1979 Ferrari 308 factory performance upgrade car

Found some info.
This was very good information, will try to do this, will pull from 3000 rpm.


So to the camshafts used in sprint package.
Ferrari 308GTB: Last throw of the 2 valve dice.



This blog relates to the P6 high performance camshafts that formed part of the Group 4 Specs Kit and were fitted to the Ferrari Type F106 engine.



In the late 70s when ordering a new Ferrari 308GTB it was possible to specify an increased performance option for the car. This was commonly known as the ‘Sprint Pack’. It included Borgo high compression forged pistons, special camshafts, ANSI sports exhaust and alternative carburettor settings. These performance parts were derived from the Group 4 Specification Kit that had been developed by Ferrari for competition use.

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It did not come cheap and added over £3000 to the overall cost of the car. If you consider that in 1979 a standard 308GTB would have cost a shade under £19,000 and at a cost of £24,560 you were well on the way towards the price of a Boxer. To be fair this figure also included the deep front skirt, 7.00J-front and 8.00J-rear Speedline magnesium alloy wheels and Pirelli P7 tyres. I suppose there was more to it than just bolting on a few goodies, apart from the additional engine work, the suspension had to be completely re-set to allow for the bigger wheels and tyres.

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As many will know, the Ferrari 308GTB was powered by a 3.0 litre Type F106 engine. This was a normally aspirated, 90 degree V8 with 4OHC and was S.A.E. rated at 255bhp. It was a 2valve engine with a bore of 81mm, stroke of 71mm and compression ratio of 8.8:1. The engine was originally designed as a competition unit with small capacity crankcase, dry-sump and scavenge pump. It had previously been fitted to the Dino GT4 in a wet-sump form, but only for the European Specification 308GTB was it dry-sump as originally intended. It was also fitted to the 308GTS, but once again in a wet-sump form.

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So to the camshafts.

The camshafts from the Group 4 Specification Kit are Ferrari designated P6.
The initial specified timing for these cams was:- Inlet opens 48 Deg. BTDC
Inlet closes 62 Deg. ABDC
Exhaust opens 64 Deg. BBDC
Exhaust closes 44 Deg. ATDC

The maximum valve lift is 9.25mm for both cams, with a duration of 290 Degrees for the inlet and 288 for the exhaust. Valve overlap is therefore 92 Degrees. The above figures are based on a setting clearance of 0.5mm.

The Ferrari factory built LM308 competition car used P6 cams with the following specified timing:-

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Inlet opens 51Deg. BTDC
Inlet closes 58Deg. ABDC
Exhaust opens 64 Deg. BBDC
Exhaust closes 44 Deg. ATDC

The above timing is used when the sprint pack is fitted and gives a duration of 289 Degrees for the inlet, 288 Degrees for the exhaust and a valve overlap of 95 Degrees when using a setting clearance of 0.50mm.

Clearly the inlet cam has been advanced 3-4 Degrees from the original P6 specification, the exhaust timing and valve lifts are as before. As to why this was done, one could surmise that advancing the inlet cam will pivot the torque curve to improve low speed and mid-range torque. The other consideration with advancing the inlet cam is that the resulting increased valve overlap is likely to make combustion stability at part load and idle conditions worse; as a result the carburation settings with such cams will be far more critical to ensure good engine running stability. This advancing of the inlet cam timings suggests that Ferrari realised that their P6 cam intake duration was a little on the long side; as such advancing the inlet cam may result in improved low speed torque with only very small penalties at peak power conditions. The result of this cam timing combination is a road car engine with an unusually large level of valve overlap; something that really was the last throw of the 2-valve engine development dice before the introduction of better breathing 4-valve engines with their potentially more modest cam timings.

As a comparison the standard 308GTB valve timing is:- Inlet opens 30 Deg. BTDC
Inlet closes 50 Deg. ABDC
Exhaust opens 36 Deg. BBDC
Exhaust closes 28 Deg. ATDC

The maximum lift for the inlet cam is 9.00mm and 8.375mm for the exhaust. The above timings give a duration of 260 Degrees for the inlet, 244 Degrees for the exhaust and a valve overlap of 58 Degrees when using a setting clearance of 0.50mm.


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Standard/LM308 valve timimgs


So it is clear that the standard 308GTB cam timings have a shorter duration than the P6 Le Mans specification. What is perhaps most notable in the comparison between the two, is the far higher valve overlap with the P6 Le Mans spec timings; this is due to both the longer duration and in the shifting of the inlet cam maximum opening point (MOP) to an earlier position. The earlier inlet MOP with the Le Mans spec P6 cams would typically suggest aiming towards lower speed torque, however when this phasing is combined with the much longer cam duration, an increase in cylinder filling/performance at the peak power engine speed will result. Based on the much lower valve overlap of the standard 308GTB cam timings, it would be anticipated that driveability at low loads would be improved and also suggests that engine setup (carburation, ignition timing etc.) would not be as critical. This would mean general carburettor settings could be used in production and calibration for each individual engine would not be required.

Another noteworthy point concerning the use of P6 cams timed to Le Mans specification (as in the sprint pack), is that it will be fairly important that they are used in conjunction with the 9.5:1 high compression pistons that also form part of this kit. If standard lower compression ratio (8.8:1) pistons were used with the P6 Le Mans spec cams, combustion stability at part loads and idle may be worse due to higher levels of residual (exhaust) gas that will remain in the cylinder after the closing of the exhaust valves.




So what difference does this all make?
It is reputed that the sprint pack added 40bhp to the output of the engine, making it just shy of 300bhp. The exhaust note is completely different to that of the standard car, you would expect it to be louder with a sports exhaust fitted, but it is also noticeably ‘flatter’ in sound. When the timings and carburation have been set correctly, the car is perfectly usable on the road. The tick-over is both stable and reliable, with no tendency to stall when setting off. As with all 308’s it starts to pull strongly once 3000rpm is reached and builds up from that point on. There are no flat spots throughout the rev range, however at 5500rpm the engine takes another breath as it ‘comes on cam’ and launches itself towards the red-line at a vastly increased rate.

Carburettor settings. Weber 40 DCNF

Main jet 1.45
Air correction 1.70
Emulsion tube F36
Slow running 0.50

Sorting out the carburation took a little time. The engine had been running rich at the bottom end and needed no choke whatsoever to make it fire from cold. A slight misfire in this range became progressively worse as the engine warmed and became totally unacceptable when hot. Two reductions in the size of the slow running jets cleaned up the carburation and transformed the way it drove low down in the rev range.




YOU CAN READ ABOUT IT HERE:
i hope it is ok to steel the info this guy had, many thanx to him, hats off..

http://yorkshireferret.blogspot.com/2016/06/ferrari-308gtb-last-throw-of-2-valve.html?m=1

 

I have several different sportcars and i have tuned and build cars and motorcycles for 35 years now, one thing that really transform old point ignition cars is modern electronic ignition, this is something i will do with the car, and easy to go back to original if you want, this can make the car go much better on low rpm.
i don't now what is best option for the 308, but maybe someone can chime in.=)

 

you seams to now ferrari stuff, is it possible to find out ho installed the sprint pack on my car with this 11 digit number? F106AB27193

 

I found the original owner ho bought the car 1979, he was a professional ferrari driver name Gustaf Dieden, he raced in ferrari on the 1960-70
He is now 82 years old and live in Sweden, i have talked to him today on the phone, he told me he raced in italy and also lived there for a couple of years when he was racing, be bought the car in italy and upgraded engine was build there, he told me that he was friends with the ferrari racing and engine builders because of his racing, he also told me that the engine was build special for him by the racing engine builder on ferrari in italy in 1979, so now i'm not sure that my
car has the sprint package, maybe something different like group 4 spec? he was a very nice old man that love cars, he had a rather big race car collection, 1 formula car that he raced with and also original Lamborghini countach and much more.=)
this is the car he compet with Ferrari 206s, only 10 cars was build, and this(His) car was sold for 2500,000 Euro
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i probaly will check what is inside, because Gustaf Dieden told me it was special piston and camshaft, he didn't remember if the head was ported, it is almost 40 years ago and he is 82 years old, but he said that it was streetable and was no problem to drive, will be interesting first spinn, have bought the car without looking at it.., im fairly used to high power cars so will give a honest review when have tested the car, a photo on where they talk about the camshaft and pistons, and for fun, a photo of one of my race cars, if not allowed, delete the post.
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Im not 100% sure of this but 90% sure it is like this, i dont have the sprint pack, that im sure, im also sure that the engine tune was made in italy, yes everything is sprint pack, but the camshaft is stamped michelotto, and my research is pointing that it is michelotto that tuned the engine in padova1980

 

But how can i prove it, ofcourse photos on the camshafts, i have send a message to michelotto, ferrari is nown to have all cars registred, i hope micheletto have that to, but in 1979 ferrari dident allow someone to tune there engine, they took legal action, so it must be micheletto, or i hope so.

 

Love the photos

Like the photos., so nice to see, about the worm hole, i believe you, only stated what was in the magazine., i have talked to Gustaf several times and im planning to put the 308 on a trailer and visit him, i think this will be a blast for him, he is 82 years old and still get so excited when we talk racing.

 

I have asked him, he says it was made in italy but not factory, then he doesent remeber ho made it, but he said that it was high comp piston and upgraded camshafts, he is 82 years old and dont want to make him feel bad for not remebering, so i need to take it slow, im gonna talk to him now and then and maby the memory will come when he is calm, talking about race cars make him very excited, he is a very nice guy, like him a lot...