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  #31 (permalink)  
Old 08-13-2014, 02:05 PM
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No, it is not the BEST solution. A proper curve that fits is best. My position is that it can be done and works.

If you wanted to get to a patent 36 total quickly, you could lock it to the proper total and run it to see if you liked the result. Then design your curve accordingly for the hot start.

Search for the HEI picture that show you how to lock the plate. Its on the 6 O 'clock pictured arm.

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  #32 (permalink)  
Old 08-13-2014, 04:24 PM
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Fbird do you need glasses now?Lots of spelling errors, I have the same problem
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Old 08-13-2014, 05:48 PM
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Ok f bird. I'm going to try it. I'll report back.
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Old 08-13-2014, 08:12 PM
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OP you ask me to clarify, all I can say is getting a timing curve dialed in can be time consuming there is no one size fits all answer.

I can recommend setting up a distributor on the bench with an electrical drill and optical tach to dial in the centrifugal if your not going to lock it, its safer than sticking your head under the hood at higher rpm with a timing light trying to see timing tape marks. Remember the distributor runs at half engine rpm...1800 distrib rpm equals 3600 engine rpm.

Lots of good articles on the web on how to do it and recommendations as well, some people prefer ported to manifold vacuum and vise versa for the vacuum advance...manifold vacuum advance can add advance at idle to lower coolant temps and pull back as load is added which can be handy for heavy or tall geared cars with tight converters.

Gofastforless website has some recommendations that work well for street cars, electronic modules for retard and complete control of the timing curve are popular as well.

Distributor advance

In all cases I suggest disregarding what anyone might say and understand what the purpose of these timing methodologies are for yourself...they exist entirely to light the mixture at the correct time so peak cylinder pressure occurs just after TDC and that pressure point changes with rpm and load...this is a known fact.

Thats all its for, and I suggest that a locked timing curve does not accomplish this at all rpm and loads a street engine encounters...hence my views on the subject.
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  #35 (permalink)  
Old 08-14-2014, 10:45 AM
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I once had the comp cam big mutha thumpr hydraulic roller cam and let me say that thing was a pain to try to tune around for it to be streetable and I had at the time a quick fuel q series carb double pumper carb which is the same as the holley HP brand but stupid me I sold it but that's another story.

I had a issue with not being able to keep it running in gear and I have a automatic turbo 350 with a 3000 to 3500 rpm rated range stall and 3.73 rear gears in a 86 s10. I spent countless hours and days trying to tune this thing and got to the point that I was ripping my hair out. I got it because I liked the sound and I fell for there marketing scheme in my opinion.

So after doing my homework and learning the hard way its better to build for it to run good more then that rumpty rump sound. I swapped to a smaller Lunati Voodoo Hydraulic roller 282/290/231/239 @ 50 535/550 lift and couldn't be happier. It still has a nice rump at idle but twice the vacuum and also makes my engine run a heck of a lot better and stronger and still fully streetable and was easier to tune everything.

You can make it work but the more overlap a cam has the more picky everything gets and they all have to work in hand from timing, to carb and cylinder heads and compression etc. Trust me I have made a lot of mismatch combinations over the years. My build is not perfect but close.

I have a holley 04777 650 double pumper like you have on yours and mine from stock was not rich enough on the idle circuit to keep my truck running when put into gear with out it stalling even with the right timing curve. I ended up having to open the primary blades to much exposing to much transfer slot on the front while while if I had the rears open too much I could not get the idle down while also having the front correct in relation to the transfer slot and getting a nice clean idle. It would run pig rich because of this.

I swapped out my stock metering blocks with a pair of quick fuel billet blocks and compared them to the stock blocks for sizing of everything etc and adjusted and tuned the blocks to what my engine liked as far as idle feed restrictions goes and also for jetting.

After it was all said and done with my 650 double pumper it idles at a nice and easy 1000 rpm and drops into gear at about 800 rpm and the idle is nice and clean and crisp and has great throttle response and I get 19 mpg and I jetted down to 65 front and 72 rear and it runs excellent with a nice set of tan looking plugs. I don't have a 02 censor setup yet to get the perfect tune but those cams have way more overlap then the comp xtreme energy line and comp cams says

"Applying a camshaft design originally created for sports car endurance racing, they incorporate early exhaust valve opening, long exhaust duration, and a generous amount of intake and exhaust overlap. Best of all, Thumprs will not negatively impact power output or streetability".

I disagree on that but that can be argued. Even the smallest thumpr one is not small by any means and needs a lot tuning involved.
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Old 08-15-2014, 08:34 AM
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You know Fbird I will never be the expert tuner like you but yeah I did not do it right the first time because of lack of knowledge and ignorance on my part. On my recent build I had everything else in place with plenty of timing with recommended amounts in the 20 plus initial range and limited mechanical travel even before touching my 650 double pumper.

I am not going to argue with you in what you know as I will never know what you do but I know enough not to mess up like before and butcher things. I am also not the guy who just adjusts his idle mixture screws and idle and calls it a day.

I do my homework.Problem is and when it comes to hotrodding there is always going to be differences in certain things. Locked out timing or limited timing etc. If you did not mean anything offensive then I apologize for my comment. But I do thank you and others like your for sharing your experience and knowledge as without it I would not have gotten this far as for many others.

Last edited by eric32; 08-15-2014 at 08:57 AM.
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  #37 (permalink)  
Old 08-19-2014, 03:23 PM
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Ok fbird. I've locked out the timing and cranked out the adjustment on the vac advance to 12deg. It does run and idle, but it is tricky to get started. The gear drive starter I have does not seem to spin the motor fast enough to catch it when I hit the button for spark. I can get it but not every time.

I does seem to be running pretty well, but I haven't got to drive it yet. Definitely seems to have reduced the fumes at idle.
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Old 08-19-2014, 08:40 PM
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Quote:
Originally Posted by gufnstuf View Post
Ok fbird. I've locked out the timing and cranked out the adjustment on the vac advance to 12deg. It does run and idle, but it is tricky to get started. The gear drive starter I have does not seem to spin the motor fast enough to catch it when I hit the button for spark. I can get it but not every time.

I does seem to be running pretty well, but I haven't got to drive it yet. Definitely seems to have reduced the fumes at idle.
Check the normal things, wiring, battery strength, grounds etc, there should be no issue rolling it over with the ignition interrupted. As for fumes and idle quality, give it a shot as is, then try manifold vacuum vs ported and see if the idle cleans up that much more. Some react differently then others.
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  #39 (permalink)  
Old 08-19-2014, 10:30 PM
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...or recurve the distributor and enjoy easy starting without the hassle.

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  #40 (permalink)  
Old 08-20-2014, 12:05 PM
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I'm curious, so now starting is hit or miss?

When it misses does it stop the engine dead in its rotation?

If it does, thats a recipe for stripping flywheel teeth or blowing the bendix apart or in some worst cases I've seen...breaking the starter flange bolt holes clean off the block.

Might want to consider a retard box as a minimum, its good insurance against disaster.
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  #41 (permalink)  
Old 08-20-2014, 04:16 PM
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The retard boxes from msd have been discontinued for the hei. Haft to call and talk to them.

I did find that I can use a 5 pin ignition module from a 1980 firebird with the 301 turbo. It has an extra terminal that was used to retard the timing on the car 10 degrees for the turbo. And it's only 40 bucks.
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  #42 (permalink)  
Old 08-20-2014, 05:51 PM
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Yeah the gear drive I got was a no name is why I am suspect of it
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  #43 (permalink)  
Old 08-20-2014, 05:52 PM
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I was originally at 24 by dc and could start no problem so I think I would benefit.
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  #44 (permalink)  
Old 08-20-2014, 08:18 PM
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Do a search on HR.com, dozens of posts on broken ring gears and cracked pinion noses.

Most had the factory support in place, over advanced timing was the cause in 90% of the cases.

Draw your own conclusions.
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  #45 (permalink)  
Old 08-20-2014, 09:21 PM
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The timing is needed, once the engine is running it is fine.

The starter retards work nice, those people needed to invest in the basics. The E curve distributor has one built in. These things need to be in place for longevity.

I have a couple retards stashed away. You say they don't make them anymore, good thing.
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