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Discussion Starter · #1 ·
MARSHMAN 442: I am in the process of selecting my platform for my BBC 8-71 build up and have been doing some research. The motor is being built for a 65 442. It will be used for weekend cruising and an occasional blast down the track...This is my first blower motor and I have a few questions. NOTE - I'm looking to stay within a budget for this build-up of approx $7-8K:
1) I have been contemplating buying a crate motor short block (453 / 502) and bolting on the accessories...cam/heads/ deep sump oil pan/ etc.
OR
buying a pre-built short block from a machine shop that has been decked / line honed / etc. What would be the proper crank / rods / pistons/ etc. should be selected? H Beam rods, Forged Pistons, Girdle, req'd?

Also...If the crate motor short block makes the most sense..than what we be a good foundation to start from?

2) Also, what heads should be considered? (i've read the threads on Alum. vs . Iron) But what would be a good basis point to start? Crate Heads vs. After market Dart or Edelbrock heads?[/QUOTE]
 

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QuenchPiston said:
Never seen a Big Block Chrysler in an Olds especially one with a 8-71 on it. I cant wait to see this. Got any pics yet?
I'm pretty sure he's talking about a Big Block Chevy. At least that's what the title of the thread is leading me to believe...
 

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Marshman,
After reading your thread a few things came to mind. First, you will love the feel of a blown engine. Before you get to that point you have a lot of research to do. I suggest to evryone that is new to blowers/superchargers to buy and read the book called "Street Supercharging" by S/A Designs. It does not have all the answers but, it will give you a much better idea of what's going on. These boards can be helpful but, you have to understand what to ask and be able to form your own opinion. I will be more than happy to offer advice and there are quite a few knowledgable guys here.

Next, your budget is a little on the light side and I doubt you can pull it off for that amount. It is a little misleading when you look at the blower kits and see $2,500, that is only the start. You will need two carbs ($1200 minimum), linkage ($150-300), air cleaner/scoop ($125 on up), etc... As you can see you just spent half of your budget and we haven't even talked about engine parts. Add a good set of heads to the mix and you just finished off your budget.

Yes, heads are important on a blown engine. Some people assume because you have that big air pump any heads will do. While you can still make decent power with stock heads and a blower, you will make more power with better heads. The Dart Pro 1 BBC heads are nice and would be a good fit. Any decent head will work (without knowing your goals) even a good GM casting.

Forged parts are a must (pistons, crank) decent rods are a must as well. Depending on how much power you are trying to make will determine what parts to buy. You didn't say what your goal was so, it's hard to say what you'll need.

Take a look on Amazon or at Summit racing and buy the book I mentioned (Street Supercharging). You are thinking about laying out $10K++ so spending $12 (or whatever the price is) on a book to help you figure out things is well worth it.

As far as buying a crate engine, that's fine as long as it's set up for boost. Meaning wider ring gaps, lower compression, etc..

You will probably also need a fuel system upgrade (depending on what you have now).

I hope this info helps you and please don't think I am trying to discourage you, I not. I just hate to see guys jump in before they know what's involved. This is only the over view there is a lot more to it once you have goals and the basics down. While it may seem like a ot, it's really not that hard, you just need to understand how things work and that will help you decide what parts and goal you want to set.
 

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Discussion Starter · #6 · (Edited)
this is a good info...I have had the car for 16+ years and restored in back in 91. The car sat in my garage un-used since (while I was in college and working on my career) and now it needs brakes, tranny seals, rear-end seals, motor, etc...I have a BB Olds 455 block (w/o internals) and 'C' heads off a junker & I figured with the money it would cost to build the Olds motor, I would rather put the money into a BB Chevy for the obvious reasons (4 bolt main, parts are less expensive, etc) Besides the #'s don't match on the car at this point.

The goal is to have a Fun week-end cruiser that will be reliable and push 600+ HP. I will get into the tranny selection, rear end, fuel system on another thread. I agree the budget is light and I should evaluate it closer. All of the "bolt-ons" do add-up. I guess my question should be clarified and look for some direction as to "what would be a solid foundation for starting my Build up? And I know the importance of head selection and would like some insight as to what heads would suffice. Iron/ Alum - Rectangle vs. oval ports - runner sizes - cc's Etc.
 

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Cylinder head material choice would depend on compression ratio. If you are slightly high on compression ratio I would go aluminum if not iron heads will be fine.

Now that I see your goal, you can EASILY get there with iron heads (bone stock, just add good valves). 600HP from a blown big block is simple. Even if you don't try you will easily be over that mark.


Head choice it totally up to you. If you don't plan on turning a bunch of RPM the oval ports should be plenty. You also need to check into what manifolds are offered, that may make the choice for you. I am more of a small block buy so, I won't give specific big block recommendations. I don't know them in detail like I do small blocks.

In all honesty your very next step should be to buy the book I suggested it will help with head selection and give you the foundation to decide what parts you want on your engine.

For your goals a very mild long block is all you need. Decent rods (nothing exotic), forged pistons, and a decent crank. If you are seriously going to keep it in the 600HP range. If you plan to step it up then you need to step up on the parts as needed.
 

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Discussion Starter · #8 · (Edited)
Thanks for the advice.....I did order the book on Amazon. Also, at what point should I start beefing up the lower end?...at the 700HP Mark? My first inclination tells me to build the lower end to handel the higher HP, and go from their. It would be easier to bolt on a set of heads, change pulleys down the road when budget allows rather than pulling apart the motor should I opt for more boost in the future. I was thinking of runnig 8.5 static CR with about 7lb's of boost to start. There is good tech material on Holley's web for boost / effective CR that I read.

Your thoughts.....

Also...Weiand states the lower end power / torque is better out of the 6-71 since the blower speeds are higher at low RPM's . I think I could compensate for this by selecting the corrrect pulleys. I don't plan on running the motor at very high RPM's. Red Line at 6,000 RPM's or so. They reccommend their 256 for the best of both worlds. Any thoughts...

PS: I checked out your ride....SWEET!! 11 seconds on street tires!! Impressive. What type of compo are you running? Heads / Cam / Boost / Carbs ..etc? Ever put it on a Dyno? Also approx. how much $$ are we talking about for the motor?
 

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My car was running 11's without the blower. I never took it to the track after the blower. It would have been useless, there would be no chance of getting traction. No dyno numbers for you as I am not the dyno type of guy. show me a timeslip not a dyno sheet. Dynos are great for tuning but, that's where it ends. These days everyone wants to say they have XXXHP. That's fine and dandy if you can get it to hook. If not then that HP becomes tire smoke. This is why I am building a new car to hold the power.

As far as my combo now it is a 388ci SBC, Dart Pro 1 heads, 215cc runners, compression is 8.47:1, Wiseco pistons, custom ground cam from Engle Racing Cams (solid flat tappet), H-beam rods, forged crank, splayed 4 bolt block. The blower is an 8-71 Don Hampton Blower, with a "The Blower Shop" "race" intake manifold (just has larger ports than the standard SBC manifolds and is a bit taller). Two Holley 750cfm double pumper blower carbs from All State Carbs. Cometic MLS head gaskets. Thats about it. Oh and I run 12lbs of boost on 91 octane.

As far as how much $$ I have into it. I would say right about $10K I didn't buy it all at once, I had the heads, crank, rods, and block from previous engine.With machine work, balancing, blower, carbs, scoop, linkage, fuel lines, etc... it does add up. I never sat down and actually added up exactly what I have into it. One day I will get out the calculator and the receipts.

On your big block I wouldn't use anything smaller than an 8-71. A 6-71 will get you to your 7psi range but, if you ever decide to turn up the boost the larger blower will be able to handle it easier (not have to spin as fast, which causes more heat in the intake charge and increases the chances of detonation). If you know for sure that you aren't going to want to turn up the boost to the 10-12 psi range then the 6-71 will work fine (just keep boost in the 8psi or lower range). Yes, it's true if you set the drive ratio correctly it will be spinning faster and give you more low end torque. I can tell you this right up front, you will NOT need more low end. Roots blowers make HUGE amounts of torque. While you read this you may be thinking, yeah I know but, seriously you will be shocked I promise. Look at it this way the 8-71 is only a few bucks more and you don't have to use it unless you want. If you go with the 6-71 and decide you want more, you will be limited. Either one will more than exceed your goals, that's a choice you will have to make.

If you buy decent bottom end parts you will be fine. You don't need Billet top of the line parts but, you don't want cast parts either. Get a decent forged crank, decent H or I-beam rods and good pistons. Don't skimp but, don't get carried away. I agree you can always upgrade the heads later and actually to reach your goals the stock head will work.

Now about the boost charts, they are a good place to start to stay safe but, they are ball park figures at best. If you look at those charts you would think there is no way I can do what I have. There are a lot of guys doing it as well. Those charts are to keep people out of trouble.

Thanks for the compliment on the car.
 
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