crate 502 ho timing issue

[Canuck 1]

have a timing issue with a crate 502 ho

No vac advance, 92 octane

14 initial with 22 of mech advance(36) it runs like a wet dog, no power and hot
27 initial and 22 mech advance(49) runs great, no detonation, just wants to kick the starter out

any ideas?

 

[obnoxious001]

What sort of timing light are you using? Have you verified TDC? What's the static compression on that particular engine, the marine stuff is like 8.75-1 or something. What altitude are you at, you should not be able to get away with 49 degrees total timing at sea level. Also, what about the carb, are you sure that's right? 36 total should be the norm for most big blocks, on the dyno I had one particular engine that liked 34 degrees better. 49 should be about enough to be burning a piston if that's what it actually is and the air/fuel mixture was correct.

 

[SBMech]

Crank balancer spun? I can't imagine it would take 49deg of timing. 34-36 total around 3k is what you are after.

 

[rivermobster]

Carb or EFI?

Is this a replacement engine? What happened to the engine you replaced??

 

[Canuck 1]

What sort of timing light are you using? Have you verified TDC? What's the static compression on that particular engine, the marine stuff is like 8.75-1 or something. What altitude are you at, you should not be able to get away with 49 degrees total timing at sea level. Also, what about the carb, are you sure that's right? 36 total should be the norm for most big blocks, on the dyno I had one particular engine that liked 34 degrees better. 49 should be about enough to be burning a piston if that's what it actually is and the air/fuel mixture was correct.

new gm crate, 30 miles
TDC verified, balancer marks verified
2 different timing lights(snap on)
8.75 to 1
3800' elevation
carb 750 holly( jetting a hair fat) and fi tech injection (removed)

all advance in by 2600

 

[Canuck 1]

Carb or EFI?

Is this a replacement engine? What happened to the engine you replaced??

yes a replacement, original engine was a numbers matching from another car and being returned to it

Started with a Fi Tech efi and pulled cause it ran like shit

 

[Canuck 1]

Crank balancer spun? I can't imagine it would take 49deg of timing. 34-36 total around 3k is what you are after.

Exactly, except for the starter drag/stall you would think that it was spun

 

[SBMech]

Exactly, except for the starter drag/stall you would think that it was spun

Double check the cam timing? Maybe a mistake was made in the grind/timing mark? I have seen it before. Once.

 

[obnoxious001]

new gm crate, 30 miles
TDC verified, balancer marks verified
2 different timing lights(snap on)
8.75 to 1
3800' elevation
carb 750 holly( jetting a hair fat) and fi tech injection (removed)

all advance in by 2600

Let's continue to chip away at the basics, since most will agree that's too much timing.

How fat is " a hair fat",, what about power valves and float bowl level? Is the carb jetted for sea level? 3800 feet of altitude is going to mean a couple of jet sizes.

Too much fuel would make it lazy, and increasing timing would make that better, but it's not correct.

 

[rivermobster]

yes a replacement, original engine was a numbers matching from another car and being returned to it

Started with a Fi Tech efi and pulled cause it ran like shit

No surprise there..

What carb is on it now? As Berry said...

What jets and all that?

 

[Canuck 1]

Let's continue to chip away at the basics, since most will agree that's too much timing.

How fat is " a hair fat",, what about power valves and float bowl level? Is the carb jetted for sea level? 3800 feet of altitude is going to mean a couple of jet sizes.

Too much fuel would make it lazy, and increasing timing would make that better, but it's not correct.

Carb is bang on in my zz 502 at 13.1 to 13.3, 13.9 to 14 .1 at idle

running 12,4 to 12.7 on this ho.... a hair fat
pv is 7.5
jetting is 72 and 78
Holley 4150
New msd hei distributor, 22* mech advance, no vac adv
cam timing not checked before install

 

[Your ad here]

Could it be something in the ignition system? Plug wires, coil, distributor, loose ground, alternator?

 

[Canuck 1]

Could it be something in the ignition system? Plug wires, coil, distributor, loose ground, alternator?

New wires
new dizzy
grounds good
alt new and tested good

 

[Blackmagic94]

Im gonna go with you are reading the timing marks wrong for 1000 Alex

 

[bocco]

Can you put more advance in the distributor so you need less initial timing? Would be easier to crank.

 

[DaveH]

verify the timing mark you are using is CORRECT.

if you really have nearly 50' of advance at full load and don't have holes in your pistons yet, you soon will.

you need to put a piston stop in the spark plug for number one and see if the TDC mark is correct.

if it is....there is something else VERY wrong. the only way you could run that much timing is if you were making no manifold pressure and power would be way down.

 

[DaveH]

if you are using an MSD ignition, make sure you don't have the pickup wires between the distributor and the box reversed. this will cause incorrect timing.

 

[Canuck 1]

verify the timing mark you are using is CORRECT.

if you really have nearly 50' of advance at full load and don't have holes in your pistons yet, you soon will.

you need to put a piston stop in the spark plug for number one and see if the TDC mark is correct.

if it is....there is something else VERY wrong. the only way you could run that much timing is if you were making no manifold pressure and power would be way down.

TDC and timing mark verified
No detonation
motor is out, disassembled and being checked
something is wrong

 

[Your ad here]

Just a wild guess but could the rod in the #1 hole be a different length than the other 7 causing this issue?

 

[Canuck 1]

Just a wild guess but could the rod in the #1 hole be a different length than the other 7 causing this issue?

I will know tonite, glad I bought a crate motor so I didn't have to spend time building one

 

[DaveH]

I will know tonite, glad I bought a crate motor so I didn't have to spend time building one

crate from who?

 

[Outdrive1]

Do you know how to set timing with a vacuum gauge? I don’t, but have seen some old school guys do it.


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[Canuck 1]

crate from who?

GM

 

[DaveH]

never seen a factory crate have an issue. aftermarket rebuilt crate engines.....that's a different story.

 

[DaveH]

Do you know how to set timing with a vacuum gauge? I don’t, but have seen some old school guys do it.


Sent from my iPhone using Tapatalk

the trick is to advance it to make as much manifold vacuum as possible. this comes into play even more so with fueling at idle.

 

[Canuck 1]

never seen a factory crate have an issue. aftermarket rebuilt crate engines.....that's a different story.

I bought 2 a month ago, a zz 502 and a ho 502. The zz is good, the ho is playing head games

 

[28Eliminator]

Just a thought. If they put one of those tape timing mark dealios on the balancer/damper. Make sure its for the correct diameter. It could read 8 or 10 degrees different.