308 Engine Rebuild & CIS to TWM Throttle Bodies Conversion Thread!

Then have new liners made, you overlooked an important factor. Ferrari thought it was a big enough problem that they changed the spec. Again on a 308 you will see no gain using a torque plate. Many shops send the liners out in a fixture and have them machined and the outcome is the same. The engine runs well and there are no issues because of the low output. An all out effort engine build would require new liners and different techniques. I was just trying to point out that its not as important as some might think on this application.

 

Well how about circulating hot water thru the block at the same time with the tq plate while honing it? And then you should also put on some kinda tq plate to simulate the bell housing ... anyone here familiar with the distortion caused by the bellhousing? Tq the main caps too but that's pretty obvious.

I measured the distortion with a tq plate if anyone is curious how much the sleeves distort.

Also honing the sleeves in the block has it's own set of obstacles which the typical machine shop might not be aware of.

I keep going back and forth about the importance of it considering the grief vs. doing them out of the block.

I've said before ... there's always a better way == more expensive/more time ... just depends how much time and effort you want to put in ... and if it's really worth it.

cheers

 

Sean,

We actually did consider having the block at operating temperature, but since the specs are given "cold", we though that doing it a room temperature was sufficient. I suspect that this is yet another subject that we all could beat to death...And yes, the grief factor can be quite large!

Regards,
David

 

Yep absolutely ... who knows ... heating up the block might make the sleeve distortion decrease? My motor is still screaming with the "out of the block" boring and honing technique but I'm sure there's power gains with the tq plates.

Cheers.

 

I was trained, in the mid 70s, by a master mechanic that had been assembling F1 engines in the "Sala Prova" in Maranello. He insisted that we save the used headgaskets and used them during honing (retificha sp?). We always placed the off side head on the block with old the headgasket and torque it. Then we would put the headgasket on the side to be honed along with the honing plate and torque that side. We also made sure the machinist had a minimum of three main bearing caps and that he torqued them to hold the block to the mandrel running horizontally in his machine. Back then most guys used a CK-10.
We never had a bad result. Often I would would attribute the twenty degree drop in oil temperatures to these simple but necessary procedures. I would be hard pressed to believe otherwise and have many engines out there to back me up.

David

 

On a CK-10 how do you deal with the fact that the stones can't exit past the bottom of the sleeve without smashing into the main caps?

I know how I do it on my equipment, but lots of hand work on the stones .. wouldn't think that's cost effective on a CK-10 but maybe there's some stone dresser for those things I don't know about.


Cheers

 

FWIW: I put NOS stock early cams in my 78gts and nothing else other than a thorough service. It cruises smog, and the power is a little better. I rebuilt another '81 2vi motor with all stock NOS pistons etc, and it feels easily as strong as my carb car with the early cams. I would love to have bumped up the compression. I hear that makes a notable difference. 300+hp sounds really nice in a 308. Someday - - - - - - - -


Your motor looks great.

 

Goes to prove either way produces great results. I could provide examples of different techniques that seem to make no difference where others swear by them because thats how they were taught and will be that way until they die. What worked in 1975 would be just fine for an old engine but doesnt always work in 2008 on new stuff. Why? because we know more now than we did back then. Tollerences are different and assembly techniques are way different.

 

Well, there's plenty of debate going on, but I haven't seen a single opinion that using a torque plate to hone 3x8 cylinders is detrimental to the engine.

The disagreement is whether it does or doesn't make things better. ie: there's nothing to loose by using one if it's available, & the very professional technicians strongly believe it's necessary to use one.

I'm pretty sure I remember a thread a few years ago where cylinders were honed w/o a torque plate, and were found to be a couple of thou out of round when one was installed.

Unless someone has some facts ie: measurements made when honing 3x8 cylinders with & w/o a torque plate, lets move on to another topic.

 

I try not to post unless I have facts or am drunk ... I measured .002" distortion .. growing in one plane ... shrinking 90 deg to that. The distortion dissapated as you moved down the bore to almost zero around the o-ring area. We can go into leakdown numbers but like David mentioned why beat it to death ... the next layer of the onion is how different ring designs effect static leakdown numbers . From the distortion I see just gripping the sleeves in my hands it's hard for me to imagine they don't move all over during combustion. The only way to really know is back to back dyno ... I want a dyno .

I would expect torque plate boring you would have whatever tolerance the guy felt like holding that day ... .0001" to .002" depending on the BAC ... LOL!!! .. really the bores should be right on with tq plate boring and it would be heat and combustion pressure doing the distortion but just hypothesizing .

I agree facts are important ... I have always shared mine ... others don't 'cause I don't think they actually measure anything ... if you've ever read "the machine shop will take care of that" ............................. I'm that guy .

cheers

 

The way the factory sleeve is installed, it is not under any compression when the head is installed. The factory liner sits on the flange in the deck counter bore. The head clamps the flange only. The large bore sleeves I machine from blanks and install in these blocks are under compression since I redesigned the assembly so the sleeve sits on the bottom of the water jacket and not in the deck surface. Thus the entire sleeve is in compression when the head is installed. I am one of the patent holders of Darton's line of MID wet liners. I am also Darton's R&D, block machining, sleeve installation facility.

Several things you guys are missing here. The main thing is these blocks are no longer straight and true after years of running. Any block distorts with use regardless of manufacture. The decks are no longer flat, usually they have a twist to them. The main bearing bores are no longer round. The bores the sleeves fit into are no longer round. One can not expect a sleeve honed outside the block to stay round when it is placed into an oblong hole. I remachine the lower bore for my large bore sleeves so the new bore is perfectly round. The block is stress relieved during the machining process to relieve machining stresses then a finish cut is taken. I use the same exact method whether I am machining a Honda, Viper, Corvette, etc block. The sleeves are fit to each individual bore.

The sleeves outside diameter where they fit into the block are usually not round, whether new or used. So even if the block is perfectly machined the sleeves themselves need to be corrected before installation. I take care of this using a brass hammer, getting the outside diameter to be within a half thou of round. Darton does exactly the same thing after they manufacture their sleeves.

There is no reason for the sleeves to protrude above the deck surface. The only reason this is done is because of the lousy stock head gaskets. Without the protrusion the stock gasket will blow. I had Cometic make modern MLS gaskets for the 308 328 engines. The MLS gaskets need a perfectly flat surface to seal on. This means the block with sleeves installed needs to be decked flat and smooth. This should be done regardless to take care of the inherent distortion. Decking the stock sleeved block can only be accomplished if the sleeves are installed with Loctite around the flange area to keep them from moving during the decking process. Loctite the sleeve in place, (you must not get any Loctite under the sleeve flange, put Loctite on the sleeve flange outside diameter only, not in the block!) install a pair of torque plates or the heads with the factory gasket, used is fine, over night to let the Loctite set up. Then you can have the block surfaced flat and as smooth as possible. Have the heads resurfaced at the same time since it is unlikely they will be flat.

An added bonus to using the Cometic MLS head gasket is the head will stay flat when torqued up. The thick factory composition gasket in combination with protruding sleeves guarantees the valve seats will not be round in service.

Lets get back to honing. Let's assume the issues I described have been remedied. Torquing up heads will always distort the block. Use torque plates with the exact same style gasket and fasteners torqued to spec. This includes the main bearing fasteners. I have found the Ferrari block will distort the rear cylinders when the bell housing is bolted on. Fabricate a plate resembling the bell housing flange and bolt in place for honing. It is best to use a torque wrench so the same torque can be used when bolting up the bellhousing.

Modern honing heads, machines need only a quarter inch of over travel to hone cylinders. When designing sleeves, machining blocks for sleeves, I have to assume the guy honing the block may not have the latest equipment. Four hundred thou is enough over travel for cylinder honing, in the block honing of sleeves. The stones may need to be trimmed depending on the honing head, machine used, but there should be no problem holding less than a half thou of taper in the bore if the machinist is competent. Another thing the block needs to cool during the honing process then touched up to finish size. You can not rush through the honing process.

Hot honing is possible but that is beyond the ability of most shops except for those doing really high end work. In other words $$$$$.

Steve

 

Good bye to the carbs........and a great big WELCOME to the 21st century

 

As the resident P hater jerk let me continue my twisted tradition and remark that there is a lot of money in pizza and those venturies look teeny,but may work better, compared to the cheap jap hayabusa ITBs.Thanks for posting your great project,you are well guided,understatement,it will work great,I read your thread right after V12 conversion begins.PAM

 

Ive kicked the tires on those TWM ITBs for 15yr? They are beautiful as auto parts goes but IMHO there is no power above 1976 levels there.Splaine it to me Lucy,I know Im stupid.Add up the time and expense and it all comes back to"if you want a faster Ferrari,buy one".

 

Follow your heart...and your pocketbook.

Looking forward to the results!

OBTW - what size tbs (measured at the butterfly) did you decide on? Do you have flow # for those heads?

 

Pizzaman, what do those bad boys cost anyway?

 

According to the TWM Website, the TWM Ferrari TB, manifold and linkage kit, (less injectors, drivers, sensors, harness, etc) is about $3400. I imagine they cut Pizzaman a deal. I am guessing less labor installed he will need about $2000 - 2500 more all told in parts, if a bit more, for all the ECU, harness, sensors, injectors, airbox, hoses, pump, regulators, tach conversion, other details, yada, yada.

C'mon, P-man - it's gotta look good and sanitary as well!!!! This should get fun now!

 

Chris,

You are a hero to us all. I remember when you weren't even sure about changing your own oil.

Props to you and Happy New Year.

Post results when you get them.

 

Very interesting, company is practically next door to my business. If you need anything done face to face with them don't hesitate to ask! Can't wait to see the results!

Jeff

PS, link to there website, I'm curious about this company?

 

Pizzaman,there is added value with the TWM itbs that I know the zuki itb setup cant add.The suki itb is just a cheap ass attempt to get something for nothing,but its also a fabulous solution,,,but each part is a job and Im 6mo away from running.I hope!! thanks,all Fchat posters