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Originally Posted by seafoam68
Hey guys. I'm looking for advice on a big block for my 68. It is a pro street build,will be a weekend warrior, so not worried about high dollar fuel. Running 33x19.5 tires,turbo 400 trans, 3:55 gear. I wanted to recreate the old crate engine,the ls 7. I have a 80's 4 bolt main 454. Also have original dimple rod/ 12.5:1 pistons from a ls7. Crank is factory cast. Thinking fuel injection would make life easy. Any ideas for a combo? Thanks.
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The obvious issue to me is old 12.5:1 pistons and "street build" don't usually work together.
I've been playing with the hotrods since the 80s. I've seen "pro street" in a lot of forms. The reason is many people have many ideas what is "Street". Some think a high compression not pump gas compatible combination is "street". Most of us who did build drag motors and drove them on the street soon found out it was far from ideal.
The 454 is a great engine. You will get to drive it and enjoy it a lot more if you don't go to far. Id suggest you badge it up as a LS7 all you want but build a solid durable streetable and powerful engine.
Scrap those heavy old pistons. They are dinosaurs and may not be the proper over size anyway. There are way better options to get compression under control, better materials, revs quicker, better flame travel, runs on pump gas, and still make great power.
Have the rods and crank checked to see their condition. If the crank and rods show significant wear and considering their age you may be better off purchasing a rotating assembly. For not much difference in kit prices you could even stroke it up to a 4.25 stroke and get the longer 6.385 rods. Very very popular modern upgrade. Will get you to the 500ci area. If your crank and rods are good purchase a set of pistons that with your heads are around the 10:1 range. These will usually be a very small dome when used with a standard 119cc chamber BBC head.
Cam choice is a critical component. I would definitely go with a hydraulic roller. No way in he__ I would use a old LS7 design or any solid cam in a BBC especially on the street. Generally speaking oils now days don't work well at all with solid cams. Not to mention the power and throttle response that a properly selected hydraulic roller will give you. Don't forget this will require a quality set of rocker arms, springs, valves, etc. especially if you go with any cam requiring heavier spring pressures. (You will need more spring pressure)
Another thing depending on the cam choice a proper built converter will sure make a big difference in drivability. Have you ever rode with people who were not good driving a standard. They were unable to engage the clutch at the proper time? Your converter is the clutch for the engine. Having a $50,000 engine would suck to drive if the clutch was coming in to harsh or to soft making it sloppy. A great clutch/converter makes driving a performance engine fun. PTC is a company I have used for a long time and would recommend.
I am installing my first EFI from FiTech hopefully this coming week. My brother has had a smaller FiTech on his wife truck with a mild 454 for some time now and it has been great. My truck has a much more radical cam so the jury is out on how it will work with the FiTech Go EFI 8 1200 HP (Power Adder Plus) System. But I have had several times I contacted FiTech so far to ask questions or get advise as I studied up on my application and they have been extremely helpful. And I got my system used but they were still extremely nice.
As for the heads if you go aftermarket a 320 sized head would be as big as I would suggest. Factory heads like the 781 castings a very good heads for what you are doing. They make good power, its not necessary but with a small amount of port work can flow quite well making a little more power. I would not pay much at all to have any work done to factory heads as there are so many very viable option. Inexpensive aluminum options that flow great out of the box and aren't 30 to 40 yr old iron just waiting to crack.
Didn't mean to blab that much but it happened.
Maybe some of it will help.