Thread: Just learning about Big Block Chevy's.

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Hello fellow Big Block owners.
I have a few questions about two Big Blocks I have.
First I have a 2000 model 454 Vortech one piece rear main seal. I was wondering about these Vortech heads. Question is will they make any h/p at the drag strip. I heard they were only about 230 cfm on intake and have small valves. I may just rebuild this engine with a mild cam and use it in my half tone pu to pull the car and trailer.
Second engine I have is an 80's model 454 two piece rear main. I have a eagle light weight crank, trw 13.5 to 1 comp pistons, factory deck height, 781 heads with factory valves, 540 lift cam and a 650 lift cam, gear drive timing set, air gap intake, and 850 holly carb double pumper. Possible turbo some day. Have to lower the comp to do turbo. I have mostly dealt with Small blocks. 600 hp is my goal. Can I make this with what I have.

uhm .. I say this in jest with a whisper .. the big block chevy expert is currently banned ...

Maybe the pretenders, oops sorry I mean the other experts, will step up to the plate

i dont blame pat one bit. he makes his living building engines every day. far cry from a google expert .oh well he'll show up somewhere else . their gain chr lose .

Guys,

I do not like where this thread is going. So, if you can assist the original poster great.


if not, please do not muck up his thread with anything else.


Thanks,


Bill S.

PS: Jerry and I are conversing offline.

Guy's I'm serious here. I know pretty much what I have to do here. I don't know if I need to put bigger valves in these781 heads or not. the machinist I talked to said all I may have to do is put in some good flowing valves. About 6000'00 is all this motor will be turning at best. I've priced a rotating assemble from scat for a 496 build. It cost around 1600.00 dollars. This should help immensely for a power gain. The two cames I have are in question. From what I have read on the 540 lift cam it will be better if I drive it on the street for vacume purposes for brakes and so forth. But I don't have vacume operated brakes on my Nova. I may need the added braking power to stop it though. The 650 solid lift cam doesn't start working till about 3000 grand I think. My 3500 stall may not be enough either. What gears do I use is another question. I was thinking 4.11 gears.

Ok, first things first. Welcome to CHR, Ivan, good having you with us! If you're going drag racing, all the engine in the world won't do you any good unless the rest of the car is capable of applying the power and getting it down the track safely. What kind of car do you have that you're building this engine for? Are there any mods done to the chassis and suspension at this point? From your post it sounds like you're going for a dual purpose street/strip car, so you should know up front that any dual purpose car is going to require compromises. Is the car going to be a daily driver, an occasional Saturday night, or somewhere in between?

You mentioned 13.5:1 pistons...Is this an estimate or is this the compression ratio you're wanting to build the engine to? IMO 13.5:1 CR with cast iron heads is quite impractical for a street car, going to take hi quality (and Hi Dollar) race gas to run it!!!!

If you would supply a bit more background on the entire project it would help people to make suggestions for you to consider!

As regards your brakes, a power boost would be helpful, but not necessarily mandatory (barring sanctioning body requirements). In low vacuum situations, vacuum pump, electric boost or hydraulic boost systems might fill the gap; then you could run just about any cam you like.

The car is a 75 Nova. The frame has been lengthened to the rear and welded in. And no it will not be a street driven car. 3 inch exhaust, 411 gears, 350 trany with 3500 stall, has not been tubbed. Im concerned about the781 heads..... I'm probably going to go with the bigger valves any way. Get as much flow out of them as I can at a budget. lol.

13.5 to 1 comp is the type piston. The deck height is factory. So the compression will probably no be that high. But I will have the deck trued.

As you start gathering your information about going to larger valves in the heads, remember too that you will probably have to do something about the small ports. Also, you'll want to know whether or not the valve guides are worn excessively, how much valve spring and at what installed height you'll need for the cam you choose, the surface of the head itself, equalizing the chamber volume, and a host of other things. Before dumping a lot of money into a set of heads that you're probably not going to be happy with their level of performance you might want to check around locally and on Craigslist, Racing Junk, eBay, etc for either a new or used set of aluminum heads that already have bigger valves and ports.... Just another consideration! Being a budget build, the time you spend doing research and a realistic cost comparison will probably save you money in the end...

If your guides are worn, you can re bush them with bronze liners and do it to 11/32 size and use 351c ford intakes for lighter weight and whatever diameter you want---------they are the same length as BBC and stocker type replacements are cheaper than aftermarket $$$$$$$$$$ stuff-

Ok here's another question for some one to pop off about. I know that the pistons will not work with a turbo I just purchased. The turbo is a bd600 that has been upgraded to a 17 pound boost, supposedly. Maybe so. What compression do I go with. No more than 10-to 1 or like a flat top piston. I thing the heads are 118 cc chamber. 781 heads.

turbos have pop offs-----