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Author Topic:   timeing and hei trouble....help me figure this out please
JT54
Dirt Maniac

Total posts: 170
posted May 15, 2005 10:58 AM  
I have a locked out hei no springs no advance ...I have always set it at 34 to 36 advanced at idle and always performed well ...for the last 3 weeks I have been trying to figure out a strange thing that is hapening with my timing .....when I set it at idle at 36 and run the rpm up my timing retards about 12 degrees by the time I hit 5000 to 6000 rpm....the engine falls flat on its face at 6000 under race conditions and starts missing and popping......to counter act this I set the timing at 4000 rpm at 35 advance and when it is idling it is at 48 to 50 advanced ......anyone ever have this happen ....I have used two distributors ....with all new parts ....do I have a wire crossed or somethig ....I am thinking it is something simple that I or my pitman has overlooked ....Oh by the way with the timing set the way I last described the engine ran strong all the way....whats going on here?

dirtracer14
Dirt Forum Champ
Total posts: 1261
posted May 15, 2005 11:16 AM  
I would pull the dist and see what kind of wear is on the gear....then i would look at cam walk.

JT54
Dirt Maniac

Total posts: 170
posted May 15, 2005 02:03 PM  
cam gear has a little wear ...but no more than usual with last engine ....I have not checked for cam walk....the timing should not retard with rpm right?...I mean with a locked dist it should stay relatively where you set it at.....I did un plug the tack before my b-main and the engine ran great but I also set the timing how I described it in my previouse post...so I dont know if unpluging the tach made it run better or if it was the timing .....I will find the problem and its probably staring me right in the face but I just have not recognized it yet.....any other help in this is appreciated..thanks JT

sdhnc29
Dirt Forum Champ
Total posts: 934
posted May 15, 2005 08:44 PM  
If the cam is not positively locked into position, it will walk forward and retard ignition timing as RPM increases. Id look for this problem first.

Steve

------------------
Hendren Racing Engines
Rutherfordton , NC
(828)286-0780
www.hendrensracingengines.com
www.experienceodessa.com

ryan
Dirt Forum Champ
Total posts: 776
posted May 15, 2005 08:48 PM  
Do you have a cam button, if your cam has been walking look for flat lobes as well.

JT54
Dirt Maniac

Total posts: 170
posted May 15, 2005 08:54 PM  
Thanks ...the cam does have a button on it but I did not check end play....after checking the timing set I found the builder installed the cam advanced four degrees at the cam and retarded 2 degrees at the crank....called crower and they said to put it in streight up....so I think the builder might have over looked installing proper end play also....I will check.....how much end play would you recomend I look for?....and what is the proper way to check it?...thanks ..JT

JT54
Dirt Maniac

Total posts: 170
posted May 16, 2005 08:22 AM  
btt

dgb
Dirt Full Roller

Total posts: 70
posted May 16, 2005 12:06 PM  

stock HEI modules are bad for doing what you are describing, but usually it's 3-6 degrees, 12 seems like an awful lot. If you can't find a mechanical reason for your problem, try changing ignition modules. I know it's been discussed on here before. I started a topic on it on here a few years ago. You might be able to search for it.

JT54
Dirt Maniac

Total posts: 170
posted May 16, 2005 02:25 PM  
I have changed module ,coil cap rotor ignition switch checked and double checked all conections went from 16 guage to 12 guage power to the distributor etc.etc.....I will check what steve sugested tonight ....can a timing cover flex enough to cause the cam to walk?....my other engine has a washer welded to the timing cover where the button rides maybe that is all this engine is lacking???we will see.

wermm
Dirt Maniac

Total posts: 107
posted May 16, 2005 04:30 PM  
on my first motor we had the same problem, motor would just go flat. What we found was the button on the cam was bending the cover letting the cam walk forward.

JT54
Dirt Maniac

Total posts: 170
posted May 16, 2005 08:17 PM  
has anyone just put a piece of steel in between the back of the water pump and the timing cover to put preasure against the timing cover?...it would be nice to avoid taking engine apart.

sdhnc29
Dirt Forum Champ
Total posts: 934
posted May 16, 2005 11:28 PM  
JT54,

Ideally you want between .005"-.008" cam end play. You would need to have the pan or the intake off to check this. Yes you can use a steel plate on the water pump, with a bolt to load the timing cover. A timing cover will flex quite a bit, but it's most common to see that type of flex with roller cam engines. There are two different length cam button's that can be used. If you happen to have the short one in the engine, and the cover requires the long one, then you will not be able to adjust your end play.

Steve

------------------
Hendren Racing Engines
Rutherfordton , NC
(828)286-0780
www.hendrensracingengines.com
www.experienceodessa.com

JT54
Dirt Maniac

Total posts: 170
posted May 17, 2005 12:05 AM  
thanks for your help....I am hoping this is the problem....sounds easy to fix once diagnosed.....thanks again I will let you know what I find tomarrow.

JT54
Dirt Maniac

Total posts: 170
posted May 22, 2005 10:23 PM  
Checked cam ...not walking....the only thing I could think might be wrong was the engine builder used a billet adjustable timing pointer and he may have had it adjusted wrong,so I put a stock chevy pointer on and guesse what....10 degrees difference between the two....set the timing at 36 and ran it on chassis dyno ...engine ran great,problem solved!...still dont know why timing was retarding but with the timing light on while on the dyno the timing stayed pretty consistent all the way to 7000.....boy what a weird feeling sitting in arace car on the dyno !....thanks for your help..JT

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