[Eddie]

I forgot to ask Dave if he 'opened' his exhaust cutouts and zinged the engine and scared any small children at the show!

Yes I did. One woman jumped and yelped out loud.

I had a feeling you would do just that. Good Man!!

[dave-r]

Some updates from the weekend.

I was having some overheating problems with the trans so fitted a better cooler unit. This has worked as the trans now runs at 160F.

The temp modification I made to the timing stop in the MSD dizzy, in order to suss out the size I needed, was starting to fall apart so I had to make a new permanent bush of the correct diameter.
I found some unused nylon fuel bowl screw washers that were just about the right size. So I stacked two together and nipped them up tight.

I am using one light silver and one heavy silver spring.

This resulted in 18 degrees initial and 36 total. Half of it is in by 1500rpm and the rest by 3000rpm. That will do for now.

I also fitted a 6.5 inch power valve, went up one jet size on the center carb to #65s, and increased the idle mixture a bit.

The car now idles stronger but is a bit too rich (12.4:1) until 3500rpm. So I think I need to go down one jet size again and open up the outer carb jets a touch more.

I wish I had been able to figure out a way to fit throttle position sensors on the carbs because knowing when they open would make things easier.

[dave-r]

Maybe I was going slightly uphill on the lower rpms and downhill on the higher rpms?

I will have to do more tests and do them along the same stretch of road. Not easy with all the traffic around here.

Idle in gear (and out in traffic) vacuum sometimes goes down from 8" to 7" too. That 6.5 inch power valve might be too close a rating.

[drewcrane]

That 6.5 inch power valve what did you have before?

[Eddie]

Looks like you're pretty close Dave. How's it accelerate? Any driveability issues? Since your changes is the idle vacum higher now or lower than before?

About the same vacuum (mostly around 8" in gear) but seems to sometimes flick down to almost 7" at times?

It drives like a bloody animal. No flat spots or bogging. It will burn rubber at anything under 50mph when you floor it.
I have squeezed the throttle a little to overtake at 70mph and find that without even noticing I am suddenly doing 110mph.

I think I will disconnect the outer carbs again and go for a test drive as it is now. If it is still too rich I will drop a jet size again and look at opening the seconday plates.
But if the mixture is OK it could just be that my throttle position when I was recording was tickling the outer carb pump shooters (remember this is a triple pumper set-up) and they may have been causing a richer condition.

I need more tests. Been raining tonight though.

[dave-r]

That 6.5 inch power valve what did you have before?

4.5 I think? My memory is terrible.

[drewcrane]

That 6.5 inch power valve what did you have before?

4.5 I think? My memory is terrible.

yea mine too,

[dave-r]

Just been out for a really good drive with Metallica turned up high on the CD player.

But it was instructional because i see i do need to go back down one jet and go down a size on the power valve too. I might even go back to the 4.5.

But it was a good drive and I just chilled out and had a good time.

Trouble is I keep hitting 100+ every time I overtake someone doing less than 70. I don't do it on purpose. Honest. I just kick down and I am doing over 100 by the time I have checked my mirror to see if it is safe to pull back in.

I will get my shoulder felt by Mr Policeman if I am not careful.

[drewcrane]

Just been out for a really good drive with Metallica turned up high on the CD player.

But it was instructional because i see i do need to go back down one jet and go down a size on the power valve too. I might even go back to the 4.5.

But it was a good drive and I just chilled out and had a good time.

Trouble is I keep hitting 100+ every time I overtake someone doing less than 70. I don't do it on purpose. Honest. I just kick down and I am doing over 100 by the time I have checked my mirror to see if it is safe to pull back in.

I will get my shoulder felt by Mr Policeman if I am not careful.

what colour is your car? ticket orange Mr po po can see and hear you coming

[dave-r]

And that is with only the center carb hooked up.

I keep forgetting the old and very wise rule of tuning. Change only one thing at a time.

So I am going to put the 4.5 power valve back in and try it again. Weather permitting.

[Jon]

That's a pretty low power valve rating. I forgot what brakes you are using are they vacuum assisted?

Cranking Metallica and a 440 at the same time may have had something to do with you speeding episodes. When you say 70 and 100 is that in kilometers? Getting caught around here doing 100MPH might get you a feel from Bubba in the county join.

[dave-r]

That's a pretty low power valve rating. I forgot what brakes you are using are they vacuum assisted?

No power assisted anything on my car. All done with muscle power.

When you say 70 and 100 is that in kilometers? Getting caught around here doing 100MPH might get you a feel from Bubba in the county join.

Nope. Good old English miles mate. Johnny Foreigner may have converted our measuring sticks to metric but we still distance in miles. They can take our inches and our ounces but they will never take our miles!

Automatic ban for doing 100mph. A fine and penalty points on your licence for anything above 70mph. Although in reality if you are on a dual carrageway they tend to only pick on people doing over 85-90mph. And there are always plenty of guys driving that fast to keep them busy.

[RedRaven]

Wow is it really a ban for doing a ton Dave?

[Tim]

Wow is it really a ban for doing a ton Dave?

30mph above whatever the speed limit happens to be, and you're catching the bus for the next three years.

Unless you happen to be a Rozzer 'testing' your new patrol car out at 155mph. Dont get me started......

[drewcrane]

That's a pretty low power valve rating. I forgot what brakes you are using are they vacuum assisted?

No power assisted anything on my car. All done with muscle power.

When you say 70 and 100 is that in kilometers? Getting caught around here doing 100MPH might get you a feel from Bubba in the county join.

Nope. Good old English miles mate. Johnny Foreigner may have converted our measuring sticks to metric but we still distance in miles. They can take our inches and our ounces but they will never take our miles!

Automatic ban for doing 100mph. A fine and penalty points on your licence for anything above 70mph. Although in reality if you are on a dual carrageway they tend to only pick on people doing over 85-90mph. And there are always plenty of guys driving that fast to keep them busy.

thats soooo funny "Jonny foreigner" rofl,man just a fine that will land you in the pokey for sure around these parts

[dave-r]

I will just be telling people I am called Eddie Nasser.

[dave-r]

Well i am glad i only made the one change before testing again.

With the 4.5 power valve the center carb only mixture is 13.0:1 give or take 0.2:1 over the whole rpm range from 2000rpm to 3800rpm. Manifold vacuum never went below 6.3 inches at any point (although I never floored it) and even then that was just the once. Coming to a stop at lights etc the vacuum dropped to about 7.3 inches at times. But I suspect the 6.5 valve was opening a little before.

For some reason the carb goes slightly richer (12.4:1) just before 4000rpm and above. Can't figure that out (venturis working better at high airflow through the little carb?) but that actually helps because the outers are slightly on the lean side so if it wants to go rich it helps me.

So I am sticking with these cards in my hand thank you.

[RedRaven]

I will just be telling people I am called Eddie Nasser.

You lookin to get strip seached then Dave!!!???

[Jon]

Don't tell me the your wife's using metric conversions for tonight's dinner recipe.

[drewcrane]

i bet ya matallica does'nt use metric

[Littlebluefish]

Wow is it really a ban for doing a ton Dave?

30mph above whatever the speed limit happens to be, and you're catching the bus for the next three years.

Unless you happen to be a Rozzer 'testing' your new patrol car out at 155mph. Dont get me started......

M54? I remember that.

Got banned for doing 31 over the limit 4 years ago, still paying for it as can't get insurance for less than my house is worth.

Dave, it was great to see your car back on the road and the strip at the Nats. Looked peachy.

[dave-r]

Dave, it was great to see your car back on the road and the strip at the Nats. Looked peachy.

Thanks Stu.

[Littlebluefish]

Rumbled...

It wasn't the best disguise really, was it?

I'll post a hello elsewhere later Dave, save Hi-jacking your thread.

[Eddie]

[Eddie]

Sounds like Daves tune is close to perfect. I spoke with Don@ FBO and he said my PV should be 2 points below my lowest idle vacum. He also is adamant about tuning the idle circuit with the idle feed restrictors instead of messing with the transition. I'm not sure about this but the logical thing to me is to have the PV a slight amount on the lean side and use the idle mixture screws to fatten up the idle to aid in the 'Tip In" to intermediate..Big cams with lots of overlap. Mines at 76 degrees,(I&E). Having that vacum reading datalogged is superhandy no. Whats your opinion on this Dave.

[RedRaven]

Sounds like Daves tune is close to perfect. I spoke with Don@ FBO and he said my PV should be 2 points below my lowest idle vacum. He also is adamant about tuning the idle circuit with the idle feed restrictors instead of messing with the transition. I'm not sure about this but the logical thing to me is to have the PV a slight amount on the lean side and use the idle mixture screws to fatten up the idle to aid in the 'Tip In" to intermediate..Big cams with lots of overlap. Mines at 76 degrees,(I&E). Having that vacum reading datalogged is superhandy no. Whats your opinion on this Dave.

...........Im dizzy after reading that Eddie.......still way over my head..........sounds great though!!

[Jon]

I'm working with jetting my (two stroke) dirt bike right now, and fat off the idle curcuit to a lean midrange will cause a surge or edge that is not comfortable to deal with. I realize the power-band or in your case Cam is involved but I think the "fuel" transition can help smooth it out.



Dave, that picture in your avatar is the best stance I have seen. No B.S. Do you have a full size for wallpaper?

Jon

[drewcrane]

best stance ,yes i have to agree a quite nasty stance ,i might have to copy that

[dave-r]

Sounds like Daves tune is close to perfect. I spoke with Don@ FBO and he said my PV should be 2 points below my lowest idle vacum. He also is adamant about tuning the idle circuit with the idle feed restrictors instead of messing with the transition. I'm not sure about this but the logical thing to me is to have the PV a slight amount on the lean side and use the idle mixture screws to fatten up the idle to aid in the 'Tip In" to intermediate..Big cams with lots of overlap. Mines at 76 degrees,(I&E). Having that vacum reading datalogged is superhandy no. Whats your opinion on this Dave.

I like the throttles completely (or almost completely) closed at idle if possible and get the right idle speed by first of all using enough initial advance and then by drilling correct sized holes in the throttle blades to get the speed i want and at the same time tune the idle mixture screws to just a slight touch leaner than max manifold vacuum.
That is all I do and it works for me.

But my metering block is from a 850DP Holley rather than the original 2bbl one.

[dave-r]

Dave, that picture in your avatar is the best stance I have seen. No B.S. Do you have a full size for wallpaper?

Jon

Sorry but as it was taken by a professional who has to make a living from these photos I can't post high res versions just yet. We don't know which ones will be used for publication in a magazine yet either. I will ask him though.