60 Fuelie without it...

[Wayne G.]

Wondering if someone would be able to suggest timing on a 60 fuelie without it... I know base is 18 per specs... with a holley vacum secondary and a dual point distro no vacuum advance unit, should I set total at 3000rpm or set base, the 2 settings are very different... also just to note I tried to set it with vacuum gauge and its about 18 but then I loose the idle sound but off idle is much better, does any one know the vacuum reading on the motor with the fuelie unit?

With the stock cam and all were would I want total to be at? 3k rpm?

Also if it help I don't really know what distro it has I think off a 65 if I had to guess i could get numbers, but the wieghts on it really kick in fast, anything over 450 idle and they come out... I tied them off to try base setting at a higher idle rpm.. she love to idle real low... 550 or so.. maybe I am to low and not used to a 650-850 idle... I forget what spec idle is... but again she sounds much better lower rpm... I am trying to tweak to get a little more off idle zip to the pedal...

thank you...

[Loren L.]

Re: 60 Fuelie without it...

Let's start simple - do you actually know what camshaft is in the motor = have you held it in your hands and ID'ed it?

[Wayne G.]

Re: 60 Fuelie without it...

Let's start simple - do you actually know what camshaft is in the motor = have you held it in your hands and ID'ed it?

I know the car is 54k original miles and know its the factory cam 290hp... the high lift solid lifter Fuelie cam... it has never been apart or out of the car... is this the 30/30 or the Duntov? I forget... but original for the 315/290hp car...

[Duke W.]

Re: 60 Fuelie without it...

The type of induction system - FI or carb - has no influence on what the spark advance map should be, but the camshaft has a big influence.

According to the AMA specs the spark advance map for the '60 FI engine with "special" (Duntov) cam is start @ 1000, 5 @ 1500, and 22 @ 6000 (max), and the 18 degree initial recommendation yields 40 total WOT advance, but it's not all in until 6000, so the centrifugal curve is very lazy.

According to what you said this has been modified if it starts at 450, so you need to determine what it actually is including the maximum advance and at what RPM it is in. You may need to get a spring kit like a Mr. Gasket 928G, and tailor it.

My recommendation is that centrifugal should start at about 800-1000 and be all in between 2500 and 3000. Then you set total WOT advance to achieve the range of 36-40.

Depending on what the actual CR is you may be able to get 40 without detonation, but if it does detonate, reduce in two degree increments to no less that 36. If this does not quell detonation, slow the centrifugal curve with stiffer springs.

If it actually has Duntov cam or something with similar effective overlap, you should set the idle speed at about 900 and manifold vacuum should be about 12" Hg.

Measure the head gasket thickness at the front corners of the head-block interface with feeler gages. The OE gasket is .018", and if this is what you measure, the heads have likely never been off, so the compression ratio is probably around 10.5-10.8, but may be as high as the 11:1 advertised by GM, but that would be a rare case.

If it doesn't detonate with the current centrifugal curve, which appears to be much more aggressive than OE, then the CR has probably been lowered with different pistons and/or a thick head gasket.

Duke

[John D.]

Re: 60 Fuelie without it...

Duke, My 63 FI car with an 097 (CS113R) has 16" at 900-950 RPM. John

[Wayne G.]

Re: 60 Fuelie without it...

Ok that makes sense I think I was going the wrong way... if I use a dial light and make all in 36 for 3k it makes the initial /idle pretty high if I recall, but that is because the springs on it now are real light... the rpm needs to be about 450 so they don't fly out... I think I will do the old dial in by ear and measure, she ran fine before just after checking the points and distro, I never marked the base... base is not really all that important as she did run fine... if I set total and then drive and see I think I will be fine... just the strange one is the power valve is 10.5"... not sure what the jet size is I would think factory the carbs off the GM parts shelf from a 65 Chevelle r3139 if memory servers me correctly matched to a single plane intake I think sort of a weiland high rise... I think at 18 and 450rpm I do not have enough base, will reset and see.... now that I know what total is.. I know I have more room to go, 18 base @ 450 she's lacking power. I just needed the specs I may change the curve, the distro(add a vacuum for better milage) and or even rejet as she pretty much is a gas hog.... and I can see she runs way to rich... the holley is vacuum secondaries and I think maybe the carb is way to much for the car...? it's from a 396 Chevelle motor, with about 325hp so its in the ballpark, was told back in the day these were the parts they ordered and bolted on when they remove the FI units because no one new how to adjust properly, hey no worries I have 2 82 crossfires that I have modded the TBI its a piece a cake if you know the baselines.... its when you don't know, don't have a dyno and cant get someone to lay on the engine while you do 120 at 6krpm and set the distro by hand.... LOL... Unless its on my 77 Chevy Van piece of cake its right next to your hip... LOL.... just tingles a bit.... hehehe

What is the AMA? I have the AIM but would love all the specs/fags/.techo data I could have about the car...

[Duke W.]

Re: 60 Fuelie without it...

You have to eradicate that "36 at 3K" myth from your brain. I know, it's "advise" that's all over the Web, but it's BS!

You have to set total WOT advance a few hundred revs over the engine speed that centrifugal is all in.

This could be 2500 to over 6000 if the centrifugal is OE, but maybe it's modified. It takes a matter of seconds to determine with a dial back timing light.

Go to the GM Heritage website, select "vehicle information packages" and downlaod those for you car and any other GM car that interests you. These include the AMA specs and lots of other useful technical data.

Duke

[Duke W.]

Re: 60 Fuelie without it...

Duke, My 63 FI car with an 097 (CS113R) has 16" at 900-950 RPM. John

It's been a long time since I measured manifold vacuum on my original 340 HP engine, but I distinctly recall about 12" at about 850-900 with about 30 degrees total idle advance. It also had noticeable lope.

Any engine that pulls 16" or more will not have that lope because flow past the throttle valves is critical, which means it' sonic and choked. That's why they don't lope, air flow is constant.

If less than 16" you pick up lope due to non-critical air flow, so it varies and that's why they lope.

I know I've explained this before in more detal on the TDB.

Maybe others can chime in with measurements, and I think you should try another vacuum gage.

Duke

[Wayne G.]

Re: 60 Fuelie without it...

Yes I was sorta just quoting the myth... seems like they all say start there? But I know all to well its no the case....
Hmm I have those guides great info, I think I missed the timing section will re read it..

I will see how much I have on the distro and check out how fast she comes in... I know I need to redo the weight guides they are pretty worn and I have a good selection of springs from all kinds of them kits..

I think what I was asking/thinking is what is base set at? 450 or 900rpm but didnt' really ask... the weights fly out big time at anything above 450... if I recall at 650 she's almost 5 degree difference... I tried also to vacuum guess adjust at idle... that seemed to be the best, I think I was at 18" which seemed high... she idles strong but then you loose the nice idle sound I know she always had.... with the side pipes it almost easy to tune by ear its nice sound...

thanks again will get er done this weekend...

[Duke W.]

Re: 60 Fuelie without it...

Initial timing must be set at an engine speed below where the centrifugal starts, but that can be difficult on some engines. For example, the 365/375 HP 327s start at 700, but they won't idle stably below that speed long enough to check and adjust the distributor.

But since it's all in at 2350 a better way is to set the total WOT advance with a dial-back light at about 2500 (VAC disconnected and plugged). The last one I did ended up at 39, and it didn't detonate, so that was good enough, and the engine ran very well.

The other issue is that on 327s with the 8" balancer the timing tab is not accurate (which has been discussed here several times), so setting total WOT advance with a dial back light is the way to go, but L-79s and late 300 HP engine centrifugal is not all in until 5100, so you would have to rev to about 5500 to set it accurately.

The cure for this is to install lighter springs to bring the centrifugal all in at no more than 3500, and doing this will also improve low and midrange torque/power and deliver better fuel economy.

The basic rule is to get the centrifugal in as fast as possible absent detonation, which is usually the limiting factor. Under most operating conditions most engines run most efficiently on the ragged edge of detonation. That's how modern engines operate since the control system can continually adjust timing to the incipient detonation value. On vintage engines with simple mechanical analog controls, we can only get close and have to leave a little margin.

All of the above is explained in my 2012 San Diego National Convention presentation, which can be easily found on the web with a Google search.

If your engine is pulling 18" at 450 it doesn't have a Duntov or other high overlap SHP cam. Engines with the low overlap base engine cam pull 18-19" idling at 500 in neutral.

Duke

[Wayne G.]

Re: 60 Fuelie without it...

Initial timing must be set at an engine speed below where the centrifugal starts, but that can be difficult on some engines. For example, the 365/375 HP 327s start at 700, but they won't idle stably below that speed long enough to check and adjust the distributor.

But since it's all in at 2350 a better way is to set the total WOT advance with a dial-back light at about 2500 (VAC disconnected and plugged). The last one I did ended up at 39, and it didn't detonate, so that was good enough, and the engine ran very well.

The other issue is that on 327s with the 8" balancer the timing tab is not accurate (which has been discussed here several times), so setting total WOT advance with a dial back light is the way to go, but L-79s and late 300 HP engine centrifugal is not all in until 5100, so you would have to rev to about 5500 to set it accurately.

The cure for this is to install lighter springs to bring the centrifugal all in at no more than 3500, and doing this will also improve low and midrange torque/power and deliver better fuel economy.

The basic rule is to get the centrifugal in as fast as possible absent detonation, which is usually the limiting factor. Under most operating conditions most engines run most efficiently on the ragged edge of detonation. That's how modern engines operate since the control system can continually adjust timing to the incipient detonation value. On vintage engines with simple mechanical analog controls, we can only get close and have to leave a little margin.

All of the above is explained in my 2012 San Diego National Convention presentation, which can be easily found on the web with a Google search.

If your engine is pulling 18" at 450 it doesn't have a Duntov or other high overlap SHP cam. Engines with the low overlap base engine cam pull 18-19" idling at 500 in neutral.

Duke

I know you know you stuff, that's why I come here... Here are the facts.. but please I was asking what is the vacuum of the Duntov Cam. I have it for sure... Whats the idle vacuum reading around?

Ok here are the facts about the DISTRO... Anybody need one? trade for a 60 FI one... ...

for sure I have a 62 1110985 its specs are 700 idle at 10 degree's / per the AMA and 11 @ 1600 and 23 at 4600 ( that explains why I get so much more if I try and set total 40...

But give these facts what would be a good setting... I really recall the idle was choppy and lobie (check that spelling ? LobeY?) as a matter of fact just cuz it would I used to ilde it at 450 for the shows and it almost sound like was ROLLING OVER... real pretty... but you have to rev high pull out good...

I know I am trying to get a 60 weight setup and or have someone make me one on this one... I see they braze the center thing in compared to GM HEI styles... I guess I could play with the springs and see if I can get it better. but not sure if the curve is ok...

So given the 62 Disto's in my 60 with Duntov cam should I be thinking I need more than 18 base to get it all in by 3000?

I am thinking maybe a Pertronix or other aftermarket distro, don't want to go crazy here with aftermarkter... really would like a factory curve, I am not sure but with the tach drive and FI drive it may not work on this intake...

[Duke W.]

Re: 60 Fuelie without it...

I can't make much sense out of your post, but I already answered your question.

Duke

[Wayne G.]

Re: 60 Fuelie without it...

I can't make much sense out of your post, but I already answered your question.

Duke

ah yes you did I missed the vacuum, what I was asking is I have Duntov and have the a 62 distro for sure 1110965, what I did was to shim it that got rid of the bounce, was asking what I should set it at since I have that distro? Still the all in at 2500-3000 range..... ?

I will try and use lighter springs and see what happens... going to be removing the points and go with the TI Specialtes conversion kit...

I read you 2012 makes sense read that a few years back but forgot about it.. - Great read....

I also read you fix on the Holley carbs to add the screw to the secondaries for adjusting the plate. I rebuilt what I had and had to use another base plate and reset the screw (just to double check it) but I have a issue with it not being correct... will do that mod and I think will be ok untill I can get the distro curved correctly... was sort of asking without directly What is the BEST curve I could get for it... if anyone knows there are folks that do the 62--?? distro and make the curve what you want...

thanks... should not post late at night LOL...

[Duke W.]

Re: 60 Fuelie without it...

The '62 dual point distributor part number ends in 985; start at 700, 24 @ 4600, no VAC, but the partial data you reported does not jibe with the original specs. The ideal centrifugal curve is the same as the 365/375 HP engines - start at 700, 24 @ 4600, and a B28 VAC. That's the setup I have on my '63 340 HP engine going back to circa 1965.

The above assumes a Duntov cam, but the idle partial behavior you reported does not jibe with that cam. There's no way in hell that a Duntov cam will idle stably at 450.

Available springs may not let you get centrifugal all in this fast, but it should be all in at no more than 3500. Then set total WOT advance at 36-40 a few hundred revs above where you determine centrifugal in all in - as high in the 36-40 range as the engine will tolerate without detonation.

What you need to is determine what the curve is now. You reported it starts at 450, but did not report the maximum @ RPM. You also need to measure manifold vacuum at whatever idle speed you choose after going through the idle speed/mixture adjustment procedure. My recommendation for idle speed is "as low as possible commensurate with acceptable idle quality". For a Duntov cam I consider about 850-900 as the lowest acceptable. If it idles acceptably at 450 regardless of manifold vacuum I doubt if a Duntov cam is installed.

Duke