NHGuy

I have a Comp XM 262H cam in my 1988 Mercruiser 5.7. I put on a new harmonic balancer too because i ruined the old one's threads. Broke it in etc, fine.
I timed it with my cheapo advance timing light. The motor runs like there's not enough advance. I can see 32 to 34 degree all in on the trailer in neutral. But the more I think about it the more I wish I had confirmed #1 at TDC with the replacement balancer.
My battery is on the opposite side from #1 cylinder, so the cord makes a long reach. Could I be getting some wrong timing from the pickup cord touching my exhaust manifold? I timed the oe cam with this light OK in the past.
It feels as if it would take right off with more advance, but I am leery to grenade my motor with too much timing.
I'm going to go out and try a puff test to see if the balancer mark is at TDC.
It would really blow if it were off cause I have the stuff at home to do this the right way.
Ideas?

motor

iTrader: (3)

Why do you think "it acts like it needs more advance".........I wouldn't expect a huge amount of top end power, out of that cam..

NHGuy

Yup. Balancer is either wrong or mismarked. Motor runs OK. Wonder if I just ought to get another one. That's what happens when you miss steps, crap.

NHGuy

Motor, the boat wouldn't even plane when I had it in the water. You're a gear head, do you think I should fear the aftermarket parts store balancer? I think it's a Dorman piece for a Chevy truck. It had the right key way. I'm going to check the crank bolt.

Jonesyfxr

iTrader: (1)

Some SBC enigines in the mid 80's were timed straight up behind the water pump. I had this issue on a 350, wrong balancer. I picked one up for a late 60's SBC and it was dead on.

motor

iTrader: (3)

FWIW I confirm marks on balancer and pointer with piston at true tdc before the heads go on.Kinda tricky to do it accurately with heads on,but can be done .At least you could tell if it is one of the bastard marked ones like jonesyfxr mentioned

SB

iTrader: (1)

They all have the same keyway but the problem usually doesn't just lie with mismarked china parts, but different diameter dampners. SBC used different diameter dampners thruought the years and diff balancers had different;y placed timing pointers.

The cam won't change ignition timing readings.

What else did you change other than just the cam and dampner ?

dereknkathy

use a piece of coat hanger in #1 plug hole. wrench on balancer bolt. work it back-forth thru tdc. u can get pretty good guesstimate if mark is on or off.

rws

iTrader: (3)

(quote)
My battery is on the opposite side from #1 cylinder, so the cord makes a long reach. Could I be getting some wrong timing from the pickup cord touching my exhaust manifold? I timed the oe cam with this light OK in the past.



YOU CAN PUT THE TIMING LIGHT WIRE ON #6 PLUG AND IT WILL READ CORRECTLY.

NHGuy

Yah, I left the boat at the lake. Life calls, kid graduation parties this coming weekend.
So when I get back I may pull the balancer and use my crank socket and piston stop to get it dead nuts. I have to do it right. It's my own stupidity not to have noted where the timing mark was. When I installed it I didn't even give it a second glance, what a dumb---.
What about putting sockets on the outer crank pulley bolts and using a lever to move the crank to check for TDC with the piston stop. Guess I'll bring everything possible to need.
I missed an 80 degree day, beginning of bike week, when I usually go over to look at the cool 2 wheelers. Instead I was scratching my head over this cluster. Won't do that one again!
Thanks for the heads up on #6. I get that.