I am trying to decide what to do with my 69 Roadrunner. I currently have a stock 383 with roughly 3000 miles since the rebuild. The car made 260 hp 305 torque on the wheel dyno with a 4speed. I was looking at building a 471 stroker with a 400 block. I have a 400 block, but after looking at the cost it was not going to be cheap. It would cost around $8000 for the complete build. My other option was getting more hp out of the 383 and trying to keep the cost down. I will have to look at pulling the heads and looking at the compression ratio and what cam was used. I paid for a stock rebuild and I am not sure if that is what I got. I am running a stock edelbrock 650 avs carb. If I keep the stock manifolds, upgrade the intake to a mopar dp4b, upgrade the carb, cam and port the stock 906 heads and add bigger valves. Will I see big improvements?

260 RW HP through a manual transmission is likley around 285-290 net flywheel HP which sounds good for a stock rebuild. It would really help to get all the specs you can on the rebuild... piston, piston compression height, estimated compression ratio and exact cam would help.

From memory, the 906 heads are typically 88-90 cc's and its hard to build compression with them in a 383. As a first upgrade to the 383, I would look at better heads. Either Edelbrock RPM or 440 source. These would be 82-84 cc's un-cut and help with compression. It wouldn't take much to mill them to further increase compression. Out of the box they breath significantly better than the 906's. Plus, porting the 906's isn't cheap. If you could get compression in the 9.5-10.0 range with aluminum heads and pick up the cam a little I believe you would see a meaningful gain in power. Down the road, if you do build a stroker, the heads could be re-used so it wouldn't be a waste.

For the manifold, the factory piece breaths about as well as the aftermarket low rise dual planes. The only gain there would be weight which may be worth it. A high rise dual plane like the performer RPM should help power if you can fit it under the hood. A 750 carb would help.

You can improve the 383, but usually the biggest problem will be if trying to use stock replacement pistons. Most "replacement" 383 pistons don't have valve reliefs, so piston to valve clearance can be an issue with just a 0.500" lift cam, and that is if they are not the low compression pistons. The low compression pistons sit further down the block where P-V clearance is not an issue, but compression ratio is? Next would be cylinder heads. Smaller, closed chamber heads will help raise the compression ratio. The aluminum aftermarket heads also flow better than stock, have hardened seats for unleaded fuel and weigh alot less than the steel heads.

Great info, I wanted to keep the stock 906 heads because I would like to bolt my A/C parts back to the stock heads. I am not sure if they will bolt up the same on the edelbrocks. The porting will cost me around $1500 with new valves, and springs. Not cheap. If I use the edelbrocks, which heads should I buy? The idea of being able to use them on a 470 stroker down the road sounds good.

All the stock brackets ect. should bolt up fine on the Edelbrocks. The stock type alternator fits fine. If you are running a GM style alternator in the stock location, clearance to the head will be tight.

You want the closed chamber version advertised at 84 cc's (from memory).

So it looks like roughly 40 rwhp with ported heads, cam, carb and my dp intake. What was the torque?

Using a calculator/formula approx. 360.

The car I had the engine in before had an auto trans.

Thanks for the help. This will give me a start, I will keep you updated.

I ported, with MP porting templates, some closed chamber 516 heads, bolted them onto a .060 over 69 383, with pistons about .070 down in the hole and ran low 13's at 105 mph with a very poor 60'. This was on slicks, with a 4.30 gear through the mufflers. 284/484 MP cam, single-plane TM-6, 750 Carter AFB.

You can do as well, or better, with the right cam, a Perf. RPM intake, headers and aftermarket alum. heads.

I would look into off-the-shelf 451 pistons, have a factory forged 440 crank turned down (mains), get some good aftermarket 440 rods, clearance the block (if any) and then get it balanced. Have a trusted Mopar guy assemble it for you and you'll save a bunch. Just make sure you buy the right pin size on both the pistons and rods.