regarding 305 ci Chevy motors

[Zedman]

Hi- I own 1981 Avanti II RGB 3269 and it will be undergoing a chassis replacement. I have heard that Chev 305 engines of this era were renowned for having soft Camshafts. How do I tell if that's the case with mine? I have had the car running (it had been laid up for 17 years prior) and it started an ran fairly well for a car that long dead, however. I was planning to replace the timing chain and adjusters as a matter of course but I'd be silly to ignore the camshaft question and I really don't want to go into a rebuild if it's not really necessary. Any advice?

[Avanti83]

The best way is to dial indicate the lift with a dial indicator. https://www.amazon.com/All-Industrial-Tool-Supply-TR72020/dp/B002YPHT76 

But any engine that has a number of miles and sat for 17 years is going to need some parts. You want to replace the timing assembly and it will need seals. Compression is probably down some and a few rings might be stuck . The bearings have sat in the same contaminated oil for 17 years so they have probably been affected by moisture and acid. Head gaskets are hard to trust after setting this long in the coolant muck most folks leave in unused engines.

I wouldn't go very far with the engine before I tore it apart and looked inside. Just that with seals, timing gears and misc is probably $500 -$1000.

My advice is unless you are going for 400 point authenticity, look it over inside and unless it is close to perfect - put in a crate 350 for $2-2500. The 305 was not Chebbies finest hour during that era and  a good 350 will make it much more fun to drive.

Edited December 8, 2018 by Avanti83

[mfg]

If you've had this engine running, and it seems to run smoothly with respectable idle qualities, changing the engine's 'accessories' (i.e. water pump, alternator, fuel pump, distributor module, and yes a new, all steel, timing set) is a sensible idea.............For small block Chevys, those parts can be purchased very reasonably!

I've never bought into the idea that the 305CI small block Chevy engine was a 'dog'!.......I've actually had good luck with them, and in an everyday driver they are fairly thrifty on fuel!

The 305 my '83 Avanti 'everyday driver' went about 275,000 miles of constant use and was still running OK when I pulled it....and the only reason I did that was due to the engine having leaky front and rear crank seals....and a friend offering to sell me an almost new 305CI 'Goodwrench' replacement engine for a very reasonable price.

One thing about installing the new fuel pump on ANY small block Chevy V8 with a mechanical pump....Pack the fuel pump cavity (inside the pump where the arm pivots) with a heavy grease, such as wheel bearing grease, before you install it....One design flaw on all these engines was little or no oil lubrication to that area of the engine, resulting in shortened fuel pump life!.................Good luck!.....Ed

[Avanti83]

The question was not how far an SBC will run when well cared for but more what to look for in starting and driving one that has sat for 17 years. If it had the old oil and antifreeze in it for that long, nothing good happens to the bearings and other parts exposed internally.

There's nothing wrong with starting and driving it, as is, but my point remains, as soon as you start throwing parts at it you are investing money in an expensive gamble unless you look it over internally. 

It may run 300,000 miles or shuck a rod next month just don't waste money on parts until you know what you are dealing with.

Run a compression and a leakdown test on it and see if oil pressure is 15 or so at idle and 40 or so on the road. Good values on compression and leakdown testing and decent oil pressure are some indication of decent health inside. Then you can make better decisions on moving forward.

 

 

 

Edited December 8, 2018 by Avanti83

[mfg]

In reality, the cost of the replacement parts I suggested above comes to under $200....and all those items could be re-used (with exception of timing set) on a replacement 350 engine "down the road"

The necessity of spending the "big bucks" to change out that 305 should be determined after driving the car at least a couple months...In my opinion!...Ed

[Avanti83]

2 hours ago, mfg said:

The necessity of spending the "big bucks" to change out that 305 should be determined after driving the car at least a couple months...In my opinion!...Ed

We agree, I'm only adding that by looking at hot oil pressure and a couple of tests that can be done with equipment on loan from a local auto store, the OP can avoid potentially destroying a usable engine. I won't drop 10% of the cost of a "new" engine into a unknown black hole. Once an engine let's loose, nothing inside goes into anything I replace it with. 

Agreeing to disagree on that viewpoint.

[mfg]

1 hour ago, Avanti83 said:

We agree, I'm only adding that by looking at hot oil pressure and a couple of tests that can be done with equipment on loan from a local auto store, the OP can avoid potentially destroying a usable engine. I won't drop 10% of the cost of a "new" engine into a unknown black hole. Once an engine let's loose, nothing inside goes into anything I replace it with. 

Agreeing to disagree on that viewpoint.

I agree Bob!....I think we're both looking to end up with a nice running Avanti, with an eye on keeping costs under control!.....Ed

[NHcamper]

Just my 2 cents worth. I drive a 66’ Impala with a 327/275 hp power glide that sat in a barn for 25 plus years, rebuilt the carb re-gasketed the motor and trans and have been running it going on four years. I agree with the guys, put the minimum into it and run it, all you have to lose is a couple of hundred if it goes south. 

I have a replacement goodwrench 350 in my 81 RQB-3352 plenty of power runs great.

[mfg]

19 hours ago, Avanti83 said:

We agree, I'm only adding that by looking at hot oil pressure and a couple of tests that can be done with equipment on loan from a local auto store, the OP can avoid potentially destroying a usable engine.

I believe it's important to note here that 'stock' Chevrolet V8's are known to have low engine oil pressure at HOT idle......That is especially true of engines with high miles.....yet these same engines can go on for THOUSANDS more miles without any problems...(ask me how I know!!)

Not speaking here of engines that will be continually beat on, I'm referring to older Chevy V8's which are driven normally!

In my opinion, we're all very lucky Nate Altman chose to use the small block Chevy V8 when he was faced with finding a replacement for the Studebaker V8 engine!

Edited December 9, 2018 by mfg

[Zedman]

Thanks all for the input- it has made me feel far better about pulling the engine down for complete inspection. I found what I believe to be sparkplug anti-foulers on three sparkplugs when I finally got my hands on the car . Because I was assured the car has genuine low mileage (56,000 !!), I felt they were there out of the car possibly being "under driven" and oil fouling might actually clear up. After all said and done, a freshen up all round ought to be in order I suppose.  Suspect camshaft will be resolved in the long run I suppose.