ericg83z28

hey guys i have an 355sbc with a hyd flat tppt 280H comp cam , its got 64cc edelbrock Estreet heads and 1.5 roller rockers, aprox 10.5:1 cr , problem im having is that the engine runs on (dieseling) only after its warm , and hot but not cold, the initial timing is set at 19* btdc and the mechanical is set about 30 *, is that right ? or should i retard the initial timing abit and make the advance to about 36 or till it pings? , its also on 91 octane btw. its driving me nuts

hdis2002

iTrader: (1)

Stock timing is 6* btdc. Your engine is obviously not stock but 19* seems a little bit too much.

ericg83z28

[QUOTE=hdis2002;5167904]Stock timing is 6* btdc. Your engine is obviously not stock but 19* seems a little bit too much.

Hmm how do I set initial timing turn the crank over where the pointer says say 12 and then drop the distributor in and make sure the rotor lines up with no.1 cyl contact on the cap? Then 12* would be my initial?

'84thunder

[quote=ericg83z28;5167924]
stock timing is 8deg. mine came from showroom floor with 8deg.

19deg...i will agree with eric83 thats too high. i have my 305 with aftermarket cylinder heads, cam n lifter kit, roller rockers set to 12deg. you have a 355 i would say maybe 14 or 16.

your other question(how do you set timing?) simple...get a timing gun and a haynes manual. aim ur light on the balancer and watch for your lil mark TDCmarker and go from there

1986Z28OWNER

iTrader: (1)

14-16 base, 30-32 total.

ninetyone

iTrader: (2)

[QUOTE=ericg83z28;5167924]You set the initial timing by moving the distributor. Advance or retard. I would set the engine to TDC first and check to see if your rotor is pointing at no.1 , and then set the timing.

ericg83z28

alright ive got it runnin and when i set my total timing to 34 degrees , i check the initial and its at about 24degrees , is that right , it sounds a little too much initial?

'84thunder

STOOOOP. ur timing should be no more than 16-18 degrees, stock timing is 6-8degrees and anything in the 12-14degrees is plenty.

u keep that up and ur engine will run wicked hot (over heat) its gonna start to ping (BAD, very BAD) im surprised its even starting.

305sbc

iTrader: (3)

You were already told several times that was too much for initial advance.

First you should probably learn what it is that you're doing. There are some links in my signature that will help explain the process.

'84thunder

thank you 305sbc....jeesh this kids bout to blow his ride up

ericg83z28

Ok I reset the initial to 15degrees but its only runnin like 28 when I rev it to about 2500rpm .... Who wants to fly up and do the timing lol

TreeFiddy

You're only getting about 10-13 degrees mech advance, sounds a bit low. Should have 18-20. Are the dist weight gummed up, or do you have heavy springs/weights?

You can run more timing at low loads like idle and cruise, for better fuel economy and temps. I am using manifold vac advance on top of the mechanical. My initial mech is 15 (best vac), rising to 34 at 3000 rpm. Then adding the vac advance bumps the idle timing to about 23. No pinging.

Give it the timing it wants, it will ping when it's too much.

ericg83z28

I'm using the heavy msd hei rebuild kit springs , if I go to a lighter spring will I get for advance ?

TreeFiddy

Most likely, and it'll come on sooner.

Setting the mechanical advance curve with springs is an iterative process, you want the lightest that the motor will tolerate without pinging uphill at WOT and still get you to 32-36 degrees mechanical over about 3000 rpm. Eg. I've got one heavy and one medium atm.

Make sure you're FULLY warmed up before making any changes.

305sbc

iTrader: (3)

Springs don't change the amount of advance, only the rate.
HEI type usually uses bushings to control the amount of advance.
Smaller (thinner) bushings gives more advance.
Make sure both arms of the weight system are moving easily.

TreeFiddy

I've observed that using the two heaviest springs gives a few degrees less than the two light. Or else I'm not revving high enough past 3500 to get it, never comfortable sustained revving that high with my face right next to it

ericg83z28

n I put the distributor at 34* and I let it idle and get somewhere about 25 degrees at idle , u guys think that could be the bushing are to tight ? I have bought a new set of hei msd springs bushings weight kit , ill use that but is there anyone that's using these in there car or has heard of this problem?