timing/tune up problems

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666mopower666

666mopower666

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Hey Guys n gals i got a fight on my hands lol jus finished getting my 318 stroker installed and running but i can't seem to dial in the timing or carb tune up

here goes with what i've done

Initial Timing set to 15 degrees

Finial timing is 40 at 4800rpm

ignition is all msd 6al box, blaster IIcoil, and pro-billet distr
is my timing curve too steep for an a-body with a stroker? have stop bushings to limit mech advance at 28, 25, 21 or 18 currently has the 25 installed. or should i install lighter springs to get all-in timing at a lower rpm?

Also once timing has been set i try and tune my edelbrock 1406 carb and turning the mixture screws have lil to no effect on vacuum or rpms, even turned all the way in.
I'm thinking i have too much initial timing causing high vacum and drawing fuel into the carb???

what do ya'll think? where should i start?

also not 100% sure on my advance timing light i left it in the sun the other day and it got very hot and the display flashed when i tried to use it hot but seems to advance and flash properly now

thanks guru's
 
666mopower666 said:
................. the mixture screws have lil to no effect on vacuum or rpms, even turned all the way in.
I'm thinking i have too much initial timing causing high vacum and drawing fuel into the carb???
Click to expand...

No way in heck that this timing/ carb relationship can happen

I don't trust "dial up" timing lights and there have been problems with various lights with MSD. If you can, bypass the MSD until you get things settled down

The idle screws not having effect could be a few things

Too much fuel pressure driving fuel past the needles, too high float level, or other problems causing the float level to be high

The metering rod springs may not be seating at idle, remove the top covers and see if this is so.

Has the carb been hacked? IE someone changing jets/ rods/ springs?
 
How big is the engine, camshaft and heads? Is it a quench engine?

Put the 18 bushing on the distributor. I wouldn't run the 25* bushing on my grannies valiant! :) If you reach back, twist the distributor a bit CCW and it picks up idle rpm, the engine wants the timing.

40* is usually a bit much total.

Like 67 mentioned, make sure the carb isn't dripping fuel. It's a common issue with the taxi cab carbs and too much fuel pressure. :)
 
Thansk for the reply 67Dart,

I've used this timing light before on this system and another msd equipped 318 with no issus but now, after the sun roasted it, wen i checked the total timing it was erradic and bouncing around on the marks engine seems to run fine but i want to get this dialed in and running smooth before i start getting miles on it :)

funny thing is when the timing was backed way off, almost knocking and sputtering the mixture screws were super sensitive one half turn and it wanted to kill the motor. So i set the mixture screws at 1 3/4 turns out from seated and then set the timing and thats when the mixture screws started to have no effect.

I don't have a fuel regulator so not sure on psi, i run a holley perf mech fuel pump. The carb is stock out of the box and havent changed jets, rods or springs...yet lol i have the kit to do a few changes but need base line set before i can tweak and set it up to my liking. I'll check the metering rods and make sure they are seated

Thanks again

and any advice on my timing curve? seems like i should be all in at lower rpm's would give me more kick off the line lol not too sure bout that though
 
I'm shocked that a Pro Billet out of the box isn't all in before 4,800? Fuel pressure could be a little high for that Eddy. I had a Holley mech. that put out close to 7lbs. before.
 
67dart273 said:
no way in heck that this timing/ carb relationship can happen

i don't trust "dial up" timing lights and there have been problems with various lights with msd. If you can, bypass the msd until you get things settled down

the idle screws not having effect could be a few things

too much fuel pressure driving fuel past the needles, too high float level, or other problems causing the float level to be high

the metering rod springs may not be seating at idle, remove the top covers and see if this is so.

Has the carb been hacked? Ie someone changing jets/ rods/ springs?
Click to expand...


this ^^^^^^^^^^^^^
 
engine is a 70 cast 318
bored .030 over
4.00" cast scat crank
scat I beam connecting rods
kb847 pistons
302 ported heads w 360 valves
Comp Cams Flat Tappet Mutha' Thumpr Cam, 235i/249e duration @0.050lift, .497i/.483e lift 107 lobe seperation

lol I'll tackle the cam bushing and lower, does that mean i need higher initial timing then? to get 34-36 total i would need 18 initial???

carb seems dry and i've tested for vacuum leaks with no increase in engine rpms, vacuum gauge reads steady 17 at 1000rpm idle
 
oldman i put the higher stop bushing in the dist. stock is 21 which, according to msd, would be all in around 3600rpm. I thought a longer spark advance would keep my power building as i revved up but now i'm thinkin i want all power available at lower rpms too
 
the stop bushin only stop the amount of mech advance, the spring stiffness is wat will control the rpm range, so i think the 25 stop bushing miht be ok so i can run intial at 8-10 degrees and if i change to lighter springs the i should be able to get all in at 2200, 2800, 3400, 4000, 4400 or with the heavy springs i have in right now 4800.

what do you all think is a good timing curve on a stroker? i am mostly street driven but hope to get a few passes on a local drag once or twice a season
 
666mopower666 said:
oldman i put the higher stop bushing in the dist. stock is 21 which, according to msd, would be all in around 3600rpm. I thought a longer spark advance would keep my power building as i revved up but now i'm thinkin i want all power available at lower rpms too
Click to expand...

First off i didn't mean i didn't believe you....lol. I just couldn't believe MSD would put out a fancy performance dist. like that. Unless you have a 2 something rear gear your gonna want the total in closer to 2500. And 15 initial should be no problem either. I would go right to the 18* bushing and that should let you play with the initial without getting close to 40* total. Give us some info on your combo, cam, compression, intake, converter, rear gear, etc. That would help a bunch.

Beat me too it....lol.
 
perfect thats the advice i was looking for rick :)
I'll def swap in the smallest (number wise) bushing and get some lighter springs to open 'er up faster too. will shoot for the 2800 rpm all in springs.

Then i will get my initail timing setup properly then turn my attention to the carb/idle

think the only info i didnt list was the intake lol eddy rpm performer dual plane :) any other info just ask.

Not sure on my rear gears but it is a 8.75 none suregrip unit. Trans is a 904 with i think 2800 stall convertor, might be 2500 lol i cant remember
 
I ran a quick calculation and using your pistons and some generic numbers your comp. ratio is most likely in the low to mid 9 range. I think that engine can take some initial timing. 17" of vacuum with that cam is fantastic.
 
ya if i remember, lol not that my memory is good, we calculated the cr at 9.2:1 during the build.

Lol i thought my vacuum was high for this lumpy cam!!!
once rings have set and its a lil more broken will/should the vacuum be lower? is there anything that could cause the high vacuum? or am i being worried about nothing haha
 
666mopower666 said:
ya if i remember, lol not that my memory is good, we calculated the cr at 9.2:1 during the build.

Lol i thought my vacuum was high for this lumpy cam!!!
once rings have set and its a lil more broken will/should the vacuum be lower? is there anything that could cause the high vacuum? or am i being worried about nothing haha
Click to expand...
The cam may have been installed a little advanced, but don't complain about those readings. Once you're all tuned up you'll probably be able to lower the idle speed a little and that may drop the vac a inch or two.
 
cool beans!!! thanx oldmanrick and crackedback:prayer:

18degrees initial and she purrs happy now woot woot:burnout:
idle is steady at 1000 and vac now at 12 lil jumpy but me thinks that wat my cam is meant to do heheheh

can't wait til daylight and i can go for a long cruise
 
666mopower666 said:
cool beans!!! thanx oldmanrick and crackedback:prayer:

18degrees initial and she purrs happy now woot woot:burnout:
idle is steady at 1000 and vac now at 12 lil jumpy but me thinks that wat my cam is meant to do heheheh

can't wait til daylight and i can go for a long cruise
Click to expand...

Progress is good:D. Maybe a little more fine tuning to come. Let us know after the ride......
 
Bump it to 20 or 22 and see if it runs better. Only issue you need a bigger bushing! As long as it start hot, you should be ok.

If you have control over the mixture screws, you're headed the right direction. If not, it may need more initial. Look down the throats and see if it's dripping. Those holley mech pumps are known to kick some psi.

Vac will be a little choppy with that cam.

Put a med and light spring on the advance weights. That should get it in the area of 2500ish is my guess.
 
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