Building a 348 Le Mans Race car for the road

Excellent pics mate!! Looks like you are both having fun.

 

Thanks!!!

By the way those buckets look like they are solid, shimless. The cam lift looks HUGE! The last thing you need is for a shim to come loose at 9,000 rpm. Especially with those big ol' lobes beating the crap out of them.

 

That looks custom.

The 348 has a spring tensioner on the left hand side of the block (looking at it from the front). It looks as though they used the standard 348 spring tensioner but just moved it to the right hand side? Maybe that was a better place to mount it on the 355 block????

 

i agree... it does look like a factory 348 tensioner, just mounted on the other side.
Can we get a pic of the strengthening beam that connects it to the idler bearing? I am curious to see if one of the holes are sloted so it would be easy to set the tension when installing the belt. If not sloted, the beam length would determine the belt tention.

"By the way those buckets look like they are solid, shimless"
yes... those lobes look like they have massive lift.... the buckets are definetly different!
how are these adjusted? must have a shim under the bucket.?.?

also valve spring retainers look different.... most likely custom made titanium ones?

-daniel
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The buckets have got to have shims under them surly.
And the spring retaining collars, are they the twin Colet's per spring type (two halves)?

 

Sy you may not want to be in the same room when Raj checks and adjusts them tappets mate The micrometers, paper, pencil, calculator and much scratching of the head and throwing of tools.
Which brings me to the most important question of all. If the cams are indeed custom units. How will one know what the correct measurement will be for each bucket to cam? If not standard factory then i wonder what measurements was used?? Various shim sizes are easy to machine but its the gap that i am wondering about. Dammed important issue.

 

Cam specs don't look right

Should be

Intake valve open before top dead center (usually)

Intake valve close after bottom dead center

Exhaust valve open before bottom dead center

Exhaust valve close after top dead center

Also duration seems WAY off.

Is this at .000 or .050?

Very cool motor however!!

 

Wonderful pictures Sy. The simularities and differences from this to my engine are very interesting. I wonder why they stuck with the single belt when using the later block... It would be interesting to see what is under that front cover! I am in the process of making the cam drive chain tensioner if you need one of those, I finally figured out what the correct plastic is where I can get rid of the rubber pad as in the updated oil chain tensioner.

The round tooth belt in square tooth pulleys doesnt look like a good answer, is this the way it was delivered? By memory the bearings look to be the same as what I have, custom machined aluminum rollers.

I will have to pull out the engine build sheets and see how close the cams are one to the other. Again by memory your lobes look like those from my Enduro engine, where as the head casting needed to be relieved to very thin to allow the cams to turn on the Sprint engine. The cam follower bore top edges had to be relieved to allow the cams clearance on that engine.

The cam belt tension is one real pucker up setting on these with the lumpy cams. I set mine to what I considered "too tight". I was living right that day as it ran for 2 minutes before jumping one crank tooth..... back out and all apart after two minutes of running, nothing contacted, nothing bent after spending the entire winter setting up those heads. The final setting on round 2 was "insanely tight" and has proven satisfactory on the last two builds. With the heavy springs used and the size of those lobes it takes a good deal of torque to turn those cams, something to consider on final assembly. Those bearings get very hot running that kind of side load, good thing they are rebuildable. I have found the belt life in the Enduro engine to be reliable for a full season plus some, 4 hours run time is a full life on the Sprint engine and the reason that is coming out now.

This is very interesting watching the progress and all of the reverse engineering being done there. I believe what you are doing here is essential and well worth the time and money investment. Sometimes you just gotta know whats in there! I am going to look for the CD's containing the photo's of my last build up on the Sprint engine and compare those to your project. I am just about to mount the Enduro engine in the stand for a freshen up, that one I have not had apart before and your photo's have given me the encourgement to get to work.

 

These don't seem reasonable. Most of the big durration cam of which I am aware generaly have specs like: 35/75, 40/80, 45/85, 45/90. And this monster is 40/102-112/42.
Note the F355 cams are 16/42-56/16

40/102 has a duration of 322 degrees
112/42 has a duratioin of 334 degrees

These are REALLY BIG cams {But what does one expect from a leMans kind of engine.}

 

I did not mean to kill off this thread.

 

Nice job, Sy !



you can tune my engine up...WHEN YOU WANT!

 

This thread is about your engine, I don't want to step on that. If it helps along the way for comparison purposes I would be happy to post anything needed.

I find it quite interesting that the 129 block was used and seek to understand the logic behind it... very interesting that it was used but the single belt system retained. I am sure there will be a great deal more to be learned as you proceed, surely I will be one learning.

One need only look at the belt for justification of a complete tear down. Understanding and reverse engineering while everything is in one piece is essential to future repairs and maintenance.

From memory... I was unable to use both std. bearings on the belt. As it was the belt was too short to fit over the tensioner bearing while it was in place. I mounted the tensioner bearing on a hardened stud I made up and had to put the belt on and then set the bearing in place to get it all together. On both the Sprint and Enduro engines I am using a Ferrari belt. One set to a miserably high tension and the other just obnoxisly tight and they have worked fine when set this way. Belt life on the Sprint is 4 hours (you an feel it fall out of time as it stretches) and about a full season to a season and a half on the Enduro.

I might be able to help shed some light on the cams as I have driven both of my engines a fair amount but with different weight flywheels. Those from the Sprint engine are extreme to an extreme, a lobe design developed for the Indy car Cosworth engines. ZERO power below 5500 RPM yet pulling like a mule at 10K. One needs a closer ratio box to use these as I was not comfortable moving the shift point from 10K to 11K at the time. The bottom end would take it as I was using Cosworth pistons and Carrello rods but I had not tested the valve train to that level at the time.
The cam design from the Enduro engine is wonderfully broad in its torque range and is extremely tuneable by cam timing for different tracks. I am in the process of building that engine back up (been sitting in a corner for 5 years since a missed shift took out one cam and a few followers) to install and use the car for club events and some street tours in the mountains. I will hang an exhaust system on it, a dealer plate and try to convince Kris she would have fun on a tour in this. Those cams have plenty of torque from about 3K to 9k for some use on the open mountain roads and a hoot on the track. I just need to find the cam cards and my build sheets and compare those results with yours, we can see how they compare knowing how mine behaved.
The other variable is I have a flywheel I was told by a Ferrari official who was present at the time of the build up, came straight out of the F1 dept. One piece aluminum with a very small dual disc aluminum clutch. With no weight it is a bugger to start the engine let alone get off a standing start. Mix that with the Sprint cams and there is a lot of fire coming out the exhaust pipes on start up and a minimum idle of 3K. Not a mix you would want to end up with for the ultimate combo hot rod. In short order I will know how the Enduro engine paired with the light flywheel will behave.
Look up **************** on YouTube, I was doing some hot restart testing at the end of the day with the Sprint engine and light flywheel. The starter gets quite a workout!

 

At the very lest, you culd have these things reground to smaller duration and a touch less lift for longer life, and better off track maners.

Does anyoone know what the stock F348 cam timing numbers are?

 

+1!