87 rag

Hi Corvette People.
I was a C4 guy for years but had a little fire and no longer have a corvette. I decided to get back into having a hobby car with some back seats so I could drive my kids around so I put together a 1981 Pontiac Grand Prix. I have always respected the knowledge on this forum so I thought I would try my luck at posting a question. My engine is a Chevy and likely similar to many on this forum. Specs at the bottom.

I have been trying to tune my new build and its a long process when I only have a couple of hours a week maximum that I can play with it and I'm learning as I go.
I know that total timing should be set between 34 and 38 degrees but my car didn't like that range. It would bog when I hit the gas, had bad run-on or dieseling when I shut it off and the rpms would drop so much when I put the car in gear that the engine would stall.
I kept increasing the advance to where the car liked it much better but I was at 43 degrees total advance.
The car did not diesel anymore when I shut it off. The timing markings were much easier to read as they weren't dancing around as much, the bog was almost gone, the car did not stall when put in gear and there was no noticeable knock.
I was actually going to give it 2 more degrees but ran out of time. It also started fine without making the starter labor.

Has anyone ever heard of a small block Chev that liked 43 degrees or more of total timing? I remember reading somewhere that some motors like up to 42 degrees but don't remember where I read it and cant find it again now.
I consulted my engine guy through texts (he is on vacation) and he told me I was crazy.
LOL, what does that have to do with my motor?

Just curious if anyone has seen this before and is it safe to drive?

Thanks in advance.

Motor Specs:
383, Dart Iron Eagle 200 Platinum Heads, 10.3:1 Compression, Manley 2.2/1.6 race valves, Comp Cams Stainless Roller Rockers and full valve train, XE274 Cam, Scat 9000 series crank, Forged Pistons, Edelbrock Thunder AVS 800cfm carb, Edelbrock Performer RPM Intake, March Pulleys, MSD Streetfire Distributor, Moroso deep pan, 3000 stall Converter, 200-4R trans with the goodies to take the power, Flowtech 1 5/8" long tube headers, true dual 2.5" exhaust, 3.73 rear end with posi......

'75

New harmonic ballancer or the old one?

87 rag

Good question, everything is new.

87 rag

Just to add to this.
I believe the balancer is the summit racing 8" balancer and says Pro Street on it.
SUM-161358
Anyone know if this balancer is known to shift/spin?
Thanks.

The Money Pit

Verify TDC with a piston stop and go from there. Either the balancer is wrong, or timing tab could be off. Once you are sure of TDC,..the rest will fall into place.

87 rag

Timing tab was dead on the last time I checked it and it doesn't move but in the last few minutes I have done a little research on spinning balancers and this seems to be a common problem.
I will check the tdc.
Is my engine going to be out of balance now?

DRIVESHAFT

Your engine doesnt want 43 degrees of total timing, but it is enjoying the added initial timing.
If you like how its running now, find out what your timing is at idle and subtract that number from 36.
Then modify your advance curve so that you only get that much mechanical advance.
For instance, if you are currently running 20 degrees of initial timing, limit your mechanical curve to 16 degrees.
Then you total timing becomes 36 degrees, which may still be more than you need but its in the ballpark.

69427

Do you have vacuum advance?

'75

Just a thought, hope someone has the answer but, seems like I've heard of the MSD Streetfire Distributor messing with some of the advance timing lights.

87 rag

Looks like I spun the damper.
Just did a quick check of TDC with a pencil in the #1 plug hole.
Showed 9* advance at TDC.

That's what you get for saving a few bucks.
what is a reasonably priced quality damper that I should buy?
Any recommendations?

Thanks for your help.

bluedawg

Street damper by fluid damper.

63mako

Return the new balancer to Summit. get one of these.
http://www.summitracing.com/parts/SCA-D-80002/

87 rag

That is quite reasonably priced. I guess the price jumps quite a bit to get SFI approved.

DRIVESHAFT

The price jump doesn't have to be too bad. http://www.summitracing.com/parts/SUM-C4265/


I just noticed the link that I posted was for a smaller o.d. balancer.
It would still work, but you would need to change timing pointers also.

87 rag

Thanks.
I'm a little hesitant with the summit brand now.
I may stick to a brand name.
I'm on the summit site now.

DRIVESHAFT

The Summit balancers are made by Pro-Race Products and are actually pretty decent. http://www.pro-race.com/
Here is another reasonable option though. http://www.ebay.com/itm/Pioneer-8720...item1c23d0da18
It costs a bit more, but it is an 8" balancer.

87 rag

http://www.summitracing.com/parts/PFS-90002/
Anyone know much about this one?

cv67

Dont touch those PP witha 10 ft pole.
The streetdampners are fine or a decent name brand
Dont skimp on a balancer

Id use a Pioneer before either of those other 2 if I had the 3 were the only choices period


Driveshaft is right on with his timing advice.
IMO most put way more initial than they actually need and have it come in too soon.

87 rag

There is a familiar name from my C4 days. How are you quisinart?

What damper would you go with if there were more than 3 choices?

Thanks for the timing advice Driveshaft. I understand it, just dont know how to adjust my mechanical advance on my cheapo Streetfire distributor. An answer is to get a better distributor and I may do that but not this year.

Thanks.

billla

I use the Pioneer stuff (they also OEM for other brands) unless I need SFI for a particular build.