Is this normal MPG?

[crvc]

When I was building the engine a few years ago I soaked the manifold in HCL then reamed the risers with a frayed length of quarter-inch cable. So they were open once. How long does it take for carbon to re-clog the risers? I noticed a while ago that the left riser was hot enough to blister while the right was merely warm-to-the-touch. I'll try the choke adjustment in the morning.

Thanks,

BTW, I had two blocks that I'd rebuilt including line-boring, all new bearings, valves, guides, etc. I used one that was originally a type-3 but had been converted into a type-1 by my dad. I used it for a couple years but had constant problems with overheating and a bad oil leak. Then I pulled the engine out and mounted the cylinders and heads on the second block, a type-2. The overheating continued until I changed the oil cooler. But in mounting the new cooler in the doghouse I over-tightened the two studs and now I have a new oil leak coming from those stripped studs.

I hate the thought, but it seems more and more that I need to go back to that block that's been in the garage for the past two years.

kevin

[aussiebug]

Hi Kevin,

If one side is very hot and the other side barely warm, then so long as it's warm/hot under the carb, the heat riser is working. If it's not warm/hot under the carb, then it's blocked and all you are feeling is the exhaust header heat on the hot side.

It can take years for the heat riser to block up (over 20 years on my 1970 1500sp engine), or it can take much less, depending on the condition of the engine. Leaking pistons rings allow extra oil into the combustion area for an oily exhaust, which clogs the heat riser. A sooty exhaust can compound that.

The oil cooler should be torqued to just 5ftlbs (60 inchlbs). That's enough to compress the seals so they don't leak, without crushing them and blocking the oil flow. Some folks like to use lock nuts if they are worried about them coming loose with the small torque used, but that makes it impossible to get the torque correct. I wonder if the "type 3 rebuild" overheating problem was the result of over-torqued oil cooler nuts crushing the seal and reducing oil flow through the cooler.

When you say "type2" engine, I presume you mean an upright bug style engine out of a bus. There was no actual "type2" engine, just the "type1" upright engine as used in the bugs, but with extra holes under the oil pump for the cross member support (otherwise identical to the bug version) and then the "type 4" engine - 1700, 1800, 2000cc with the heavier case, better cylinder finning, and fan mounted at the rear of the crankshaft, similar to the type3 pancake engine.

[crvc]

I thought type-2 engines had a specific camshaft that allowed more torque at low rpms. Because buses being much heavier than bugs. My engine with a stock muffler doesn't have that 'chirpy' sound typical of bugs. I wondered if that contributed to the low mpg. This other short block has a type-1 camshaft. Another reason I was thinking of trading blocks.

kevin

[Max Welton]

Same cam in both type 1 engines. Different gearing.