I was reading about RjAquaponics L300 blow up saga and at one point he said the engine made bad metal noises around idle but would sound better if revved up around 2k.
It reminded me of my brother's '69 Camaro he had in the early '80s. It had the 230 c.i. Chevy straight six with the 3 speed in the floor.
That engine was stone cold reliable and had a surprising amount of power.
The strange thing about it though was that it made a horrendous valve train noise on decelleration.
This was back in the mechanical lifter days so of course it had some lifter tap at idle. That was expected and it wasn't unusually bad at idle.
If you revved it up and especially if you were accelerating there was very little valve train noise.
If you held it at a steady rpm above 1k or so the valve train noise would get worse but it would kind of come and go.
If you revved it up and then let off the gas, and it was especially bad if you were decelerating in gear, using the engine to slow the car, it would be so loud that other drivers and pedestrians would look around to see where all that noise was coming from.
After he put it into a tree he got rid of it and we never did figure out why it did that.
Just wondering if anyone else has heard of this kind of thing or might know what it was?

Picture taken at sunset on the Blue Ridge Parkway 1 week before the wreck.

 

Sounds like possibly a defective camshaft and worn lifters to me. Probably not adjusted right either.

 

We used to race a Chevy six back in the 70s in our stock car at Saugus Speedway in SoCal. The engine came stock with a fiber cam gear that was just pressed on the cam. They would work off and let the cam float forward and back in the engine. We had an aluminum cam gear with a bolt in our race engine. We also ate distributors in our race engine. Partly from the 50w Kendall oil but mostly because the gear pulled the distributor down not up like the v8s. We got 375 hp out of 265 inches at 8000 rpm, needless to say it it was big $$ to get and run that for a whole season. I think it was 1977 we finished 2nd place in points, two wins a couple seconds and a bunch of dnfs. If we had finished any of the races we broke or crashed out of we would have won the championship that year. They quit racing the 6 cylinder class the next year and racing the v8s was much more expensive. It took us a couple years to move up to that class and be competitive.

 

Cool story, Andy, but that doesn't answer jamnars question.

 

Actually, I think the part about stock Chevy 6cyl cams just might. I think you got caught up in the imagery, Rube......

 

Pretty sure the cam gear was half off the cam. Under acceleration the cam would slide back against the cam plug and on decel the cam gear would hit the front cover. This would tear up the bottoms of the lifters and really change the timing.If the car had not been wrecked it probably quit running fairly soon.

 

I think you might be right Andy.
I think I remember now having read about that cam situation somewhere but didn't make the connection.

It's probably just as well since if he didn't wreck the car and if the engine did die he would most certainly have put a V8 in there.
He might have got himself killed then.
The wreck occurred when he was doing 70 on the twistys and ended up doing a full 360 before he hit the tree head on.
With more power he probably would have been doing 90.

 

Is that crappy cam gear similar to the ones that Pontiac had in the 2.5 four bangers they ran? I had one those piles of junk for a few months and it knocked like hell. I thought it was a bad rod and finally sold it to some guys that had another engine they were going to put in it. They told me when they tore it down, that cam gear was missing 3 teeth in a row and 2 others in various spots. No wonder it knocked!

 

Yes the same setup on the early ones 4 and 6 cylinders. They went to a chain on the later versions in the S10s.

 

Those fiber gears were an interesting concept. If they'd cast them in aluminum, they MIGHT have held up a little better, but I'm not too sure aluminum would have taken the pounding any better.