Advise / Information Sought / Head Gasket Failure

[allansieben]

Hello all,
It's been a long while since I've posted and I hope all is well in the world of Lancia's and your personal lives.

I need some advise to help solve a mystery (please)...consistent and systematic head gasket failure.
For the past 7 years or so I have gone through 3 head gasket failures, all total under 25k miles.
My most recent failure has caused damage to the head (burn hole) and reoccurring damage to the head gasket itself...always the same problem. It appears that the metal reinforcement rings keep burning through thus causing misfire etc. I will attach photos and value any input as to the cause and solution.

Here's the back story...

I've owned my 1977 Scorpion for over ten years now. It came with the original 1800cc twin cam engine which was mostly stock at purchase.
One of my best friends happens to be my mechanic who specializes in Italian Cars...particularly Fiat engines. He has well over 30 years experience on Fiat and Alfa Romeo. Under his advise and guidance, a few years after I purchased the car we decided to upgrade the engine. It was a work in progress for several months but here is what we did.

1) Added twin Weber carburetors (40 DCNF's)
2) Head rebuilt including Valve grind, new valve seals.
3) Polished and ported intake Alquatti intake manifold.
4) Upon reassembly, my friend / mechanic insisted on changing the valve timing by advancing the intake cam by one cog notch and retard the exhaust cam by one cog notch. This would produce a very noticeable power band in the upper range and improve the overall performance.
5) Resurfaced head at a reputable machine shop.
6) Added custom fabricated stainless steel headers and custom exhaust.

Since the upgrades, I have gone through three head gaskets. All three failures are similar in that the break is either between pistons #1 & 2, and most recent, #3 & 4. (See photos)
All this time my engine ran normal temperatures (according to the stock temp. gauge) Both fans would kick in just over 190 degrees F.

I have always had suspicions about the unorthodox cam timing trick as the culprit, yet my friend insists this is not the case since he's done so many conversions without incident.
In fact, he is convinced that the block surface may be the cause and we will be having it checked and decked if necessary.

I don't want to bore any of you with details but I hope the information provided gives someone some insight as to what may be going on here and which direction I should take.

At this time the engine and gearbox are completely removed from the engine bay and sitting in my friends shop. We will be conducting a complete engine rebuild at this time since the engine is out.
With the cylinder head having that divot that was carved out by extreme heat,my friend says its an easy fix with aluminum welding. I am feeling that perhaps I should purchase a replacement head just to be safe. Your thoughts?

I would like to thank anyone who responds in advance for some advise or solutions to help me rectify this ongoing problem with my engine.

NOTE: What would one expect to pay (ball park) for a complete engine rebuild for the 1800cc Lempredi Twin Cam Engine? I am holding my friend to some accountability for two reasons.
1) He hasn't resolved the issue since he first did the upgrades.
2) He was driving my car (by himself) at the time when the head gasket blew for the third time (very recent).

Thank you,
Allan

 

[kmead]

I don't have any answers, just a few questions.

From reading your post and looking at the pics my understanding is that the engine was basically stock and that the actual upgrades were the intake manifold and exhaust header. The work to the head was just maintenance with a head skim to increase compression and likely to clean up any issues with the surface.

Do you know how much the head was cut and if the head had been previously cut prior to your ownership? If it was cut too far either in aggregate of all the cuts made or in the one cut, you may have a compression ratio which is untenable and is producing preignition which is blowing out the head gasket. The damage to the head is the result of the gasket blowing out and then uncontrolled combustion burning into the head. To me it looks like it started with the little dimple you can see before the cut across the cylinders above it (in your pic) that may have undermined the head gasket and started the channel to the othe chamber.

As for the advancing and retarding the cams, I wouldn't think there would be much benefit or much that would go wrong with factory emissions type cams in doing this. If there was any negative it would be the retarding the opening of the exhaust valve which may be raising the temps in the combustion chamber.

It it were my engine I would be reticent to mill the top of the block unless there is a provable issue with it. I would absolutely not weld that head. I would start with a clean, new (if possible or new to you) head that is proven to never have been cut or have any damage to the surfaces. I would not cut the head to raise the compression ratio, compression ratio should be managed by the pistons chosen in combination with the connecting rods. I would not do the retard/advance trick as it is a pretty crude approach to "dailing in" the cams and likely isn't doing a very good job for you.

As Steve (FiatFactory) would say the cost of the engine build depends on what you want the engine to deliver to you. If you want the engine to be OE stock it would be much less than one that is built for all out performance. If you look at Vick Auto they charge between 5300 and 7300 US to build a complete engine depending on your choices. I don't know what Jon Logan, the pre-eminent US Lampredi twin cam builder at MWB, would charge. I would ask him for a quote, he or any other engine builder will want to know what it is that you want the engine to do for you.

If it is to remain stock it may just be a matter of getting a properly provisioned head and having it installed with all the parts you have already installed. Getting to higher performance is a multi-faceted process which will not be cheap as Vick's prices show.

I would post over at Mira and on the Lancisti forums to gain additional viewpoints as they are a bit more twin cam knowledgable than those of us here (with exceptions, Steve, Carl and a number of others).

 

[lookforjoe]

Following Karls' line of thought - did you ever document your compression after any of the repairs? It would seem increase in compression due to head work is the most likely culprit. When I read the opening to the post, I was thinking perhaps ign timing / advance issues like mine - however your HG doesn't exhibit the type of failures I (repeatedly) experienced due to poorly mapped timing curve.

I would however trust my machine shop to fix that head - he's done incredible repair work on Porche, Ferrari & other exotic heads that are simply NLA. Whether the shop you have access to can repair that is something you would have to thoroughly investigate. The further issue, as Karl pointed out, is whether it has already been shaved more than is acceptable for the compression range.

 

[phillips82]

Clean the head and check it for flatness. Few machine shops still belt sand to resurface heads so it should have been even.

The burnt area looks to me like it melted. Detonation leaves a more ragged area of destruction. If I were you, I would get a set of adjustable cam gears and dial in the cam timing to exact zero. I would also get a wideband O2 sensor and use it to properly dial in your carbs.

 

[Rod Midkiff]

I am by no means a motor man. But with the mantin of shaving the head and then moveing the belt a tooth of makes Me ponder if He was trying to complensate for the shaved head..

(again) I am not a motor man. so I am just re hashing what I have heard here and everyone is proably rolling their eye's at Me.

 

[fiatfactory]

Head gasket looks like it was lifting (yet again) at 2/3 as well as burnt through at 3/4. What head fasteners and torque method are you using for the cylinder head? Are you torque on build, retorque after a heat cycle and retorque after 500km? What brand and type of head gasket? Same type of gasket each time or have they been different?

"This would produce a very noticeable power band in the upper range and improve the overall performance."
Did it? Did you back to back test/compare? Or is this your mechanics statement?

Was the head resurfaced with the intention of increasing compression or was it just as part of the reconditioning? Hard to tell how much has been removed overall from your pics. Doesn't sound like it was heavily surfaced from your initial description, a picture of the head with valves removed to determine how close the valve seat is to the head face would indicate how much material has been removed.

SteveC

 

[EricH]

If the head has been milled/skimmed.... the locating dowels may need to be shortened or they can bottom out and prevent the head from clamping down properly. That's a long shot here, but something sure seems to be allowing the head gasket to lift.

 

[allansieben]

Thank you to all for the comments and questions
My friend Bernie (AKA The mechanic) has been specializing in Fiat's, Alfa's, Ferrari's and Lancia's for 40 plus years. He's an old schooled gear head who knows his stuff.
That said, I have made the decision to have him rebuild my engine but place the valve timing back to factory specs. As far as I know, The head has only been planed once and at ten thousands of an inch. I purchased new head bolts and the head gasket the last go around from Vicks and Bernie had torqued the head to factory specs. It is quite possible that he didn't re-torque the head, although he "thinks" he did. I don't recall him doing that so maybe I'm to blame. Everything else was done correctly as far as I know, yet something has definitely caused a burn so hot that it melted aluminum between cylinders 3 and 4.

Bernie has performed over and over the same type of engine rebuilds for many clients without incident so...who knows whats going on?
At this very moment my car (sans engine) is back in my garage while Bernie sorts out the engine bits. Everything will get disassembled and checked. Bernie is even talking about installing high comp pistons. Oy-vey!

I will report back all progress when I can and send more detailed photos if anyone is interested.
Thank you again for all your input, I greatly appreciate itRegards,

Allan Sieben

 

[allansieben]

Here's the latest pic of my Scorpion with Mt. Baker, WA in the backdrop