Hey y'all, just curious. What is the best way to get the most compression possible out of a 300. I've heard about the 240 head swap and all. I want to build another 300 at some point to put in a hot rod project that I'm going to start at some point and I want to go all out on this next build. I'm guessing flat top pistons would be a good start, then the 240 head. Are there any ways to get EVEN MORE compression? As i said, i'm just curious, not gonna go out and build something tomorrow or anything so go crazy on what ya post lol.

 

How high do you want to go? Do you plan on using pump gas? Regular? Premium? Hi-octane Race gas? Methanol? I've seen race motors in the 15:1 CR range. A flat top with a 240 head will get you in the 10.5 - 11.5 :1 range. Probably capable of 300 HP with the right parts. But just barely runnable on pump premium. Custom domed pistons are available from a number of suppliers. Of course power output is directly proportional to the amount of money available to be spent. More compression will demand premium parts throughout the engine to take advantage of it. For example, a FelPro Hi-performance gasket Part # 1024 will definitely be needed, available for around $50.

 

There is 2 ways to raise CR...use pop up pistons or cut (mill) the heads or a combo of both.

 

Well, that, plus using a longer stroke crank and decking the block...

 

If i can get a hold of a 240 head, i will definitely do that and the flat tops on my next build. Thank y'all for the info!

 

What you are talking about is an engine that will only run with racing fuel.
A flat top piston with a 240 head is a 12:1 compression ratio.

Not sure if you intend to be able to run on the street with pump gas?

 

I'd like to be able to run on premium with maybe an octane booster.

 

OK let's talk about a very potent street Hot Rod engine.

The main component that determines the power potential of your engine is the cylinder head.
We are completing what is tagged as the SR (Senior) head which is presently showing intake flow numbers near 260 CFM at .600 valve lift.
It is based on new head castings from Engine Quest and should have a finish combustion chamber volume around 68cc same as the 240 head.

Then add a steel billet roller hydraulic cam from Bullet Cams with an .050" duration around 242 degrees with .600" valve lift (.375" lobe lift) ground on a 112 degrees LSA.
The wider LSA will still leave a very lopey low rpm and will transition into the power band smoothly.
If you want a more abrupt transition into the power band the LSA would be tightened up to 108 degrees.

With the 112* LSA the compression ratio would be 10.6:1 on 91 octane gas without octane booster.
If you want a 11:1 compression ratio it is recommended to use water/methanol injection instead of octane booster.
The 108 LSA cam would drop the compression ratio to 10.2

For this engine you need either the Clifford 2 carb intake manifold or make your own multi carb intake.
My preference for the Hot Rod look is Stack Injection with six 50mm throttle bodies and six EFI injectors.
I'm looking at supplying such a system later this year. I need to complete my new shop first.

Either the Hooker 5/8" diameter tube headers or custom made headers to fit your vehicle.

You want a 6.8" long connecting rod to reduce piston side loading as well as reduce piston weight.
It will require a custom forged piston.
I used the 1965 to 1968 240 rod. Polished beams, shot peened and resized with ARP bolts.
https://www.dropbox.com/s/k9u6bhvzw0..._0010.jpg?dl=0

I would expect at least 350 hp with hopes of 375.

 

That sounds very very promising! What would I be looking at cost wise on an engine build like that?

 

The cost depends on how much work you can do and what your machine shop work will cost along with parts.
Just looking at my receipts the cost will be not be less than $8000 for your engine.

What vehicle do you want to put this engine in?

 

Oh wow that's a fair chunk of change. I honestly have no clue what i want to put it in. If i build an engine like this, i will most likely build the car around it. I was thinking about an off road t bucket that i've had floating around in the back of my mind for a while though.

 

In your first post you asked for "all out" and crazy and I gave you a combination that I'm looking at doing for possibly a 33 Ford. Looking at the Factory Five Hot Rod.
You can do a 300 hp engine using a flat tappet cam and 4 barrel intake a save some but not the same WOW factor.
For the same power a V8 is certainly cheaper to do but won't get the same attention of a straight six being something different.

The $8k figure is the starting point.
For a good looking bucket car you would want some straight tube polished Stainless Steel custom headers.
Steel flywheel and performance clutch.
Depends on the induction system you choose, the EFI system including in tank fuel pump and plumbing.
Ignition system
The list of extras will always surprise you.

 

I did say all out and i'm not saying that it's too much, i'm just saying that nearly 10k is a lot to spend on a 300. The car i would be building is a rat rod so it doesn't need to be "pretty". and as far as being different with wow factor, that's why i'm looking at doing a 300 in general. I think i've maybe seen a half dozen hot rods with 300s in them. Recently that is.... seems like no one knows of any other engines other than a sbc....

 

Good to know that you are doing a rat rod.
I hear you on SBC at rod events and now LS in everything.
At the PRI trade show you hardly see much about early generation small block Chevy. It's all about LS small block. Makes me tired.

Do you have the skills and equipment to fabricate bolt on stuff?

 

Man dang ol I tell you what, I got me a welder and a cuttin terch man I can fabrimacobble anything. But yeah, I can fabricate most anything within reason. In other words, I dont have a lathe or anything fancy, but I'm pretty good with metal.