After reading an earlier post a guy was saying that he found what he thinks is/was the correct timing tab. I was never able to find mine. I bought a timing tab at the parts store, was labled for Chev 305. I've since put it on in the area on the timing chain cover. I can now look straight down past the AC Compressor and view the tab that I installed. Since then I located an indicator of sorts, kinda like a wedge tab directly behind the water pump, just like the guy in the other post. It points out over the balancer, just like timing tab. Is that the correct timing tab for the motor or is the area straight down from the A/C. the difference is probably about 20 degrees difference. Now I 'm concerned?!?!?!?!?!

What's correct?



'86 T/A 305 TPI

 

we just changed the engine in my brothers car, and had the same problem. GM changed the d*mned timing tab on late 70's or early 80's cars(not sure of exact year) If you have the original timing chain cover, and the original harmonic balancer, you should be ok, except that is it extrmemly difficult to see the timing marker, as it sits almost directly under the water pump. We added a bolt-on style timing tab, and with the car on a lift and a mirror, brought the engine to TDC using the factory timing marker(had to look up from underneath and look at the reflection in the mirror). Then we added another small mark to the balancer(filed a small groove on the edge, which lined up with 0 degrees on the bolt-on job. A quick dab of some white paint with the end of a screwdriver, and we can now see the timing marker from above and set the timing right. Hope that helps. If you don't have the right factory peices, the only way you can verify(the right way) that the balancer reads correctly at TDC is to use a degree wheel. Hope that helps.

 

Thanks for the fast reply jwscab!

So the add on timing tab is not correct for Pontiac. The part was labled 305 Chev. Does Chev and Pontiac have different timing mark locations. How the H*** are you supposted to be able to time the machine with the original tab?

 

Futhermore, did Camero have different timing tab location than Firebird?????????This is weird. Need the answer. If the old rusted thingie at the top of the water pump is the real deal then I'm running about 20 degrees ATDC. The Beast sure seems to be running pretty good for being 26 degrees late.

Come on guys this is really bugging me!!!!!!!!!!!!!

 

well, for your car, the engine is a 'corporate' engine, meaning that it IS a chevy engine, regardless of the fact that is in a firebird, these were the only engines made, 350,305 v-8's. That was changed around 1982, with the 3rd gen body style. Prior to that, you could get a weird mix of engines in all GM cars. Anyway, back to your question, the timing tab for that engine, a 305, should be way up under the pump like you described. The other timing tab, the bolt on one, is for earlier engines, which used a different placement of the timing mark. I don't think you are running quite that high in advance, you have to reference your timing mark to the old timing tab, unless you've made a new mark. Also, make sure when you are checking timing that you disconnect the timing control from the ecm, it's a single wire connector floating around your heater box area. If that is plugged in while you check, the timing will move all over the place.

 

Thanks again jwscab.....

If your still there...........If I have been timing the engine using the bolt on tab, would that not mean that I'm runing way retarded (I'm that way anyway.. LOL) I guess the only sure fire way is to bring #1 to TDC and see where the mark falls in relation to the bolt on tab. What do ya think. If I understand it correctly the mark should be lined up with the original tab under the W/P.

 

yep, thats exactly right. if you used the 'new' tab and the existing groove on the balancer to set to 0 degrees, you're like 20-some degrees retarded, and it should be pretty lame-running. You will need to turn the engine around by hand, and use the existing groove to line up with the 0 mark on the tab under the water pump. Then add another 0 mark to your balancer where the new timing tab is(at 0). just mark it differently then the groove that is there(we used white paint to fill in the notch, so one was white the other was just engine color)

 

OK jwscab I'm with ya, should be pretty straight forward fix.....

I still have this lingering doubt about which tab should be the correct one to use. The tab under the WP is there for sure. About a year ago I had the engine checked at the local dyno tune place, the one where all the guys go, and the "expert" says that the timining was advanced way to much. Engine was surging while at constant speed at 50/60/70 mph. He said that the timing tab was missing(he obviously did not find the one under the WP) and adjusted it by ear. What I am assuming is that he did it by ear and was guessing at the mark position where the bolt on tab shoud have been. Car seemed to run fine and runs fine now, not the fasstest by good, with the exception of high idle when first started, then settles down to about 650 in drive until its started up again. Just for laughs I purchased the bolt on tab to see exactely where the timing was. It was dead on at 8*. The car never has started "right off" like it did prior to the timing adjustment awhile back. Maybe a turn or two and than lights now. Then again sometimes it lights right off.

I guess I feel, because I know the car, that if it was that far retarted it would be much more noticeable. Maybe the ECM is compensating. I just don't know. Guess I'll just have to play with the timing to see. Did Camero have the same odd timing tab location under the WP? I'd appreciate any suggestions from here.

thanks...............86 T/A 305 TPI stock, street chip, supposedly stock jasper engine rebuild, questionable timing, runs good and strong..........maybe operating below potential with screwed up timing!!!!!!!!!!!!!!!!!!!!!!!