7 replies to this topic

[Johno]

I have a 355 stroker and have been trying to get it to run better. It’s currently running really rich. I’ve rebuilt the carb and as it’s an edelbrock 600, I’m about to lower the fuel pressure from 6.2PSI to 5 as I’ve heard a common problem with them is they don’t like fuel pressure over 5PSI.

It’s got a lumpy cam in it. The Edelbrock 600 carb has the electronic choke disabled (choke is wide open all the time).

When I got the car, the initial timing was set at about 25 degrees advanced. This seemed high to me to I lowered it to 16 and still can’t get the engine to idle smoothly.

At 16 advanced, the car idles too low so I have to turn up the idle screw so much that I believe the transfer slots would be too far open. As far as I know, they say if you need to open up the transfer slots too much, the timing needs to be more advanced.

Is it possible the engine really does need that much initial timing (25)?

If the engine really does need 25 degrees advanced to idle right, what would usually be the ideal total timing?

Would it still just be around 36 total?

Is it ok to have a distributor curve like this?

Edited by Johno, 02 October 2023 - 04:09 PM.

[yel327]

Are you certain the balancer timing mark is correct?

[dron]

25 sounds too much starting advance. A agree check the timing marks.

 

Bigger cam normaly means it may need  higher idel speed. It would most likley kick back on cranking and kill the starter motor with that level of advance. I have killed 1 just tuning it by ear to where it idled best and not checking it with a light (About 20 deg)

 

I set my 355 to 12 Deg static and max advance is arround 29 to 30  No vac advance. every set up is differant, I have a smaller cam than most, Quickfuel 700 on top of an elderbrock torker and a cutom converter at about 1600 stall and a smallish cam and 9.8 comp. A little more static timing may be ok for a bigger cam but not a lot I would have thought.

[Johno]

I’ve got a piston stop on order and will double check timing marks.

At this point I think the marks are roughly correct but will definitely make sure.

So I shouldn’t be so concerned about the transfer slots and just give it the idle fuel it needs?

[rexy]

After you check the timing marks are correct you need to check the total timing and at what rpm this is.

Total timing above 30 degrees can be a problem on early (pre VN) style headded engines on pump fuel. The only way to be sure you are in the safe zone is to dyno it.

[Johno]

Pretty sure total ting at 3000rpm was about 45 advanced or something rediculous like that.

Im wanting to replace the distributor ASAP.

[Bruiser]

I had a panic not too long ago when I saw 45 degrees on my 202
Had a bit of a read up on the subject since then, the vac advance can take it up there.
Before you dive into your wallet, maybe investigate further.
What is the total timing at revs with the vac advance plugged off?
I believe a big cam and not enough compression needs extra initial timing to
Band-Aid the lessened bottom end power. Big cams like extra initial, anyway.
If your engine doesn’t like less timing, it may be what your engine needs.
Does it ping at all?
If the total is 30 - 36 ( I am not sure on typical v8 timing numbers, by the way)
with the initial set at 25, someone has set the dizzy up that way on purpose.
Hard to be sure if you don’t know the cam spec and compression numbers, though
The smooth idling issue could be a combination of the timing and the carb tune
not quite being matched to each other
If edelbrock transfer slots work the same a holley ones, opening the idle screw too much can
lead to a new set of off-idle stumbling type problems

[ozyozyozy]

45 total is way too much.
MSD dizzy’s are common to create way too much total timing.
Need a good timing gun that allows you to see intial and total timing, a good tuner will have one.
Looking at the spark plug is a good indicator. Looking at the burn mark on the strap, if it’s all the way down near the thread there is too much timing, should be roughly half way.
Best way to check, using the plug method, is to do an engine pull under load, then switch off engine as you get to the end of the pull. Remove a plug and inspect. If you let it idle before removing the plug, you will get a false reading as they will start to soot up.