'302' Combustion chamber volume?

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tomcopbar

tomcopbar

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After a while of dreaming of a 318/390 stroker with alum. heads and all that good stuff I am realizing that I will either build a monster engine and live at home for years longer or use the 302 heads I have lying around and build a budget engine but still push 400hp. So, I am looking at building a more mild engine with some warmed up 302s and am needing to know the size of the combustion chambers over other 318 heads with open chambers so I can select the right piston. I have been looking at the KB399 pistons. I would like over 10:1 compression if possible. Also, Mancini has Eagle I-beam rods on for $240 instead of $260, is that a decent price?
 
302s are around 64cc. Stay clear of the eagle esp I beams. To many horror stories about them. Look at the Scat I beams instead. prices around the same.
 
You can have the heads shaved some to bring up the compression. I had a set of 302s shaved down to 57cc in which I used the thin Mopar Performance head gaskets which brought the compression up some more. I believe the compressed thinkness after mounting the heads is .020 ... anyways all said and done the compression of my motor is 10:7 it's a 360 by the way. I might later on install larger valves more than likely on the exhaust side and port them.
 
So far so good then, stay away from Eagle, alright, is there a better place than others to buy Scat? All in all this is sounding like an excellent alternative as long as everything mechanically checks out which I'm sure it will. Thanks Adam and mullinax for your input so far and anyone else that wishes to expand my brain.
 
I bought a set of scat I beams recently on ebay from kmj performance for $269. Also, if you search for 318 pistons on ebay you can find KB-845 forged pop up pistons for under $400/set. think it's 909 Race parts that sells them.
I haven't cc'd my 302 heads yet, but I thought they were 57cc stock. Could be wrong.
 
I've only been doing mopars for 48 years. But for a small block I prefer Badger pistons along with the SCAT I beam rods. With iron heads it's not a good idea to go over 10:0:1 compression because of pinging witch will kill an engine.
302's shaved 50 with a steel shim gasket and a 9:5:1 piston will give you a CR of 10:0:1. You also need to bore that 318, 60 other wise you don't have enough bore to create the velocity needed with the big ports to create thge cylinder pressure needed. Getting 400 horse out of a 318 is very easy to do. A 750 holly or edlebrock card on a performer intake works real good. Also Summit headers are private label headers made by hooker for half the money.
 
alcusswhen said:
I've only been doing mopars for 48 years. But for a small block I prefer Badger pistons along with the SCAT I beam rods. With iron heads it's not a good idea to go over 10:0:1 compression because of pinging witch will kill an engine.
302's shaved 50 with a steel shim gasket and a 9:5:1 piston will give you a CR of 10:0:1. You also need to bore that 318, 60 other wise you don't have enough bore to create the velocity needed with the big ports to create thge cylinder pressure needed. Getting 400 horse out of a 318 is very easy to do. A 750 holly or edlebrock card on a performer intake works real good. Also Summit headers are private label headers made by hooker for half the money.
Click to expand...

Not trying to be a smart *** or anything like that so please don't take it that way.

I have been running 10:7 compression with iron heads with no pinging but I do run 93 octane ALL of the time. I believe what really helps my situation is my cam a more overlap than others (from what i've told anyways).

I thought the 302 had the smallest ports of iron heads.

My friend runs 11 compression but runs 110 octane race fuel with iron heads.
 
Here's what you need to do. Get yourself flat-top zero-deck pistons and mill the heads to get 10.5:1 compression (or more if you want to experiment). Then have ALL of the edges in the combustion chamber radius'd; not just smoothed, but ground into a definite round shape. Also kind of smooth the curve into the squish pad to create a "wedge" effect, and grind down that pointed "ridge" going between the valves. What this does is greatly increase flow across the valves and greatly reduce the tendency for hot-spots to manifest in the chamber. Also, when the flame front begins to move across the chamber, it will take on a true "wedge" shape as it approaches the squish pad area and will force itself into the squish area, leaving much less unburned area on the piston than is common with closed-chamber heads. You won't have to worry about ping and mileage and power will also improve, especially on the low-end (and you won't need to use a high-overlap cam to reduce cylinder pressure).
 
66dartman, I have been looking at those exact same peices for a bit, they are decent prices compared to the likes of Summit. I will probly end up going in that direction, it is just a pain to think I need to add 20% to the price at least just to make up the difference between the US and CAN dollar. I liked it better when our dollar was worth a little more than yours for a couple weeks a while back, I did well on a carb and a couple other things. Once again, thanks for all the input, there is always something out there that someone knows better...
 
In the January 09 Popular Hot Rodding issue, they did a write up on Adney Brown's 318 build up for the 07 Engine Masters competition.

He made 477 HP at 6500 (it probably would have made more but they only spin them to 6500 for the competition) and 427 pound feet of torque at 4900. The torque didn't drop below 400 until they were past 6100 RPM. Yhis was done using a set of well-ported former SS iron Magnum R/T heads w/2.02, 1.60's for valves. The block was .030" over with 10.44 comp Diamond domed pistons. The cam was a big Comp solid with 1.7 rocker on the intale and 1.6 on the exhaust.....622"/.597"....247/247 at .050".
It was origianlly a roller hyd factory block. The change to a solid flat tappet is a bolt in. He used a stock 340 forged crank that he worked over quite a bit...balanced and lightened.

You could do a similar build with less cam and get all the power and reliability you are hoping for, but you will need to upgrade the valves and do some decent touchup work on the ports.
He has his own shop.... www.performancecrankshaft.com

P.S. I prefer the shaft mounted rockers over the later model Magnums.
 
mullinax95 said:
Not trying to be a smart *** or anything like that so please don't take it that way.

I have been running 10:7 compression with iron heads with no pinging but I do run 93 octane ALL of the time. I believe what really helps my situation is my cam a more overlap than others (from what i've told anyways).

I thought the 302 had the smallest ports of iron heads.

My friend runs 11 compression but runs 110 octane race fuel with iron heads.
Click to expand...
The small ports of the 302 is what makes it work so good on a 318. And cam overlap increases time to full cylinder pressure. It can also increase it to thats how you get big power with out over high compression. The reason computer controlled engines have knock sensors is the ear can't hear real light pinging. It takes all I earn to have my hot rods I can't afford to run high buck gas.
 
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