Does anyone produce a new factory replacement RB block that would bolt into my '69 roadrunner?

Sorry, but what does that have to do with a 383? Please

350 - 361 - 383 - 400s are "B" engines
383 - 413 - 426 - 440s are "RB" engines (383 "RB" was '59-'60 ONLY)

I do NOT believe there are any currently available aftermarket NEW "B" or "RB" blocks.

Okay, I guess I got the letters wrong? Maybe it was HP that I remember reading on the block...in any case, 69 roadrunners came with specific 383 engines...I am interested in purchasing a new block that is as close as possible to the OE specs of that engine...are they available?

Don't think so. But you can still find factory 383 blocks without a problem. Nobody has a reason to raman a 383 block. Everybody wants more than that from an aftermarket block. That's like asking do they make an aftermarket 283 block. Now a low deck block with a big bore may be available through indy? But I think even then they didn't get enough sales and are discontinued? I could be wrong, but im pretty sure that's the case.

Thanks for the info 6bbl gt

You could do a 400 low deck and stroke it to 512 cubes and make it look like a 383.
Just an idea .

Also there is nothing specific to a 383 from a roadrunner, in fact the only differentiation is between the 2 barrel and 4 barrel engines with the latter having the 4 barrel carb, more cam, and more compression. Even if you looked at 440s the only difference between the 440 in an Imperial and that of a 4 barrel roadrunner is the car surrounding the engine.

Surely you have an extra 383HP you can sell? If not there is a 69 383 forSALE IN B-BODY PARTS SECTION.

My engine is the original numbers matching engine but I have been trying to solve an overheating issue with the engine for over 4 years. This car is not a driver but has up to this point been a show car and without getting into all of the diagnostics I've done over those years, I am relegated now to removing the engine and tearing it down. I suspect blockage or restriction of some sort in the cooling jackets but my last last resort would be to buy a new block to insure there are no issues. I don't really think that will be a possible outcome, I was just curious, if I needed or wanted to buy a new 383 block, are they available.

As far as I know there is no cast iron low deck block available that looks the original 69 383 block.

Yes you can buy a new lock deck block, Indy sells one and Keith Black sells one but they are both aluminum and I'm sure you could get them with a 4.25 bore if you wanted.

I have seen your many posts on your overheating issues and without actually what you see as the issue it's hard to say what it is or isn't.

Your other option is to find another 69 383 HP block and put your original in the corner.

I helped a member deal with an overheating issue , it turned out there was a thin spot in the side of the block that was not allowing the cooling system to pressurize , it was found as a stain in the paint on the side of the block , ran a couple of bottles of Moroso ceramic seal thru the block and it fixed it.

JohnRR, yes we have had many posts over the years on this and like I said, I'm basically down to pulling the engine, the engine overheats at idle on a warm day. I've tried different thermostats, radiators, water pumps, timing, different gas, etc. etc. etc. nothing has helped. If the weather is cool 70 degrees or less, no problem, it can idle forever. but on a warm day, if the engine is warmed up, it will over heat to the point of spark knocking within 15 minutes. Rush hour traffic would be "killer".

Thanks for your information and ideas.

Bob

Yes, I used a fan shroud but the car is not coded for a fan shroud...it shouldn't need it.

The system is holding pressure. It does not boil over unless I fill the radiator higher than 1/2 inch below the radiator neck. I don't have a broadcast sheet but can see from the parts book a 4 bbl 383 only came with a shroud if it had A/C or Max Cooling (26 inch). When I purchased the car the engine had been rebuilt and I only took it down to the "short block" when I restored the car, put new gaskets in everything and detailed the engine. I didn't realize at that time it had an overheating problem. The seller never mentioned it but since has pretty much come clean. No one knows if the block was "hot tanked" when it was rebuilt. I have put an analog Temp gage with a probe installed in the water pump housing where the heater hose nipple is located to validate my heat gage on the dash. Both appear to be correct. Day before yesterday it was 93 degrees here and I tested it with a NEW after market aluminum radiator to be sure it wasn't the OE radiator causing the problem (even though 2 shops told me my OE radiator was fine). The engine reached 215 after about 20 minutes of idling. That is with a 180 degree thermostat. I know people will say 215 isn't too hot but the point is, if it would have been 97 degrees, the engine would have gotten exponentially hotter.

I will have my car at the Mopar Nationals under the OE Tent this year and when I return I will be pulling the engine and disassembling it part by part looking for an anomaly. I suspect the block but don't have any idea what I will find. My nightmare is that I go to all of this work and don't find anything. That is why I was asking if there are any 383 OE blocks being produced. I'd just put the matching numbers block in the corner and put a completely different block in the car rather than go to all of this trouble to just have it continue to overheat. It is a quandary.

JohnRR,correction, I didn't get the shroud information from the Parts Book, it was the Service Manual and yes, my car came with 323 gears and a 4 speed transmission...although I don't think the 4 speed has anything to do with it having or not having a shroud.

I don't think you really have as big a problem as you think. Maybe the seller didn't mention it because it isn't a problem ?

First off you can't fill the radiator to the neck, many people do that , guilty as charged , but that system does not have an overflow tank or a recovery system so it needs room to expand without burping out. Make sure you have the correct cap on it, a cap for a recovery system is going to allow fluid to escape because it thinks there is a tank on the end of the overflow hose. I'm sure that was already brought up.

Now I'm going to ask the really STUPID question ... why are you letting it sit and idle till it overheats? What's your timing set at and what octane fuel are you running ? did you put steel shim gaskets back in or composite?

When you took off the heads did you make note of the overbore size , if any?

Here's a silly test for your idle adventure , put a fan in front of the car and see what happens .

Also I wonder how hot it would get wit han original 190 degree thermostat in it ?

I'm sure there is an OE unbuilt 383 block out there in an obsure warehouse or buried in the back of an engine shop somewhere.

Do you have a 26" rad you could put in place of your 22" to see if the same problem with your extended idle till it overheats test?

I had the same thing happen once with it overheating with an extended idle , 26" rad and a shroud, std bore 383 sitting in a line of traffic for 45 minutes. I didn't think about it while i was sitting in my truck and I do not know why my father sat there with it running for that long not going anywhere