OK, I just had a huge blow to my 'car' ego. Being the car nut that I am I like to think that I have a good working knowledge of engine building, general mechanical knowledge and so on. Well, not to long ago I was assembling my forged 346 and I had purchased an adjustable timing set. My intention was to retard the cam 2 degrees because that was the sweet spot according to my engine building software. So, I use a degree wheel to verify TDC and some other cam timing events and after I verify which keyway is straight up I decide to roll it back 2 degrees. Now this timing set is supposed to be adjustable in 2 degree increments with a total of -8 to +8 degrees. So I roll it back one notch and assemble the motor. Fine, no problem.

Now the car is on the road and tuning it is a real pain. Power seems no better or even worse than before. The converter won't stay locked up...goes into open loop and low RPMs. Time to start troubleshooting. First vacuum is at 5 inches at idle...not good. Power does not seem to come on until above 5500 rpms...not good. I check everything obvious and the only thing I can come up with is the cam is too far retarded. Tore it down last saturday and discover that my cam is 22 degrees retarded!!! Holey Crap! So I reinstall it straight up and now she runs like a top with plenty of power all around.

How the hell do these adjustable timing sets work? According to my findings you can adjust it up to ~90 degrees + or - in 22 degree increments. Am I just completely retarded(no pun intended) or am I missing something?

Sorry for the long post but maybe the humor of it all will make you laugh at me and double check your own work.

Thanks
Josh

 

Being one-tooth off on the cam gear would be a little over 8 degrees. Sounds like you were WAY off. Are you sure you got the correct reference points to line up? To tell you the truth, I would have to stare at one of those 9-keyway crank sprockets a good long time to figure out the correct reference point. They only give you a mark for "straight up" installation, right?

 

Yes, they give you marks for straight up. But I verified that their dots were correct by installing it straight up and checking it with a degree wheel. After I verified that their marks were correct I rolled it back one keyway on the crank...it is supposed to be adjustable from -8 to +8 degrees. There are 4 notches to either side of straight up so I logically thought each notch was 2 degrees. I 'assumed' each keyway was 2 degrees so after I rolled it back I did not check the cam timing with the degree wheel...stupid stupid stupid.

I was just wondering if anybody had experience with the adjustable timing set so they could explain to me how I screwed up.

Thanks
Josh

 

who are you?

 

My name is Josh...why do you ask?

 

cuz thats where Im at

 

San Antonio? Where abouts?

 

So you used the "straight up" mark even after you clocked the crank gear for 2 degrees retard? That would explain it. I've used the 3-keyway crank gear adjustment before (same principle as 9-keyway). You have to use a different mark than the "straight up" mark to orient the cam/crank correctly.

 

yup. i was going to advance my old 230 with my rollmaster adj chain but i couldnt figure it out so i said **** it and installed it straight up.

 

what he said

there is a different mark you have to use when not installing the cam 'straight up'. i bet that's where the problem was.

 

"But I verified that their dots were correct by installing it straight up and checking it with a degree wheel. After I verified that their marks were correct I rolled it back one keyway on the crank"

Originally I just checked to make sure their markings were correct...then I attempted to retard the cam. Since the crank is keyed I just figured that was how you adjusted it. So what I did is just turn the crank gear back one keyway and put it in dot-dot.

Does anybody have their original instructions or know how these things work?

Thanks
Josh

 

off the instruction sheet:

"All crank keyways are in 2* increments advanced or retarded 2-4-6-8 the middle key being STD. Keys to the 'left' of STD. are Advance and keys to the 'right' of STD. are Retard. Note the spacing of STD key to STD. timing dot this must be dupliucated from the actual non STD. key you use if dialing in the cam. Do not use STD. timing dot if useing non-STD keyway"

Thats all thats really in it for instructions.

JR

 

Advancing or retarding the cam only 2 degrees is a miniscule amount of movement. It is such a small amount I doubt you can actually see it very well. If you went 22 degrees you either retarded the cam quite a distance or advanced the crank a by half. 2 degrees is just barely turning the cam in relation to the crank. You either more one or the other, not both. The instructions with the Rollmaster aren't very clear and I think something is lost in the translation from Austrialian English to Yankee English.