just rebuilt runs bad

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We have almost sorted out a 440 with the same problem. Built by Dvorack, so cam should be good at degrees. Ran good, then started to slow down. Replaced the carb and dist at the same time. The pos procomp dist had 1 reluctor blade at .010 gap, 2 @ .oo8, the rest touching the reluctor.

The msd, runs good, self shifts into 2nd at 70 mph, full pull in 1st and 2nd, then doesn't climb rpm as fast at 4400 in 3rd {3.55 gear}, seems not to be fuel starvation. It wants 22 @ idle, like my bigger cammed 340. That puts total @ 42 today; no ping.

We are scratching our butts, also.
 
And I watched 4 pulls on a rear wheel driven dyno last week, and it pulled hard, in 3rd gear up to 5500 rpm, where the rev limiter came in.

????????? Don't feel alone.
 
you are a patient man ,in every sense of the word. if it were me,i would have already loaded it up on a trailer and taken it to the shop where they built the motor, and made one of those guys come out and watch while i pull off the whole front end of that motor and the timing chain cover and made them show me exactly how they degreed the cam and installed the chain.im betting the timing dots they used were not the correct marks and/or the crank is not in time with the camshaft. better yet,have yourself a new and comparable cam ,new in the box,and make them slide that puppy in there with a new double roller chain with the traditional timing marks and one slot keyway ,bolt it back together and fire it up,and i bet 10 to 1 it runs the way it should. just a suggestion and please dont take anything i say the wrong way.i feel your frustration,that is why i put together my own internals. im frustrated along with you because your machine shop should have already been all over this since you havent gone inside the motor and already gave them your busines and you would think they would want a happy customer at every expense...just a thought
 
did you check for a vacum leak like the port on back of manifold brake booster also check the valve spring retainers make sure they are not rubbing on the rocker arms pressure seems low.
 
green1 said:
And I watched 4 pulls on a rear wheel driven dyno last week, and it pulled hard, in 3rd gear up to 5500 rpm, where the rev limiter came in.

????????? Don't feel alone.
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Thanks. Interesting about the reluctor blade. Good luck with everything.
 
6tfo said:
Just got 340 engine back from the machine shop with pretty much a full overhaul. Set up includes mild Comp cam, KB 10:1 pistons, new RHS heads, Edelbrock RPM air gap manifold w/1806 thunder series carb (650cfm). Installed the motor in 71 Duster and configured MSD 6AL, MSD 8203 blaster coil, MSD 8534 distributor. We set initial timing by findingTDC on the compression stroke, rotor lined to number one plug, then distributor turned about a quarter inch counter clockwise to add 12-15 degrees advance. Starting with number one, wired plugs 1,8,4,3,6,5,7,2. Problem is, when started, the engine backfires through the carb and we hear tapping noises. Verified TDC on compression stroke and correct firing order several times. The machine shop believes TDC is right but thinks the issue has something to do with the ignition system. Timing light connected to #1 indicates 12 BTDC, twisting distributor a little either way doesn't help.


Any thoughts on why this engine would be backfiring through the carb and tapping?
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i went through this same problem with my motor, it turned out to be the positive wire from the MSD box to factory ignition wire it was hooked into ky hot, not a const hot once the car is running, so its getting signals, but not a steady signal....also make sure you have a good ground....make sure your coil is not on an angel, (some are filled with gel on the bottom to make a solid connection.

its hard for me to word it, but its something to do with your ignition wire from the firewall
 
73AbodEE said:
you are a patient man ,in every sense of the word. if it were me,i would have already loaded it up on a trailer and taken it to the shop where they built the motor, and made one of those guys come out and watch while i pull off the whole front end of that motor and the timing chain cover and made them show me exactly how they degreed the cam and installed the chain.im betting the timing dots they used were not the correct marks and/or the crank is not in time with the camshaft. better yet,have yourself a new and comparable cam ,new in the box,and make them slide that puppy in there with a new double roller chain with the traditional timing marks and one slot keyway ,bolt it back together and fire it up,and i bet 10 to 1 it runs the way it should. just a suggestion and please dont take anything i say the wrong way.i feel your frustration,that is why i put together my own internals. im frustrated along with you because your machine shop should have already been all over this since you havent gone inside the motor and already gave them your busines and you would think they would want a happy customer at every expense...just a thought
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Thanks for your thoughts. I'm a lot smarter now, in a large part, due to the feedback I've received in this thread. After this experience I may be ready to try doing my internals next time. The other thing I've learned is maybe "pay in full" should be negotiated up front with final payment being made when the engine is street ready.
 
pat d said:
did you check for a vacum leak like the port on back of manifold brake booster also check the valve spring retainers make sure they are not rubbing on the rocker arms pressure seems low.
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Have checked for vacuum leaks by spraying around the manifold and carb. Will look at retainers. Thanks.
 
604 Racing said:
i went through this same problem with my motor, it turned out to be the positive wire from the MSD box to factory ignition wire it was hooked into ky hot, not a const hot once the car is running, so its getting signals, but not a steady signal....also make sure you have a good ground....make sure your coil is not on an angel, (some are filled with gel on the bottom to make a solid connection.

its hard for me to word it, but its something to do with your ignition wire from the firewall
Click to expand...

I think I follow you. Make sure there is a constant 12v going to the MSD Box when the ignition is "on". Good info on the coil. Thanks.
 
like i said, its the EXACT same thing i went through, with the back fire through the carb, etc. with a msd 6al, and a msd pro bil dist.

once i fixed that it was fine.
 
Just got off the phone with the machinist. He's going to come out and look at the motor, he hopes next week. So that's great news.

Regarding the Mancini timing chain. He said with the intake valve at TDC (Maximum lift?) it was off spec by around 10 degrees (ref degree wheel). He said there are two keyways on the Mancini kit that can compensate 4 degrees, but that wasn't enough to bring it to spec. When they tried another chain kit everything lined up.

Before he comes out I still plan to put a timing tape on the balancer and measure the #1 cylinder valves opening and closing the best I can without a degree wheel. I have a dial indicator if I can figure out how to set it up to measure lift.

I'll post anything new that I find. Thanks everybody.
 
6tfo said:
Just got off the phone with the machinist. He's going to come out and look at the motor, he hopes next week. So that's great news.QUOTE]
that is great news. dont let him leave until that thing is ripping pavement! glad to hear they are going to make time for you.
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6tfo said:
Just got off the phone with the machinist. He's going to come out and look at the motor, he hopes next week. So that's great news.

Regarding the Mancini timing chain. He said with the intake valve at TDC (Maximum lift?) it was off spec by around 10 degrees (ref degree wheel). He said there are two keyways on the Mancini kit that can compensate 4 degrees, but that wasn't enough to bring it to spec. When they tried another chain kit everything lined up.
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These are all good: First, a second set of eyes and a fresh outlook always helps. Second, he's agreeing by action that there may be an issue with the work and he's concerned enough about you (beyond the cash) to make his investment in unpaid time. Third, he described why the chain was not good enough. In truth, I don't use MP cams anymore because I've found them to be so badly ground. It does happen. New doesnt mean good. Keep the faith and your patience.
 
Beware of the mopar performance piston stops. there are a bunch of them out there where the threads do not match the spark plug holes. Chrysler is trying to pawn them off on customers instead of scrapping the bad ones and getting a good batch out there. Take it out of the package and test it on a good set of heads before buying. I hear the comp cams ones have the same problem. Buyer Beware....
 
With a home made 360 degree tape going around the harmonic balance 360 degrees TDC to TDC. Set up a dial indicator on the rocker arm roller for each valve separately.

Intake:
At TDC compression stroke the intake is closed, stays closed a full revolution (360 crank degrees) then starts to open at TDC, full open 95 degrees, full closed 190 degrees, goes past TDC then begins open 360 degrees later at TDC, full open 95 full closed 195, goes past TDC then begins to open 360 degrees later at TDC, full open 95, closed 190, etc…..

Exhaust:
At TDC compression stroke exhaust is closed, begins to open 155, full open 245, closed 135, starts to open 155, full open 245, closed 135 etc……

I understand this is very shade tree. I'd give it an error of margin of 10 degrees, 5 if lucky. Is any of this info useful? When I get home I'll be able to analyze more but thought I'd through it out on the thread now.

Thanks.
 
6tfo said:
With a home made 360 degree tape going around the harmonic balance 360 degrees TDC to TDC. Set up a dial indicator on the rocker arm roller for each valve separately.

Intake:
At TDC compression stroke the intake is closed, stays closed a full revolution (360 crank degrees) then starts to open at TDC, full open 95 degrees, full closed 190 degrees, goes past TDC then begins open 360 degrees later at TDC, full open 95 full closed 195, goes past TDC then begins to open 360 degrees later at TDC, full open 95, closed 190, etc…..

Exhaust:
At TDC compression stroke exhaust is closed, begins to open 155, full open 245, closed 135, starts to open 155, full open 245, closed 135 etc……

I understand this is very shade tree. I'd give it an error of margin of 10 degrees, 5 if lucky. Is any of this info useful? When I get home I'll be able to analyze more but thought I'd through it out on the thread now.

Thanks.
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Even 10 degrees out on your tape that cam is not in right.
The intake should start to open around 34 BTDC and shouldn't completely close for 280 degrees which would put it closing at 66 ABC.

If your saying the intake is starting to open at TDC and completely closed at 195 it not only is in wrong it only has 195 degrees of duration on the intake instead of 280.

I'm going by the specs of the cam you said went in it but even if it's a different cam no cam will start to open the intake valve at TDC, it will always start to open sooner.
 
Be sure you are not confusing yourself with degrees, IE your timing tape probably goes right from 0 around to 360. So bear in mind that the degree figures CHANGE in their reference, that is:

Intake shown opens at 34 BTC

closes at 66 ABDC

Exhaust shown closes at 30 ATDC

opens at 78 BBDC

So on your 0-360 tape, you have to figure these depending on how the tape is marked. If BDC is marked 180, then you'd have to add 180 to the 66* ABDC figure, etc

Here are the specs according to Comp:

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=640&sb=2

bdprmh.jpg


A link to the Comp catalogue:

http://www.mediafire.com/file/48l3a5fn4qtsgj1/COMP_Catalog_2011.pdf

or online

http://www.compcams.com/Company/CC/Catalog/COMP/Default.aspx
 
Thanks for posting the my cams specs. Keith had also hooked me up with a link in an earlier post.

I'm attaching a couple of pics of the test set up. I used a summit timing tape. It only covered 60 degrees in units, not in this picture but I ended up extending the summit tape with gray electrician tape and marking every ten degrees. It took a few tries because the tape stretched easy. As you can see in the pic I put the tape on backwards for the purpose of this test. I'm going to take some time and try and wrap my brain around yours and Keith's comments. Thanks much.
 

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Ya kinda want to shove that dial gauge down to the outer lip of the lifter, and use a piston stop first, to check for balancer for being correct.
 
green1 said:
Ya kinda want to shove that dial gauge down to the outer lip of the lifter, and use a piston stop first, to check for balancer for being correct.
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Thanks, I believe after I messed with it for a while, it ended up in the middle of the roller at about a 90 degree angle. I have to pull the intake to get to the lifters wouldn't I?

I've done the piston stop probably 5 times now so I'm pretty confident that the balancer is correct.
 
Pull the shaft, and 1 pushrod; get an extension for the dial, and good flashlight, especially one on a flexible shft, stick it in next pushrod hole to illuminate down there. I feel your pain, been there. Could only figure it out at 50, each side of lobe. All other readings erractic. Hope your card has .050 measurements, if not, call manu.
 
Hope it turns out ok for you; we have 43 total, no ping on the 9.5 cr. Next week we are going for ping, the more advance we put in the better it runs. Throw out the timing light until ping. Back off ( this is new to me. the power curve at peak, is about 4,5 degrees below ping; researching this).
 
So the valve that my dial indicator is pointing to is the exhaust valve right?
 
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