Well today I have finally got some long over due tuning done to me new engine. I have done allot of searching and reading on the boards and got some good ideas.

Today I have only done the timing part of the tune. I am hoping you guys good give me some thoughts on how the timing part is looking and then I will goto the carb. It is a 750 with stock jetting the only thing I have done with it is put in the 8"hg springs.

Now in July I burned up my engine with just 371 miles on it. broke two pistons (Ring Lands) on 4 and 8. I believe it was because I was running either too lean or to high of timing. So To get this engine broke in I kept the timing to 8 (Base) w/ No Vac can and put in the 8"hg springs to make sure I was not over timing and running lean.

Here is what I have the timing at now....



Distributor is....

85 Series HEI from Mallory

Plugs......

Autolite regulars part number 666

Timing kit from CraneCams but I did not use the Vac canister because the one on my new Mallory I can limit the amount of timing from it.

I am running the 2 blue spring (Heavy) w/Full Manifold Vac for the Can

CR should be about 9.8:1

Now I did the tuning that the CranCams kit told me to do......

==============================================

With the vacuum hose disconnected and plugged, set the

initial timing at 2° advance from factory specifications and

make full throttle acceleration runs, listening for audible

spark knock. If spark knock occurs, then retard the initial

timing 2° and check for spark knock by making another full

throttle acceleration run. If spark knock stops, you have the

ideal centrifugal advance curve. If spark knock continues,

then select the next heavier spring combination and repeat

the test procedure. If no spark knock occurs on the first

test, select the next lightest combination and repeat the

test.

Connect the adjustable vacuum advance unit to the manifold

vacuum source.

Test-drive the vehicle in the city and on the highway while

listening for audible spark knock under heavy load and part

throttle. If spark knock occurs under part throttle conditions,

a change in the vacuum advance curve is needed.

This adjustment is made by inserting the 3/32" Allen wrench

into the vacuum advance unit and turning the adjuster

counterclockwise two turns at a time, testing the vehicle

after each change, until part throttle spark knock is eliminated.

==============================================


Here is what I have ended up with for timing......


Idle 8 deg w/No Vac can

All mechanical timing in by 2400 @ 25 deg w/No Vac Can

26 deg @ Idle w/Vac can

44 deg @ 3000 w/Vac can in park. (No Load)


How dose this sound? Now with the heavy spring I should not be getting full mechanical advance till 3200rpm according to Crane but that is not what I am getting. I think because the weights on the Mallory must be heavier???

Any insight would be great!

 

You haven't got nearly enough centrifugal advance. You should have somewhere around 34 degrees when it's fully in. Vacuum advance should add around 12 degrees on top of that.

 

The thing is is that if I bring my Base timing up to 14 to get my mechanical timing up to 31 then I have ping pretty bad...... I had to back it down to 8. I am running 92 gas..... You think I am running the wrong heat range on the plugs?? I am having a hard time trying to find 5/8 reach plugs for the sportsman heads. Anybody have a plug range for heat range on plugs w/ 5/8 reach?

 

Don't worry about the heat range on your plugs, that probably won't be your problem. How sure are you that your timing tab is in the right place?

 

When I put the engine together I made shure the timimg chain marks were at 12 o'clock and #1 was at top then I put the timing cover on and balancer then adj. my timing pointer right at 0

 

When does it ping?

 

It is not now with the timing specks above. But when it did it was anything more then 1/2 on the pedal. I have a 3000 stall so I would just get rolling let it get into 3rd gear hold the break down and get on it then I could here it.

 

Was that with the vacuum advance connected?

 

No, it was not hooked up..........



Well here is what I have found....... When I got my sportsman heads it said I needed a 5/8 reach plug and the only plug number they gave me was a Accel 276. Well my parts stores here could not find a cross referenced to that plug so they gave me a 14mm 5/8 reach plug NGK TR55.........Well I cross referenced that plug to a Autolite plug part number 605. Well I was telling myself that the pinging was just to easy with such a low advance so lastnight I did some homework and here is what I found. I did a search on Google and found a different tech sheet for the sportsman heads and they gave me AC-Delco and Champion spark plug part numbers. So I went and picked some up just now to find out the plug I was using was WAY to LONG! Here is a pick of them. The one on the right was what I was using I feel like a SHMUCK! So I would have to say That would be the problem why I can't run more timing because the hole end and part of the threads were in the chamber and I bet that made one big A$$ hot spot to pre-ignite the mixture. If I am wrong on this please let me know...... I have to put them in and go back out and tune it again going to have to start from scratch..........

 

Well I went out and re set my timing here is what I have now tell me what ya think.....


Idle 16deg

34deg @ 3100rpm

Idle w/vac can 30deg


How dose that sound??

I have not taken it for a drive yet to check for ping but with that plug thing I don't think I should have a problum!

 

So how did it work after ya drove it?