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Discussion starter · #161 ·
Naw, aint no race car. 16 INI + 20 mech = , 36 TOT by 2600. Blame Dave Ray, I run his unit.
 
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#162 ·
novadude said:
Just curious... you say 36 mechanical. Are talking locked timing? No curve?
Click to expand...
10 degrees of vacuum advance might give you a highway mileage boost ? Does your dist even have a vacuum can ?
13 mpg is darn good for an engine like that. (y)
 
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Discussion starter · #163 ·
Beth a Crane adjustable can with a neat scroll plate installed courtesy of Dave Ray. Fully adjustable vacuum advance.

Trouble with an engine that OUTPUTS like this, and has decent dynamic compression, you can't throw 50 degrees at it and expect it to last. Builders orders are NO VAC ADV , it's written on the dyno sheet. When I do rescind that order, it will be for the whopping +4 degrees dialed up on the scroll limit plate. And then will monitor to se if it makes any difference. If not. I''ll unplug it.
Do the math, waste a incredibly well built machine for pennies in savings?

LT plan may be finally succumbing to installing an OD, btw. I KNOW that'll work! Only question there will how much timing lead does the engine need to pull a load at 2200 rpms, most easily.?
 
#164 ·
427L88 said:
Beth a Crane adjustable can with a neat scroll plate installed courtesy of Dave Ray. Fully adjustable vacuum advance.

Trouble with an engine that OUTPUTS like this, and has decent dynamic compression, you can't throw 50 degrees at it and expect it to last. Builders orders are NO VAC ADV , it's written on the dyno sheet. When I do rescind that order, it will be for the whopping +4 degrees dialed up on the scroll limit plate. And then will monitor to se if it makes any difference. If not. I''ll unplug it.
Do the math, waste a incredibly well built machine for pennies in savings?

LT plan may be finally succumbing to installing an OD, btw. I KNOW that'll work! Only question there will how much timing lead does the engine need to pull a load at 2200 rpms, most easily.?
Click to expand...
Whenever the warranty ends I would try an extra 10 degrees vacuum. That's what Dave recommends.
The danger would be adding advance at wide open throttle, and your vacuum advance should disappear at WOT (low vacuum).
I think you might see 16 mpg. That gives me hope. I will be using a TKX 5 speed with a 3.73 gear. (along with that nice flywheel you sent me) :)
Should be a 2.54 gear on the highway (.68 x 3.73)
 
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#165 ·
427L88 said:
....LT plan may be finally succumbing to installing an OD, btw. I KNOW that'll work! Only question there will how much timing lead does the engine need to pull a load at 2200 rpms, most easily.?
Click to expand...
If Mark specified no vacuum advance, then I would heed those words--unless you're willing to add a good splash of race gas (or 100LL) to the mix.

As far as mileage goes, an overdrive will offer far more benefit than anything else. Not sure what you have for a gear in the back now, but with the silly torque Mark's mill grunts out, you could probably get away with a 3.08 or 3.31 in lieu of an OD trans.
 
#166 ·
Engines need more advanced timing to burn lean mixtures. That's why vacuum advances were added, so engines would get more timing when idling and cruising.
It shouldn't have an effect on the octane the engine needs at full load because vacuum is zero at full load. Of course if there is too much vacuum advance, the engine can ping.
That's why most limit it to 10 degrees.
 

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#167 ·
nashville beth said:
Not speaking from experience, but I read a lot. LOL
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nashville beth said:
Engines need more advanced timing to burn lean mixtures. That's why vacuum advances were added, so engines would get more timing when idling and cruising.
It shouldn't have an effect on the octane the engine needs at full load because vacuum is zero at full load. Of course if there is too much vacuum advance, the engine can ping.
That's why most limit it to 10 degrees.
Click to expand...
You read a lot.

Mark builds--and dyno's--and races a lot of engines.

There is a world of difference.

There's a reason Mark advises not to run vacuum advance, and it's based on his personal experience, not stuff he's read.

Practical theory is one thing, real world experience is another. When they collide, the results are seldom good.
 
#168 ·
Vintage Musclecar said:
You read a lot.

Mark builds--and dyno's--and races a lot of engines.

There is a world of difference.

There's a reason Mark advises not to run vacuum advance, and it's based on his personal experience, not stuff he's read.

Practical theory is one thing, real world experience is another. When they collide, the results are seldom good.
Click to expand...
I always knew you were smart.
 
#169 ·
427L88 said:
Beth a Crane adjustable can with a neat scroll plate installed courtesy of Dave Ray. Fully adjustable vacuum advance.

Trouble with an engine that OUTPUTS like this, and has decent dynamic compression, you can't throw 50 degrees at it and expect it to last. Builders orders are NO VAC ADV , it's written on the dyno sheet. When I do rescind that order, it will be for the whopping +4 degrees dialed up on the scroll limit plate. And then will monitor to se if it makes any difference. If not. I''ll unplug it.
Do the math, waste a incredibly well built machine for pennies in savings?

LT plan may be finally succumbing to installing an OD, btw. I KNOW that'll work! Only question there will how much timing lead does the engine need to pull a load at 2200 rpms, most easily.?
Click to expand...
Gene

We should have built you a 517 HP combination, much more forgiving and vacuum advance friendly. Just think how happy you'd be with one of those:)
 
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Discussion starter · #170 · (Edited)
NOOOOOOOOOOOOOO WAY! You built EXACTLY what was requested AND MORE! Hey, I was actually pleased with 13.3 mpg. Even THAT was a surprise! ( with my low TQ garage built 427, it only mustered 10 mpg, at exactly the same settings - with VAC ADV on! )

Eric, the car sports only the OEM 3.31 now so it's pretty high.

Mark, I may be calling for one of the 517s, but not for me, for a young friend who now has his deceased dad's 69 and having all sorts of engine issue with a "professional build". And its not tuning - I;ve tweaked it.

I told my buddy to call you when he had the thing built, but he chose some "guru" In Toronto who apparently is less of a guru than even me the amatuer building in my garage. :( .. . Anyway, it may end up being a "garage refresh", don't know yet as my young friend's landscaping career isn't making him well off. Or I buy my 427 back from the racer who hasnt used it yet ( cheap 2K) and give it to the kid. Cant even get to the car now due to covid.

So I may need to order one of those 517s soon after all ! And it WILL use a Qjet! :)

PS Mr Jones, the only thing ive screwed up so far is electing to reuse the exhaust gaskets the engine shipped with. My "morel lifter tick" was actually #1 and #5 ex ports leaking a bit. Those white headers leave a tell tale sign! Total PITA to change out properly in the car, but I have some very forgiving PERCY's to install ;assuming it'll end up with some surface anomalies as I cant scrape the ports 100% clean on the drivers side.

.
 
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#171 ·
427L88 said:
NOOOOOOOOOOOOOO WAY! You built EXACTLY what was requested AND MORE! Hey, I was actually pleased with 13.3 mpg. Even THAT was a surprise! ( with my low TQ garage built 427, it only mustered 10 mpg, at exactly the same settings - with VAC ADV on! )

Eric, the car sports only the OEM 3.31 now so it's pretty high.

Mark, I may be calling for one of the 517s, but not for me, for a young friend who now has his deceased dad's 69 and having all sorts of engine issue with a "professional build". And its not tuning - I;ve tweaked it.

I told my buddy to call you when he had the thing built, but he chose some "guru" In Toronto who apparently is less of a guru than even me the amatuer building in my garage. :( .. . Anyway, it may end up being a "garage refresh", don't know yet as my young friend's landscaping career isn't making him well off. Or I buy my 427 back from the racer who hasnt used it yet ( cheap 2K) and give it to the kid. Cant even get to the car now due to covid.

So I may need to order one of those 517s soon after all ! And it WILL use a Qjet! :)

PS Mr Jones, the only thing ive screwed up so far is electing to reuse the exhaust gaskets the engine shipped with. My "morel lifter tick" was actually #1 and #5 ex ports leaking a bit. Those white headers leave a tell tale sign! Total PITA to change out properly in the car, but I have some very forgiving PERCY's to install ;assuming it'll end up with some surface anomalies as I cant scrape the ports 100% clean on the drivers side.

.
Click to expand...
Speaking of white headers Gene, what did you end up doing and how did they come out?
 
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#173 ·
Vintage Musclecar said:
You read a lot.

Mark builds--and dyno's--and races a lot of engines.

There is a world of difference.

There's a reason Mark advises not to run vacuum advance, and it's based on his personal experience, not stuff he's read.

Practical theory is one thing, real world experience is another. When they collide, the results are seldom good.
Click to expand...
You said an engine will need higher octane gas if a small amount of vacuum advance was added. That makes zero sense.
Mark Jones is a skilled builder. Why are you dragging him into the conversation ?
 
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#174 ·
nashville beth said:
You said an engine will need higher octane gas if a small amount of vacuum advance was added. That makes zero sense.
Mark Jones is a skilled builder. Why are you dragging him into the conversation ?
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I didn't drag Mark into the conversation, he's been engaged in this conversation from the get-go.

I've done work for Mark and for several of his customers--as such, we've talked on numerous occasions. He & I discussed Gene's engine as well so I had first-hand information to work from when building Gene's carb.

Mark is the one who instructed Gene not to utilize vacuum advance--Gene stated that early on in this thread. I simply reiterated Mark's advice.

Again--consider how many engines Mark's built and tested. Don't you think he's experimented with timing variables along the way? Did you notice his post above where he states his 517 HP combination IS vacuum advance friendly?!?

Again, Mark is advising Gene based on his own personal experience with this specific combination--if Mark cares to elaborate as to why he advises against vacuum advance in this instance, he can tell you personally. I know why as it's one of the things we discussed about Gene's build, but frankly I'm weary of debunking automotive internet lore ad nauseam and those who parrot it.
 
#177 ·
>> Because, y'know, I'm just a stupid female as you and Mark Jones have noticed ?
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Please lay off that stuff. People here already know you're a smart and talented professional engineer.
 
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Discussion starter · #179 · (Edited)
It was not condenscending. Why get snippy Beth? You sort of ask questions, belligerently with a POV, and then " TRY READING SOME EDUCATIONAL MATERIALS".?

I'm no fan anymore either ma'am, of yours. Also as this thread is now dead, I wont have to ask you to haul your ass the hell out of it. In fact in review, all you did was obfuscate and challenge in fact. I was being MORE courteous than if you had been just another swinging dick, but no more. . .now I get to treat you like just another rabid dick-wearing asshole. Lovely. See chivalry is in fact dead. And y'all killed it.

I go from peaceful to asshole in a heartbeat. Always have, so it aint male menopause.


NITROFOX - bought these 2"/3.5" collectors Hookers in 2001 from JetHot, on their third recoat now in white. ( i'm not fastidious enough to own white headers btw - SUPER hard to maintain)
 
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#180 ·
Gene, my apologies if I contributed to this thread getting knocked off the rails. I just can't sit by and remain silent while someone continuously parrots what they've read and in doing so put others at risk of damaging their cars.

My writing style tends to be "matter of fact", it's not meant to be condescending--but I'm not going to mollycoddle for the sake of someone's feelings either. It does however astound me that simply reminding someone by their own admissions that they have no personal first-hand knowledge on a particular subject that they get completely bent out of shape.

As far as "reading some educational materials"--who's being condescending there? I am in fact a voracious reader, have been since I was little. Like most others here, I've read everything I could get my hands on about cars over the years. I have also applied many of the things I've read over the years. To no surprise, some of the things I've read worked in a positive manner while others worked out in a negative manner.

The moral here?: One size does NOT fit all.

In the 20+ years I've been on this site (for a while under a different user name back when I first joined) and over at the Yenko site, I've tried to pass along as much first-hand knowledge as I could in an attempt to help others avoid making the same mistakes I've made over the years. I wasted so much time and money over the years it's not funny, and I would've given my right arm to have someone looking over my shoulder when I was less experienced offering me the free advice I'm trying to offer others today.

What do I get in return?

This.
 
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