Schrick 284/272 timing

[redlightpete]

I just installed a Schrick 284/272 and set it to what I think is supposed to be the TDC center position based on the German catalog. The #1 intake valve is open 2.2 mm and the #1 exhaust is open 1.7 mm (as closely as I could measure). In this position ,the stock cam gear is retarded approximately 4.5 degrees. Is this typical? Did Dr. Schrick just put the dowel pin hole in the wrong position? Am I doing something wrong?

I was really hoping not to have to spend another couple hundred dollars for an adjustable cam sprocket. Arghh!

[digger]

its not uncommon for cams if installed in stock position for them to be actually advanced several degrees, i plotted out a 288 and was that way to. so do not worry as long as the PtoV clearances are all good (inlet side gets better clearance when retarding, exhaust gets worse). you can run it in several positions to see what the engine runs best at anyway.

[redlightpete]

its not uncommon for cams if installed in stock position for them to be actually advanced several degrees, i plotted out a 288 and was that way to. so do not worry as long as the PtoV clearances are all good (inlet side gets better clearance when retarding, exhaust gets worse). you can run it in several positions to see what the engine runs best at anyway.

So what angle did you end up running your 288? And was that the angle measured at the cam sprocket or the crank? Thanks

[digger]

I didn't run it I just measured it. I'd run the 288 advanced slighty though, but not a 284/272 I've seen some guys do testing on this forum and advance didn't work well for 284/272 it dies in the top end will depend on specs if engine though.

[redlightpete]

I didn't run it I just measured it. I'd run the 288 advanced slighty though, but not a 284/272 I've seen some guys do testing on this forum and advance didn't work well for 284/272 it dies in the top end will depend on specs if engine though.

Perhaps that explains why a lot of strokers with the 284/272 flatten out at 5k. People might be accidentally running them in this default advanced position.

Guess I'll go ahead and buy the adjustable gear. It's still frustrating to buy a 'premium' cam and then have to buy a $200 cam gear to get it to the recommended angle for the intended application.

[digger]

for a stroker a 284/272 is relatively small duration and lift. a few degrees retard on a 3.1L was best overall according to Tinkerputzer. Nando did tests on a 2.8 but dont remember the conclusions.

[dvallis]

Digger, what's the max you'd recommend advance or retard on a 284/272 ?

[digger]

i usually ask the engine, run it straight up and head to the dyno, advance/retard it a bit and see what happens.

whenever i've done adjustments ive favored advanced about 4 degrees or more but thats relative to how it went in and if the cam is ground exactly as it says on paper. if it went in retarded by 4 degrees and you advance it by 4 degrees its actually straight up. the best position will depend on the engine specs but its hard to simulate thats why testing is best

you just need to know the limits of how far you can move things before clearances get too tight before you start messing around too much.

[redlightpete]

Thanks for that reference to Tinkerputzer. I looked back through his cam angle comparison and your follow-up question. Seems quite possible that the 0 degree reference he was using was actually the advanced position the cam would be in if you installed it with the stock gear. If that was the case, the cam may have been at Schrick's recommended position during the '4 degrees retarded' test.

[nando]

advanced on the 284/272 killed low end torque *and* power. I think I retarded mine a few degrees but I can't remember exactly what I set it to.

IMO, an adjustable cam gear is money well spent.