Lifter tap on 1973 454

[Ted K.]

I have what sounds like a loose valve lifter on 454 cu in engine. The reason for writing is when the engine is cold everything is quiet. When the engine is fully warmed up a slight valve tick is evident. It almost sounds like a loose solid lifter but we know this engine has hydraulic lifters. Is it a indication that the lifter needs to be replaced to correct the tapping/clicking?

[Joe L.]

Re: Lifter tap on 1973 454

I have what sounds like a loose valve lifter on 454 cu in engine. The reason for writing is when the engine is cold everything is quiet. When the engine is fully warmed up a slight valve tick is evident. It almost sounds like a loose solid lifter but we know this engine has hydraulic lifters. Is it a indication that the lifter needs to be replaced to correct the tapping/clicking?

Ted------


I'd try adjusting the lifters first. They do not adjust like mechanical lifters but there is an adjustment procedure.

[Edward J.]

Re: Lifter tap on 1973 454

Ted, hyd. lifters are generally the opposite the make noise on cold start, But as Joe says its worth a try, I would locate what side its coming from first, then with the car idling touch each rocker and see if you can feel which one it is. try a couple of 1/4 turns on rocker arm- slowly, the engine will run rough for a split second when tighten, then will smooth out, this normal. if this does not work try applying slight pressure against the top of the valve spring I have used a flat head screw driver for this, and listen for a change in noise or the noise disappearing. if so this maybe a worn valve guide.

[Ted K.]

Re: Lifter tap on 1973 454

Thanks, makes sense, will try.

[Jimmy G.]

Re: Lifter tap on 1973 454

My 72 BB would make lifter like noises turned out that the rocker arms and push rods were worn and no oil was flowing If all else fails try replacing rockers and pushrods. Easy to tell which ones are bad i.e. no oil flow. After 5 - 6 individual replacements I gave up and replaced them all --- no noise since

[Edward M.]

Re: Lifter tap on 1973 454

I had the very same thing on a 73 base motor automatic car. Quiet until it warmed up, then a ticking noise like a lifter.

I got the old mechanics stethoscope out and started tracking it down. The noise was coming from the fuel pump area.

It turned out to be the fuel pump rod (from the cam to the fuel pump arm).

I replaced the rod with a new GM rod, and all was fine from then on.

[Ted K.]

Re: Lifter tap on 1973 454

Very interesting. Who would have thought fuel pump rod. I will get my stethoscope out.
Thanks, that's what this forum is all about.

[Duke W.]

Re: Lifter tap on 1973 454

Too thin oil could be an issue if a lifter has a high bleed down rate. What API service category and viscosity range are you using?

Duke

[Ted K.]

Re: Lifter tap on 1973 454

Probably not thin oil. I recently added a quart of Lucas, which I believe should have increased the viscosity.

[Joe L.]

Re: Lifter tap on 1973 454

I had the very same thing on a 73 base motor automatic car. Quiet until it warmed up, then a ticking noise like a lifter.

I got the old mechanics stethoscope out and started tracking it down. The noise was coming from the fuel pump area.

It turned out to be the fuel pump rod (from the cam to the fuel pump arm).

I replaced the rod with a new GM rod, and all was fine from then on.

Ed-------


GM #3704817. This is the fuel pump pushrod used for all 1955-81 Corvettes, small block or big block. This part number dates back to 1955 and it's still available from GM to this very day. It probably will be for some time. Imagine that----a part released 63 years ago and still available from GM.

[Dick W.]

Re: Lifter tap on 1973 454

Exhaust leaks at the manifold and header pipes have a tendency to sound like lifters

[Edward M.]

Re: Lifter tap on 1973 454

Ed-------


GM #3704817. This is the fuel pump pushrod used for all 1955-81 Corvettes, small block or big block. This part number dates back to 1955 and it's still available from GM to this very day. It probably will be for some time. Imagine that----a part released 63 years ago and still available from GM.

Wow. We should get them while the getting is good .

I still find it hard to believe that the fuel pump push rod was the issue back then. I rolled the old one on a pane of glass, it was not bent. I did not have the tools to accurately measure the overall length, but I could not (and still can't) figure out how it would have worn.

But I can't argue with success.

[Michael H.]

Re: Lifter tap on 1973 454

In the old days we use to add a quart of ATF to the oil to help clean the lifters.

Mike

[Edward M.]

Re: Lifter tap on 1973 454

In the old days we use to add a quart of ATF to the oil to help clean the lifters.

Mike

Yep, did that many times.

[Peter G.]

Re: Lifter tap on 1973 454

My '73 LS4 cracks valve spring nuts. Has done it three times in the last ten years. A retired Chevy parts manager told me that I should carry half a dozen of these nuts in the car with me. They are just $1 each. He said these big blocks break these nuts all the time back in the day.

That was the fix when the engine started tapping.