289

[BigBlueIron]

A buddy has a 63 or 64 (i think) Fairlane Sports Coupe with a 289, factory 4 speed. He has had the car since he was 16 and is a good mechanic. Engine was built decades ago but he cannot remember the details but it runs hard and sounds great. Headers and good exhaust and certainly some bump on the cam, best idle tune only achieves 11" of vacuum.

 New Quick fuel 600 or 650 vac secondary carb (I can't remember), duraspark ignition. Has been sitting quite a bit over last 10 yrs maybe out once a yr for a couple hours, until this summer since my turbo 390 is running we have hit a few car shows together.

The problem is it's breaking up at higher rpm and seems down on power compared to what he remembers with a 600 double pumper from years ago. He has jetted the carb up a few numbers which helped he thinks it needs more, initial timing has been bumped up which also helped unsure of total at this time, vac secondary adjusted to come in sooner also helped. Fuel pressure is good throughout rpm range. Thoughts? still to lean, over advanced, other ignition problem?

I'm looking for more ideas as I about have him talked into letting me pull the distributor to give it a seat of the pants recurve and control the total. Also what would a good total be for  But I don't know if it will solve breaking up at high rpm. My gut tells me it ignition related somehow. We do not suspect any mechanical issue with the engine it has to be in the tune, but we have been wrong before.

[machoneman]

Why not a compression test first? Better, a leak-down test. Then, some vacuum readings at idle and higher. Plug reading after a run? Easy stuff 1st,

[blykins]

Ignition.  Junk in carb.  Valve springs.

[BigBlueIron]

Maybe I should clarify "breaking up" not falling on it's self more like a rev limiter, dropping random cylinders and popping out exhaust. Like its happy and wants more but something is holding it back.   Honestly it runs to good up to that point to even think its a compression problem but maybe. Vacuum at idle is 11" and steady, seeing what it does at WOT might reveal something.  Valve springs, that one sounds very plausible.

I'd like to try another coil too maybe another box since they are so easy to change. Just need some time with it, just fishing for ideas out of the norm for when that time comes. We had plans to mess with it last weekend but he was at Cordova, pat time pit crew member on a Funny Car. Told me they where chasing some power and rpm issues with it as well, chased a boost leak to a warped intake. Which I guess is fairly common on those engines, that fixed the power problem but not the rpm. All in all guess they got along fairly well though.

[machoneman]

Advance weights under the point plate could be stuck. If it ran good before (and it sounds like it) I'd not try a re-curve until the weight situation is checked. On the note about exhaust popping, yeah, weak valve springs will do exactly that. 

[turbohunter]

Has been sitting quite a bit over last 10 yrs

This is the key phrase.
Start with blykins list.

[Heo]

Also check all wire connections for oxide

[Falcon67]

Per Brent's list.  That sounds like ignition, not carb.  A 600DP stock jetting should be plenty for a 289.  Going up "a few numbers" adds more like 10~12% more fuel that it doesn't need.  Engines that were running well on carb X don't suddenly need 10~12% more fuel just because.  My 460HP 351C uses a 650DP, stock front jetting and the back is up 2 for best MPH.  Been like that for 15 years.  Same carb, same jetting used on a 300 HP 302, 460 HP 351C and the 575HP dragster.   

Ignition or valve springs IMHO. 

[BigBlueIron]

My personal thought has been an ignition problem all along. But I hadn't thought about valve springs so that's good advise and why I asked. Hopefully mess with it sometime and update those interested.

Falcon it no longer has the DP has a new entry level model Quick fuel vac secondary. I'm not going to argue that jetting it up a little helped it, because it did.

[cammerfe]

Look carefully at the points. Point bounce will create the effect you've described. Years ago on my '65 Mustang 'K' car, I used to put a bit of wet-suit neoprene foam behind the point arms to keep them from bouncing. Several years before that I had the same sort of effect with my '53 Merc Flathead. I replaced the factory points with a Mallory dual-point kit. Problem solved. Dual points give more dwell time. I finally replaced the stock distributor with a Mallory dual-point distributor and coil. Heaven.

KS

[Falcon67]

Falcon it no longer has the DP has a new entry level model Quick fuel vac secondary. I'm not going to argue that jetting it up a little helped it, because it did.

No argument at all - kinda odd that it needed it though.  Especially on a QF unit as most of those are good out of the box.  BUT - every engine has it's own needs, so if it works - it works. 

I run an old "points" distributor on the 302 to clear the tunnel ram.  It's a trick though - its really a converted Duraspark with an MSD pickup and a small cap.