over to an adjustable system.

As for the Mark IV heads leaking, I need to clarify that what i was trying to say is, if you install Mark IV heads on a Gen V block you will more than not have problems unless they are aftermarket heads that are desiged to seal the larger coolant holes in the Gen V deck.

there not much to good about the V block other then it may not be to hard to find stock heads are poor and no justable rockers there open deck .the bowtie cnc block fix some of this closed the deck down .made it so it could take a two pc seal cranks and older heads.pc adapter bolted in to the block as for the mark 5/6 having a 4 bolt main that fine and you can run a two pc seal cranks in the stock mark 5/6 with the seal adapter .you can buy the ARP 7/16 to 3/8 studs for the heads but i just drill and tap for 7/16 top and bottom rocker studs. i would not over look the mark 4 block two bolt block have put alot of power thru one of them blocks then i would trust with a mark 5 block. mark 6 has the stands to mount a cheaper GM hyd roller lifter then a retro roller lifter for the mark 4/5 blocks .i built both mark 5and 6 blocks there ok if you have nothing i have had the cnc mark 5 blocks. i mix and made thing s fit them but for someone starting out you need to watch out for parts that may bolt on but will not work on the 5/6 blocks . after all this i should say i have built the 5/6 way past 650hp there just not on the top of my list for hi HP with the open deck bores moving and head gaskets failing but have not had this happen on the ones i did .i just do not like the open deck and other things as well ....for mild builds they are fine if thats all you have to work with

I totally agree Pat. It sounded like he was possibly looking for a core for a mild build and a Gen V or IV might fit the bill if he ran across a complete donor motor fairly cheap. But as for me I would pick a Mark IV to start with.