My replies in bold type

Hi guys, hope someone can help me figure out which timing chain/gear set to order to fix up my dad's 1969 Chevy C-10 pickup. Unfortunately, he is not around to ask any more...

My dad bought the truck new in late 1968, I believe it had the 305 engine originally. He bought a "crate" motor from the local Chevy dealer in the mid-to-late 70's (not positive of the date). It is a "Targetmaster 350", blue in color, and the block casting number is 3970010. Excellent heavy duty block came in two or four bolt mains but you gotta look in the pan to tell what you’ve got. Again, reading around on the web, I found a recommendation for a Cloyes 9-3157 timing chain set as a suitable single roller setup for a non-high-performance SBC. No! It may have even been on this forum. I ordered a set from Summit, and when I got around to installing it, I quickly found a major problem...the bolt circle for the cam gear was too small. Yep wrong part that is for factory roller cams with their unique small bolt circle 1987 to 2002 production from 87 thru 95 only passenger vehicles, 96-02 on trucks as well. The 010 block does not have the needed provisions for a factory roller cam. I did some measurements and found that the new set had the three bolts fixed on a triangle with 1.000" on-center spacing. My old gear had the mounting holes on 1.170" centers. So much for thinking a 350 was a 350! I could find no specifications anywhere that spelled out the bolt circle for the various timing sets on offer anywhere, and Summit just said to consult the fitment specifications, which are built around model year and engine size, not replacement engines. Further sleuthing leads me to believe that the difference in bolt circles is defined by the camshaft being for flat-lifters vs. roller-lifters, but I'm not positive. Grab that thought it’s correct! I am assuming that I have flat-faced lifters. Yep, unless it has an aftermarket retro roller in it.

I emailed Cloyes directly and explained my problem (and the email was longer than this one!) and received a one-sentence reply that said "Yes, the C-3055 set should work in that application". So, having returned the 9-3157 set and paid return shipping and 15% restocking fee, I am hesitant to blindly order another set without knowing it would be a fit. Heck, I may even consider putting another OEM set with the nylon teeth in, if it gets me 50K miles that will probably outlive me! Again, I can find no information about the bolt-circle of the C-3055, the only possible clue is that Summit's site says "Fits LO5 engines only", but I don't know whether that is what I have. You do not have an LO5, this is a member of the original 55 through 86 Gen I, SBC family that lives on with some specific crate engines, however an LO5 flat tappet cam gear should have fit. What you need is the 55-86 timing set. I’d send you to Competition Products, their on line catalog takes some learning so I’ll give you some part numbers for double row rollers short of the real racers really expensive stuff: Cloyes CLOC3023K single key, CLOC3023X three key if you have enough cam to justify fiddling the lobe center angle. Howard’s HRC 94200, SA Gear SAG78100 which is a three key gear.

Can anyone give me some guidance to get my Dad's truck back on the road?

Look to the years as a general indicator flat tappet cam SBC’s are 1955 through 1986 for everything. 1987 through 1995 are a bit of a mixed bag but in general passenger cars got the factory or OEM is an often used term, roller cam while trucks got flat tappet cams. Starting with 1996 all the SBC’s got OEM roller cams. You can run a flat tappet cam in any Gen I block but OEM rollers are confined to roller provisioned blocks. Aftermarket roller cams, now referred to as retro roller cams. These use the same timing set as the flat tappet cams plus a thrust button that rides between the cam gear and the timing case cover. For factory OEM rollers that start showing up in some 1987 models these cams use a thrust plate between the cam gear and block. These cam gears are shallower in thickness to accommodate the space the thrust plate uses and use a smaller bolt circle so you can’t or at least should find it difficult to cross these applications up. A lot of guys get tripped up be this. The Gen I engines start getting complicated in 86 and by 87 to 96 your in crazy land with changes, some so extreme they are called Gen II SBC’s and after 2000 we get the clean sheet of paper totally new design Gen III and beyond to which GM adds the difficulty of using the same model identifiers as used on the Gen I and II motors. So if you feel confused and overwhelmed, welcome to the club.

Bogie

 

Thank you Bogie for the details about the 350 SBC evolution. I now have a better idea of where my engine fits in the Chevy family tree. Your suggestions for timing setups are appreciated, perhaps in the future if I get a little more ambitious with the old truck, right now I just want to get it moving reliably again without pulling out the engine. I have other cars in my driveway and garage that I need to get moving again than have sat a lot longer! Retirement is now letting me get after that.

 

The smaller bolt circle is for the '86-up roller cam engines, you've got that figured out right.
The set you need is for the '55-85 flat tappet engines.....but there were some exceptions to the" '86-up are roller cam " rule

The LO5 engines were the flat tappet cam '87-95 Truck engines with TBI injection, so that timing set will retro-fit back to the '55-85.....so the Cloyes C-3055 set would be correct to fit a single roller set into the earlier flat tappet engine..

What about a Cloyes link belt replacement that has metal gears?? I've used them before on stock stuff and they are tough enough so you don't have to worry about nylon breaking.

Cloyes, Heavy Duty Timing Set, Chev SB - Competition Products

i think the ones I used in the past were either Melling, Hastings, or Sealed Power, along with the Cloyes. I used one several different times.

Just some added info, on your '69 truck....if it was just a standard basic engine package it would have been the 307".....the 305" didn't exist until 1975

 

Now that we’ve educated you on timing chains, don’t hesitate to come back and ask for tips on installing the timing cover to keep it leak free.

 

I'm all ears! I had bought one of the one-piece blue pan gaskets (with snap-ups that I thought were a great idea!), and started to pull the bolts from the pan so I could, amongst other things, see if I had two or four-bolt mains, de-sludge the bottom end, and take steps to eliminate oil leaks. I quickly found out that the pan could not be easily removed without either pulling the engine out, or at least undoing the engine mounts and partially lifting it, neither of which I want to do at this time. My major goals right now are to refresh the timing chain setup, replace the corroded, leaking thermostat housing, de-rust the front and top of the engine (combination of thermostat housing leak and rat-pee from a family of rodents that moved into the engine bay while it was sitting at my dad's house). I have already cleaned, sanitized and painted the rusty engine (top and front for now...), rebuilt the carburetor and replaced the brake master cylinder/booster...

So, I'm anticipating replacing just the front pan seal when I put the timing cover back on...I'm sure I need to clean and totally de-grease the lip on the pan, and use gasket adhesive, but do I put the new front seal on the timing cover or the pan-lip (both sides with abundant gasket adhesive...) and then offer up the timing cover (stock one that was on the engine, but with new balancer oil seal) lower end first, or what? I am eager to get the advice from experienced SBC gurus! Should I start another thread for that, or is there an already existing discussion about that I can refer to? Thanks in advance for your wisdom!

 

This is the set I would get, ignore the fact it's for a 76 Corvette. IIRC, all Gen 1 sbc will accept this set


1976 CHEVROLET CORVETTE Cloyes Gear 9-1100 Cloyes Street True Roller Timing Sets | Summit Racing

 

This is the set I would get, ignore the fact it's for a 76 Corvette. IIRC, all Gen 1 sbc will accept this set


1976 CHEVROLET CORVETTE Cloyes Gear 9-1100 Cloyes Street True Roller Timing Sets | Summit Racing

Thanks for the suggestion. This one looks like a double-roller though, which I thought I should avoid, as I have read about them interfering (sometimes...) with the cast oil galleries behind the cam gear. Unless that issue is truly not applicable, i.e. there is an offset to the gear, or a spacer or some such, I think I will go with the recommendation from Cloyes and order the C-3055 single-roller chain setup. If I were pulling the engine and doing more of a strip-down, that might be the one to go for, but I'm hoping to be able to put on a replacement timing set with the engine in the truck, as I need to get it out of my driveway to move other cars around!

 

Normally you need to drop the pan front down enough to slide the timing cover in place.
put a little oil on the new timing cover seal so it slides on nicely.
Compare the old pan lip seal with your new one. There are two different sized ones.

 

You can trim away the back upper corners of the metal lip on the stock SBC timing cover to make the job of putting it back in with a new seal lip a bit easier and with better success, and not have to drop the pan down at all.
It does take a decent bit of strength to force the cover with the new seal in place, you kind of have to wedge it back in there, tip it back into place starting with the bottom.

 

Never saw this before. Great tip. I assume the cut needs to be made on both sides?

 

I was going to mention that also Eric but considering his lack of experience I didn’t think he’d be lucky to get it back togethor leak free.
Tough enough job for those of us that do it more than once. It can be tricky and frustrating.
sometimes better to keep it simple.
drop the pan a 1/2 inch and slide the cover on. No worries about seals.

 

I have done a few of these without dropping the pan. I degreased the pan lip and the rubber seal between the pan and timing cover. Then put Permatex Ultra Black on the seal and in the corners between the pan and block. Use a couple of bolts just a bit longer to hang the cover and gradually work the cover on while working the seal over the pan lip. Install the regular bolts when you can to finish pulling it in. Cutting the corners off of the seal flange should help also. Patience is key here. I’ve never had one leak.