Overheating BBC 468 Pro Street Willy's Coupe

[Keith Morganstein]

One thing determined from the temps, there's a coolant flow problem in the block.

Im not sure if coolant flow would be better in this situation with series flow gaskets.
I have a bunch of mark IV stuff around ( but no gen 5) I think it's worth mocking things up to help visualize the flow paths.

On another note: you had leak down and comp test that were of concern. How is the cylinder wall condition? How is the valve seal? (Flip heads over and fill chambers with solvent, blow some air in the ports). I'm not saying that is the issue, but how is the overall condition of the engine?

[rp930]

I went from series flow with wrong gaskets to parallel flow with correct gaskets (Cometic) and it cured mine. Are you sure this isn't a filled block?

[Keith Morganstein]

I'm wondering the block (mark IV) is drilled for series or parallel flow. (Two extra holes for parallel) I think that some of the parallel flow gaskets block off the rear hole.

I also did a search on this site about it and this thread seems to cover much of the series/parallel gasket issues.
viewtopic.php?f=1&t=33247

[geraldtson]

While you got the heads off you might check the breakaway torque and rotating torque required to turn engine over maybe with converter unbolted and post results. Someone on here should be able to compare those numbers. It looks aggravating in your application but i think i would do it while your there.

[rp930]

Pictures of the gasket and block might help.

[topradman]

Ok, I will try to address all the new questions as they came.

Pictures of the gasket and block might help.

Here are some pics of the engine w/the heads off. The block, as stated is definitely Gen V. The gasket that was on was a Felpro 17046. Again, after careful examination, this gasket should be the correct arrangement for parallel flow which is what the block was designed for. The cylinder heads do not care as they have provision for all coolant ports in Mark IV or Gen V blocks.

While you got the heads off you might check the breakaway torque and rotating torque required to turn engine over maybe with converter unbolted and post results. Someone on here should be able to compare those numbers. It looks aggravating in your application but i think i would do it while your there.

The rolling resistance was 41 ft/lb but that is still hooked up to the torque converter so won't tell much until I get the torque converter released from the flex plate so stay tuned for that.

I'm wondering the block (mark IV) is drilled for series or parallel flow. (Two extra holes for parallel) I think that some of the parallel flow gaskets block off the rear hole.

I also did a search on this site about it and this thread seems to cover much of the series/parallel gasket issues.
viewtopic.php?f=1&t=33247

You are indeed correct on the Mark IV having provisions for series or parallel flow, at least on the later model Mark IV's. I have not seen the gasket you are referring to but indeed, all the parallel flow gaskets I have looked at have the larger of the 2 rear holes blocked off and I assume that is to allow more coolant to move through the 3 lower holes between the cylinders to "even out" the coolant flow.

I went from series flow with wrong gaskets to parallel flow with correct gaskets (Cometic) and it cured mine. Are you sure this isn't a filled block?

If you had a Gen V block, the change you made would have indeed fixed your problem. Using a MarkIV gasket on a Gen V will most assuredly cause the coolant flow to short circuit through the front of the block, straight into the front cylinder heads and into the manifold, then water outlet never forcing any coolant to make it to the middle or rear of the block or heads. After tearing down the top half of the motor and examining this arrangement, I already have the supposed "correct" gasket for what I am working on. With the cylinder heads off and being a GenV block with huge casting holes to look through, I can very nearly see all of the water jacket areas in the engine block and it has not been filled, partially or otherwise. There would have been no reason to do this on this engine anyway as since I have the top end off, the engine is only bored .030 over and with flat pistons #H661 sealed power Hypereutectics for pistons, this is no high compression race motor for sure, especially with the semi-closed chamber, little valve heads off of the 427 tall deck truck engine which these heads trace back to ( #14092359 oval 2.06 intake/1.72 exhaust, 86-89 trk..

One thing determined from the temps, there's a coolant flow problem in the block.

Im not sure if coolant flow would be better in this situation with series flow gaskets.
I have a bunch of mark IV stuff around ( but no gen 5) I think it's worth mocking things up to help visualize the flow paths.

On another note: you had leak down and comp test that were of concern. How is the cylinder wall condition? How is the valve seal? (Flip heads over and fill chambers with solvent, blow some air in the ports). I'm not saying that is the issue, but how is the overall condition of the engine?

The cylinder walls have some scoring but it doesn't appear to be a pattern on thrust or coast side of the cylinders, just some random scratches, some cylinder worse than others. They do not seem to line up with the top ring gap. I can move the pistons around slightly and see the top ring gap and although I have not great way to check them with any measuring device while the pistons are in the holes, eyeballing the ring gap, it would appear they are around 0.017" which should correlate to roughly ".004 per 1" of bore". The opposing ends of the rings do not appear to be touching each other anyway, best I can tell. I have not gotten to check the cylinder heads myself yet as I just ran them over to a local machine shop I trust for their examination of valve stems, seat sealing, etc... They will not be able to look at them much until later in the week. I took them over to at least get a 2nd opinion. Base on the leak down check and a quick visual, they do not appear to be compromised.

Sounds like the head gaskets are ok. Do you have a picture of them?

Sorry, I do not have a pic of them handy as I ran them along with the cylinder heads over to the local machine shop for a 2nd opinion.

[rp930]

Yes your block is parallel cooling for sure. In my situation I had parallel head gaskets on a Mark IV block. Not good. I see no issue with the head gasket on yours. I wish I had an answer for you. Interesting but perplexing problem.

[MadBill]

To check the top ring gaps on my 495 BBC, I hammered a short length of lock wire flat enough to fit between the top land and the bore, then filed tapers on the wide edges and inserted it as far as possible into the gap. I clamped a pair of locking pliers on the wire right at the piston top and checked the piston to pliers gap with the gauge sitting on top of the ring. This told me how deep the taper went into the gap, so I could then measure up that far from the tip of the gauge and check the width at that point. In this case, they averaged ~ 0.040"
(Re-reading the foregoing, it was a whole lot simpler a deal than it reads. To paraphrase, I built a tiny taper gauge.)

PS: with a 'performance street'-type Total Seal gapless ring package and their recommended bore finish, rotation torque as assembled was from 25-35 lb-ft.

[Keith Morganstein]

You have a markIV marine gasket

You need these conversion gaskets, they correct the coolant flow issues that are causing the overheating.

http://www.mahle-aftermarket.com/media/ ... r-g-05.pdf

.

Im sorry, I completely misunderstood what combination of block and heads you had before.

I would still have probed for temps (as you did) before I ever pulled the heads off. Now we know what the temps look like in this situation. We will all learn something from this one.

[rp930]

Here is a rather long article on the subject.

http://garage.grumpysperformance.com/in ... info.3968/

[topradman]

Yes your block is parallel cooling for sure. In my situation I had parallel head gaskets on a Mark IV block. Not good. I see no issue with the head gasket on yours. I wish I had an answer for you. Interesting but perplexing problem.

Thanks, I appreciate that! In fact, I REALLY appreciate all you fellas taking the time to try and help out, I really do!

To check the top ring gaps on my 495 BBC, I hammered a short length of lock wire flat enough to fit between the top land and the bore, then filed tapers on the wide edges and inserted it as far as possible into the gap. I clamped a pair of locking pliers on the wire right at the piston top and checked the piston to pliers gap with the gauge sitting on top of the ring. This told me how deep the taper went into the gap, so I could then measure up that far from the tip of the gauge and check the width at that point. In this case, they averaged ~ 0.040"
(Re-reading the foregoing, it was a whole lot simpler a deal than it reads. To paraphrase, I built a tiny taper gauge.)

PS: with a 'performance street'-type Total Seal gapless ring package and their recommended bore finish, rotation torque as assembled was from 25-35 lb-ft.

Thank you MadBill! LOL .. I will check the ft/lb rolling resistance tomorrow with the torque converter released from the flex plate and report back.

You have a markIV marine gasket

You need these conversion gaskets, they correct the coolant flow issues that are causing the overheating.

http://www.mahle-aftermarket.com/media/ ... r-g-05.pdf

.

Im sorry, I completely misunderstood what combination of block and heads you had before.

I would still have probed for temps (as you did) before I ever pulled the heads off. Now we know what the temps look like in this situation. We will all learn something from this one.

No worries Keith. I appreciate all your assistance! I will get to the bottom of this one war or the other! This is beyond a mission now! There has to be an explanation.

Here is a rather long article on the subject.
http://garage.grumpysperformance.com/in ... info.3968/

Thank you rp930. Here's what I am now considering. Because I don't think I have ever had a problem that required this magnitude of ciphering before and because I have only ever had one BBC that the customer would not let me research to a conclusion before ( Merlin+12:71+57 chevy, custom sold car instead ) I am becoming inclined to return this set up to series flow. ( SEE EXPLANATION, ILLUSTRATION ATTACHED ).... I feel like the electric water pump, although a great brand and all ( Meziere ), and although does pretty good at idle and just off idle, is struggling to push enough coolant through all those large holes on the way to the back of the motor, thus, starving the rear of the motor of enough coolant to make this deal work. I already have the heads off anyways.

I will still check to see if I have too much rolling resistance to rule too tight of an engine out of the equation but after that, I don't think there is much left. I also discovered after closer examination the the distributor weight springs are the really heavy ones that come with the distributor out of the box and my local engine guy said at a glance that those are too heavy and probably not bringing in the advance soon enough. I am satisfied with the all in timing numbers but I am going to have him dial in the curve on his distributor machine to be sure it's coming in soon enough. I am satisfied that the vacuum advance should be to manifold vacuum.

I also intend to block off the EGR ports in the cylinder heads so exhaust heat can't get to the intake directly. I think I will also replace the 1/2" phenolic spacer with a thicker one, maybe 1", as I have the air cleaner/hood clearance to do so.

Of course the heads will be examined thoroughly before we would put them back on.

I feel like these couple of things, although maybe small in and of themselves are creating the perfect storm. I just have never had this much struggle before, struggle a few times, but not this much. I have to admit, I was especially disappointed not discovering the wrong head gasket.
Look over the attached drawing and tell me what do you guys think? Thanks again for all the input, seriously!

[topradman]

PS.... I just looked over the heat graphs again and the graphs seem to support the parallel flow just isn't working very well on the passengers side head or block, making me still wonder if that one larger hole out of the 3 on the parallel flow gasket which ends up located to the front 1/2 of the cylinder head just isn't allowing enough coolant to get to either the center of the block or the rear of the head.

Doesn't this make some sense?

[Keith Morganstein]

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[Keith Morganstein]

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[Keith Morganstein]

The gasket you have now is the wrong one!
The victor reinz 4918 and 4923
conversion gaskets (left and right) should solve the problem.