SBC 302 is in, running!, Needs some tuning, any suggestions? Options

[marks914]

Got the 305 out and put the 302 in, runs pretty well.
I am running an edelbrock 600,
Hydraulic roller cam .56 lift 236/236 duration.

I am in the process of tuning it right now. I have HEI vacuum advance hooked up to the timed port on the carb.

The engine has some lope to it, when I advance the distributor to smooth out the idle, it purrs like a kitten and no spark knock. The problem is when I advance the ignition timing this far, it is difficult for the starter to turn over the engine.

Here is what I am going to try, please tell me if this makes sense:
I was going to put the vacuum advance on the manifold vacuum port, thus giving more advance at idle, I do not think this would affect the initial start up advance, making the starter able to turn the motor over when hot.

here are some pics

Thanks

Mark

PS, the car is a bit quicker now, the power comes on at 3000 RPMs, so it is very driveable around town with the power where it needs to be.

[marks914]

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[marks914]

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[marks914]

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[marks914]

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[herman maire]

That looks like a VERY nice and clean V8 swap (IMG:style_emoticons/default/beer.gif) .

Cant help you with the tuning probs though.

Just a question... I bought a used speedo for my 911, can you reset the miles to match my car and maybe clean it up a bit?

If you want PM

[JB 914]

looking good (IMG:style_emoticons/default/smile.gif)

post up the tuning results. i've got a 327 with HEI setup too.

[tyler]

Looks great. where did you get the valve covers?

[pffft]

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Is the distributor vac advace or retard?
Maybe hang a vac guage on the manifold vac port and see
what it pulls at starter speed. I kinda doubt that cam pulls
very much vacuum at that low an rpm.

Is that the same plumbing you had before?
Radiator to filler to engine with a radiator cap on the
filler and a line from the filler to and overflow/catch tank?
Do you have any pics of how you plumbed the heater core?



patrick

[race914]

Your project is looking awesome!

The Porsche Valve Covers reminded me of AARDEMA Development.

Have you seen this Chevy/Porsche V8 Hybrid?

[914-8]

Nice!

Be careful with that air filter. Most of the guys on the hot rod boards hate those, because the foam ends up crumbling and getting sucked into the carb. And it easily catches on fire if you get a backfire through the carb.

[rick 918-S]

Nice!

Be careful with that air filter. Most of the guys on the hot rod boards hate those, because the foam ends up crumbling and getting sucked into the carb. And it easily catches on fire if you get a backfire through the carb.

(IMG:style_emoticons/default/agree.gif) BTW: The distributor needs ported vacum to work properly. If you connect it to direct intake manifold vacum it will be advanced all the time. Check you starter. It may be weak. I got a 911 starter from Oklahoma Foriegn for something like 50.00-75.00 no core charge. They even gave me thw option of spade terminals or stud connections.

[greybeard50]

Ballpark answer to your question...SBC's like a bit of idle advance ~6 degrees @ 6-800rpm and ~ 30-32 degrees total mechanical advance all in by 3000 RPM. All set without any vacuum to the pot. Most will tolerate another 6-10 degrees from the vacuum pot.

Now, you tell me how much you know about timing a SBC. Have you done it before? Do you have a timing light? And know how to use it? I am not trying to dis your Dis. ...I'm trying to understand how detailed I must be to get your Beastie up and running.

Things you need:
#1 true TDC for #1 cyl marked on the vibration damper that aligns with
#2 a TDC marker on the block
#3 a timing light that dials in the advance you want, or
#4 if your timing light does not dial in the advance, you'll need a degree strip for either the Vib Damper or the block marker

Answer these & we will get back together. Keep the Faith!

[messix]

it's ok to run the vac advance to the manifold vacum.
you will want to check to see what your total advance is at 3k rpm or so.
you shouldn't need any more than 36-38 degrees total advance.

[andys]

As greybeard50 mentions, and perhaps a bit more information regarding what you have. How much advance in the vacuum pot, and at what vacuum level? If you have a hand vacuum pump, you can read the level at which it advances and by how much with that dial-back timing light. Rick is correct, that cam may not have enough vacuum to pull it down. How much mechanical advance in the distributor, and at what rate?

Sometimes you get lucky and there's enough mechanical advance that when you set initial (I'd probably go more than 6*), the numbers work out. Been some years since I've done any SBC tuning, but that's what I recall.

Andys

[messix]

what heads are you running? iron or aluminum? later model fast burn type? or old iron lumps?

later heads don't need as much timing, same with aluminum.

this is all in total timing.

if i remember right i think the standard vac advance pots take 6-8 psi to pull them all in.

that cam should do that.

don't turn the idle screw at the throttle plate in so much the you get out of the idle circuit and into the main fuel circuit. take the carb of and check, if the throttle plate isn't with in the first slot your in the main circuit.

you should idle around 800- 1100 rpm
use a vacuum gage to adjust the idle mixture screws to the highest point [it a balancing act, a little more here a little less there, small adjustments.]
then recheck timing and adle rpm.

that cam is gonna lope pretty good, yer gonna have to live with it.

[marks914]

Thanks for the input,
The Dizzy is a summit blueprint HEI, 36 deg total timing can be gotten out of it.
I am going to put a vac gauge on it tonight and see what its pulling. the lope is not bad, i was just trying to get a more stealty sound. I guess it won't matter when I put my foot into it.


TYLER- I make those covers, i still have a set available in stock height, I have tall ones on my car.

Mark

[messix]

Thanks for the input,
The Dizzy is a summit blueprint HEI, 36 deg total timing can be gotten out of it.
I am going to put a vac gauge on it tonight and see what its pulling. the lope is not bad, i was just trying to get a more stealty sound. I guess it won't matter when I put my foot into it.


TYLER- I make those covers, i still have a set available in stock height, I have tall ones on my car.

Mark

that would be 36 =centrifugal advance and vacuum advance. then add the static timing at idle with no vacuum advance hooked up.

so if static is at 8 degrees + 30 centrifugal advance, all in = 38 [ 6 degrees is standard vacuum advance can.]
you can get bushings that will limit the centrifugal advance, they go over the limit pins.

[Dr. Roger]

Hey Mark,

I had the same thing going on with mine. Only my dizzy is a Mallory with vac advance. BTW, the vacuum advance goes on a spark port. If you hook it up to a vacuum port you will get max advance at idle and it will retard when you stomp on it. I don't think you want to do that.

I've tried different things including running the mechanical advance just to the point where it won't turn over and backing it off a degree or two. That worked fine but I believe I never did get all the HP and torque out of the motor. I believe I have come up with a better solution now.

I agree with greybeard in that they like advance but if you're 6 degrees while turning it over, it will not turn over. =)

I have just recurved my distributor so it has very little advance while turning over but advances up to around 6 degrees at idle RPM.


when I bought my EBay/second-hand dizzy I never noticed it had heavier springs in it and in order to get all the HP out if it at higher RPM's it needed more advance. Now, with lighter springs, it will get it's advance sooner and still allow for turning it over.

Recurve kit= cheap.
Just make dang sure you don't start pinging at any RPM.

Best of luck,
Roger

[messix]

BTW, the vacuum advance goes on a spark port. If you hook it up to a vacuum port you will get max advance at idle and it will retard when you stomp on it. I don't think you want to do that.





yes this is exactly what you want.

running the vac advance to manafold will help with lumpy cams for idle quality.
the "spark" port is just a vacuum slot just above the throttle plate, and only gives vacuum signal at part thottle, smog engines.

look it up on wikipedia if you don't beleive me.

i've run to many lumpy engines as daily drivers and learned from that.