Just wondering if anybody has heard of this.It's a 302 30 over flat top. Crank is turned 10, 10, under. All clearances seem good. Has excelent oil pressure. About 60 to 70 psi.Here is the problem, It seems to make a slight diesel noise. That is the best way I can describe it. It isn't near as loud as the actual diesel but it has that sound. It's not something that you can hear while in the cab but if I have the hood up and rev it I can hear it. Hope somebody has an idea because I have no idea at all what would cause this. I have rebuilt many engines Ford and Chevy and never heard of this. Thanks

 

i use to have a f-350 with a 460 in it that did the same thing from the time i bought it till i sold it never had any problems with it though i was told it was something lose in the engine because it was rebuilt but I just drove it for 2 years like that firguring I was going to fix it when it finally went but it never did so i wouldn't worry about it

 

is it fuel injected?

 

I would have to agree with Jenkins are you sure that everything it tight?

I could also be that your timing is not set right and your hearind a pinging.

Can you adjust the timing on the engine?

 

sounds like piston slap to me. double check those pistons and bores.

 

did you service the wrist pins?

...zap!

 

Here are a couple of ideas.

Flat top pistons....valve reliefs? What lift and valve size are you using? Could a high lift cam be causing some valve contact?

Are you using RHODES lifters? RHODES lifters when adjusted properly will give you some slight clatter. As will some timing GEAR sets.

The next idea is wrist pins. What type of wrist pin are you using? Floating or pressed? If you went with floating, did you use spiral locks or C-clips as wrist pin retainers?

Loose fuel pump cam eccentric?

I hope this helps.

Good luck

 

Timing too high
Wrist pins
Piston knock (due to clearance or bad skirt)
Bent pushrod

Does the sound continue when the engine is hot?
Is it there when the engine is cold?
Timing is usually when the engine is hot, however it can be far enough out to do it cold too.
Wrist pins or piston knock is almost only when cold.

Did you replace all plugs in the block???
Are you using new lifters?
Did you check the lifter bores for size/clearance?
Any of these could lose your oil to the valvetrain.
This may or may not show up on the oil pressure gauge.

Good luck
Dave

 

Well I tore it down and found out that the crank is egg shaped on a couple journals. Kinda makes me mad because the guy i bought the shortblock from had Napa check the crank. I know he did because I was there. So i decided to just install new rings since it's a fresh bore and all new bearings. I also ordered a crank kit. I also sent the rods off to be checked and resized if needed. I should of done this from the beginning. I thought the engine would be fine since the crank was checked and new bearings and rings were installed. It wasn't my buddies fault it was that damn Napa machine shop. Anyway I'm starting over doing it all myself so I know what I have this time. Thanks for all the info. Marc

 

I had a 302 in a 81 Mazda RX-7 that made a similar diesel like noise. I came to the conclusion that it had to be the fuel pump eccentric. I had checked everything else and everything was within spec. The engine is still running to this day and still making the noise. The engine has buried a 8000 rpm tach on many a missed shift. It was a fun car, sold it and built one with a small block chevy instead. The grin keeps getting wider and wider the more I drive it.