Well, I wasn't sure if she would go in General Engine or here, so I posted it here. I apologize if it's not high tech enough of a discussion ahead of time, so move it if necessary, I won't mind

With that said, I've got an old 60's 327 I'm looking to rebuild. The crank is shaved and balanced, I believe she has stock GM pink rods, and it's .020 over with 10.1:1 pistons. I've also got a set of 2.02 fuelie heads that are going on top. Now, my plan is to stick a Weiand 6-71 blower on those heads with a way underdriven pulley to push ~9psi of boost to the engine. This is going to be a normally driven street car, so I'm not looking for anything radical, just something that will have power and note need a rebuild every month.

My first question is regarding the boost. 9psi down to a 327 with fuelies on top should generate plenty of power for a street machine, correct?

Also, I have not measured the block to see if the cylinders are out of round. If they are, I'll be going .030 over. Would 10.1:1 pistons be a good idea in a forced induction motor? Would I want to go higher, lower?

Now, from what I understand, when doing less than 10 PSI, it is recommended to use hydraulic lifters still. Is this correct? Also, when doing forced induction, I also understand that a radical cam overlap is not necessary. With that said, can anybody offer a cam lift/duration suggestion? Lifter ratio suggestions? Anything else in the drivetrain I should look out for? Being a street motor, I'd like to generate some pretty raw low-end. And, of course, I'd still like to have a nice erratic lope at idle

Again, sorry if this is the wrong forum for this.

 

A few random thoughts...

Let the builder decide on the bore. The idea is to bore as little as is necessary.

Let the cam manufacturer or engine builder decide on the cam specifications. On that same note, let your engine builder spec the valvetrain components that work best with the cam profile selected.

Your static compression is too high for a your supercharging goal. Should be 8.0-8.5:1.

Not trying to take the easy way out by suggesting you go to the builder but it sems to me that you'd be better off having an experienced builder put this package together for you. Were you planning to put this together yourself??

Are you sold on the heads you have now? How much money do you have in them right now?

-Mindgame

 

I do all my work, myself, all the time. I've just never built a blown motor before, so I don't want to jump into it and blow the thing up.

Zero money in the heads now, but I like the idea of using old iron heads vs. new aluminum heads. Plus, I already have the heads, which essentially makes them free. New heads, even Vortec heads, cost money.

The bore isn't really an issue. If it's within round specs, it stays .020 over, if not, I punch it again to an even .030.

So 10.1:1 plus 9psi of boost is too much, huh? You don't think that would run fine with properly timed ignition?

I guess I could call Weiand/Holley and ask them for suggestions on cam profiles and then cross reference the idea with Crane.

 

Get a good estimate on rebuilding and porting those heads... then take a look at the Vortec again. Then keep in mind that the combustion chamber design of the Vortec is much better. Not to press the issue, but being a desirable vintage head, you could offset some of the cost by selling.

As for aluminum, there are some real advantages to running them... especially in a blow app. You can always paint them and tell everyone they're cast iron. Talented airbrush guy and you can even get a little rust-look in there.

The whole point in boosting an engine is to run as much boost as you can. More boost and less compression = more output. I wouldn't want more than 4psi with 10.1:1 iron head engine... definitely not ~10psi. Sure way to do what you're trying to avoid... "blow up the engine".

Yes, either that or I can give you the phone number and/or address to a couple of guys who can model your combination for simulation and have a cam specced for it. PM me if you're interested.

-Mindgame

 

dont forget the vortecs and fast burns have different intake bolt setups also. and they probably wont want to bolt to an old school blower manifold. but if i was going to the hassle of using vortecs it'd be those new 206cc bowties since it'll develope plenty of velocity and tq with a huffer. i'd ditch the fuelie heads if it was me but if thats what you want go for it. i like to see a rather large head on a blown engine compared to what i would run n/a. as a last thought if you really have a mind to do it yourself go buy yourself a book on building a blower motor or look online at some of the car rag buildups and maybe try to copy them.

 

This was a common combo when I was a kid.

Just thought you might like to know that most of those guys liked to run about 7.5:1 - 8:1

 

One problem you might have with this set-up is the crankshaft. The 327's had an oddball damper on the front and the snouts were fairly weak even with them being forged steel. A roots style blower adds serious stress to the crank snout. My father ran 327's in stock/super stock years ago and this was an ongoing problem they had even with unblown motors(broken cranks, dampers flying off, etc.) If it's just street/show, I think you will be okay, but if you plan to rev it, you might think about an aftermarket crank. You can order them with an extended snout with a full keyway just for blowers. Something to think about.