LT1 Damper install question

[speeder]

Please don't flame an inliner for this Chevy V8 noob question -- I didn't find any info by searching.

 

I'm building a crank trigger for an LT1. Looking at the removed damper I see no keyway or other means to index it to the crank when installing. The damper's inner bore that fits over the crank does appear to be tapered - Can I install this damper at any index I choose to be held in position by a taper press fit, or am I missing something?

 

Also, where are the timing marks on this engine?

 

Thanks,

 

Rick

[piston]

the engine looks to me like it doesnt have any timming marks except for the edge of the harmonic balancer, thers little cuts on the edge im assuming its the timming marks. i havent done the timming on mine yet myself but about the damper, if your talking about the harmonic hub, its pressed on or more like forced on by using the bolt to work it back onto the crank. on mine, i had to make sure the cam was in tdc and need the dist. to be removed in order to see the tdc mark on the cam. pin pointing right at 180*. beside that, im not sure on the timming also. ill be second on the question..

[bodie]

the bancncer are zero balance, you can index then any way you want, but

 

there should be a little nub between 2 bolt hole on the hub,

and one the balancer there is what looks to be 2 simicircle and 1 triangle between the hub mounting bolt holes line the triangle to the nub. that the way the were mounted at the factory and i just like to put them back the way they were.

[bodie]

http://www.hashmarks.com/techtips/cam_install/500/31%20Balancer%20and%20hub.jpg

 

here a pic of what im talking about you see the nub on the hub and he triangle on the balancer

unfortunally this look to be an aftermerket bancer and doesnt have the 2 simicircles

[bodie]

http://www.impalasuperstore.com/naisso/superstore40/storepics/balancer.jpg

 

heres and oem type balancer

[speeder]

Thanks for the replies, Guys...

 

I just got back from the local parts store with the old trusty Haynes, and here's what I found:

 

[wheelman]

The LT1 harmonic balancer has no timing marks, at least none that are meaningful and is simply press fit on the snout of the crank. There are no timing marks because there is no way to adjust the timing by moving the distributor, it's totally controlled by the PCM.

 

Speeder,

The crank does have key ways cut into it so if you want to index the balancer hub you could machine a groove into it and then align the trigger wheel based on that, otherwise it'll be difficult to get an accurate timing setup.

 

Any reason you couldn't use the optical section from the opti-spark and decode the signals from it? The high-res signal provides 1 degree accurate timing and the low-res can tell you which cylinder is at TDC.

 

Wheelman

[speeder]

This one's crank appears to have no slots in it for keys that extend out to where the balancer hub slides on. The only ones there are way back inside the front cover for the timing sprockets & stuff. The crank does have a tapered nose.

 

Talking with some local Chebby mechanics, they say that the taper fit of the hub does not permit slippage if proper bolt torque is used - like the taper fit of the chuck on a drill press - and that you can indeed unbolt the damper from the hub and use the marks on the cover and hub to reference timing. I will find TDC and align these two for my reference when setting up timing.

 

The owner of this car (a Mazda RX-7) wants to get rid of the opticrap, as he calls it - and needs a programmable fuel system for the huge turbo that will be installed. We're doing a MSnEDIS with a 36-1 tooth trigger wheel. Just to feel good about this I'll go out to the Megasquirt forums and see if anyone has experience with the keyless crank..

[bodie]

i never tried it but if you have some spare sbc parts laying around, you could try

replacing the key with one for a gen 1 motor

and use a regular 350 balancer

then index the balancer

but you would aslo have to fap up some accsories brackets

of if you have room you could fab a dis in the rear in the intake.

[piston]

im wondering if ther is no timming marks, then how in the heck does an average person check the timming on the lt1? i could of swore in my haynes manual, it shows a timming gun checking the timming on the enine but i need to double check that one. that sucks and that also explains my off timming lt1 running like crap.

 

wheelman, on mine, i think i did what you where refering to speeder anout using the opti. turn the cam and have the pin direct then turn the pin on the opti to match the tdc mark on the opti but i think on non vented ones like the long block i just got from a 94, it doesnt have the marks on the opti.

[speeder]

Well, It looks as if I didn't do enough investigation.

 

Seems that people who do high performance work on LS1 and LT1 engines use a drill fixture to enable a pin to be installed to prevent spinning the damper on the crank. This is mostly for the supercharger guys, but looks like something you should do for a modified motor.

 

ATI makes a drill fixture for an LS1 - I'm checking to see if it will work on the LT also. I'll report findings.

[wheelman]

Piston,

The opti should only align with the cam in one orientation and assuming the cam timing is correct the ignition timing will be also. What makes you think the timing is bad on your engine? You could use a timing light on it but without accurate timing marks what are you going to be looking at?

 

As for a person adjusting the base timing on an LT1, it can't be done with a stock opti-spark. MSD made a "cap" that is supposed to be adjustable but I don't see the point, it's to easy to make changes in the timing map of the PCM and there are no "standard" timing marks on the engine. Getting at the opti with everything in place is also a major pain.

 

As for the haynes manual, don't place to much emphasis on it being accurate.

 

Speeder,

I thought I remembered there being 2 sets of key ways cut into the crank and 1 was exposed to a point it could be used with the hub, guess I was wrong, it's been a while since I had mine apart. Using a pin seems like a good idea, it would prevent slippage and make re-alignment after assembly much more acurrate.

 

Wheelman