I recently bought a couple sets of 1971 340/360 B,C, and E-body exhaust manifolds (ebay) and found something I hadn't seen before. One set had earlier casting dates, and the other had later dates. The odd thing is that the passenger side later date piece (March of 71) had never been machined for a heat riser assembly. It is in super condion but has been on an engine for quite some time, I'm guessing it was a REAL early replacement part sold over the counter? Maybe from some oddball truck application with a hand choke? Have any of you seen one of these?

2

The early one for comparisons

Casting #

Non automotive 340 or 360 application.

Boat? But they don't have those type manifolds like that do they?

Would a 360 Motorhome have to have a heat riser? I would think so?

What about a stationary 360 2V engine?

Yea, I don't know, could be any of the above. The drivers side was a correct 1971 C/B/E body 340 & 360 piece as well with similar date code and identical condition so they came together on something.

Any guesses why the e bodies went to the long type in 71 but the a bodies still had the upswept type.

My guess is that it had something to do with the routing of the rest of the exhaust system. The 70-71 change from single to dual E-brake cables might have been a factor.

I have one also, it came off a 340 duster.

Really! What is the casting date? How about the spd of the Duster?

The exhaust manifolds I used on my 360 in the Sport Satellite are from a 72-73 Road Runner. Base engine being a 318 - however, the manifolds have the port size for the 340/360 heads. AND the right side was never drilled for the heat riser, like the manifold you have pictured. Also, the right side has 318-RR cast in it (upside down). . .

no heat riser- I have seen exhaust manifolds from small blocks with no heat riser- and were definitely off a car- I don't know why not? Maybe sales in South or SW- or if no heater ordered??? Assuming warm environment- Seems weird when consider emission of late 60s early 70s probably required when cold started?

The set I bought for my 74 360 duster clone were not drilled for heat riser either.The are dated Jan of 74 IIRC.I thought it had something to do with 74 being the first year for EGR but your manifolds throw that out the window.

I wonder if single exhaust cars had/needed a heat riser?

Ok, with a few examples existing it's becomming evident that at least some cars might have recieved the non heat riser style from the factory. Now, what can we put together to determine which cars recieved heat riser assemblies and which cars did not, and then why?

Thats what I have on my Duster. I think the guy I bought if from thought it was for truck.