Cranky motor

by **suikishell** » 02 Mar 2008 1:00

Hey everybody..love this site, like reading random posts and threads..very good and engaging contributors. So..my 74 Chally was running very nicely. But lately it seem to be missing ever so slightly on kickdown. High rpms,, back off a little right back to normal. It has a 360 built, port matched and polished 750 edelbrock, edelbrock DP manifold and an MSD ignition, iwas thinking maybe a little timing adjustment, would that be normal? Thanks in advance,

by **Eddie** » 02 Mar 2008 1:28

suikishell wrote:Hey everybody..love this site, like reading random posts and threads..very good and engaging contributors. So..my 74 Chally was running very nicely. But lately it seem to be missing ever so slightly on kickdown. High rpms,, back off a little right back to normal. It has a 360 built, port matched and polished 750 edelbrock, edelbrock DP manifold and an MSD ignition, iwas thinking maybe a little timing adjustment, would that be normal? Thanks in advance,

Welcome, sounds like a nice set-up! Any pics? Usually a miss at high RPM's that doesnt exist at lower or cruise RPM's is either fuel or ignition related. Sounds like a bulletproof ignition! What is the timing set at now? Did they re-place the timing set? It's easy to check if there is any slack in the chain by popping the cap and observing the rotor move with the crank turned over with a breaker bar. There should be very little deviation in movement, very little!! What type of plugs do you use? Have you pulled them to see if they are tan/normal and not white and lean? How big is your fuel line and the pickup tube in the tank? Is this a prior V-8 car? Did this just start after a fresh engine re-build? My plugs were a tad to cold so I went to a one step warmer plug and it cured my fouling problem. More info would be appreciated. :s002:

by **suikishell** » 02 Mar 2008 3:20

Ipulled the plugs and they dont look fouled or anything i will pull them again and check the heat range, and address the other items in your response. Thanks Eddie. Terre Haute...Home of I.S.U? I grew up in suburban Indianapolis. hoosiers...good folk...again THx..

by **Eddie** » 02 Mar 2008 15:18

suikishell wrote:Ipulled the plugs and they dont look fouled or anything i will pull them again and check the heat range, and address the other items in your response. Thanks Eddie. Terre Haute...Home of I.S.U? I grew up in suburban Indianapolis. hoosiers...good folk...again THx..

Yep, Graduated there with a 4 yr. B.S. in Criminology. :mrgreen:

by **suikishell** » 03 Mar 2008 1:47

Hey all, here is some info from the binder on the car. 1978 360 CI engine installed in 2000. Eng. mods..bored with boring plates to .30 over. 9.25 to 1 with hypereutectic pistons and pins. crank reground and fitted with clevite bearings rods reconditioned and resized. new mopar harmonic new roller chain and cam gears. mopar 268/272 cam and lifter package. Heads. bronze guides. bowls opened and port matched. 2.02 intake and 1.60 exhaust valves. .the carb and stuff you already havve. i pulled the plugs and they are champion RN12YC they are not white. kind of a ruddy tan color. tried to check the timing set but my largest 1/2" drive socket 1-1/8" not large enough. will check current timing and post. cap and rotor look OK. not sure if cap or rotor would be culprit but i dont think so/ some pics to follow. Shes powder blue ext. with blue interior all original.N>O>M..Thanks Keith.

by **Eddie** » 03 Mar 2008 8:37

With a new timing set it should be pretty "tight". Did you check your timing? The engine build sounds healthy! :thumbsup:

I'm sure you meant .030 overbore. :mrgreen:

by **Jimiboy** » 03 Mar 2008 12:07

Welcome.. We want pics! We want pics! :mrgreen:

by **suikishell** » 03 Mar 2008 19:53

OK>>here are some snaps of the 74 Chal. I am terrible at atttachments

Shes unrestored. i have copies of all previous titles. well documented 89000 miles. original color. came with a 318 from factory. I am checking the timing today. it bugs she aint runnin totally right. thanks for all the support everybody :s019:

by **Jimiboy** » 03 Mar 2008 22:02

wow! sweet as a caramel!

Have you checked your vacuum houses from the carb?
I might be out in the dark, but i think i have had some sort of missing before cause of leaking houses.. Easy check anyway... :s022:

by **Jimiboy** » 03 Mar 2008 22:03

wow! sweet as a caramel!

Have you checked your vacuum houses from the carb?
I might be out in the dark, but i think i have had some sort of missing before cause of leaking houses.. Easy check anyway... :s022:

by **Eddie** » 03 Mar 2008 22:07

by **suikishell** » 04 Mar 2008 0:27

Glad you enjoyed the pics of the Chlgr. Thanks Eddie and Jimi for positive response. Its nice to know she is admired. As we know every body loves to look at these cars, ....and touch 'em. So, the timing light set at 0.0 degrees advance on the display reads 20 degrees at 890 rpm. That is with the vacuum line connected at the distributor. If i am performing this correctly or not, let me know. What's next? I'll wait for replys...Thanks all..for bearing with me..

by **suikishell** » 04 Mar 2008 2:45

Okay,Okay...Hang on..After pouring over many searches on carbs and timing and everything i read something about an automatic choke on edelbrocks. well i dont have an automatic choke...and ...then...the light went on! I have a manual choke and the cable from the inside to the carb is flimsy. i grabbed my trusty needlenose and physically completely opened the choke, cause the cable is not stiff enough to do it.. and it looks like that was the prob. idle is down from 860 to 790 on the light. I'm taking the driver for a drive......I'll post a pic of the engine bay soon, nothing earth shattering but clean and correct. :V8:

Thanks all, peace/out

by **patrick** » 04 Mar 2008 6:05

Very nice suikishell! :thumbsup:

by **dave-r** » 04 Mar 2008 9:09

Nice colour that. Very pleasing on the eye.

To check the timing you dissconnect the vacuum hose. You want 34 degrees at 3000-3500rpm and something between 12-18 degrees at idle.

Your idle rpm should be about 800-850rpm with that cam I would have thought.

Put a vacuum gauge on the carb port that feeds the distributor. Make sure there is no vacuum signal at idle.

by **Jimiboy** » 04 Mar 2008 9:10

by **dave-r** » 04 Mar 2008 13:24

790rpm is too low for the automatic though. Adjust it to a little over 800rpm keeping in mind that you don't want to open it up enough to get vacuum on the dizzy feed.

by **Eddie** » 04 Mar 2008 14:25

I would run the choke open all the time in Cali. I lived there for a while and it never got that cold enough to run one. :mrgreen:

by **dave-r** » 04 Mar 2008 15:40

Choke.....angle grinder....trash bin. :wink:

by **suikishell** » 04 Mar 2008 15:48

Great replies! Thx again everybody. It is amazing how much knowledge you guys have, very impressive. The timing with vacuum detached and plugged is 15 degrees. The timing at idle with vacuum attached bounces between 790 and 830 on the digital tach. I need to acquire a vacuum gauge. And perhaps make a few adjustments. Is the car supposed to smell so gasoliney idling there. Really strong..curious. Might be alittle rich but better that than lean. again thx for the positives onthe car. i was surprised to see positives on the color. it is not the hottest color for a challenger and i thought about changing it but it does "pop" pretty good live. and it is the original colour on the broadcast sheet. its a retro color for sure and i really dont want to go in and pull the motor to do the engine bay, door sills and trunk. with the interior, dark or midnite blue would be my really only options. so ill just leave it, its cool. thx again. you all are "the man"

by **suikishell** » 04 Mar 2008 15:57

Choke...disconnected....removed....trashed... :s001:

done. stupid interior actuator knob...gone. :thumbsup:

thx

by **dave-r** » 04 Mar 2008 16:57

There should be zero vacuum at idle so if the timing is changing when you hook it up at idle it sounds as if you have some there.

Having vacuum means that the throttle blades are open too far on the carb. Very common on cars with a bigger than stock cam.

Because the throttle blades are open you are actually not on the idle circuits. You will be on the main jets. So yes you will be running rich and the transition from idle to part throttle will not be as smooth as it should be.

The fix is simple. But how you do it depends on what carb you have. Holley and Demon are both the easiest.

by **suikishell** » 05 Mar 2008 0:09

Thanks Dave, Its an edelbrock 750. Any pointers..Keith

by **Jon** » 05 Mar 2008 2:55

On my 340 with similar set up ( but Holley 650 DP) the Champion RN11YC caused detonation so I went back to the stock 9's. Your plug color sounds right though. Maybe too rich and too hot a plug.

by **dave-r** » 05 Mar 2008 9:31

suikishell wrote:Thanks Dave, Its an edelbrock 750. Any pointers..Keith

In that case you might have to drill two very small holes in the throttle blades.
Best to get yourself a vacuum gauge first and see what the situation is.

When you get the carb set up right you will feel a difference if it was not quite right before.

by **suikishell** » 05 Mar 2008 19:07

Thanks everybody. Much aprreciated... :thumbsup:

Re: Cranky motor