Crate engine swap advise please?

[73 C10]

I think Rich was right in that you need to get your timing settled first. The 20 on the vac can is too much!

As far as the rods and jets go, its simple math. The higher the rod # the leaner it goes with in a given jet size. So a rod size of 057 x 042 is the richest going all the way up to 075 x 057. And the same for Jets 077 is the smallest leanest and 119 is the largest richest jet

Yeah. He wants me at 16. 16 base + 18 vac + 20 mechanical = 54

Sorry Rich if I got that wrong. This was a while back.

 

[73 C10]

I think Rich was right in that you need to get your timing settled first. The 20 on the vac can is too much!

As far as the rods and jets go, its simple math. The higher the rod # the leaner it goes with in a given jet size. So a rod size of 057 x 042 is the richest going all the way up to 075 x 057. And the same for Jets 077 is the smallest leanest and 119 is the largest richest jet

Why do you think it was doing it at 11* VA?

 

[350runner]

Why do you think it was doing it at 11* VA?

Because the engine is seeing way to much timing....

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[MadOgre]

See my above edited post for the rods and jets^^^

The vac can shouldn't be any more than 16 and set your timing tab at 8-10

 

[rich weyand]

You both have the same Cam? Where did I miss this ?

Not necessarily the same cam, but he's pulling 19" of vacuum, like me, and that tells a lot about his cam. That's also was the carb is seeing: same displacement, same vacuum, same carb response. That's why I suggested he try my mixture settings.

My recommendation remains to buy the meter and do it right. Everything else is by guess and by golly, whether you do it or I do it.

 

[73 C10]

Because the engine is seeing way to much timing....

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You know I'm lost... or somebody else is.

I was just told 34* would be a good total. Then I find out that he did't mean total. He was adding mechanical to base without va. That sounds strange, He must be timing at 2000 RPM or something.

I'm getting the feeling that when some guys say total, they mean partial.

Rich says the total would be in the low fifties if counted in crankshaft degrees.

The stock timing curve in the distributor paper work says it adds 20-22 total mechanical, and 20 vac. If counted in crankshaft degrees. It's a GM blueprint Summit distributor.

If you had 12* base and plugged the vac in you would have 32-34* at 600 RPM.
And 52-34* once the mechanical is all in.

I thought.

 

[MadOgre]

Yep you time it with full mechanical engaged which should be some where between 32-36. You need an adjustable timing gun to do that or a timing strip on the balancer itself. So vacuum advance plugged and 32-36 at 2500rpm. Then with that set you can calculate what your vacuum advance can be woth out going over the maximum of 52 although that doesn't mean that you particular engine will run best at that. It may actually like a little less.

 

[73 C10]

Not necessarily the same cam, but he's pulling 19" of vacuum, like me, and that tells a lot about his cam. That's also was the carb is seeing: same displacement, same vacuum, same carb response. That's why I suggested he try my mixture settings.

My recommendation remains to buy the meter and do it right. Everything else is by guess and by golly, whether you do it or I do it.

I do plan to get the AFR meter.

I don't think you can blame me for trying to apply some things I'm learning in the mean time.

Timing number are confusing people. I know you know. You have been very careful to explain crankshaft and camshaft counts.

 

[rich weyand]

And actually the 6857 rod on a 98 jet is not correct. The 70 x 37 on a 98 jet is what I was referring to as 10-12% rich


the 57 is now lean on power and the 68 is rich on cruise from stock. If you were to run 57 on the rod you would have to go with a larger jet otherwise you are leaning it out

MO, without a meter reading from him you don't know that. You can't just read their stupid chart, which makes no allowance for displacement or vacuum or anything really except "how far off Edelbrock stock am I?" I'm running 62/52 on a 95 jet, which is same as 67/57 on a 98 jet, and I am dead on the money at 600 feet above sea level.

JET NEEDLE AREA

0.095 0.062 0.0081
0.095 0.052 0.0099

0.098 0.067 0.0080
0.098 0.057 0.0100

 

[350runner]

Let me help you find your Way...
If you can't read the timing off the balancer due to not having a timing Mark how do you know where your timing actually is? I suggest finding tdc and marking your balancer https://youtu.be/xg6eAWWvrPA

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[rich weyand]

Yeah. He wants me at 16. 16 base + 18 vac + 20 mechanical = 54

Sorry Rich if I got that wrong. This was a while back.

At the crank: 16 base plus 15 VA plus 20 mechanical.

On acceleration at rpm, that is 36 (base+mech). That's what MO is talking about.

At idle is 31 (base plus VA).

At cruise is 51 (base+mech+VA).

 

[73 C10]

MO, without a meter reading from him you don't know that. You can't just read their stupid chart, which makes no allowance for displacement or vacuum or anything really except "how far off Edelbrock stock am I?" I'm running 62/52 on a 95 jet, which is same as 67/57 on a 98 jet, and I am dead on the money at 600 feet above sea level.

JET NEEDLE AREA

0.095 0.062 0.0081
0.095 0.052 0.0099

0.098 0.067 0.0080
0.098 0.057 0.0100

Argument aside, didn't I vary the mixture enough to disprove a mixture theory? That's what I was trying to do. I was not concerned with getting it perfect.

 

[73 C10]

Let me help you find your Way...
If you can't read the timing off the balancer due to not having a timing Mark how do you know where your timing actually is? I suggest finding tdc and marking your balancer https://youtu.be/xg6eAWWvrPA

Sent from my LGLS991 using Tapatalk

I have a timing mark. It used to spend all it's time away from the tab when measuring anything but base.

I bought a adjustable timing light, as stated previously, so I can now measure all phases of timing.

 

[350runner]

Doesn't work like that... You still need a tdc mark on your balancer.

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[73 C10]

At the crank: 16 base plus 15 VA plus 20 mechanical.

On acceleration at rpm, that is 36 (base+mech). That's what MO is talking about.

At idle is 31 (base plus VA).

At cruise is 51 (base+mech+VA).

Yeah. I remembered you said 15* va most recently.

People have been telling me total should be ~34*.
Those same people usually say that any timing number in the 50's is stupid advanced.

I think those people are not talking total. Just saying total.

When I say total, I mean total.