Chris Craft 350Q unreliable

" The port engine in my 350 Ca

" The port engine in my 350 Catalina (Chris Craft 350Q) fails to operate reliably. I have rebuilt the Carter Carb, check the compression in the engine and it is fine. I investigated the Mallory distributor, which was changed over to electronic ignition vice points, and the voltage and resistance measurements are ok. I found the flyweights in the distributor sticky, lubricated and exercised the flyweights. The fuel pump failed and I put in an electric fuel pump. Replaced the spark plugs, checked the firing order, replaced the distributor cap and rotor. The coil was checked also. After all the above the engine runs and comes up to full power (3800 rpm), however after a few hours of operation the engine fails to idle and stalls out and is difficult to start or will not start until the engine has cooled down (the engine floods out). While operating I have a gas smell emitting from the exhaust. This leads me to believe the engine is running rich. Am considering replacing the old Carter Carbs with new carbs. Any recommendation as to make and model and what size carb to get? Is there anything else I should check on the engine? Also, I am unable to find timing marks to set the ignition timing, need help here. "

" You need to find out what th

" You need to find out what the PSI is on your electric fuel pump. If higher than 6 you need to change it. Your carburetor can be replaced with Holley or Rochester marine carburetors. I will need to know if you have a spreadbore or square bore intake, or actually just the bolt pattern dimensions. If you need any help call Dania Marine 1-800-748-7739
Good luck, Gabriel "

I had the same problem with m

I had the same problem with my 327Q. It's most likely a carburetor problem. I had the Carter AVS professionly rebuilt and it has run perfectly for over 30 years with a 5 year rebuild schedule. These carbs are reliable and simply designed for good reliability. I can't say the same for the Holley or Rochester. Would also suggest replacing the wedge plates under the carbs with the newer high temperature plastic ones. They help insulate the carbs from heat and do not warp like the original aluminum ones that C.C. used.

I having a similar problem with my 350Q (Carter Carbs). Did you ever resolve the issue?

re: "comes up to full power (3800 rpm),"

If this is the max rpm you can get out of either engine, you have other problems.

Also as a thought... pull the plugs and check for water in the cylinders as this may be trouble with the riser. Another suggestion is Coil replacement, if the coil is not putting out a crisp spark you can still have a running engine but without the power. That would definately put a damper on the engine speed.

sandkicker said:

re: "comes up to full power (3800 rpm),"

If this is the max rpm you can get out of either engine, you have other problems.

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I fully agree with this!

You mention that you are not sure about the timing marks. This is of great importance to have this ignition system timed correctly, and more importantly, your TA.... (Total Advance).
Without adequate timing marks, this engine cannot be timed with any accuracy..... nor can TA be checked!

Also, with twins, many parts can be swapped with little expense, gaskets being one!
Swap what you can as to help with your P of E..... (process of elimination).

Also, and probably not a contributing factor, but you mention Mallory Distributors. Both LH and RH rotation engines rotate the distributor in the same direction!
The distributor in the RH Reverse Rotation engine will sustain a "down-load" force on the shaft (the nature of the gear cut)......., as appose to the Standard LH rotation engine distributor, of which undergoes an "up-ward" lift force that the wear washer takes care of!
A Mallory AV (std LH rotation engine) can be changed to a Mallory BV (RH rotation engine) by simply changing the gear. However, according to Mallory, this is not the correct method to do this. (changing a BV to an AV is not an issue)

If the distributor in the RH Rotation engine is not equipped with the correct bearing to counter this "down-load" force, it will prematurely wear (according to some Mallory information).
If I understand Chris Craft's engine oreintation......, your Port engine is a RH/Reverse Rotation engine...... the one you are having trouble with, correct?

Again, just simply a suggestion that may be worth investigating!

.

If you have the Mallory coil with the high tension wire that presses (no post) into the top of the coil, check it for good contact. Had similar issue on Chris/Mallory conversion. End of wire in coil was burnt, same symptoms described.

RISER LEAKING..... Just as an idea, your going to have to pull your plugs and check the cylinders for WATER. A small riser leak will initially give you engine trouble especially in achievig the WOT. And now you metioned that it doesn't want to start which may mean the riser leak has gotten worse and dumping water into the cylinders. After you pull your plugs, naturally check the plug gaps and burn on them. Then turn your engine over using the starter, (with distributor spark wire grounded) and look for water spray or vapors coming out of the cylinder. This may be an easy fix for your trouble and worth taking a look at.

Re: I had the same problem with m

H Brown said:

I had the same problem with my 327Q. It's most likely a carburetor problem. I had the Carter AVS professionly rebuilt and it has run perfectly for over 30 years with a 5 year rebuild schedule. These carbs are reliable and simply designed for good reliability. I can't say the same for the Holley or Rochester. Would also suggest replacing the wedge plates under the carbs with the newer high temperature plastic ones. They help insulate the carbs from heat and do not warp like the original aluminum ones that C.C. used.

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Do you have part #'s and a source for the plastic wedge plates?

Thanks,

Dave

Re: I had the same problem with m

I am having the same issue with my engine (1968 327F) stalling out after a few hrs of running. The first hour or so it runs great. After that it will run fine WOT but stalls when you try to idle it, even in neutral. I pulled the carb and found the mounting gaskets to be wet with fuel. I also found some pitting on the manifold itself where the carb mates. I am going to clean the carb (rebuilt last year) and replace all the gaskets. I will smooth over the pits in the manifold as best I can but I really don't want to have to remove the manifold to have it re-surfaced. Does anyone have any opinions on whether or not to use gasket sealer together with new gaskets to help seal the carb?

Dave

UPDATE

I did some more troubleshooting and discovered that the stbd. coil is hotter than the port (130 vs. 90) when the stbd. engine fails. Also no spark until the coil cools down below 100. This is a new Hot-Spark coil that I just purchased along with their electronic ignition conversion kit. My question: is this considered too hot for a coil (I have also emailed Hot-Spark on this) or am I still chasing some other electrical malady. As a side note, I discovered a capacitor mounted to the coil bracket. I believe this is related more to the charging system than the ignition system correct?

Thanks,

Dave

Re: I had the same problem with m

Had that problem w/ my 350 Q. Dist. were set 180 degrese off! this was done by a marine mech.??? Believe it or not they ran, not bad, but would only make about 3700 rpm and would not idle after run for a while. Get yourself a fireing order scamatic and check your firing order.