Seized exhaust cam

Yep don't argue even though you're right ... pick your battles .. be different if he wasn't gonna fix it.


Cheers

 

Line-bored sure, but what happens to the journal-head clearance. I'd think it's time for a new head. At the very least, break out your mic and bore gauge.

 

Yeah good point to measure it and document how much material got taken out but I still think she's okay ... mechanic might start getting nervous unfortunately if you ask for that or it might confirm there's no problem at all. It's still supported 100% of the way around the journal on at least half of the length of the cap and once it'd deburred/cleaned up maybe only .002" came out at the absolute most (my trained eye ... maybe only .001" at second look ).

If this was some guru that I just dropped $10k with for incidentals I might have a different attitude ... but that won't work out 'cause the guy will just call all us idiots 'cause he's already said he put the cap on the right way and doesn't have his own explanation ... "those guys" can be a treat to work with LOL.

Cheers

 

Nobody's buying a new head.

In the real world, it's probably just fine like it is. Line-boring, while an ideal fix would be expensive, require some adjustment for material lost and probably wouldn't be noticed in the finished product.

 

In the OWM, camshaft bore alignment is ONLY to be checked with the head on the block (used head gasket) and torqued down to spec. If the head is on the engine you should be able to freely turn the cam without resistance (valves out of the head). Also, finish boring the cam journals is done with head on the engine as well.

I does appear the cap was installed backwards by the mechanic, and I agree that you should continue to work with him as long as he is doing the work to make it right, even though he wont own up to it. Mechanics is hard work, and mistakes can happen some men dont often want to admit to, or dont want to believe happened.

Spin the cap around and clean it up with crocus cloth, should put it back good as new. You probably needed to replace those valves anyway.

 

Or you have to have a head fixture to stress the head when you linehone. Dave helms Scuderia ramparte has the proper ferrari tools by the way.

 

"Proper Ferrari tools"????? ... what are they? LOL ... you mean that big reamer? ... do they make something for tq plate boring the sleeves? ... uuuuuuh no.


I just made my own "piloted reamer" for I imagine a fraction of what that Ferrari tool costs ... and I know it's right ... FWIW every head I played with turned freely on the bench and turned freely when I checked it tq'd on a block even after making new caps from scratch.

 

Well,

I have been in countless FNA shops and many indy shops. Dave Helms is one of the truely devoted. I have never seen the OEM Ferrari line hone tools for the block and heads. Dave has them. Sure it is a big reamer but how often have you seen the real Ferrari reamer?

 

I totally respect Dave but not 'cause he has a reamer from Ferrari ... if he had a reamer made that did the same thing who cares ... just a tool ... I don't think Ferrari ever supplied tq plates, etc. so what I was implying was a guy having all the Ferrari tools is good but there's a lot more you need unless you're just farming it out "to a machine shop" and not check anything which alot of guys do ... I'm sure Mr. Helms has a bunch of goodies that the factory never had .

Cheers

 

I completely agree and I have rebuilt these 308 motors myself with non-ferrari tools. But it is nice to know there are a few really devoted guys out there who will acquire the OEM tools when they are available at an acceptable price and make tools where appropriate. I also think a plug for this kind of guy goes along way to keeping these top pros in business and weeding out the guys who have to fix their own work or worse yet....leave it to someone else to fix.

 

so am I ... you don't have to take people's money to be devoted mate . I mean that as no insult to Dave ... I've just been cutting metal for a long time and see few "mechanics" that cut ... most farm it out ... Dave cuts metal from what I can tell but anyone that farms it out is relying on "someone else" ... you realize that right?



cheers

 

Dave for sure is one of the top notch guys around...

I for one, don't go for the Ferrari pre-honed "drop-in" sleeves...
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I'm not really sure how to respond to this statement, it seems to suggest a number of things.... Some I completely agree with and some I find exception to.

If I thought I could do the job to Ferrari standards without the costs involved in purchasing the correct tools, rest assured I could have found many other areas to have spent the money and if I failed to find those areas I am sure my wife would have ideas. I don't see this as a debate on weather or not one is capable of doing the job with alternate tools anymore than a debate on if one cuts the metal in house. In this case the line reamer in question allows the job to be done to far tighter tolerances than a machine shop using a line hone or a free handed piloted reamer. I have drawers full of piloted adjustable reamers and choose not to use them for this application. There has been a rash of seized cams in the last number of years and I have found a number of them to be due to oversized clearances, stretched caps, mismatched caps, over tensioned cam belts and resulting galled journals... Yes, I have a full machine shop and tooling because I was unable to find shops to do SOME of the work to the standards I wanted. I also do a great deal of prototyping work on new ideas so this is needed in house. Its not how one cuts it, its knowing how much to cut, where to cut, how the aluminum grows, how much it grows AND knowing when a specialist in another field can do a job better or more efficiently than myself. When spending other peoples money, this is not the time for ego's to be involved. Part of my job is to find the most cost effective solution to any problem that consistantly meets the standards I set for the job regardless of where its done.

In this case, if the cap was not stretched out of round and the damage is limited to the scoring that can be seen I would choose to use a ULTRA HIGH tech method of a bearing scraper (yes I was taught this by the true best of the best many years ago) and dress it out as Paul suggested. With the angle of the camera it does look a bit skewed at which point I would install the "test bar" with the head torqued down and see how it turns. Could one use the cam for this? Sure, what is the assembled clearance? Just able to spin doesn't answer the questions to my satisfaction but I have no dog in this fight and I am not doing the job. Personally I think it will be fine with minimum effort.

Dave

 

+1

After years of repairing, rebuilding and racing unobtainia etceterini cylinder heads (Fiat Abarth Bialbero, Bandini, OSCA, Moretti), I can tell you that the idea of line boring (or even align honing) the cam bores on this head is beyond the pale and not necessary.

Clean it up and reassemble. Sorry the guy is adamant that the cap was on right, no way with the mismatched scoring but he is fixing it and you do want a decent future relationship. Sounds like it'll work out just fine.

 

didn't meant to ruffle your feathers Dave

I guess this is what you find exception too? ... far tighter? ... I would expect .0005" or maybe .0002" difference to what I can pull off ... I have not seen the entire tool or used it though. Just my opinion though Dave and I'll admit you have way more experience than me. I doubt many people can even measure that accurately which is why that tool is useful. I make A LOT of assemblies that I heat and shrink together ... very similar to putting bearing races in gearboxes, etc. except you get one time to put it together right. The craziest thing was shrinking a 2ft diameter gear on to a 4" diameter drive shaft that's 2 feet long for a prototype airplane gearbox. Probably 80 hrs in each of those parts.

I started buying my machinery back in 1995 and started learning to run it myself the same year because I couldn't find any shops to do the work to my standards for a reasonable price. Even back then I'd been in the biz long enough to know how long setups take. Plenty of hacks but I'd have to fit everything or take it back to the shop for them to fit. I'm an engineer by trade but learned to cut metal out of necessity. I have a bit of an attitude 'cause it's impossible to find competent machinists out here. "Knowing how much to cut" ... this is what really seperates making money and going bankrupt/raping customers 'cause they don't know. There's a lot of guys that cut metal that take all day on the simplest frickin' thing. Then there's the engineers that give me prints with NO tolerances and don't want to pay for my time to "make it work". The world is just simpler for some ... mostly 'cause they're not checking anything LOL. EVERYTHING I relied on others for when I hopped up my Ferrari motor was wrong or failed ... pistons were wrong twice even though I gave them drawings ... cams failed ... springs ate the Ti retainers and are leaning. I just rely on myself now 'cause I can't afford $100/hr to some guru to f'k things up and tell me I don't have as many years as him so it's me ... or even more insulting is "you can't do that RIGHT because you don't have the factory tool" ... total BS.

I would use plastigauge if I didn't feel confident about what I was "feeling". If I was in the biz of building these motors I'd have a tooling bar ground to size as a "go/no go" if I was seeing this problem enough.


I just refuse to accept that I have to pay some inflated price for something just because Ferrari supplied it ... if it will really make the final product better I'll duplicate it for way way less than what Ferrari charges. To take just a basic example cam pullies .... I could make one set for what "most people" have to pay for them and I'd still be making a decent living with the time & material invested. The markup on some of these parts is just stratospheric compared to manufacturing costs, and I don't care about quantity ... it's machine hrs. The liability one takes on though is another issue entirely which is why I pretty much shy away from doing Ferrari bits for others ... too much can go wrong that I can be blamed for.

If I've not annoyed you (hope I haven't) post some pic's of that tool ... if it's what I think it is I can get something ground up pretty much identical for a few hunderd bucks.

Respectfully,

Sean

 

This is why I don't take the WSM as gospel among other things ("Ferrari Rebuilding for Dummies" I was going to call it one day but figured no one would find that funny ) and question why Ferrari reccomends certain procedures ... "mass production"/cost/time is usually the answer meaning there's a better way ... maybe not cheaper and not easier for the typical service guy, but for "the equipped" there's a better way ... the tq plate boring is a perfect example.

I measured the distortion of the bores with some tq plates I borrowed from someone who knew I'd make my own if he didn't loan me them . He wants me to make a tq plate to simulate the bellhousing distortion. Has anyone actually measured the distortion from the bellhousing? Does it matter????

Cheers,

Sean

 

Now you've got me thinking about it that reamer doesn't tell you if you've got too much clearance right? ... just tells you the cam isn't gonna seize and takes the offending "high spot" away?

So if you don't see witness marks all the way around from such a tool, do you trim more off the caps 'til you do? ... measure with typical tools? ... plastigauge? How do you actually measure clearance if not by conventional methods? Like all things in life, a guy needs to know how to use his tool properly and not damage sensitive areas LOL .

Sean

 

Nothing ruffled here, just disagree with some of your views and thats OK. You must have got kicked hard a few times and I have seen it all too often and paid for it myself. Pay for poorly done work enough and you find the investment in the proper tools justified. Damn Tough pill to swallow 25 years back when I stepped up and bought the reamer but it has saved many a head since that day. No heat generated when doing it by hand so no thermo expansion. One year later I bought the block honing bar to fix a 275 block the machine shop mucked up in a bad way. Nothing happens fast when doing it by hand using lapping paste but no machine will do it as well when it really counts. A really bad line bore requires starting with 400G and working down to 2000 Grit. With the right tools the only question is how good do you want it, it only takes time.

Posted for the sake of discussion only. Couple hundred dollars wont get you one of these made up. Machinests dye for starters, knowledge of the tool and the feel of working with it for 25 years then bore gauge and micrometer after that. Plastigauge is for lawn mowers and weed wackers in my book.
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Aw, Dave. You're killin' me!

I was a Plastigage devotee when I built my first VW Type 1 engine thirty years ago... Never used it on F-cars.

Learned the fine craft of using my Starrett tools right after that...

 

+1

 

Thanks for sharing that Dave ... I would do that on one of my own motors and I guess guys will pay you to do it .... you need an apprentice?

I agree ... nice tool!!!! holy cow

Happy to hear that ... still doing it all old school .... instead of hiring good help or training most of the machine shops around here invest in CMM's and a $20/hr operator ... talking about generic machine shops making heart pumps and stuff ... not this complicated Ferrari stuff LOL.

Cheers

 

I have to say it again ... that is a nice friggin' tool mate!!!

I thought it only had 2 sets of flutes and 3 pilots ... without that tool or some kinda tooling bar just measuring with mics and bore gauges is futile so sounds like some other guys have that tool or made something similar ... maybe they'll elaborate?

Dave you are the real deal ... thank you for sharing and explaining. Can we go somewhere else and talk about TR diff's? .. that'll be my next muse .

Thanks & Cheers,

Sean

 

While I've been in my profession for many years I can tell you it is specialized! Just because we're a job shop doesn't mean were prepared to take on any type of work. There's several reasons for that like, investment in specialized tooling which I can't fully depreciate, time required to properly implement the process, and does it fit our business. I'm a manufacturing engineer that has owned and operated a machine shop that does nothing but close tolerance, difficult, and extremely challenging parts. The parts we manufacture are very expensive and time consuming.

With this said I wouldn't consider doing any engine or transmission machine work for money. Personally it doesn't meet my criteria above and theres no money in it. While I do make my own parts for my cars, I judge the cost relationship to determine if I can improve the design, quality, or cost enough to be worth it. If someone has the proper tooling to do the job better and I'm not prepared to invest in it, then their going to do it.

John

 

""I would do that on one of my own motors and I guess guys will pay you to do it""

Not many! Mostly vintage engines where replacement cant be had at any cost, Race engines and my own engines. Few get to experiance what an engine built to .0008" cold main clearance, where the crank will spin freely with ones finger tips actually runs like. I cant describe the feeling but it is unique to say the least. The NART master that taught me the fine points and hooked me up with these tools would never consider using anything else and showed disgust in the fact I didnt personally own them at the time. The fact I had young children and the bills.... made no difference to him, "if your going to do it, your going to do it right" Different day and time then.

FBB had stopped by the shop when I was lapping the block for the IMSA348 some years back IIRC. Long damn process but oh what a difference. Sometimes old school has its merits.