Had an engine gone through by a rebuilder..... started it and had a bad knock when timing advanced and half throttle... sounds great if idle or little throttle.... any input would be great.... thanks in advance Keith... 860-307-2850
Rods not straightened?
Supposedly new rods....
I would first call the re builder I would also look in the bottom for anything loose. Philip
I have a another model t with a similar knock and it's had it for two years with no problems...... but this is a new rebuild so I'm worried..... what should I check first??????
Any kind of warranty? I'd sure let the rebuilder know about the knock. That's the first thing I would do.
It's a situation where I dont want to bother the builder if I don't have to.... wondering if it might be a "easy" fix..... wondering if there is something I should check that is common for this kind of noise... like I said it sounds great at minimal throttle/ retarded.... but once you advance spark or really increase throttle it sounds like a rods ready to launch.......
Rod bolt striking cam?
Does it knock with the timing retarded? If it doesn't you are probably advanced too far. Will knock every time.
I'm just saying if I was the rebuilder I'd want to know because ultimately it would come back to me by reputation either way. Good or bad. Most rebuilders take pride in what they do so I would call the builder or take the vehicle to him for inspection. Remember you are responsible if you continue to run the engine knowing something is wrong. Give the builder a chance to correct the problem.
Trust me I'm in the business.... I'd also want to know if my work is sub par.... the gentleman who does my engine work is in the hospital and my engine is not a priority........ so I'd like to investigate the problem myself..... trust me ..... if he's out of the hospital and doing good health wise I will let him know.....
Glenn... it doesn't knock retarded.... only when I advance it will it start to knock ..... and only at higher idle/speed........
Could be to advanced
Could be rod not straightened- just because it's been redone doesn't mean the wrist pin and crank are parallel
I would call the rebiulder
If the knock is a bit "random", then I have encountered this as end play in the camshaft. It is actually not uncommon in T engines
Keith, if you have the ability to take a vid and post it here, it might help to diagnose the source and severity of the knock. Especially when you say it sounds like it wants to "launch a rod".
Kieth I had a similar knock on a new rebuilt engine last summer. It was rebuilt 17 years ago, was put on an engine stand and the owner died. There's no idea who rebuilt it.
I put it in the car and there was a knock. The first thing I did was make sure the rods were in right and the rod bolts weren't hitting on something. Everything was good there.
Then I checked the clearance on the rod and cap bearings to the crank. Everything was good.
I checked the cam and cam bearings and all was good.
I pulled the pistons and checked for evidence of piston slap. All was good.
Then I checked side clearance on the individual rods. One rod was .025", one was .020", one was at .017" and one was at .006". It seems the crankshaft journals were too wide.
So I took the three rods that were running in the wide journals and had the Babbitt repoured and remachined. Now the knock is gone. Moral of the story? Hell I don't know. Maybe check the rebuilders work before assembling the engine.
I have no trouble trusting our local rebuilder. I don't know if there's anyone better. But ya just never can tell.
Keith, Check the timing. Retard the spark. Remove Spark Plug #1. Turn ignition to battery. bring the piston up on the compression stroke. The coil should start buzzing just after Top Dead Center.
Agree with Glen, a 'starting' point would be to check the timing but not only #1 but all 4, if the front cover is out of alignment when fitted then the firing timing is out of sink with crank degrees giving you 2 cylinders way to far advanced and a bad timing knock as you describe.
Larry Reid nailed it
For all the time it will take, it is easy to check the end play of the camshaft. I've seen fresh engines that sound really bad and that was all it turned out to be. The fix is easy. Pull the front cover and install some shim washers on the front of cam gear nut (1" ID shim washers are quite available in packaged sets at better industrial suppliers). A really easy fix if that is the problem. And it will sound just like a really bad rod knock, but if you play with the throttle it will just not QUITE always be there And I've seen it over the years enough times to eliminate it first!!!
Perhaps the timing gears were not aligned. Too advanced. Easy to skip a tooth. Some do it on purpose. For sure call the rebuilder. He will be wanting to correct it, my guess.
Didn't read all the posts due to my short attention span, but I agree with Richard above, take it straight to the rebuilder, do not pass go, do not collect $200. You start tinkering with it, now you own the problem, not him (if it was a rebuilder problem).
I have seen a similar knock on a car with a high compression head when there is insufficient clearance in the squish area. A long shot but worth looking at and easy to fix.
There are several possibilities mentioned that could be the issue. With that said I have to say that I would let the rebuilder know about it before I did anymore to it. Especially if its an internal issue. If the rebuilder has a good reputation he'll make it good.
I vote to take her to the engine builder as soon as he is healthy again. Engine work isn't cheap but I would check the timing as suggested.