the lvferraripilot engine rebuild thread

Can't be too careful: I pulled a cam cover tonight to check the cams, journals, and those roll pins to make sure all is right in the world. Everything looks as it should. Video coming hopefully by this weekend

 

Dave, I ran it through the rev range pretty well before pulling the cam cover and goosed the engine while hot. Ran out of time last night to do much anything else. Young Kids!

 

Read the thread. I have high compression pistons. Over 10.5:1, probably closer to 10.7:1. Better valves, angled seats. I did not tune the engine from the stock cams as I wanted to throw these in, tune it and be done with it.

And yes, that is the Carobu engine which I have reviewed in great detail with Tate. Those cams were set to 104 and 108 lobe centers and were never changed once off the dyno as the owner did not want any further tweaking. They were going to tighten the center up a bit further as that is what the engine wanted, but the owner did not wish to do so. Also, the exhaust ports were port-matched but nothing was done to the intakes. Since the exhaust on these already flows far too much, I didn't see the point to port-matching the exhausts. I have the cams tightened in mine up to 97 and 100 center per factory spec and am expecting at least similar results.

Next time you go throwing out your opinions, read the thread and see what has already been done. I put down 200 at the wheels prior to rebuilding the motor in the first place. The sheet and video is around if you feel like searching.

 

For those of you just tuning in and for clarification:

The first dyno run of this new motor was done with stock cams and high compression. Lobe centers were set at 110 with early Euro cams which are 235 dur @ .050 and .352 lift. The engine was running incredibly lean at 15:1 and the plug heat range was still too hot causing some detonation up top which was probably due to a combination of the plugs and lean mixture, or just the lean mixture. She pulled 202 at the wheels in this ill form at 6500rpm. I have no doubt this engine with the correct mixture and plugs with stock cams could have been tuned to 210-215bhp @ 7300rpm range easily enough. Stock lobe centers are set on this motor at the factory at 96 intake and 91 exhaust which make stock power peak at 6600rpm. Stock I was making 200 at the wheels in top form so another 15 on top of that is not at all unreasonable considering the modifications. I am expecting 220+ at the wheels with the P6 cams. We'll see. It's a busy weekend at my house.

 

thanks for the well wishes!

 

Ok all I finally drove the thing yesterday. These best way to describe these cams is that they are like a switch. On or off!

Idle timing is set to 12 degrees and they idle a little lumpy but moving from a dead stop and staying below 4k rpm is not a big deal. A little drama, but not a lot. It will definitely take some getting used to. Below 4k rpm there is adequate power that I would describe as about stock or maybe a little less. The cams are definitely 'off' around this rpm. Liveability for me, but probably not for some.

However, rev beyond 4000-4500 and the cams turn on or goes 'on cam', a more harsh metallic sound/snarl kicks in, and the acceleration is far more aggressive and twitchy to well over 8k. By twitchy I mean the pedal is far more responsive. Total timing set to about 39-40. The sound, oh the sound. I didn't think a 308 could sound this way. I have no doubt I can set my rev limiter up to 8500 and be just fine but I think I will keep it at 8k.

The power difference? SUBSTANTIAL. Really. Any misconception that the 308 is a slow car with this setup immediately evaporates like the 4-5mpg I was getting. The stock cams with these pistons was pretty ok power, but this is fabulous power for this engine. It's amazing how cams with correct compression pistons in this thing wakes up the beast inside. The caveat is that you have to be 'on cam' which is way up in the rev range. My grin was directly controlled by how deep I buried my right foot and how high the engine was revving. I didn't go too nuts, but I did have an opportunity to wring out 4th gear and it did so with a commanding performance. Too easy, I am going to get a fat speeding ticket.

Jetting: 135 mains F24 tubes 200 air correctors 55 idles. might be a shade rich. 34mm chokes could be doable....we'll see.
Plugs: Autolite AR50 racing plugs (NGK 10 heat range equivalent). Still going to tweak this a bit as things were still running a bit hot.



Video coming when I have time!

 

This new setup wants to gulp air as much as it gulps fuel. I have gutted my airbox but I can tell it's just not going to cut it any longer. Hot starting with the airbox on is a pain.

I am considering adding extra slots in the airbox around the face giving a bit more area to suck from. A tuner car in the 70s did this same sort of thing but I cannot recall which tuner.....

 

gutted it quite some time ago. she wants more air!

 

Thanks Doug. I will leave it alone. One less thing to think about and do

 

Drove the car for about 30 minutes last night. I was concerned about heat as the engine was getting all kinds of hot. I was doing mostly highway driving last night. About 95 degrees out yesterday evening at dusk. I varied speed quite a bit and temps were in the 180 degree range and opened the heater valve to make sure that was not trapping any air. Oil temp was a little higher. I think the cooling situation is solved, but I still may swap to a higher efficiency radiator regardless for those track events I plan on doing.

Now that jetting is just about spot-on, I heated up the plug heat range again and put BP8ES in. So far so good. The ground strap annealing looks very nice and is right where I want it. The mixture ring might be a little rich at WOT. I will sort this out with a wide band soon enough. It's amazing how much more fuel the F24 tubes gulp......

 

Drove quite a bit this weekend. I notice a bit of light detonation in the mid range which sometimes does not allow for a smooth transition to upper rpms. It's usually ok, but for peace of mind I am going to shim a couple of the advance springs slowing the curve down a bit. Let's say 10-11 degree idle slowly transitioning to 34 degrees by 4500 capping at 38-39 by 6k. Man a programmable ignition would make this easier......



Currently I have about 32 degrees dialing in by 3k with 34 at about 3500. The Lemans spec sheet for this engine specify the need for a stiffer mid range advance spring for some reason which is starting to make sense now.

 

A couple reasons made me play with spark plugs. The first was higher compression adding more heat to the combustion chamber, and the second was ignition timing with the more efficient combustion process that the added compression brings. I saw it as better to go cold than start hot and destroy something. Stock engines like about 38-39 degrees total ignition timing @ 6k, while this engine seems like about 35-36 at most. I still haven't got the mixture exactly where I want it. Dyno time I am hoping will happen in the next couple weeks.

As of now, I am using BP8ES but am on the cusp of being able to use 7s if I fatten the mixture a tiny bit. No way of really narrowing it down until I am on the dyno.

 

Update.


I was at the dyno yesterday evening. I didn't really make a full pull as the upper end was just too lean. More on that later. I have A LOT to hash out in the carburetor low and mid-range jetting department which is primarily due to the F24 emulsion tubes.

Idle is great sitting at around 13.5:1, but as soon as the acceleration phase kicks in, everything gets stupid rich for a while. The pump jets shoot fuel down the throats and I assume the idle jets feed the progression holes causing everything to dip down into the 10:1 range and slowly climb up to somewhat acceptable ranges by 5000-5500rpm. The pump cam I have is pretty steep which really kicks the fuel through the pump jet, but I think rather than changing the pump cam I will change the idle jets down a couple sizes to 47 and change the pump jet to the next size down. I am pleased with the idle a/f ratio now, so with the 47s I am going to have to turn the screws out a bit more which is fine as with 55s I am only 3 turns out anyway.

Now for the upper end. I have 200 a/c and 135 mains. Yeah..... by 5800rpm she is at almost 14:1 and moving up to 6500rpm is even more lean at around 14.8:1. The plan with the upper end is going to a 140 main and 190 a/c and seeing how that works. I never took the engine over 6900rpm on the pulls as it was just way way too lean. I clearly have 15-20bhp hiding way up there with this lean condition.


The cams showed peak torque being in the 5k range but at that rpm it was still reading 11:1 so it's really impossible to tell anything at the moment. I suspect peak power will be around 7300ish. At 6900 it was nosing off a bit at 203bhp, but it's really just not possible to tell much of anything with how lean it is there. So we can see I have two extremes in one engine with the only thing I am pleased with being the idle lol. Ahhhh Ferrari's.


I adjusted the timing a bit and it seems to be happy with 36 degrees total, but this is all moot with the lean condition way up top. Until I have that hashed out a little better I can't really be sure about the timing, but I suspect once I richen the mixture up a bit I might be able to go a degree or so more. This is getting just plain rediculous.....

In all, I left the shop in utter discontent due to the mountain I have to climb.....again. Will keep everyone updated as usual.