Don Terrill’s Speed-Talk

Has anyone else noticed that the new timing sets seem to be looser and looser right out of the package?
SA, PBM, & Melling.....Then I went straight to Rollmaster set up & yet it is still looser than I like. My cam to crank dimension is right on the money. I was just wandering if anyone else has noticed this.

YES IVE had the same problem exactly like you describe, center to center cam to crank didnt call for undersize. ill tell you if some of the manufacturers dont wake up pretty soon we all will be out of business. went to cloyes seem to be ok, but thats today.

I have been complaining about timing chains since Dynagear went under. I always had good luck with Dynagear. Now they seem to go in new, OK but are lose the next time I look. The Dynagear stayed tight forever.

When I ask my supplier if anyone is complaining, I get the standard "...haven't heard anything..." answer.

JP PERFORMANCE uses Rolon true roller chain just like Dyna Gear used. the rest use offshore crap chain, that's my opion. cloyes is over priced!

We have been using the cloyes hex-a-just and those have been fine and they are using the iwis chains.

Rolon seems to be the same as Rollmaster both made in AU using German IWIS chain. From what I learned from Cloyes and some engineers at the office. Chains do not stretch. Sprockets wear it is a result of using 2 diferent diameter sprockets that will cause ware. I'm sorta glad & dissapointed to hear that others have in-countered the same issue. My engine builder has given up on the manfacturers and has begun to install the tensioners. I want to find a solution not a band-aid, by no means busting on my engine builder he has done all he can at this point. I'm mearly trying to find a solution or better product. At this point I have ordered the .004 Rollmaster, and will have to wait and see. IMO, timing chains should be so tight to install that you think you have the wrong one. Otherwise you have wasted everything you have invested into your valve train and engine.

If chains don't stretch, then on my bicycle the gears must wear alot. Chains stretch after so long, don't care what any high tech engineer claims

Now if the chain is a bit loose but the cam timing is correct, what is the harm if the cam moves 2 degrees at high rpm's..would you really notice it power wise, I would think not.

Bring back the wide Morse silent chain with good steel gears.

Dodge Man I don't want to fight I'm looking for a solution or better product.
1. A 7000 RPM 2 to1 crank to cam ratio can not be compared to a pedal bike.
2. If there is no harm in 2 degrees, then why even bother checking piston to valve clearance?

The next time you look real close at a used timing set pay close attention to the top sprocket and it's teeth. At the top you have a inverted V shape which leads to a ramp and then finally down to a radius (pitch diameter) where the roller rides. You will notice that all the wear is at the point where the V hands the roller(chain) off to the ramp. This is because of the entrance angle from the lower sprokets smaller diameter. With very, very little wear I'm talking .001 or less, can make your chain very loose. When you are dealing with pitch diameters it doesn't take very much to be off a mile.

dfitz16 wrote:Has anyone else noticed that the new timing sets seem to be looser and looser right out of the package?
SA, PBM, & Melling.

Don't know about Melling, but PBM are SA Gear timing sets.

CNC blocks and i agree the hex adjust is what i use. how about tight loose as you turn it over, called factory after measuring gears cam gear way out of concentricity, differnt set no problem, engineer at factory tells me the main housing bore was mismachined that was my problem. told him pick a new profession and hung up phone. it used to be amusing once in a while, but not every day.

I don't believe chains stretch. I think they wear. If each link pivot point wears .0001" after awhile, then your chain is going to be alot longer under tension.

The roller links wear a little, but it is indeed the gears that wear.

The pre-stretch routine that chains go through before you buy them load them more than any valvetrain you could possibly run in any engine.

if its a race motor its cloyes or nothing. if your on a budget their "street" true rollers are a good buy for the money.

I do not like the loose street cloyes street true rollers..i got 3 from the parts store 20 years ago and they all
were taken back ..too lose..I ordered a summit true roller and have used them ever since,,they are always tight ..

another good one is mercury marine for the 350 chevy boat engines,,they are a thick single roller ..i have taken 3 of them apart and all 3 had real snug chains