Camshafts Euro/US

Your US GTS is carrying about 150lbs more weight compared to a Euro GTB. US bumpers and bumper shocks and chassis stiffening for the GTS are the primary difference.

As far as the engine is concerned, the 78-79 US engines all had lower lift and duration cams compared to the 76-77 US engines which used the same cams as all Euro carb engines. The difference isn't huge, but they are good enough for another 12 or so bhp. Carb jetting really isn't all that different, the Euro in stock form is running a slightly fatter main jet for that year, but all jets these days should be tweaked due to how different gasoline is now compared to then. That combined with the additional weight for a US car is definitely enough to make the Euro machine feel a bit quicker, because it is!

Here's what works for your engine: make sure you are seeing around 32 or so degrees of timing in by 3000 or so rpm, with a max timing of say 38-39 degrees at 6000 or so rpm. Idle timing of about 10-11 degrees makes for nice pickup. If you're running stock jetting in your engine, I would run either a 135 or 130 main jet with 190 air correcters and 55 idle jets. On most engines that setup works wonders.

Getting the timing set up to the above is difficult with stock distributors so I highly suggest getting an Electromotive set up from Nick at Forza Ferrari, they make life infinitely easier when tuning ignition timing.

Make those changes, stick it on a dyno (or just use an a/f meter with an O2 sensor on the street) to check the tune at wide open throttle and you're good to go.

 

I too have a '78 GTS and love it. I know it's not the fastest thing out there, but it sure is a lot of fun.

I have changed to early/euro cams, and I can tell you it makes a difference. I didn't dyno, but my butt dyno says 5-10% gain. It also revs better and did away with the slight hesitation under acceleration. Rejetting the carbs should be done whether you change your cams or not. I have also replaced the ignition system with an Electromotive DIS. Not sure if the ignition added much HP, but it does make it more efficient...I have gotten up to 20mpg on the highway. I think it also helps with emissions, so it's a win win situation. I have also changed the exhaust with a custom set up.

PM me with your phone if you want to chat.

Henry

 

Wow, I was typing my response the same time as John's, and after reading John's they are near identical.

 

Anybody running the P6 profile cams that came on the Euro 285 hp engines?

 

I built and ran for about a year a full P6 factory'sprint kit' engine with factory high compression pistons which were about 10:1. Car went pretty well but was an absolute bear to drive on the street. P6 cam duration is just too much for a non full out race engine. I had nothing in the way of power or torque below 4k rpm. Above 5k rpm the engine was fantastico. I have a video on YouTube somewhere.... Anyway, I tuned and tweaked that thing in every way I knew how and I think I got the best out of it.

 

Correct me if I'm, wrong but there is no stock 285 HP 308 engine,Euro or US.The early Euro had a nominated 255HP compare to the US 240HP.

 

Correct, although the Euro engine never had anywhere near 255bhp even. 235-240bhp is more correct which is the same as the early US engines as they used identical cams/compression. The US figure was listed as being lower because it had air pumps to drive and different jetting otherwise the engines during 76-77 were identical.



Ferrari sold a back door sort of kit in the day called a 'sprint kit' for European customers. The kit was P6 cams and high compression pistons and different jetting. It has been largely conjectured that the sprint kit brought about 285bhp but I believe that is pushing it, 275bhp max is my estimation after spending so much time running and tuning such a kit. What P6 cams really need are *really* high compression, like 13:1 or so. The dynamic compression ratio even with 10.5:1 pistons is still too low to really take advantage of these cams. A P6 engine with 13:1 and flowed intake valves easily makes over 300bhp, there are better options these days though as far as cams are concerned though as P6 cams didn't have very much lift.


[ame=http://www.youtube.com/watch?v=ogjKRhQua_w&list=PL5C98747F97CDAD79]Ferrari 308GTB with modified engine opening the tap - YouTube[/ame]

 

I have a set of early carb inlet cams if anyone is interested and a full set of P6 cams . John's P6 cams and pistons came from the same source .

 

Dave is the man. Couldn't have ever done anything minus Dave.

 

John you are embarrassing me !!

 

That was fun to drive with the P6 cams....not too many people can say they drove a P6 308!!!




PDG


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I did this conversion about a year ago and I can tell you that there was a dramatic difference before and after, can't really equate a percentage increase to it all I know is that it accelerated much quicker, on the top end the car just kept pulling and pulling, and the sound was incredible!!

 

How much do you want for the P6 cams?