440 jetting changes.....these plugs looking kind of lean?

[KillerBee]

Doing some carb jetting after fixing a major intake oil leak on my 440 engine.

Engine a 1966 440 with bone stock bottom end.
 It has it's original 516 closed chambered heads that have been slightly modified with bigger exhaust valves.
Cam is the MP .528 solid
Intake is an old single plane Torker II
Carb is an old Holley 4150 750 double pumper
fuel bowl levels are set
air/fuel screws responded good and are set at a max vacuum of 7hg
currently using a 4.5 power valve in carb
front squirter is 28
rear squirter is 35
Current jets are 76 in front and 84 in the rear

Firecore distributor with vacuum advance plugged
Timing is at 36

Took it for a quick blast running it hard then got it home quickly and pulled the plugs

What do you all think? Pretty lean?
They all look very similar.

Previously, before the intake oil leak was fixed the plugs were covered in oil and fouled so this is a major improvement.
Car currently seems to run very strong but it is seen to run out of breath at around 5400 rpm

I'm not real experienced with jetting but how high can I safely go with jetting on a close to stock 440?
How high of jetting are some of you guys at?

Thanks.

[cudabob496]

look good to me
jetting seems fine
maybe a 6.5 power valve?

[HP_Cuda]

They look like they are doing just fine to me.

What was your vacuum at idle? If you are running at 4.5 PV then you should be pulling like 9-10" of vacuum.

[KillerBee]

Thanks guys.

I'm going to leave the jetting alone for now.

The engine vacuum at idle was 7 but quickly jumps up when the engine is revved.

The carb had a 6.5 in it previously and I replaced it with a 4.5 when I did the jet change today as that was the lowest power valve I had at the time.
Interestingly, I think the car revved quicker/better off idle with the 6.5 power valve.
The 4.5 power valve didn't stumble off idle but just felt a little flat compared to the 6.5 that felt much more "instant" on power.
The front squirter is adjusted and seems to work fine so I don't think that's the issue as the only difference was the power valves.

I know the common suggestions on choosing a power valve based on 1/2 the idle vacuum but I've also heard and read that using a higher power valve is also good on certain engine with more aggressive cams(with lower vacuum) and manual transmissions as it gets the fuel enrichment going in quicker at the higher vacuum point.

Here's a quote from a Holley tuning expert:
"On a manual transmission vehicle, hook up the vacuum gauge and take the reading with the engine at idle. Then use a power valve that is rated 1-2 inches below that amount. For example, a motor that shows 7" of vacuum at idle should use a 6.5 or 5.5 rated power valve".

I might just go back to the 6.5 power valve and drive it for awhile.

[HP_Cuda]

Never heard of using the higher PV on a more aggressive cam but try it and report back.

I'd love to hear how it goes.

[cudabob496]

I think the 6.5 is giving you more gas when you need it.
7psi vac at idle. I'd up my idle or timing

You seem like a very precise guy, like me. You gotta get an AFR meter.

[KillerBee]

Never heard of using the higher PV on a more aggressive cam but try it and report back.

I'd love to hear how it goes.

I pulled a couple spark plugs this morning BEFORE changing the jets and installing the 4.5 power valve.
They were just as light as the ones pictured.
That was about 50 miles of driving with the 6.5 power valve and 73 front and 80 rear jets.

Car is running real strong, will bark the tires hard in 2nd and 3rd gear running tiny 2 1/4" full stock exhaust.
 I can't spend a lot of time tinkering with this engine until next spring, too many other projects.....just happy it runs as strong as it does considering I thought the engine was shot and I was jump limping it along. If I make good progress on the wife's car I just might sneak this one down to my local 1/8 mile dragstrip and see what it will do. 

[KillerBee]

I think the 6.5 is giving you more gas when you need it.
7psi vac at idle. I'd up my idle or timing

You seem like a very precise guy, like me. You gotta get an AFR meter.

Yes the AFR will be going on this car next spring with FITECH fuel injection and aluminum heads.

[HP_Cuda]

The idea behind the power valve is that it opens when you hit the number stated on the Power Valve.

If you are running 7" of vacuum at idle and you have a 6.5 PV then you will be opening quite quick and dumping fuel.

See here:
http://forums.holley.com/entry.php?430-Holley-Power-Valve-Tuning

[CUDA JAS]

Thanks guys.

I'm going to leave the jetting alone for now.

The engine vacuum at idle was 7 but quickly jumps up when the engine is revved.

Wait...is that typed correctly.

The engine vacuum increases when you hit the throttle??

Jason

[KillerBee]

Wait...is that typed correctly.

The engine vacuum increases when you hit the throttle??

Jason

From what I remember the vacuum jumped up on the gauge when I increased the throttle.

I'll check at it again.

I'm curious, what port is everyone hooking the vacuum gauge to?
I'm using a plug on the intake manifold itself, not the ports on the carb.

[HP_Cuda]

You want to be hooked to a manifold port.

The vacuum will rise a little when adjusting idle rpm up but will drop like a rock when the throttle plates open.

[CUDA JAS]

You want to be hooked to a manifold port.

The vacuum will rise a little when adjusting idle rpm up but will drop like a rock when the throttle plates open.

 

That's why I asked!



Try it on the bottom port on the card...that is usually manifold vacuum.

[Chryco Psycho]

Yes that is orret as throttle is opened the vacuum leak becomes larger so vacuum drops but ported vacuum inversly will rise

[HP_Cuda]

 Vacuum leaks will also show themselves as a very poor idle