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  #91  
Old 10-12-2017
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kmathis kmathis is offline
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It is interesting that DanR and I are having similar issues with idle and whatnot, I just spoke to John at Delta Camshafts and he feels that the cam is the same profile as they have been grinding for 30 years...he did say that it was a mild cam not a full race cam and he will grind one and check the specs to the original specs to see if anything has changed.

The grind is called the Jose Grind, however it was a collaboration between the performance that Jose expected and the cam grinder did the engineering, so we will see what he comes up with.

My old Delta Camshaft that I had in my original motor is being used by Rich Gordon in his stock V6 and it runs great, doesn't have any vacuum issues or timing issues, so that makes two motors that ran great on that Delta camshaft.

I may want to buy those camshafts from you Dan, should you want to sell them, if nothing else for a comparison for Delta. I'm thinking that there is more here than meets the eye, if it does turn out to be the cams, then I will definitely change mine out. I will give them a chance to defend themselves.
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  #92  
Old 10-12-2017
RootesRacer RootesRacer is offline
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Quote:
Originally Posted by Ken Ellis View Post
Would an auxiliary source of proportional vacuum help? Like an electric vacuum pump governed by RPM? In other words, would being able to adjust timing dynamically thru the distributor vacuum advance do the trick?
Are you suggesting to use a pump to give some vacuum to the dizzy since the engine makes not idle vacuum?

No, bad idea. The vacuum is used becuase it is an indicator of engine load (to a large extent). The engine makes no vacuum at idle due to valve overlap but WILL make a strong vacuum at some higher RPM with the engine unloaded.
It is at these engine speeds that you do need the advanced timing that the vacuum port now indicates.
Connecting a pump that just makes vacuum will put full advance on the vacuum advance regardless of the actual engine needs.

An engine that is cammed with such overlap should not be run with a dizzy mapping that was designed for a much milder (stock) cam.
Why? becuase that (stock) engine config wanted to idle with about 10 degrees of (base) advance at idle and 30ish degrees and full load at max mechanical advance. This is a dizzy with 20 or so degrees of mechanical advance (30-10=20).
When the throttle is partly opened and your stock engines copious vacuum is supplied to the vacuum advance via the carbs port, the timing advances to a level that will ignite light load (lower density) mixture early enough to make efficient use of the air/fuel.
It works becuase the vacuum level indicates engine load (high vacuum means light load, no vacuum high load). As such the vacuum advance drops to zero as the throttle is opened more and vacuum is lost. This later timing is what is needed for the higher density mixture at higher loads.

An engine with a big cam will want more initial advance (like 15 to 20 degrees)
since the overlap and subsequent loss in volumetric efficiency at that load point will want more timing than the 10 degrees the stock engine wanted.
The engine will still want 30ish max advance timing at higher RPM WOT so the dizzy would be setup for 10 or so degrees of mechanical timing.
The vacuum advance would probably then be inappropriate in the light load higher RPM due to over-advance so it would be wise to remove the vacuum advance line and you would thus be running mechanical only advance.

Race engines with distributors very often dont even run mechanical or vacuum advance becuase the engines dont run in the regime where mechanical advance would be helpful for driveability and the resultant vacuum advance is just plain wrong when the engine doesn't even get on the cam till the MAX advance RPM anyhow.
Such engines have a locked distributor set somewhere around 30 degrees with the magic spot found on the dyno.

This is a lot of words for what I mean to say which is to have your dizzy recurved by someone who knows what the hell they are doing and run a mechanical ONLY curve and leave the vacuum advance line off.
If it was my car I would recurve for 10 crank degrees max timing and set the base timing to 20 degrees (20+10=30). Vary the base timing on the dyno to find peak torque and live with the timing at idle, its max timing that matters anyhow as far as engine power and life are concerned.

If street drivability is a great concern to you (and the above compromise is insufficient) then consider buying an electronically 3D map-able ignition system becuase a mechanical distributor timing system will not be able to give you the timing curve that your modified/cammed engine needs.

Last edited by RootesRacer : 10-12-2017 at 09:21 PM.
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  #93  
Old 10-12-2017
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Well, I was kinda shooting for a proportional vacuum based on RPM... but that doesn't exactly equate strictly to a power-based proportionality, just RPM. Seemed like something a basic raspberry pi microcontroller could handle, given a controllable metering valve. Not my area of course/obviously. But even a manually-adjustable vacuum source to actuate the distributor could help determine if idle issue is vacuum-related, as Dan could stand by the car and adjust while idling.
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  #94  
Old 10-12-2017
RootesRacer RootesRacer is offline
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Quote:
Originally Posted by Ken Ellis View Post
Well, I was kinda shooting for a proportional vacuum based on RPM... but that doesn't exactly equate strictly to a power-based proportionality, just RPM. Seemed like something a basic raspberry pi microcontroller could handle, given a controllable metering valve. Not my area of course/obviously. But even a manually-adjustable vacuum source to actuate the distributor could help determine if idle issue is vacuum-related, as Dan could stand by the car and adjust while idling.
Raspberry pi to control a vacuum pump? Talk about bringing a rifle to a thumb fight...

Ummm, just disconnect the vacuum line and twist the dizzy and see if more timing = better idle. Doesnt matter if the vacuum changes the timing or you twist the dizzy, advance is advance. If the engine idles better due to the added base timing, chances are it will also run better at light load on the street.

If it idles better, follow my instructions above, that technology has been making cammed engines run good for 60+ years.
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  #95  
Old 10-12-2017
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I TOO, just awhile ago spoke with the Delta Cam rep. He restated again what He told me the last time I called that the cam I purchased as a jose grind is a "BIG CAM meaning a FULL RACE CAM it will not have vacuum under the 1000RPM and will not idle at or below the 1000 rpm range.

What is going on here?

It has been stated other than by me here several times that "a car with the jose grind does not idle well, that a car with the jose grind is not good for town driveability, that it would not be recommended...etc., etc...
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  #96  
Old 10-12-2017
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Quote:
Originally Posted by RootesRacer View Post
Raspberry pi to control a vacuum pump? Talk about bringing a rifle to a thumb fight...

Ummm, just disconnect the vacuum line and twist the dizzy and see if more timing = better idle. Doesnt matter if the vacuum changes the timing or you twist the dizzy, advance is advance. If the engine idles better due to the added base timing, chances are it will also run better at light load on the street.

If it idles better, follow my instructions above, that technology has been making cammed engines run good for 60+ years.
Rootes, I did disconnect the vacuum line and twist the distributor as far as I could. It seemed to run a bit better. Cut it off and attempted to start it acted as dragging, so I reversed the distributor a bit. Hit the started=r again it fired right up. Still did not want to idle below the 1200 mark...

That is the way I ran it at the UNITED XXXVI in Va. It ran good and performed well on the highway keeping up with some tigers. Just does not want to idle unless it is set high.

Driving on the road at a normal speed 2K in 4th very little if any vacuum. In 5th at same rpm no idle and will not pull it hat off. BUT, If at 2500 and above it begins to perform well,...

It will be removed this winter. I shall not make any more comments about the idle problems encountered with the jose grind. Unless I am asked

DanR
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  #97  
Old 10-12-2017
RootesRacer RootesRacer is offline
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Quote:
Originally Posted by DanR View Post
Rootes, I did disconnect the vacuum line and twist the distributor as far as I could. It seemed to run a bit better. Cut it off and attempted to start it acted as dragging, so I reversed the distributor a bit. Hit the started=r again it fired right up. Still did not want to idle below the 1200 mark...

That is the way I ran it at the UNITED XXXVI in Va. It ran good and performed well on the highway keeping up with some tigers. Just does not want to idle unless it is set high.

Driving on the road at a normal speed 2K in 4th very little if any vacuum. In 5th at same rpm no idle and will not pull it hat off. BUT, If at 2500 and above it begins to perform well,...

It will be removed this winter. I shall not make any more comments about the idle problems encountered with the jose grind. Unless I am asked

DanR
You need to measure the timing not just turn the dizzy and see. If you go beyond 30ish degrees, the engine will want to buck when starting so obviously that much timing would be inappropriate.

I dont know anything about the Delta "Jose" cam grind (got specs?). But yeah, if its a big cam you are gonna have trouble getting a carb to idle at conventional RPMs.

As before, I'd set the timing to 20 degrees then do everything else I could to get the carb to play nice at the lowest acceptable RPM. A big cam with lots of overlap will need a way richer idle mixture becuase much of the fuel will make it out the exhuast unburned.

Its apples and oranges here but I have a pretty big cam in my 1725 and between the 12 degrees cranking timing and 20 degrees idle timing the engine starts nice and runs smooth at 900 RPM once the engine is at temp.
Webers dont have a high idle cam or a choke so till it gets up to temp, you get what you get.

Last edited by RootesRacer : 10-12-2017 at 10:24 PM.
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  #98  
Old 10-12-2017
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kmathis kmathis is offline
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Quote:
Originally Posted by DanR View Post
I TOO, just awhile ago spoke with the Delta Cam rep. He restated again what He told me the last time I called that the cam I purchased as a jose grind is a "BIG CAM meaning a FULL RACE CAM it will not have vacuum under the 1000RPM and will not idle at or below the 1000 rpm range.

What is going on here?

It has been stated other than by me here several times that "a car with the jose grind does not idle well, that a car with the jose grind is not good for town driveability, that it would not be recommended...etc., etc...
What ever, Dan...all I'm saying is that this cam has been used for years without issue, and if there is a possibility that there is an issue now, then Delta should be able to check to see if anything has changed, which they are going to do. I will let you know what they find out. Dang your touchy...yikes!
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  #99  
Old 10-13-2017
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I suspect something changed at Delta. I've gone back through old messages and emails (back to 2008) and found that with the suggested mods, head porting/polishing, 2.9 valves, 390 Holley, etc, that the Delta grind has been the way to go. Is it actually called the Jose Grind or is there a spec number at Delta?
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  #100  
Old 10-13-2017
todd reid todd reid is offline
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Default What is the most power you've been able to acheive

RootesRacer: I did a search on the Jose cam grind and found the following on our forum from a 2009 posting by Jose himself:

Intake: 290* duration
Exhaust: 280* duration
Lift: as close to .500 as your billet will allow.

I hope this is useful. I am enjoying this discussion - there is always more to learn!
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