I have 235 rebuilt for a carburetor i have langdons weber carb. I can idle only at 700rpm. I have vacuum gauge installed and my needle will sit where i have marked blue line on it. Its around 13 in Hg. I played with timing various ways and only able to land in red area. I played with the carb and cant really get nowhere close to 17-20in Hg Is an engine rebuild shop suppose to adjust valve to spec?
you can also play with ignition timing. and there are other things that will affect vacuum readings, such as elevation, etc. I've never ever worried about a low vacuum reading, as long as the engine is running and performing properly.
The concern on low vacuum squirrel, i am trying to break in the engine. On idle my engine does not overheat. Temp guage will not go pass 190*. Metal fan has been removed and installed electric fan which will engage at 180*. Will let idle for 20 minutes no overheat, however raising rpm to 2000rpm temperature will climb to 210* if i leave it running i feel it will go past it.
Engine man they are solid lifters i believe. Its 53 235 i looked over my rebuilt parts list and says solid lifters. Dont believe they ran the engine, no oil inside the engine when picked up.
Subtract approx. 1" per 1000' above Sea level for a corrected figure. In other words, if you live in Denver you're doing OK. Valve lash is important. If they are two tight you'll lose compression (and have a low manifold vacuum) It's pretty easy to set valves once you get the hang of it. You'll need to at least check them, and maybe an adjustment or two as it breaks in. Then they should settle down for a good while. Just make sure the lifters are on the base circle of the cam lobe when making the adjustment. A shop manual is your friend here. There's different ways of doing it. The engine does not need to be running.
IRe: running or not, the specs in all the books I've seen are hot lash specs, since 235's don't have a bolt on the balancer, makes it a real pain to adjust them after warmed up, with the engine off. I let the engine run at a fast idle for 20-25 minutes, slow the idle down, pull the valve cover and adjust them while running,when set right, you feel the tug on the feeler gauge as you slide it through...doing it this way, you know they are all pretty much the same, as none have cooled more than the others. Yes, you're feeler gauges will sorta "round' a bit, but they are pretty cheap to replace every 30 years or so.
Idling fresh engines has never been a good idea - very hard on cam lobes. If the rockers and valve stem tips were refaced, chewing feeler gauges should be minor. After warmup of 20 minutes, tighten the manifolds & set intakes .006, exh. .016.
I recall a customer of mine relating a similar subject. He had a flathead in a '40 Ford, built and installed in a known San Jose shop. When he went to pick the car up, he paid the owner, got in the car, started it, and headed out of the driveway. In the rear view mirror, he saw the owner standing with one of the mechanics. He thought the owner started to wave as he left, but said owner was making the Sign of the Cross! 'Guidance'? I think not...
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