|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
11-03-2013, 06:44 PM | #1 |
Senior Member
Join Date: May 2010
Posts: 527
|
Engine Timing Curiosity
I have a friend whose engine seems to be running at idle very poorly. The engine rolls - like the timing is too far advanced. Also, it doesn't sound like a Model A. However, the timing seems to be spot on according to the instructions from FS Ignition. This engine was rebuilt recently within the last year.
My question is - what would the engine run like if the timing gears were displaced by one tooth? I believe that the crank gear has 25 teeth and the cam gear 50. If the setup was off by one tooth that means that the valve timing would be off by 7.2 degrees. Would the engine even run? BTW, rolling down the highway this engine has lots of power - climbs hiss well etc. Dick |
11-03-2013, 07:21 PM | #2 |
Senior Member
Join Date: May 2010
Location: Largo Florida
Posts: 7,225
|
Re: Engine Timing Curiosity
Most engines won't run if off a tooth. I don't know about an A though, never tried it. Does the engine start like the ignition is too far advanced ? Does it have some kind of special camshaft ?
|
Sponsored Links (Register now to hide all advertisements) |
|
11-03-2013, 07:26 PM | #3 |
BANNED
Join Date: May 2010
Location: Bucks County, PA
Posts: 11,454
|
Re: Engine Timing Curiosity
i have found most engines will run a tooth off with the symptoms being lack of power, lower than normal compression. a proper leak down test will show this
|
11-03-2013, 07:32 PM | #4 |
Senior Member
Join Date: May 2010
Location: santa cruz, calif
Posts: 2,011
|
Re: Engine Timing Curiosity
Fuel mix too rich will cause a rolling idle. So will a hot cam. Given it has plenty of power, the timing is probably good.
|
11-03-2013, 08:13 PM | #5 | |
Senior Member
Join Date: May 2010
Location: NC
Posts: 2,975
|
Re: Engine Timing Curiosity
Quote:
Some of the crank gears from the 70ts were off by a 1/2 tooth. They ran but were low on power. |
|
11-03-2013, 08:24 PM | #6 |
Senior Member
Join Date: Jul 2010
Location: Cow Hampshire
Posts: 4,188
|
Re: Engine Timing Curiosity
Sponsored Links (Register now to hide all advertisements)
Joe K
__________________
Shudda kept the horse. |
11-04-2013, 09:31 AM | #7 |
Senior Member
Join Date: May 2010
Posts: 527
|
Re: Engine Timing Curiosity
Patrick: The engine starts right up very easily. It has a Snyder's 5.5 head and I believe the cam is stock.
Dick |
11-04-2013, 09:34 AM | #8 |
Senior Member
Join Date: May 2010
Posts: 527
|
Re: Engine Timing Curiosity
I will get the owner to do a compression check. I think that he told me that the compression was OK on #'s 1 and 2, but low on #3 and I am not sure about #4. I will get him to redo it. Would it be possible to have good compression on a couple of cylinders and not on one or two?
|
11-04-2013, 09:37 AM | #9 |
Senior Member
Join Date: May 2010
Posts: 527
|
Re: Engine Timing Curiosity
I will get him to do that as well. Thanks
Dick |
11-04-2013, 11:53 AM | #10 | |
Senior Member
Join Date: May 2010
Location: santa cruz, calif
Posts: 2,011
|
Re: Engine Timing Curiosity
Quote:
|
|
11-04-2013, 12:06 PM | #11 |
Senior Member
Join Date: May 2010
Posts: 527
|
Re: Engine Timing Curiosity
Thanks Pat; What I meant to ask is whether #3 could be low due entirely to a misalignment of one tooth on the timing gears. With the recent work done on the engine I am assuming that the head gasket and rings are OK - but you never know!!
Dick |
11-04-2013, 06:41 PM | #12 |
Senior Member
Join Date: May 2010
Posts: 527
|
Re: Engine Timing Curiosity
Checked my buddies engine this afternoon and found that you can just see the edge of the cylinder from the spark plug hole. I inserted a very long and thin screwdriver while he turned the engine over by hand. When the timing pin went into the dimple the piston was at TDC. No problem with timing gear misalignment.
Will now chase air leaks. Thanks for all of the input. Very much appreciated. Dick |
|
|
Sponsored Links (Register now to hide all advertisements) |
|