Exhaust Cam Timing - Any advantage in shifting to EU spec?

Awesome!


I went through this exercise 20+ yrs back. After 'exhaustive' research (Oh boooooo! ), my guiding experts led me to stay with a factory recipe. I went with factory euro cams which have .2mm greater lift and different timing. These exact cams were provided with the US early pre-smog 308GT4, so there's my recipe. I needed to make minimal carb jetting adjustments to have a well tuned machine. In other words, if you're setting cam timing to known and proven formula, the results should be satisfying or at least predictable. Now, adjust only one cam and you're trail blazing. A chunk of work which may or may not provide any benefit. I'm assuming the euro qv calls for different intake timing as well ?

BTW: Does the euro qv have different comp ratio? If so, that is dialed in to go with the cam timing. Also, the CIS has vacuum requirements to work properly. More things to consider.

Hopefully someone on Fchat has a definitive answer.

 

Interesting. Makes sense that as you approach quasi-static (low speed), the burning fuel charge pushes piston for 4 more degrees crank rotation, which you may gain back at higher rev's. Does the published data show show good HP gain for euro motor? Also, the euro exhaust must breath better which is part of the recipe for the euro car. Same gear ratios? 308's varied transfer case gears changing rev range. Good catch on timing. For carb cars: Early GT4 and later smog GTS used same advance curve. Last point to share i.m.h.o. Drive a euro car to see if performance is notable or hopefully someone on F-chat w experience will weigh in. Possibly low end torque loss might be a more important loss for general drivability. When I used to do appreciably more driving events (Hillclimbs and track), I was enlightened by seeing how the 3X8 cars all performed in a 'group' meaning small differences. To step up meant the TR, Boxer etc. These cars could easily pass me on the main straight when my foot was to the floor. Otherwise, just tuning it as best as possible delivers the most smiles.

Overall, sounds like your approach is low hanging fruit worth investigating and is totally reversible if you don't like results.

 

You have hit it, in posts above....it was an early NON CAT 2V thing, to revert to Euro specs.
From 1975 to 1977, there were differences...

As discussion above shows, IMO by the QV there was no Euro difference and the fuel injection does thrive under the Factory specs.
Perhaps some hard core tuners can offer guidance, but for street use, and no other mods, I would say "no"...

At that point punching it out to 4.0L is the best way forward....

 

I timed my my '84 US QV to the euro specs but didn't do back to back dyno runs and I also used the euro ignition timing curves, which might makes as much difference as the cam timing. Also had EFI and a blower so really all you can take from my test is that it is possible to do

 

Blower -> Sweeeeet!!

I recall prepping my car for paint and I stripped out just about everything. Big heavy stuff like bumpers, interior, spare tire, etc etc etc. The car felt significantly faster! I was recently looking at the Ant-Gravity battery to shave off another ~50 pounds; although, I was concerned the placement of that heavy lump is in an ideal spot low in the chassis between the front tires and might upset handling.