Any new Camshafts worthwhile for 308 Carb cars?

So, yes and no. There's a good bit of work involved in setting it up correctly. Also, stock compression isn't all that great to be swapping cams but Dino and Daytona ran even hotter cams also at same compression which tells me there can be some nominal flexibility with stock compression.

Stock US 76-77 cams (same as Euro) are about .345 lift and 234 duration @ .050. They're not terrible cams for stock compression, it's the later 78-79 US cams that are really terrible. Now, the Daytona's and Dino cam profile is something like 252 duration @ .050 and .360 lift, better but that's a good bit of duration and may make the engine too peaky.

I have yet to do this with a 308 but I've always wondered if I could find a cam profile right around 240 duration @ .050 with .420 lift or thereabouts. I'd bet a stock engine would take to that cam profile very well. Note that stock springs cannot be used above .380 lift or so as they bind at something like .420-.430. Higher lift springs are well-available and not very pricey IMO. Lastly, whatever profile is chosen, your Webers will have to be rejetted.

Your cams can either be hard-welded by Webcams and reground to one of their profiles, or I know a few places that grind off the base circle of the cam then grind new profile. Thicker valve shims have to be used with grinding off the base circle so be mindful of that.

In the end it's an awful lot of work for what may land you at another 15hp.

 

Speaking of cam shafts, is there a difference between the Euro QV and the US QV cams?

 

AFAIK, only difference is exhaust cam timing.

 

Cat Cams in Belgium do a few profiles for about $1500/set and they have the Opel springs for higher lift. I got their ‘402 cams and with 10.5:1 static they are very manageable in traffic and have decent torque lower down. I’ll rejet the carbs and fit bigger venturis using a dyno once run in and I find time.

 

On our 308's...Are the 2v and 4v heads interchangeable? If it's indeed possible, what gains could one expect? Thanks.

 

So it’s not the cam shaft itself but just the setting of the timing?

 

It will also feel and drive a bit different which I think has some value. More Duration will make it continue to pull to a bit higher rpm so only say 10% more hp over the early carb cams, but also more free reving and feeling it asking to be reved. Its a different feeling. If you have the later US carb cams...well they belong in the dumpster and the change to say a 245-250 should net more like north of a 15% bump I'd think.

245-250 @0.50 sounds like the right place to be on a hot street engine. With EFI you can get away with maybe another 10 degrees but not with carbs.

Caveats - duration @0.05 lift is better than no comparison point, but ramp shape also really matter and USUALLY more lift means steep ramps. This means if you have 2 cams with the same 0.05" duration, the one with higher lift will most likely a higher lift cam will normally have more duration at every lift above 0.05 and will make hp at higher rpm. So more lift acts a lot like more duration at higher rpm.

Low rpm, idle, how the carbs behave is more about 0.006" lift duration which can vary quite a bit between cam designs with similar 0.05" duration. my cams for example came with a recommended clearance of I think 0.006/0.008" I think it was but I run 0.010/0.012 because the grind I have on the intake has pretty long accel/decel ramps and the extra lash shortens the 0.006 lift by 2 or 3 degrees which really helps the low end. Cams with similar 0.05 lift but different lifts, the one with more lift LIKELY has shorter 0.006" duration and will idle better.

I think Scott designed some cams Nick sells that bend these "rules" a bit so having good profile data is the only real way to know for sure.

Lots to think about. I think several on this forum are using Cat Cams grinds and should be able to give more exact answers about how those grinds perform.

 

I believe so. Years I retimed my US QV to euro QV specs timing wise.

 

308 QV Cam timing, Base (Euro) and US versions.

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They are close, I think Scott has swapted them and can best answer that part.

The difference is more valves have more valve area and can flow more, but that is not how ferrari used them as 2v and 4v heads have exactly the same peak flow. Also the QV cams are the same as the 2v pollution cams.....but 2 small valves don't need to open as far as 1 big valve so the same grind in a 4v head acts a lot like a much bigger grind in a 2v head making the QV very close to original 2v car hp.

To get the most from the 4v heads you still need bigger cams, then they will out perform the 2v heads and still behave nicely. My cams (in TR heads, very similar to QV heads , but modified for more flow) are 247/251 with lift at .452/.420 and it idles at smoothly 700rpm with peak hp around 9000 rpm. I'm using efi too though which helps some.

 

No.

 

Thank you for this John, this is very helpful

 

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I reached out to a cam grinder in Asheville, NC I've worked with and he has a grind that I think would be great for either stock or higher compression street engines. I do believe this profile can be ground to a stock camshaft without any hard-welding required but note you will need higher lift valve springs and slightly thicker valve shims, likely about 1mm, which are available if coming from these run at around stock.

 

That is a very nice looking grind option but I've never seen anyone recued the base circle as much as would be needed to get that lift without welding, I think you'd end up removing the whole base of the lobe and be right into the core itself? It's nearly 2mm over early carb lift and 3mm on the emission carb cams isn't it?

The lobe center look about right too. I have mine at 104/110 but I could see the 104/114 as it changes almost nothing in the simulator on my engine.

I do agreed that should run and drive very nice though.....but with stock heads I would be very tempted to go about 5-10 degrees more and give up a little at idle to gain on top. I don't thing the extra would cause any serious tuning or drivability issue and would shine above 6k for those who like that kind of thing. 260 degres would be BAD, but 245-250 I think should be pretty nice.

 

So I had the same concerns about grinding off the base circle as well, but I learned from this guy that you can cut into just about any base circle and into the core itself a bit so long as the surrounding area is back cut to clear the valve tappets. It's perfectly doable as long as thicker shims are available. I'm not entirely sure how a US 78-79 emissions cam would shake out with just .325 or so stock lift so I may send him one just to see for funzies........ need to scratch the curiosity itch

245-250 dur @ .050 with stock compression is just about pushing it for stock compression IMO. Would be perfect with at least 9.5:1 or so.

 

Fair.....moderation is not my strong suit

I think the P6 cams are 260 or so and for sure that is too much. 240 seems very safe though.

 

Just thinking about this.....ferrari cam cores are hollow but i guess a 1mm or 2 can still be removed. I think its like an 8 or 12mm hole.

 

imho: Early carb cams have a slight lift & duration increase. Car still starts well and drives well. I think the euro cars also had slightly higher compression (?). Can someone confirm?
Like 9.0 : 1 (as opposed to 8.8 : 1)

 

same compression US and Euro 2v.

 

Interesting thread! Is it recommendable to only modify the intake cam? (Thinking economy versus performance increase) I’m tuning my QV and consider to use webcam for modification of my original cams?

Best, Peter

 

The K-Jet cars have different cam issues/concerns than the carb cars (e.g., K-Jet does not tolerate a lot of overlap well).

 

What Steve said, CIS really limits what you can do. If the CIS stays there is very little gain to be had from cams options that will work with the CIS. Porting the heads might be a better option.

To your original question, intake and exhaust cams need to match each other. Not that they need to be identical, but they need to work as a pair, adding more intake flow is not helpful if the exhaust can't get out.

 

Thanks both. I forgot to mention that I’m converting to efi and high compression pistons. But I’m getting the point, kinda waste of time and money not to modify both intake and exhaust. I’m a bit frustrated over how difficult it is to find a trusted European company that can supply the cam service, either it’s new cams, welding and grinding old ones or just grinding to moving the center line. 2v cams are readily available from several sources but 4v seems not.

best, Peter