Itinerant Air-Cooled

Kind forum,

Apologies for the long post...

Took the first long trip of the season in the bus today: two hours down the parkway. About halfway, my tailpipe shimmied off the damper pipe and did an elegant cartwheel on the asphalt. Damn! Just replaced the whole exhaust system with Colin back in the spring. I tightened everything up after an initial break-in, but not enough, apparently.

But the real reason for my post is that I am getting unusually high cylinder head temp readings from the old VDO. Unusual in the sense that I did not get these readings last summer under similar conditions. I've done some work on the bus since then, so I am wondering if the high temps could be related to any of the following variables.

First, the conditions and the readings:
1600 DP
85 degrees ambient temps
Maintaining 55 -60 MPH
Oil pressure @20
Oil temp @210
CHT @425 - 450+ at load (this is higher than what the CHT readings usually are)

The things I've done in the last 4 months:

Complete exhaust system replacement with Colin, from an extractor type back to stock. Replaced everything, including heater boxes.

After the new exhaust install, Colin noticed a blapping sound coming from the engine. Retorqued cylinder heads. Had some loose nuts.

After that procedure, the idle was revving higher, so I followed the procedure to even out the idle and adjusted the mixture. Still haven't gotten this right; idle is low when the engine is cold and I honestly can't tell if it is running lean or rich.

Any ideas of where I should start?

Thanks,

James

appetite wrote:Kind forum,

Apologies for the long post...

Took the first long trip of the season in the bus today: two hours down the parkway. About halfway, my tailpipe shimmied off the damper pipe and did an elegant cartwheel on the asphalt. Damn! Just replaced the whole exhaust system with Colin back in the spring. I tightened everything up after an initial break-in, but not enough, apparently.

But the real reason for my post is that I am getting unusually high cylinder head temp readings from the old VDO. Unusual in the sense that I did not get these readings last summer under similar conditions. I've done some work on the bus since then, so I am wondering if the high temps could be related to any of the following variables.

First, the conditions and the readings:
1600 DP
85 degrees ambient temps
Maintaining 55 -60 MPH
Oil pressure @20
Oil temp @210
CHT @425 - 450+ at load (this is higher than what the CHT readings usually are)

The things I've done in the last 4 months:

Complete exhaust system replacement with Colin, from an extractor type back to stock. Replaced everything, including heater boxes.

After the new exhaust install, Colin noticed a blapping sound coming from the engine. Retorqued cylinder heads. Had some loose nuts.

After that procedure, the idle was revving higher, so I followed the procedure to even out the idle and adjusted the mixture. Still haven't gotten this right; idle is low when the engine is cold and I honestly can't tell if it is running lean or rich.

Any ideas of where I should start?

Thanks,

James

Let's do the essentials first:

Check timing (advance hose off) at 3,200 rpm and make sure that it does not exceed 30* total advance. I suggest 28*

You can always tell where you mixture is by turning the small mixture screw CLOCKwise until the idle drops noticeably. Then bring it back until engine recovers. Try little 1/4 turn counterclockwise and see if engine likes it. If you can't tell, leave it at the recovery point above and give 1/4 rich counterclockwise from that known spot. Then adjust idle speed big screw, to 950+.

A clean engine will cool better. Make sure fan belt is decent, not tight, but not loose. Make sure spark plug ring terminal is not allowing combustion gases to escape past the plug. This makes CHT readings skyrocket.
Sorry I am late to this thread.
Colin

I have to clean my dirty engine, yes.

I will need to procure a timing gun. Any recommendations?

Also, if memory serves, I think my combo of carb and distributor are not correct.

Check the fan and see if you have a rag in it