New Overhaul Noise

2

25 TA

Junior Member
I am new to this forum so excuse my errors.
I just overhauled my 1930 Model A Motor, had inserts installed on the main, had block line bored to 125, crank turned to 30 over, connecting rods are babbits at 30 over, had the head and block cut (that's another story).
Started engine easy and have been using Snyder's break-in method, have run the motor for 3 hours, changed oil and new oil is valvoline 30 wt non detergent. Oh I used 10/30wt during break-in.

The problem I now have is it starts and idles really good, no noise, solid engine very quite. I have taken out on the road twice for about 1 1/2 miles each time and I hear a hissing noise, but when it idles you can't hear the noise. If I move the spark advance all the way up, you can hear the hissing noise and sometimes if the advance is about 3/4 way down, and rev engine a little, I hear the hissing noise.

Any ideas what might be the problem, or where I should look into??

I have a tilotsen carb; electric fuel pump (carver low volume 2 to 4 lbs), I have preasure regulator and a gauge set at 2 lbs, new auto lite plugs 64, temp gauge stays at 160, new water pump, new timing gears, new rebuilt oil pump, new distributor (modern type) new distributor gears, new clutch, perfectly timed, starter works very good, generator works very good and puts out 6.5 volts at idle, new radiator hoses, new fan belt new oil in trans and rear end 600 w from Berts.

I still need to fine tune the clutch, it's a little to low, have to go flush to floor board

One last thing, this is was my dads 1925 Model T and he installed the model a motor in the mid 60's and it ran untill now. I will post a picture of the runabout pickup as soon as I learn how to do pictures and when I get her running perfect

Sorry for such a long post. I live in Las Vegas, New Mexico
 
With the tillitson you need to check the mounting flange. The pot metal carbs are very prone to this flange warping with even moderate pressure to the mounting bolts.
 
Carbs with no air filters or silencers make a sort of hissing noise from the air rushing past the edge of the throttle plate. Could this be the hissing noise? Or, are you sure there is some other hissing noise? Take a length of plastic tubing and stick one end in your ear and move the other end around the manifold to see if you can hear the noise. I've also used an unlit propane torch to sniff around the intake manifold. When the propane finds an entrance to the intake, then the engine will run faster or smooth out.
 
I am curious why you changed from detergent to non-detergent oil ?

I personally run 20-50 detergent in all three of my A's; have for the last 25 years; have never lost any rods or mains and engine stays very clean.
 
I'm with Ron on this also. Many people believe in only using non-detergent oil for breakin, then go with a good detergent oil for the rest of the time.
 
Not for the sake of disagreement but just another personal experience opinion. It could well be a vacume leak like others have said. I have had vacume leaks on other engines that would give a chirping sound. I have found the breathers such as the air maze to cause the carburetor to be very noisey. Though this wasn't the question, I use 30wt non detergent for break in and 20 W 50 after break in with my model A engines. The reason for my oil choice is that most non detergent oil doesnt have any additives to prevent wear. You need a certain amount of wear to seat the rings. The higher quality Lubricant will slow or prevent breakin, especially in an engine that won't be used for primary transportation and won't be driven that much. To some this may not apply but the last GM 350 crate engine that I purchased it was recommended or required for the warranty that the engine should be run the first one thousand miles with the low cost 30 weight non detergent oil for this reason.
 
It can be one of two things as most of the other guys have mentioned.
1- a vaccume leake
2- the sound of the air being pulled into the carb. Usually this is more noticable when you are accelerating or under a load ect... My car makes the same noise especially since I no longer run an air cleaner.

My question is why are you running a fuel pump? Just wondering what kind of intake and carb set up you have?
 
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