Inliners International Forums General Discussion Engines Engine troubles

Hi
I am in need of some ideas suggestions. I am having some troubles with my engine. It's a 56 235 as far as I know stock. It idles great can get it down to about 2 to 3 hundred rps just to see how low it will go. I keep it at about 5 to 6 hundred rpms. I had a holly webber progressive in it changed it out to see if it was a carb problem and it was not. It now has a single carb in it. The plugs all look as if they burn good slight black carbon seems ok mostly ash color. I do have a NAPA ECHLIN coil in it ic1600 oil filled high performance says to use with primary resistance or external resistor. I had an external resistor in it when I first started running this motor and had to take it out it was running very rough. The coil does get real hot on the outside. I did a compression check tonight and it was num 1) 120 2) 118 3) 120 4) 120 5) 118 6) 108 I have adjusted the valves while the engine was hot. So much for basic information now for the problem. As stated it idles great once I get it up to about 2000 rpm it bcgins to run very rough rpm drop and or bounch up and down as I rev it more. It seems that the rpms should at least stay even. At this point I am loosing power going down the road. At first I was thinking about changing or having the head rebuilt but I am not sure that is the problem. While going down the road I don't see any smoke of any kind. I can use any advise or suggestions.
Thanks for your help
Steve

Have you checked fuel pressure at the carb? It sounds like it might be starving for fuel. If your coil calls for a ballast resistor, and you dont use one, your points will usually burn up pretty quick, Have you checked points too?

Vigil,

Interestingly, I ran across a very similar problem with a '38 Plymouth 6 recently.

In that case, the problem was that the owner had replaced the distributor points with a new set....the new set being "brand X". The point spring was weak, allowing the points to "flutter" at speeds above a fast idle.

I've seen a somewhat similar situation caused by bad wear in the distributor bushings, which allowed the dist cam to "flutter" a bit at speed, so that the points weren't always opening consistently.

I'd suggest that you have the dist out, and go through it completely, replacing the bushings if you see more than .002-.003 TIR play at the dist cam, check the weights/springs, fit new best quality points/cond/rotor/cap, and, if at all possible, take the dist to someone who can set it up on a Sun distributor machine.

Refit the dist, make certain the vacuum advance unit is functional, time the engine to the ball, fit a temporary substitute coil which is known to run well on another car, and then try it on the road.

If you still have the same problem, look for fuel starvation.....weak fuel pump?.....substitute a known good one, and try it.

You may possibly have that nasty little surprise that happens sometimes in older cars....the steel fuel line has rusted somewhere, and developed a "pin-hole" leak, partially breaking the vacuum developed by the fuel pump.

Check for that by fitting a known good vacuum gage to the fuel line at the tank, cranking the engine until the max reading is obtained at the gage, and then noticing whether the gage reading drops off only extremely slowly, or whether it drops fairly quickly.....if it drops off quickly, suspect a pin-hole leak somewhere in the line, or a damaged flare/flare fitting.

If the steel line is leaking/damaged, there's nothing for it but to make up a new one....thats a tedious job, to be sure.....

cheers

Carla

Are you using a 3 spd OD with all of the original type electricals with it? I have heard of something similar happening with these setups. If I remmember correctly, it's related to the govenor, but I'm not entirely sure. Check a shop manual. Try disconnecting the overdrive and see if that cures it.

As I recall, the ignition is interupted when it goes into overdrive. If that part of the circuit isn't working correctly, that could be where the issue is.

I have to agree with Carla. The problem source is most likely in the distributor. Before pulling it for rebuild check the points and especially replace the condenser. But it's always smart to rebuild the distributor too in 235 that old and well used. They are very easy to rebuild, but occasionally rebuilt/NOS ones show up on EBay.Remember you can use a distributor up to 1962 so parts are at NAPA.

The distributor shaft play was a some what common problem on high mileage 6 engines in the sixties GM service school taught you to install two bushing in distributor instead of the one as original. There was room for two in the housing and on the shaft. This solved a high speed miss problem. If this is a really serious problem at higher RPMs you may have a broken valve spring that has enough tension to close valve at idle but not when rpms increase.
Big Bill

Dear Steve;

Two things come to mind here.

First: If you have an 'in line' fuel filter make sure It's on facing the correct direction and that It's clear. Simply remove it & blow through it.

Second: Put a 'dwell meter' on your distributor and see if the dwell changes (a lot) when the speed is at 2,000+ . The worn bushings mentioned or a bent shaft will do this.

Good luck.

Hi
Thanks to everyone for the ideas. I believe my answer is here. I will first put the ballast resistor back in. I don't believe it is the fuel pump but i will check on it, the fuel filter is on correct. It is not the overdrive sorry forgot to say it's not electrically hooked up yet. I have another dist. that I will try and if it runs any different I will rebuild or get another one. I will check with dwell first. Running and adjusting this engine I think I am going to find my answer in the distributer somewhere. This is great information I will keep everyone informed as to where and what I find.
Thank you Steve

Did you check your points after having run with the ballast bypassed?

HI
Thanks for the info to all. I first looked at the points and the spring tension was weak. I looked at the distributer and it had some play in it so I took it out and put the other distributer and vacuum advance in it and put some new points. Adjusted the valves, set the timing and took it out for a ride and that took care of the problem. I will play around with it some more and see about fine tuning over the weekend. It got dark on me, but was able to take it out for a ride and it ran great. Thanks again I am very happy with the way it ran tonight.
Steve