Tried starting a new engine, 292, today. Flames shot out through the carb. Plan for tomorrow is pull the plugs, remove the valve covers, bring the engine up to TDC, check the valve lash on number 1, rotate the engine clockwise 1/4 of a turn to check cylinder # 5, and so on until done. Then try again! Any suggestions?

 

Howdy,


Pull the timing cover and ensure that someone didn't time the cam like a Chev 350!

Then make sure you have some tappet gap!


Regards,


Rick

 

Yep and the dampers are notorious for slipping off their clock (or index), so the timing may be way off.

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First thing I would do is check the plug wires, firing order. If that is correct, then check valves and cam timing.
Edit: Consider who built this "New engine". Someone who knows their way around the Y block or some SBC or other builder? Unless the builder knows what he is doing, cam timing wise, he probably got it wrong, as mentioned. A direct question to the builder may reveal a lot.

 

I agree with Ray. Bring number 1 (front cylinder on the passenger side) to TDC then pull the distributor cap and make sure the rotor is pointing to the spark plug tower for number 1 cylinder. Then check firing order 1-5-4-8-6-3-7-2 tuneup.htm



Here's a post on Backfire thru Carb.

https://www.ford-trucks.com/forums/9...gh-carb-2.html

Keep us up on what you find.

 

I purchased the long block from a reliable rebuilder. When I received the engine the marks on the cam and crank were pointing toward the oil filter side of the engine; from everything I read that's where they were suppose to be.

While I had the engine on the stand I adjusted the valves, by following the instructions in the book Ford Y-Blocks.

The first time I cranked the engine I had nothing although I had fire to the plugs. So I figured I had the distributor 180 out. I then moved the distributor and then re-adjusted the valves following the Ford Y-blocks book.

The next time I cranked the engine I had ignition in some cylinders. So I pulled the valve covers to re-check the valve lash. Some of the valves were so loose the push rods were no longer on the lifters.

So I went back to the repair manual, which is for a 239 up to 276 (I think) and check on how it suggested to set the valves. It said to bring it up to TDC, which I did, and then set the valve lash for #1 intake and exhaust, rotate the engine 1/4 of a turn clockwise and set the lash for #5 and then so on and so forth. After doing that I cranked the engine and had flames coming out of the carb. So I figure I have something wrong with an intake valve or my timing was right before I changed it just the valves were not adjusted correctly.

 

I tried a bunch of different methods for setting the valves on my flathead, and the one that works best was to bring each valve to fully open, then spin the crank one full turn. It takes longer, but it absolutely guarantees that you are on the base circle for each valve. There was a significant difference compared to some methods that are quicker.

 

Trying to sort this out. Was the engine purchased as a long block (with heads) and if so, the valves should have been adjusted. I would ask the builder straight out, "How was the cam timed". Did you count links between gear marks?

 

Ray, before I put the timing chain cover and water pump on I did count the links on the chain between the cam and crank marks.

It was purchased with the heads on; so I think I may have screwed up by checking the valve lash when I had it on the stand.

 

I'm going to try that. The manual I have said to bring it to TDC, adjust #1 intake and exhaust, then turn the engine until the rotor is at the next cyl in the firing order and adjust those valves and just keep going until you've adjusted all of the valves.

The book Ford Y-Block said to start @ TDC adjust the exhaust valves on #1, #4, & #5 cyl adjust intake valves #1, #2, & #7. Rotate the engine a 1/4 of a turn and then adjust exhaust valves #6 and #8, adjust intake valves #4 & #5. Rotate the engine another 1/4 of a turn and adjust exhaust valves #2, #3, & #7, and adjust intake valves #3, #6, & #8. But that obviously is too complicated for me.

 

There is a similar shortcut method for the flathead, and I've found it to produce poor results. see below. There's a wide range of rotation where the two valves listed are "open", just not accurate. I've got time to do it right.

Note that with the method I described earlier (the good way), it doesn't matter which way you rotate the crank. With all other methods, it matter that you turn it clockwise.

 

My view is don't make this any more complicated than it has to be. You'll want to re-adjust after run-in or break-in. From what you mentioned though, they are way too loose.

A simple method for adjusting valve lash with good results: Find TDC for the #1 cylinder. Adjust both valves by first tightening adjustment nut until they will barely spin with finger pressure. Tighten further 1/4 turn. Continue on in the firing order, adjusting both valves until done.


Next, make sure the rotor points to #1 tower at TDC, what made you think the dizzy was 180 degrees out?

 

We are talking about a Y block with mechanical lifters. That procedure will not work.

 

Damn, that's a shame!

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Over the years I have found that if an engine is backfiring through the carb that is usually a timing issue. If the valves are close in adjustment then with correct timing it will run. As suggested put #! TDC and check the rotor position in the dist.

regards Bruce