Small Block Chevy Question - Page 3

rmb_cobra · #41 (**permalink**) 03-06-2004, 08:04 PM

To the Bruces (and other Chevy experts):
I made some progress today. Checked all the wires for proper connection, readjusted the throttle cable (it was improperly routed) and bought a timing light. Went to check the timing and the bozo mechanic struck again. Apparently he put the pulley on in the wrong positon for TDC, so I had to set the idle timing to a felt tip pen mark the rocket scientist used to mark TDC. I disconnected and plugged the vacuum advance tubes, and discovered that the timing at idle of 800 was 2 degrees advanced. I backed it down to -6 or -7 retarded and it seemed to idle much better. I reconnected the vacuum advance and ran it up to 2500 and it only advanced to about +6 or +8. Is it supposed to advance farther than this, as you indicated it should be to +36?

Also, called tech rep at Lunati and he stated that for that cam the setup was fine if the valve springs were strong enough. He urged me to check the rocker clearances as well as time it. I was told by the mechanic the cam was "mild" for street, the Lunati guy said it is not mild at all, more for a street/drag bracket racer cam.

Took it for a test drive, and it is worlds better at the higher revs, but it feels like there needs to be more power. Also, it idles high (1500+) in neutral (once completely warmed up), but if I put it in Drive at a stoplight, it idles way down to 500-600 and sounds like it is going to die.

Next steps: I am going to replace the aged HEI cap, rotor and coil (over 10 years since intallation, with lots of dwell time covered in the yard) as well as the vacuum advance unit. Is it worth it to get the adjustable vacuum advance? Go with stock HEI cap, rotor and coil or upgrade to aftermarket? Feel great to make some progress and drive the car in 70 degree weather today! Advice? Thanks again for the help.

Bruce Edwards · #42 (**permalink**) 03-06-2004, 08:22 PM

You can not install the balancer wrong. It may have slipped and that is why the timing is off with the light. If it has slipped replace the balancer. It is on it's way to a failure. It may also be the big problem with the engine. You will have a hard time setting the timing if it is moving around. Your parts changer should have noticed a bad balancer.
Did you ever get a vacuum gauge on the engine yet? You need to get some idea of what your base vacuum is.
Do yourself a favor and do not throw parts at the problem. Figure out what is wrong and fix that first. Then move forward with any other repairs you may wish to make. You may just make it harder to find the problem.
The high idle may be due to timing still. When you put it in drive the load slows the motor to a point were the vacuum drops off and the advance starts to fall off. As it does the idle comes down.
Again this may all still be tied to timing.
Look at the rubber insert in the balancer. If it is cracked and splitting out the sides you need to replace it NOW! You do not want it flying apart.

xlr8or · #43 (**permalink**) 03-06-2004, 09:52 PM

RMB,
The comments about adjustable cam timing are correct. The timing gears can be for pre and post smog motors and they are indexed differently. Your balancer however has only one keyway on it and should not be misaligned with the timing mark when the piston is at top dead center. If it is, replace it as suggested. If it comes apart at speed it ain't gonna be pretty. It's as simple as pulling the plugs and turning it over slowly with a large ratchet and use something down the plug hole to indicate when it is topped out.
When done right it should be able to idle at about 1000 RPM in nuetral or Park and drop to about 800 or 850 when in gear.

Junket · #44 (**permalink**) 03-07-2004, 07:06 AM

Yes you can only put on one balancer the outsice ring might of moved also I belive in 77-78 they changed the position of the timing marks on the balancers as well as the pointers (if they have the factory color on them Red is early & Blue is late also late is wider) to check this you might run the motor up to about 3500rpm move the distributor till it runs the best then RETARD it about 1/4" this should put your timing close then use the lite and check it aginst the factory if you are off 6-8 degrees you could have the wrong combination of timing marks.
Ken

rmb_cobra · #45 (**permalink**) 03-07-2004, 07:24 PM

Man, the deeper I get into this motor, the more upset I get. Would the part failure be due to improper installation, correctly installing a worn out part, or???? I looked up a company called Fluidampr that sells a high performance damper. the website explained what the part does and how it is installed. It sounds like it is basically disintegrating, causing the outer ring to rotate slowly? If so, I am amazed it hasn't come apart considering I have driven it a couple of times. It mentioned that the first step is a significant loss of power due to slap.

One comment referenced the timing mark tab/pointer should be in blue or red. My unit appears chrome; the car is pre smog. I looked up the GM parts website and found one for 70-74 350's, part # 12555879, which requires a chromed timing pointer #12341915. My engine block is a 69. More mysteries.

Can you rent/borrow a damper remover/installer tool? Is it tough to replace? Retail for a stock unit looks to be around $210.

Thanks again to all who comment. I feel like I should suck it up and take it in to a mechanic (familiar with hi perf '69 SBC's, not mom's Camry...) to really make sure nothing else is screwed up. I got so burned on the first round (quality and $$ wise) that I am real gun shy. Anybody out there recommend a shop in the Richmond VA area? Sure glad it isn't June, I'd be real P.O.'d.

Appreciate all the help...

xlr8or · #46 (**permalink**) 03-07-2004, 10:09 PM

Here's a link to a puller from Harbor Freight.
http://www.harborfreight.com/cpi/cta...emnumber=37714
It's only $10. remove the pulley and big bolt in the middle then use the puller.

Bruce Edwards · #47 (**permalink**) 03-08-2004, 03:59 AM

You can buy a puller for less than $20.00 at most parts places. If you are not running a race engine you can also pick up a new balancer for around $60.00. The stock unit is good to 6,000rpm. Just check over everything before you spend more money looking for the problem.

rmb_cobra · #48 (**permalink**) 03-14-2004, 08:40 AM

I spent some time on the car yesterday. I believe I have eliminated the damper from the list. I pulled all the plugs, rotated the engine so #1 is TDC and the mark lined up exactly. I then pulled the distributor cap, and discovered the rotor was pointing about 15-20 degrees advanced to the #1 cylinder. Looked like it was installed at least a couple of teeth off, and then backed up to try and get it timed correctly. That's my guess.

The rotor was very pitted, the cap had quite a bit of pitting on the contacts. The advance weight pivot points looked real worn and sloppy, and the little springs looked kind of bent around. So, I am opting to replace the entire distributor assembly. The unit looked like it was 30 years old. When replacing, I hope to get it positioned correctly and then begin the timing process again.

Thanks for the help so far. Waiting for parts to arrive by mid week, then time to dive back in.

Chaplin · #49 (**permalink**) 03-14-2004, 09:19 AM

RMB-
Your timing might be correct. If the motor is at TDC, and it looks like your rotor is pointing 15 or 20 degrees before TDC, that might be right. (I'm assuming that when you said "advanced" you meant before TDC). For example, the initial timing on my motor is set at 18 degrees before TDC, and, if I pulled the cap, the position of the rotor would be exactly as you described yours, so yours may be right.

As for the bushings and springs, you can buy a kit to recurve your distributor which contains new bushings and springs for less than $20. Unless you have other problems with the distributor (like worn busings in the shaft) I'd go that route before investing in a new distributor.

That's my .02

edit: I just went back and read the previous posts. The above assumes that your cam gear is set up properly. So get that straightened out first and then set your timing.

rmb_cobra · #50 (**permalink**) 03-25-2004, 09:13 PM

Update: sorry, good news and bad news....
I replaced the distributor and continued to have problems getting it timed right. The old distributor was definitely in need of rebuild so I don't feel bad having the new unit.

Tried resetting the position to no avail. Next step was to check the cam timing. I pulled it apart tonight, and it is lined up per spec, exactly. And the damper was fine as well. I am going to spend some time cleaning up everything as I reassemble, so it may be a day or two, considering my booked schedule, before I take another whack at resetting the dist. I have the engine set at absolutely TDC, so it will help in the dist. reset.

Could my problem be in the wiring somehow? The wiring is pretty cheesey, but it did run great before the "mechanic" took it apart for the original repair. Any suggestions in that area (short of rewiring the whole car)?
Thanks again for all the help.

Roger

RallySnake · #51 (**permalink**) 03-26-2004, 02:51 PM

Hi Roger,

Don't feel lonesome man. I went through a similar experience with mine after the vacuum advance quit. I hope you got the MSD distributor. That's quality stuff.

The hard part is the get the slotted shaft that drives the oil pump aligned right. It took me days to get it right. My engine is so far back that the distributor sits under the body of the car. It's a major pain to work it out of the hole.

The installation instructions found here should help: http://www.msdignition.com/pdf/85551...8547_dists.pdf

Good Luck!
Paul