So my neighbor and I changed my intake manifold and carb. to a new Edelbrock intake with rebuilt Holley 4 barrel 600 cfm carb. We have been working on dialing it all in by adjusting the distributor that we had to remove to put on the new intake. So we have it running ok, but not great. Here is the thing that has us puzzled, the recommended timing range for this engine is suppose to be between (8 and 14 BTDC) from what I read. My neighbor says the truck wants to run best over 30 BTDC. So something is definitely wrong. My neighbor pulled the #1 plug and we bumped the motor to find the TDC, does it matter if the TDC is off of the exhaust or compression stroke? We don't have a owners manual, is there a good informative thread on this. Is it possible the harmonic balancer moved?

 

Yes, it does matter whether you use TDC compression or exhaust.

All timing specs are taken off #1 TDC compression. The spark plug fires on the compression stroke, not the exhaust.

Make sure you have properly identified #1 cylinder. On Ford V8's #1 is the front cylinder on the passenger side of the engine.

A wise investment for you would be the purchase of a shop manual, or other DIY manual, for your truck. I personally don't care for the Chilton and Haynes manuals and would opt for an original Ford / Helm manual. They are available on CD from many different vendors.

 

In addition to what Roger Carter has stated -good stuff by the way - make sure the distributor's vacuum advance can is connected to the "timed" or "ported" nipple on the carb. The vacuum advance connected to manifold vacuum would give you those high timing readings.

Set/verify #1 piston to TDC on the compression stroke and then peek at the numbers on the balancer. You should read "0".....or very close to it. If so, the balancer hasn't slipped and/or the rubber is still good.

 

Thank you Roger Carter for the info. and advice. I thought that was right about using the compression stroke to find TDC. My neighbor is a good mechanic but was wrong on this. I will dig deeper to find out the proper way to set timing. Thanks again.

 

First, the distributor vacume advance can is hooked up to the front base of the carb., is that ok? Next, how do you tell the difference between compression and exhaust stroke? Thank you Filthy Beast.

 

The Holley 4V....(model 4160, list - 1850-xx...,yes?) has the timed/ported vacuum nipple on the right side (passenger side) of the metering block about halfway up. Your current vacuum advance is connected to manifold vacuum....hence the timing atrocity.

Compression stroke test: Pull #1 plug...have a helper crank the engine over (CW) by hand - a 15/16" half inch drive socket and breaker bar is optimum - whilst you have a finger plugging the plug hole. When you get near compression on #1 TDC, yer finner should be blown out of the hole....or at least, you'll hear a "puh-cheee" sound - like airbrakes - on the compression stroke. You won't hear/feel anything much on the exhaust stroke @ TDC.

 

I always thought you wanted to time the engine with the vacuum advance disconnected from the distributor. Is that not correct?

 

Excellent info. Filthy Beast, I was bumping the engine with the ignition, we will try the breaker bar next time. Also it's great to know the vacum advance is hooked up at the wrong port. I'm not exactly sure the model of my carb. I'm watching youtube videos right now on this timing issue.

 

We did unhook it from the distributor when we were trying to check timing.

 

Ok, just wondering. I was always told to keep it disconnected when you're setting it, because the high vacuum at idle will kick-in the vacuum advance and throw you off.

 

On yer carb...the info you want should be stamped on the choke horn.....not so sure if the model/list numbers I gave you are correct for your carb, but (as a general rule) any time you have a vacuum line hooked up below the venturi, you have manifold vacuum........

And, yes, any vacuum line to the distributor should be unhooked/plugged when checking/setting the timing.

Enjoy the videos...

 

1976 Ford truck shop manual volume 2(engines)ordered and on the way.