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Cadillac Head Gasket....Again!!


Well-known member
Another head gasket...another day! Just when I thought I had my head gasket troubles behind me I lost another one Sat. on the canal to Lake Cypress. Engine has about 55 hrs on current head gaskets. The week prior, I had the vacuum advance seize up on my distributor causing a god awful idle that nearly shook the boat apart. I'm wondering if this could have created the gasket failure due to detonation? The part in the distributor that seized was not the vacuum advance canister but the mechanism that the canister moves. I replaced the distributor and put about 30-45 minutes total run time before the gasket let go and the temp shot up. Am I thinking in the right direction or do I need to be looking for something else? I did have the heads surfaced on a rebuild 55 hrs ago after going through several gaskets in the same amount of days. I don't want to go through that again! :angryfire: :angryfire:
Many of the built Cadi airboat engines around Pasco and Hernando utilize ss roll pins located in the biggest gaps between head bolts for added head gasket strength. Buddy Branch in Tampa will not let an engine out of his shop without the roll pins.
The usual problem that I have seen is the failure to get the block and the heads straight. If they arent, no head gasket will live. I dont see the purpose of locating pins---its not like we are hitting these with a huge Nitrous hit or anything. And lifting is vertical, so I dont see what additional locating pins, that have zero additional clamping force will do. Anyone have experience with these and why they would work? (And I recommend the Corteco gaskets by far. I run copper o-ringed gaskets, but mine is close to an all out effort.)
Regards, Charles
The best thing to do is get a Mr. Gasket spring kit from Summit ,Jegs, Auto Zone or Discount. They are $10 then install the lightest springs in your distributor they go under the rotor above the weights. Then set your total timing with a light. How much total timing are you running now?
I've set it with the advance disconnected at 8 degrees BTDC. Not sure what the total is. I'm not completely sure the timing mark is properly lined with the pulleys I'm running and I've tried to establish correct marks by finding TDC, measuring and marking the pulley from there. In the past I've set timing by securing boat and adjusting distributor to get max rpm at WOT. I'm a little leerie of doing it that way now since I've gone to a reduction box. I did notice that the pins the distributor weights go were worn almost to the point of being cut in half on my old distributor. They had worn through the plastic bushings and half way through the metal pins. I have been running light springs already.
Stan had trouble with his balancer being mismarked I beleive so pm him for more info. it cost him a couple of motors before he found it.
You need to fix that right and find TDC mark the balancer and ask the Caddy racing exsperts what they run total timing at on motor. Then take off 3 deg and set your total timing there. Timing it by sound or RPM's will blow head gaskets or burn pistons.
Nice posting above guy's!

This kinda stuff is what makes this place the best. (and I don't even have a caddy!)
Maybe its cheep, but on my Buick engines I brazed the advance rod and capped the vacum actuator. Then used a 3 degree offset key in the timing chain lower gear. The set the RPM by setting balancing the distributor and the WFO 4BBL secondaries. I was in a situation that had no changeable pitch props so had to match the engine to the prop speed.

This was for DD application. For redrives, I think it would be set up like about any other racing engine. Assuming the right ratios. Seems to me, its easier to get the right ratio than to rebuild an engine to an oddball ratio/RPM.

IS this old school thinking or is it close?

Every motor I build I find true TDC with a deck bridge then check or calibrate the timing marks. Look at it this way each crank has a key way that can be off then each balancer has a key way that can be off, the marking tabs are usually metal and can be off let alone the fact 1/2 are bent. Each of these tolerances can add up to a substantial amount. I would say on average the average timing marks are off 3 degrees. I have seen many balancers over 20 degrees off. With a performance motor 3 degrees is the difference between no problems, good pistons or pistons that become conversation pieces like ash tray's.
i would give an opinion but after i scatterd my caddy out of pure stupidity i dont trust my self anymore.i may have faith again in myself after i finish putting my caddy back together and i am problem free for atleast the first run.now with that beeing said i will run my mouth anyway.i set my caddy at total 32deg. timimg.changed pulley's so i had to buy a piston stop to find true tdc.and rescribed a mark on my pulley.thunder makes a good point with the key if or when you degreed your cam and used an offset key you will have to compensate for the key for the cranksleeve and pulley whether retarded or advanced.with the head off you can use a bridge plate buy one or just make one and scribe the marks on the pulley i found my set up after changing gave me a 4 degree false pulley pointer.and if i would have set it point to point on the pulley pointer i would have had 36degree total.with alot of pinging.
You can also buy aftermarket pointers that are adjustable ...... find TDC on #1 with a positive stop, and then bring the pointer to the mark on your harmonic balancer, assuming it's not too far off of course.

For a direct drive unit, 32 degrees is fine. With my 2.38 gearbox, I run 35-36 degrees total. I run an MSD billet distributor with an MSD timing computer so I set the initial and then check the engine at 3000 with a light. Its dead on. One thing about the Cadillac is there were four different balancer combinations and they are not mix and match. So you certainly need to check for TDC and go from there. Regards, Charles
so maddog your best pulls were 35 / 36 i may have to give that a shot when i get my caddy together.
First did you go back and retorque your head bolts after a good warm up. Next have you checked your torque wrench to see if it's accurate, with the clicker type wrenches you should back off the adjustment knob when not in use or they will loose their calibration. In other words if you set the torque at 90 lbs and use the wrench, before you store it back it down to zero. And yes even the high dollar wrenches go bad in time, It's Murphy's Law. And one more thing ,did you run a tap into the headbolt holes to clean them out. Aluminum heads are much more prone to give problems when ins
also i forgot to mention jdotson alot of the cowboyseven cadillac guys do 130lbs instead of factory torque spec.
Bondsman sorry to heard about your luck.

I'm still waiting for my pistions for my build up. I hope to have it in the water 1st week in June

( down 2 months :shock: :shock: :shock: :shock: :sad2:)