exhaust smell after trips

My 426 engines, being built in 1965, keep me busy. After a 20 min ride, when we come back to the docks, I need to turn on the blowers to get exhaust smell out of the engine room. I dont get this smell when the engine is idling, at the docks. I get it only when I come back from a trip.

My thought: On both engines, i have a pcv valve on one side and a breather on the other. Breather tube goes to the top of the carb, to the flame arrestor and the pcv goes to a vacuum outlet on the bottom of the carb. The pcv valve works propely, it sucks air and and when I blow on it, it stops 90% of the air flow. (is that good enough??) I heard the pcv valve works good at idle, but as the throttle opens up, the vacuum drops and does not work as well. If that is the case, while underway, the pcv valve should not be sucking any of the fumes?

I tend to smell exhaust after a long trip with load on the engines, so I am wondering it would help if I put breathers on both sides, and take them both to the flame arrestor. Any thoughts on this?

What kind of condition are your engines in? Assuming breaker-point ignition, is point gap, timing, carburetor all set correctly? Is spark arrestor clean?

These are some O-L-D friggin' engines. When was the last time the valve seals and/or valve guides were examined. If your normal run-ability/maintenance items are in check, you may be getting unburnt fuel up through leaky valve seals. How's the compression? Check it dry then wet - compare numbers. If improved when wet, go after your cylinder heads.

Yes, distributor has original style but brand new points, Carburators are marine edelbrock, 5 years old. The heads were send to a shop and got new springs and new seats 9 years ago. The flame arresters - I’ll be honest, I have not cleaned them in the last 3 years but visually, they are clean. I will clean them up this weekend though. Pcv valves work well.

when you say test the compression wet vs dry, what do you mean?

Is this a burnt oil odor or a burnt fuel odor?
Can you isolate the engines to determine whether it's one or both?
B & RB Chryslers have heat crossovers on the bottom of the intake manifold. If these are not sealed, it's possible they can expel exhaust fumes. On rare occasion they have been known to crack. This his happens more with aftermarket aluminum manifolds.
This Edelbrock CH4B RB manifold had cracks repaired and it cracked again........

good idea to isolate the smell to one of the engines.
Any other suggestions?

PS?: HAs anyone pulled the engines out and had them rebored, and new rings? what was the cost?

akintosyali said:

when you say test the compression wet vs dry, what do you mean?

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Perform compression test right after you pull all of the spark plugs out, and record pressures. Then, one by one, squirt some new engine oil into each cylinder to be tested and perform compression test again. Compare readings. If readings are significantly greater wet, there is likelihood that either rings or valve guides, or in best case valve seals are needing attention.

Also, in my last response I failed to recognize one item. You have 426, hemi with spark plug boots going through valve covers, yes? You could be getting blow-by there as well, possibly. Maybe try to clean really well around boots before going out, and see id residual oil/soot shows evidence of seeping from them.

Good luck. ,Noel.

I dont have the hemi, it is a 426B marine engine. so spark plug boots are not going through valve covers.