The 1947 - Present Chevrolet & GMC Truck Message Board Network

The 1947 - Present Chevrolet & GMC Truck Message Board Network (https://67-72chevytrucks.com/vboard/index.php)

- The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board (https://67-72chevytrucks.com/vboard/forumdisplay.php?f=4)

- - SBC 350 top end noise (https://67-72chevytrucks.com/vboard/showthread.php?t=662139)

Re: SBC 350 top end noise

Pop them valve covers and do some diggin. You might have to start taking rockers off, checking pushrods and lifters. If you got a bad lobe then you'll have a bad lifter.

I am starting to agree with Shorty Wide in the above post. If it was making the noise before the swap then you might have something goin on in the bottom end.

Re: SBC 350 top end noise

Quote:

Originally Posted by 77 350 Shorty Wide (Post 7074345)

Good Morning, I'll chime in on this a bit. Have you determined if it is cam or crank rpm based. If cam rpm... have you listened to the fuel pump yet? They have been known to make sounds like this. If it's crank rpm based... When does the ticking start, cold, hot, when revving up or winding down? This should lead to whether it maybe a piston or rod sound. Well just trying to help. Seems to me if it was there before all the work was done and it's still there, the fix would be something entirely separate not yet addressed.

All have a great day, God bless, Terry

Thanks Terry. It is cam based. Fuel pump and pushrod are brand new. That was one of my first suspects. As I mentioned earlier, the only parts not new in this engine are the rods and pistons. I'm not hearing any typical wrist pin double tap and piston slap tends to have almost a bell ringing sound to it. This is definitely top end, but just can't isolate it.

The more I think about it, I didn't put new cam bearings in when I did the swap. Did everything with the block still in the truck. I had an old Ford T-bird years ago with a 400 that had a similar but more subdued sound both before and after a cam swap. Turned out that one had a bad cam bearing in the rear journal.

Re: SBC 350 top end noise

Quote:

Originally Posted by Slammed84 (Post 7074984)

The only top end component not replaced was the cam bearings. Had something similar in an old Ford I had. Engine's gotta be yanked to change them out and if I'm pulling it, I'll be building up the 355 block I have to throw back in it...with ALL new parts.

Re: SBC 350 top end noise

I'm sure your cam bearings don't look the best but, your oil pressure would be low if clearance was excessive.

Re: SBC 350 top end noise

New twist to this mystery noise. I get home this evening and do my nightly ritual of scratching my head going through all the same things I've checked a million times before and happened to pull my PCV valve out while the truck is running and the ticking noise gets louder. Put it back in place and it quiets it down to the previous level. The PCV valve rattles freely and isn't plugged. Now I'm more puzzled than before.