Technical Changing Cam on a stock SBC 350

The lock washers are original, but they're usually covered with grime, a LOT of it collects on these engines over the decades, if no one works on it. You have to scrape for a while to find the bolts on cherry engines.

 

If you're only doing about 150 mile a year it could be suffering from stale fuel or it just needs a good 'fang' to get the cobwebs out. Didn't smog engines have retarded ignition for pollution reasons. Bang a bit of advance into it and see if that perks it up. Are you chugging up the hills and trying to avoid the trans kicking down a gear for fuel consumption ?

 

By the looks of the motor in you good pictures, I would not bother doing anything until you actually need to. Save your money, You do not use the truck enough to warrant it. 150 miles a year it will last for years to come. Good luck.

 

Yep! I was only getting 60% or so... fixed that yesterday morning but have yet to drive up a hill (including after rochester carb rebuild). it did feel torquey this morning around the neighborhood...

 

Hmmm I fill it 1 gallon at a time here and there to avoid too much stale fuel and drive it once a month or month and a half for 10 miles... going uphill I try to avoid engine rpms getting high... just because I'm nervous with an old engine.. but I do this with my daily driver too so it must just be my driving habits..

 

Thats exactly what I was thinking but Chevy Pope told me even if I drive it very little I have a grenade on my hands with the nylon gear set and that threw me into panick mode and I ordered all the timing set stuff from Rockauto... I was thinking if i drive it a little and go easy and maintain it, i have some good years left with this thing as is... if the body was perfect I'd be pulling the motor and getting it rebuilt but its not worth it given the rust on the truck... thats what makes this truck a lot of fun... as little as I drive it, I enjoy it way more than my radical kustom shoebox ford that makes me stressed out about where to park it when I (eventually start driving it). I have 10x in money in the shoebox than I do in this truck.

 

Thanks you have quite a good eye! I'm going to look back underneath later today a little more closely out of curiosity.... after I get back from surfing ;-)

 

I think the bolt for the power steering bracket got put in the lower motor mount hole on the passenger side.

Gary

 

Put 10 gallon's of good gas in it, bump the timing up some, and beat the shit out of it for a little while! Don't worry about the timing chain, as long as it doesn't backfire and kick back, it'll be fine. You might be surprised what happen's. It's not really a ticking timebomb.

 

Chevy pope mentioned he’s seen so many sbc Chevy motors get killed by the nylon gears failing and Valves getting bent etc so it freaked me out . I suppose I could see if rock auto will take the parts back since they would be new.

 

When did he see those nylon sprockets fail? Was it a few decades ago, perhaps?

 

here’s what he told me in my other post


“Google gm nylon timing gear failures. Timing set is like $30 plus mebbe a $5 gasket. If it is still a nylon cam gear (1975 350 would have a nylon gear originally) AND has slack its literally a grenade. Being an interference engine if the nylon teeth completely let go and it jumps time there goes your valves. Not to mention all the nylon chunks in the pan. Even if you only drove it an average of 1 mile per week at 60 mph.....id assume the engine is turning around 2200 rpms..... meaning that time bomb cam gear is turning 6000 revolutions total during said one mile trip not counting the time it spends idling. The 76 350 in my 53 still had the original nylon gear when I got it at 80k miles last year. Was literally the first intact nylon gear id ever seen despite tearing into literally thousands of sbcs over the years. Also the first intact one many of my buddies had ever seen. One older friend that has worked in the service department at a Chevy dealership since the eighties said it was a first for him and that usually you removed them from the oil pan not the cam lol. But yeah first thing I bought for my 350 was a new timing set”

 

@The Chevy Pope maybe you can help? I referenced what you told me in my Rochester carb thread

 

What worries me is even though the timing cover may have been removed what if the previous person said ah the nylon gears look just fine and left it alone that was 15 or so years ago? Or even more? I got this thing 7 years ago.

I’m aware the nylon gears will fail more because of age than mileage.

 

Last couple years. The one I pulled out of my 76 350 August 2022 was the first intact one I'd seen. And even then the chain had noticable slop. Lot more of those nylon cam gears on the road than many realize

 

Was that an untouched engine? Or had it been worked on like this one?

 

150 miles a year?
Just keep repeating that to yourself. Do you even use a tank of fuel?

 

Long block had been untouched but engine had been messed with. But in any event It was one of over twenty I found since 2017 when I started working at the low volume shop in the same junkyard. A 305 I pulled trashed one from the gear was bolted to an RV cam

 

I have replaced many failed nylon cam gears in a small block chevy's, never any internal engine damage.

 

Agree , never ever any internal damage . Plus I noticed in the pictures that blue silicone is present on the bottom of the timing chain cover . Indicating to me , that the pan or cover or both were off .

 

This!!!!!

 

Mom would always ask me what I did to her car went she would let me drive it. I would ask what's wrong, she would say it runs so much better.
For any engine that has a RPM red line can be run to the red line and any RPM below that for as long as you want. If the engine is good it should not cause any internal problem as the engine was designed to operate in that range. JMHO.

 

nope that’s why I fill one gallon at a time every so often . I still enjoy the truck.. I use it to load my paddleboards and rowboat or occasional Home Depot run. I only paid $2500 usd 7 years ago and people compliment me all the time on this. Hilarious but I really can’t complain!

 

I think that’s the original pan cover which is blue and then painted over in orange?

 

what’s the worst that would happen just getting stuck somewhere? I’m never more than a few miles from home and have aaa… no bent valves when the nylon gears break off and a chain slips? If risk of damage is low to none I rather leave this thing as is and see if rock auto will take the parts back…. Some say this is a 6 hour job… I’m slow and often distracted so likely a 12 or more hour job over a few days and I have other things I need to take care of and could even work more of my 50 ford shoebox instead.

 

It doesn’t look like the hole aligns if I wanted to put a bolt in and I saw the bracket mounts to the side on one exhaust manifold bolt. Maybe someone used the wrong bracket?

 

Never seen any with bent valves or pushrods. I have seen the chain wear a hole in the timing cover and steal run.
Worst problem is the pieces of the cam gear feeling up the oil pump pickup screen.

 

I replaced the timing chain on an OT 70’s 350 with a nylon gear at 110,000 miles. I also bought an advance/retard button kit and figured with dish pistons the valve wouldn’t hit a piston and put in a 6* offset button advanced….the wife thought I put in a new hopped up engine…

 

Since you already got the timing chain set, put it in for peace of mind, degree the cam while your there

Might want to check the timing curve to find out what rpm the mechanical advance starts moving and if and when it moves the full 22 degree.

 

I'd find another engine you can rebuild/ overhaul cheap on the side then swap the engine out.
I know money is tight but a cam change requires pulling the intake to change lifters and that was most the work to put the 4BBL on you passed on for the 2bbl.
Cam change with more lift means vale guides running were they haven't, worn rockers running on balls in areas not worn in , likely need better/ correct springs it starts adding up and then there is a good chance upping the cylinder pressures will create new issues with rings , pistons and such .
So you end up with a lot of time money and parts you cant reuse in a worn out engine


Old tired engine, bad carb that's messed with , not the greatest compression , obvious oil leaks and such. Your going to want to likely do water pump, belts hoses all that good stuff, unless your dropping the pan you got get the timing cover off and back on . Trimming the corners on the inside of the timing cover will get you there but there is a good chance it's going to leak .
Will the pan come down in the truck?

Keep a eye out for a 350 with a usable bore that you can put a cheap overhaul kit from a place like Northern in with a mild cam .

I just helped kid do a 76 350 truck engine did rings ,bearings , polish the crank , valve job with existing valves and bit of port blending and inexpensive mild rv type cam for about $400.
I gave him a performer intake and helped him rebuild his 600 Holley .