TOO LEAN

[kreinhederta]

Well have everything together and am trying to get it on the street! Here is the issue, Headers start turning red after about 1 minute. I have the timing at 14 degrees initial and 32 overall. I am wondering what jets and power valve to upgrade to. It is a 383 with AFR 195 cc heads 240/246 duration @050. Fuel pressure is at 5 1/2 psi. The carb is a Holley 750 with a proform center section with a 6.5 pwr valve and 72\'s up front and 84\'s in the rear. I was thinking of going to 78 up front with an 8.5 pwr valve. Any suggestions??

[ZR1BLAZER]

man i wish i could help you on jet size but i am struggling with the same problem as far as jetting (im to rich) but i would try 6-6 1/2psi instead. you have a healthy combo stock is 5-5 1/2psi.

[elv408]

Red headers usually indicate Timing too high. Try 12* or 10* on the initial timing, reset the air/fuel adjustments on the carb and see how see runs. What\'s your compression ratio?

[kreinhederta]

CR is approx 10.5:1. I have brought the initial down and richened the mixture screws but it is when I am at about 1000 RPM and higher that the tubes begin to glow and the higher the RPM the quicker they glow. The pwr valve in there now is a 6.5 so I will probably try the 8.5. All I can figure is the AFR heads pull everything out of the cylinders that much quicker. Well back out to the garage and hook up the exhaust system once again.

[redneckgames]

A serious vac leak somewhere can cause a very lean condition?

[kreinhederta]

No vacuum leaks. Already checked all of that.I can choke the motor out instantly with one hand over the carb-.

[Scotty_S-15]

Or the timing could be too LOW (retarded) .... 14 degrees is good, but are you sure TDC is accurate? Any other symptoms that timing is retarded? Such as throttle blades needs to be open too far to idle properly?

[mzoomora]

If the tubes are changing colors at idle then power valves and jets wont change anything. As far as higher RPM\'s, the power valve should only be open at full throttle or close to it. 1000 rpm you should be making more than enough vacuum to hold it closed unless you power valve is bad. If it is hanging open due to low idle vacuum going to a higher numbered one will only make it worse. Either way that would still make it run rich and not lean, which usually doesnt cause high EGT\'s.

Could be a timing issue like stated previously. Get or make a piston stop to check for accurate TDC. If the tune is off the hand over carb test will not always work well. You should check with some water or carb cleaner(even propane) by the intake or carb base for leaks.

So many things to check. If the valves are lashed too tight or your cam timing is off it will cause fuel to burn in the headers also.

Just an elimination process really.

[mzoomora]

On 2006-02-01 14:47, Scotty_S-15 wrote:

Or the timing could be too LOW (retarded) .... 14 degrees is good, but are you sure TDC is accurate? Any other symptoms that timing is retarded? Such as throttle blades needs to be open too far to idle properly?



That will definetly cause fuel to burn in the exhaust. But you would think if it was that retarded you would have a hard time getting it to idle at all.

How does it start? Do you have to play with the throttle a lot to kepp it runiing?

[kreinhederta]

Once it is at 180 water temp it starts right up with no fuel at all. And if I turn off the electric fans and let it get to 200/210 and turn it off it fires right back up. That\'s the weird thing, it acts like a taxi motor as far as starting so I know the timing is right on the money. When we put the motor together we used a dial indicator to get exact top dead center so I don\'t think that that is it either. This is just driving me crazy! The engine is running great, it is the EGT\'s that are killing me from being able to drive it. Like I said it\'s not so much at a low idle but more as I hold the RPM\'s at a constant 1500 or start to increase. Then they get red hot and I hear detonation in the cylinders and shut it down. I have pulled and checked the plugs and they are a tad lean but not that much.

[Scotty_S-15]

On 2006-02-01 18:16, kreinhederta wrote:

....................................... When we put the motor together we used a dial indicator to get exact top dead center so I don\'t think that that is it either..................................

Is the balancer new? because if it\'s a used one, just one little backfire or hiccup when trying to start it could have spun the outer ring on the balancer, rendering the timing mark useless.

.............. Also, I was presuming that the headers were glowing at idle. Is this a fact??

[kreinhederta]

Yes the balancer is brand new so I very highly doubt that it has changed. They are not glowing when I drop the idle down to about 800/900 rpm but they are when I set it at 1400/1500.

[Scotty_S-15]

If it IS making the headers cherry red at idle, I\'d try this: Advance the distributor while it\'s idling another 10 degrees or so as an experiment. If the idle speeds up and the headers cool down....... http://www.s10v8.com/images/smilies/icon_smile.gif That should quickly indicate something. http://www.s10v8.com/images/smilies/icon_wink.gif

[kreinhederta]

Wouldn\'t that lean it even more hence cause pre detonation?

[Scotty_S-15]

Well it wouldn\'t \"lean\" it out, and it wouldn\'t hurt anything as an experiment at idle. The main thing is not to run it under heavy load with the ignition advanced beyond 38 or so total advance for most setups.

........... To do that would only take a few seconds, and if the idle doesn\'t speed up and the headers don\'t mellow out, and/or it runs crappy, put \'er back where it was.



In fact, you\'d want to put it back to 14 initial regardless. But if the advance at idle helped, THEN for sure I\'d re-think the accuracy of TDC vs. balancer marking.

[kreinhederta]

Well I guess the first thing to do is check tdc and go from there. Just want to drive it and have fun. It\'s been down for about 9 months now and I am getting ready to go out on a 6 month deployment.

[mzoomora]

What do you know about the carb? How high are you able to get the RPM\'s? It may have a prolem with the main (jetted) circuit in the carb causing it to lean out with higher RPM\'s. The idle and off idle are on seperate circuits than the jets which would allow it to idle fine. The jets you have sound a little lean but still safe, it should run fine all the way to redline with them.

Im just throwing stuff out there to consider. If it can maintain higher rpm\'s (3k or so) then it probably isnt an issue.

[kreinhederta]

She\'ll spin right up and stay right there if you want her to. That\'s the crazy part. The throttle response is great it just seems as if it is to lean at rpm increase. The carb is (after checking the #\'s) a Holley 650 dbl pumper with the Proform center section with 72\'s up front and 84\'s inthe rear. Rebuilt it last summer and ran it for about 500 miles then pulled it drained it and bagged it and tagged it till 2 weeks ago. Like I said it seems to be fine I am just leaning out quick for some reason.

[4x4blazersbc]

the carb could have some dirt in it causing it to lean out. just my 2 cents.

[kreinhederta]

Just waiting on the parts, hopefully today to change out everything.

[kreinhederta]

Well I set the timing at 12 degrees and changed the plugs to autolite 25\'s for a cooler range and bumpedup the power valve in the carb and still have the same issues. Any good suggestions? For some reason it is leaning out real quick.

Thanks,

Tom

[adh383]

If you have a choke on your carb---get engine running and when the header tubes start getting red------close your choke till or if you see the headers start to cool down, that will show i think that you need more fuel and less air. You have probably checked you float levels? just a few thoughts. also - that set up you got takes in a LOTS of air-so you need a bunch of fuel.

[adh383]

Can you borrow a carb to try? One other thought--i have seen some weird shit happen in my 35 years of messing with engines-Are you sure that when this engine was assembled -- you did not have the crank or cam gear one tooth off? I\'ll shut up now

[kreinhederta]

Yea I\'m going to try and borrow a carb tomorrow to check it out and see what it does. I am just going crazy!! I was also looking online at the Barry Grants and by their website I should be running their Mighty Demon 825. Seems a little big to me though. No I am sure when we put it together we were good to go and I even pulled up the pictures of the timing assy we took as we were doing it to make sure. Also I did check the float level and it\'s right on. I know you are saying it needs alot of air and I need more fuel but is it that much more than a steel headed stroker?????? Like I said before it is a 383, AFR 195 heads 10:7 to 1, the cam is 507/510 lift 240/246 duration at .050, .043 quench and an MSD 6AL ignition with Autolite 25\'s and the gap at .035/.040. I appreciate all the help and hopefully soon it will all work out so that I can drive this thing before I leave on a 6 month Deployment.



Tom

[eigthmile]

Try and bump your timing way up while its running. Retarded timing will cause egt or exhaust gas temp to sky rocket. I can pull out 4 degrees on my 383 and egt rises 200 degrees. Even if balancers on and you have timing at twelve bump it to around 30 at idle and see what it does. I would just about bet it stops.

[kreinhederta]

But where will that put my overall?? Isn,t that just ALOT of initial. I know we set the roundy round cars at36 lock out but I want to be able to start it when it is warm.

[Scotty_S-15]

Like I said earlier, and Eigthmile just said, try bumping up the initial JUST AS AN EXPERIMENT. Can\'t hurt anything, only takes a few minutes, and you could learn a lot.



................ Don\'t even worry about the total timing problem until you know if advancing the initial works or not.

[gdmclnh]

I agree about the timing. If I don\'t keep my initial advance above 20 deg when I disconnect the dist. adv. vacuum line my headers will get very hot.

[adh383]

Hey Krein---- i am running 210 runners with a little more cam than you posted with a 750 holley. I personally think that 825 carb you spoke of woul be borderline on being a little much. Tryed one on my 383 and it did not help at all as far as performance. In your case--TRY anything. If another carb dont help--??????

[kreinhederta]

My fuel pressure is at 5 to 5 1/2 is that enough or as I am accelerating am I draining the bowl????

[adh383]

Since pipes are getting red at 1000 rpm -i doubt you are draining the bowls---does your carb have sight glasses? Look in them and see if level is holding up while you hold engine at 1500----2000rpm

[kreinhederta]

Well I advanced the timing to 36 overall which put initial just over 20 and put on another carburator and the pipes do not get as red as they did but there is still a red glow when I hold it at 1500-2000 for a couple of minutes. Only on 3, 5 and # 8 cylinder the most. It seems as if I am ggoing in the right direction but I can\'t see going above 36 degrees overall. As for the initial being over 20 that also gets me because it is telling me that the distributor is not advancing properly. At 36 overall it should be at 15 due to the advance button installed is the blue one which should give me 21 degrees of advance. So I guess that is another story. This finiky B***H is killing me. So now I need to look into which carb to get and call MSD once again on the advance and I\'m thinking the super unleaded isn\'t enough and I will have to mix fuel or run straight CAM2. Has anyone else running the AFR\'s run into any of this??

[adh383]

Those are good heads--- with your compression i dont think the high octane is gonna solve your problem------ at the rpm\'s 1500-2000 your pipes should not be getting red. As for the timing 36 should be plenty. It could be your dist. But since the other carb helped- it puzzles me. Have you ran the truck hard on the street? How does it run? The way i set my timing --- i set it up where i hear a slight spark knock when i run the shit out of it--then i back it off about 2---4 degrees and lock it down. STILL GONNA THINK SOME MORE ABOUT YOUR ISSUE!!

[kreinhederta]

The truck runs great and starts up like a taxi. That is whay has me puzzled also. I have had small blocks 4 ever and have had no such issues, everything is brand new except the carb so I am going to start there. I really haven\'t driven it on the street yet because of the lean issue and I don\'t want to hurt the motor. Call me a little to over cautious but I\'d hate to blow it up because of being a knuckle head. I know my buddy had a 406 with 58cc heads and didn\'t run cam2 and the motor pre detinated and tore up the bottom end. So I am going to keep looking into the problems and with all the experience and suggestions I am getting from the site. Thanks again.

Tom

[mzoomora]

Are you runing the vacuum advance? If so, are you using ported or manifold vacuum? If you arent using manifold vacuum, try it. It will give you extra advance at the RPM you are have trouble, which may help.

[rayL]

ok ive been following this thread to see if the problem is figured out. Bottom line is this...your headers are glowing cause its lean.OK you have figured this part out. lean is caused by two things...timing or not enough fuel. I think yours is gonna be timing cause you said you had put another carb on. What i would do is this.. i would crank the truck and let it warm up and start advancing the timing till the glowing exhaust goes away or you start hearing or feeling something that isnt right. I think one of your marks are wrong. Doing it this way you will have to readjust the carb. You cannot adjust a carb properly if the timing isnt correct so its a damned if ya do damned if ya dont thing there. advance the timing some then fatten up the idle and see what happens. Continue this till you feel comfortable

[ChevyKiD_69]

hey i havent read threw all of the threads yet but i have a friend with a 406 in a nova the headers was doing the same thing he thought the timing was right but the more he retarded it the better it got i think he got to about 14 or 12 some where around there and the tubes stoped turning bright red. id say go to 14 deg. hope you get it fixed. nick

[coppergmc]

The reason why your headers are glowing is because the timing was too low. I\'m not saying that the intitial is all wrong, just the total curve is wrong. With that cam, the initial timing of 20 degrees isn\'t unusual. You can try different carbs and I garantee you will have the same problem. You need to recurve your distributor so that the timing comes in a little quicker.

[kreinhederta]

well I have already tried to change springs once. Does anyone have an idea which ones to go to next????

[mzoomora]

Like I said, if you are not running vacuum advance, try it. It wont add to your total timing at WOT, just cruise and idle.

Also, with the springs I usually just use the lightest one, but that is just my preference.

[kreinhederta]

I would like to use the vacuum advance if possible, so tonote when I get home I will try again with different springs. Thanks again and if there are any other ideas out there I\'m always open for more suggestions.

[bowtie316]

What kind of headers are you using? Coated? New? The reason I ask is because when I got my engine assembled it did the same thing. The headman elites I used have a special metallic coating that glowed for a while. Timing was spot on, jets and idle mixture were perfect. I run 19 initial and 34 total but that is with fast burn heads. I would find a infra red thermometer to check actual header temp. They may not be as hot as you think.

[kreinhederta]

They are new Hooker Super Comps. Ceramic coated. And AFR 195 heads. I am going to go and put it at 18/19 initial and 34/36 overall tonight and see what I get.

[bowtie316]

This is a gimmie but did you adjust the idle mixture screws?

[mzoomora]

On 2006-02-07 15:57, bowtie316 wrote:

This is a gimmie but did you adjust the idle mixture screws?



He isnt having an idle problem, he is having problems just off idle. I would say its a timing issue since he has used 2 carbs already.

[bowtie316]

He isnt having an idle problem, he is having problems just off idle. I would say its a timing issue since he has used 2 carbs already.





First, both the carbs may be pre-set for an engine with less fuel/air requirements. Second, where do you think the engine is getting it\'s fuel from \"just off idle\"?

Hint hint, Not the mains!

[kreinhederta]

One of the carbs is off of a 406 and we never had the issues so I really don\'t think that is the issue. When I get home I am going to put another light on it and see exactly where I need to be for the glowing to stop. Plus I have changed the power valve and jets also, also adjusted the mixture screws and it did\'t help either.

[adh383]

Question------what type of timing gears are you using?

[mzoomora]

On 2006-02-07 16:51, bowtie316 wrote:

<!-- BBCode Quote Start --><TABLE BORDER=5 bordercolor= ALIGN=CENTER WIDTH=85%><TR><TD><font size=-5>Quote:</font><HR></TD></TR><TR><TD><FONT SIZE=-10><BLOCKQUOTE>

He isnt having an idle problem, he is having problems just off idle. I would say its a timing issue since he has used 2 carbs already.

</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR></TD></TR></TABLE><!-- BBCode Quote End -->



First, both the carbs may be pre-set for an engine with less fuel/air requirements. Second, where do you think the engine is getting it\'s fuel from \"just off idle\"?

Hint hint, Not the mains!



Hint hint-

Actually it would be getting some fuel from the mains(due to the fact the booster are getting some signal), along with fuel from the transfer slots. If it isnt lean at idle then all adjusting the idle screws will do is make the idle worse and have very little affect on the 1500-2000 rpm problem he is having.

As far as the carbs, they arent going to be that far off unless they were from engines that were waayyy over-carbed. As far as engines needing less air or fuel requirements, that isnt all that determines jet size. Booster signal is the most important thing. You can put a 750 carb from a 454 on to a 350 that makes less power and it will require more jet due to a weaker booster signal. I know cabrs pretty well, maybe even better than you, who knows? http://www.s10v8.com/images/smilies/icon_confused.gif All I was doing was giving some insight into the problem he was having that maybe you overlooked.



Next time keep the sarcasm to yourself.

Hint hint.

[kreinhederta]

Well I used an old timing gun and got everything set at 15/16 initial and 36 overall. Put the old carb back on it and filled her up with 110 octane. The red has subsided drasticallt and she runs like a scalded deer! I\'m hoping now that if I go up to a 74 or 76 jet this will bring it down even more. What a finiky pig it is. Of all the small blocks I have ever run it is the pickiest. I drove it around the neighborhood and got in it a couple of times and now I am mainly getting a glow on cylinders 5/7/6/8. Well hopefully this is all going in the right direction.

[adh383]

I spoke with a friend if mine that probably has forgotten more than i\'ll ever know and he said that with the engine specs you got -he thinks the carb change and the fuel octane you went to are covering up the problem. He said that it is a slim chance that the cam may be ground in a retarded state! There are factory defects ya know. In his view your headers should not GLOW---and by glowing on a few cylinders-he thinks its a matter of cam timing or possibly cam grind---???? trying to help!!!

[coppergmc]

Headers are going to get hot especially if you are running pretty hard. I\'d try running about 2 more degrees of timing and drive it for a while. Sounds like it\'s getting better all the time.



I kind of get what adh383 is saying but don\'t think that\'s the problem here. Maybe he could elaborate some.

[mzoomora]

On 2006-02-07 22:07, adh383 wrote:

I spoke with a friend if mine that probably has forgotten more than i\'ll ever know and he said that with the engine specs you got -he thinks the carb change and the fuel octane you went to are covering up the problem. He said that it is a slim chance that the cam may be ground in a retarded state! There are factory defects ya know. In his view your headers should not GLOW---and by glowing on a few cylinders-he thinks its a matter of cam timing or possibly cam grind---???? trying to help!!!



I also agree that the fuel is just covering up the problem. It very well could be a cam timing issue- like the exhaust valves are staying open too late. It could also be a distributor timing issue. If the pick up isnt timed correctly it can give you problems. If you have an old cap you can cut a hole in you can check it. The main thing is to make sure that the pick up is firing at the same time as the rotor and cap line up.

Another suggestion, but I would say it probably isnt your problem- I have had rotors that bound up in distributors and didnt allow the advance to function properly.

There is also the fact that you could just have a valvetrain problem. Maybe valves hanging open, pushrods improper length, etc.

[kreinhederta]

Ok I am now looking at the cam timing issue. On the cam card it states that the lobe seperation is 110 degrees but on the cam card everything is set at a 106 degree centerline. If I installed this straight up as I have will this throw the cam timing off that much to give me this problem???? If so I should just be able to use the 4 degree retard slot on the craank gear to give me the proper alignment???? I have double checked everything in the distributer a half dozen times and it all checks good, and as of now the timing is consistent at 15 initial and 36 overall. It has got to be something as simple as this because everything else seems as if it is right on the money.

[mzoomora]

The ICL and LSA are two different things. Most cams will be recomended to be installed at a 106 intake centerline, but that doesnt affect the the lobe seperation. I dont know what timing set you use, but some have the multiple keyway on the crank gear and then multiple marks on the crank gear and cam gear. Are you sure you lined up the proper markings? I would think if you didnt it wouldnt run, but I havent had any experience with that. They will usually have a set of shapes on the inside of the cam gear to show what keyway to use (or the keyway will have a certain shape to it at the top) and then a set of shapes to line up with the corresponding shape on the cam gear. They are usually circle, triangle and square. Dont know what yours is though.

Also, what did you do for valve lash? I know some say up to 1 full turn, all the way down to 1/8-1/4. If you did the full turn it may be hanging valves open.

[kreinhederta]

I lined them straight up dot to dot. I am wondering do I need to retard the crank gear or advance it to get me from the 110 to the 106 centerline?

[redneckgames]

call the cam company and tell them what cam you have and where it should be installed. tell them about your problem. they should know what, if , and but .

[rayL]

that 110 is ground into the cam...you will not change that. the centerline being at 106 tells me you have 4degrees of advance built into the cam. your intake centerline is is just that...where the center of the intake is.

[kreinhederta]

Well after pulling everything apart once again and checking the TDC and valve lash everthing was as I thought good to go. So on to old school timing we went, started her up, loosened the distributer and put on a vacuum gauge. At 1000 RPM I was only getting 4Hg so I cranked on the distributer until it came up to about 14 Hg at 1000 RPM and loced it down. Ran it up at about 2500 for a couple of minutes and the headers didn\'t glow. I\'m almost afraid to put a timing light on it, All I can figure is the cam might be off just a little so I will need to tear it down and degree the cam when I get back from sea. She is running great though, went out on the maiden voyage today to get a state inspection. A little more converter than I originally thought but what can you do, it\'s definitly not a daily driver. Thanks again for all the help and suggestions!!!

Tom

[ZeroGravity58]

you could have a band hormanic balancer or your timing pointer in the block might not be in the right place. Also something to try(if you can) try locking out the timing. In all my performance motors i always lock the timing out.

[coppergmc]

There is nothing wrong with the cam. I told you that the timing was too low. Take it apart if you want but you will be wasting your time and money.

[kreinhederta]

The only problem with leaving this way is that the timing is way high and it turns over like a pig. Good thing I have a seperate ignition switch to turn the motor over and then fire it off. She runs great though. Just that streetability thing.

[coppergmc]

You will probably have to make a compromise on the timing. Try about 20 initial and 36 to 38 total. Change the springs so that timing comes in a little quicker. Probably one fairly stiff and one spring a little soft should do it.



This truck should hall pretty good. I don\'t really feel like going back through all the posts but have some ideas on the carb settings. I built a motor \"similar\" to yours. I found best power with 73s in the front and a 6.5 power valve. I left the secondaries alone. I hope this helps some. Keep me informed.

[kreinhederta]

I am running 72\'s up front w/a 6.5 pwr valve and 84\'s in the rear. I am thinking of moving up to 73\'s also though. She sucks some gas though and now I am running Sunoco Race Gas 114 octane at $5.00 a gallon.

[coppergmc]

You shouldn\'t need the race gas. High test should do it. That bigger cam really knocks the cylinder pressure down. How does it run? Is it as strong as you thought it was going to be?

[kreinhederta]

I don\'t really think I need the race gas straight but last year my buddy blew up his 406 on 91 octane and I\'d hate to do that.Oh yea she is strong!! Now I\'ll just wait to tear up the rearend. I just need it to get me to cruise. And next November I can do the rear. I think one ood hook and it\'ll be destroyed.