80 Rocket

I wouldn't waste hours of time grinding. I just put it on the Serdi and use a 90* cutter to take the material out. It also makes a nice concentric bowl. I know not everyone has access to a Serdi, but taking it to a machine shop to have them do this would be worth the money.


Here are some J head numbers for the exhaust @ .500 (I flowed these):


J head, stock valve (30* seat) no porting at all: 131.1cfm
J head, 1.71 valve (45* seat), bowl opened up on Serdi, competition valve job, no porting: 155.9cfm


For comparison, here is a stock E head with no porting and a 1.625" valve, average valve job: 163.7cfm


Also, the E head was not flowed with a stub pipe because I hadn't made the pipe yet at the time I flowed them. So you can add about 10-13 cfm to the stock E head numbers. Keep in mind the E head outflows the J head with a smaller valve as well.

80 Rocket

To the OP, I ran your build through one of my engine simulation programs, and I show 226hp @ 3900 and 344 ft-lbs @ 3000.


It might actually be less because I used a cam with 204* @ .050 on the intake. Using a stock cam, it is likely smaller.


If you are simply rebuilding it so it runs and drives, it will work. If you are expecting anything when you touch the gas pedal, this one will be lacking.

1BOSS83

OP,
Here is my build: Idles at 180* in the summer heat, 93 octane is a must, very polite street manners, no ET or dyno numbers, the motor has less than 1k on it. If you put a baby shoe on the gas peddle it'll smoke the tires (from a roll) until the gas tank is empty- $3,100 build.


70 short block, stock crank (cut and balanced), stock rods, 5.8cc dish Speed Pros, stock #6 heads, 224/230 @.050, .485/.490, proform distributor (35* total timing) 9:5:1 static CR, performer RPM intake, 750 carb 78/82 jets, full length headers->x-pipe->magnaflow cats-> flowmaster 40s, 2.25 system, 2400 stall, 2004r, 3.73, 245/60/15 tire.

MyFathersOldsmobile

1BOSS83 - Thanks! That helps ALOT! Not sure if I could mind my manners though.

MyFathersOldsmobile

Well, I just found two places that sell oversized 14 CC dished pistons. Thinking I might go down that road with the cam that 80 rocket is using.

80 Rocket

I have never seen those available. Usually they are more like 24cc. Use the flat tops, you already have them. Take some cc's out of your combustion chamber to lower compression.

olds 307 and 403

How many CC's can you remove with a grinder? Is there a limit?

Fun71

I'm not sure how much that means to anyone who lives outside of the far northeast. Your summer temps are probably similar to spring/late fall temps in a lot of the country and may require 100+ octane to run in "real" summer temps.

Summer where I live:
120degrees2.jpg

1BOSS83

Which is why I said "MY build"

In addition, 93 Octane is must year round, even in the Arctic chill of the "far northeast."

olds 307 and 403

I thought with the extra duration on that cam, you might get away with mid grade. No wonder my car runs shitty on 91.

1BOSS83

My theory is that the gasoline at the pump, over time, will gradually clash more and more with higher compression non computerized engines. So for me; building an engine with iron heads, a carb etc and blue printing it for more than 10:1+ is silly if you intend to drive it on a Regular basis. Just one man's opinion.

MyFathersOldsmobile

Anyone have any experience with an edelbrock 3712 cam? Throwing this ball around at the moment along with having my pistons dished 5-7 CC's. The dishing should bring my compression down to around 9.5:1.

olds 307 and 403

Running that cam in my 350 with 9.5 to 1, pings at times on 91 and runs shitty at times. I even added 1.72 to 1 true roller rockers. Increased the lift to .483/.508 lift and more duration at the valve, which should help. I am running heads with the cross overs filled which I am not a fan of in anything but nice weather. I have have another set of number #6 heads with 64cc chambers vs 55cc and 2.07/1.56 valves BBC springs with unfilled cross overs. It will be right around 9 to 1 with .028" head gaskets.

1BOSS83

The use of that cam has more to do with gearing and driving style. That is a low end grunt cam profile suited for a numerically lower gear.