Camshaft Upgrade

[EWEuropa]

Hello. I am a visitor from the Europa World. I have a Federal 72 Twin Cam Europa with stock Stromberg carbs. My exhaust camshaft broke, and I was planning to upgrade my cams to Burton BLF46, but they sent me BLF14 by mistake. Both versions have a duration of 280 degrees and timing of 34/66/66/34. The BLF46 has a lift of .380, the BLF14 has .410. My mechanic is concerned that the engine may be hard to start with the higher lift cam. With my previous cam (lift of .358), the car started immediately with no cranking as soon as I turned the key. Do any of you in Elan land have experience with this, or an informed opinion?

Thanks,
Eric 72Europa TC

[bitsobrits]

Cam lift, in and of itself, does not make an engine harder to start, so not sure what your mechanic is on about. Higher compression, cam timing, and ignition timing can all impact ease of starting. I have a 1720 cc twin cam with 10.3 compression, .420 lift cams (sorry don't have other cam specs) and of course a very modified head and it starts fine. Idles fine. Runs fine.

Of course if your valve to piston clearance is not sufficient with the .410 lift cams then it will be hard to start when the pistons start running into the valves

[EWEuropa]

Steve,
Thanks for the information. My mechanic is checking the valve to piston clearance. What carburetors are you running?

Eric 72 Europa TC

[mbell]

My concern would be if you're valve train can cope with that amount of lift. From the comments I've read on here you will likely have issues if you have a standard valve train with .410 lift cam.

[rgh0]

I presume you have both inlet and exhaust BLF14 cams. There should be no problem starting but you will need to do a dyno session to reject your carbs and potentially ignition timing to suit .You will need to fit a new valve spring pack and probably new followers to fit in the higher lift cams.

cheers
Rohan

[StressCraxx]

Suggest your engine builder also checks for coil bind in addition to valve to piston clearance. Use best quality valve springs. Iskenderian makes some excellent ones. The Lotus factory engine builders used them.

[EWEuropa]

Thanks for all of this valuable information. Along with the cams, I purchased the springs from Burton designed to match these cams. Also, I am confident in the ability of my machine shop to make this work mechanically. They are now checking the valve to piston clearance, that is the last mechanical obstacle. In particular, I appreciate your input on the starting issue.

As for rejetting the carbs and optimizing the timing, I am getting concerned about mission creep. How much issue would it be to leave that as-is for now and put it off until a later time? I realize that would result in a bit of a performance shortfall, but how bad of an issue is it? Would it lead to the engine running too lean?

Thanks,
Eric 72Europa TC

[Billmack]

Ideally you would have benefited from a cam like that on the inlet side if you were changing one only. Since it's exhaust you will need a pair. Those have been popular since the engines seem to benefit more from lift than duration. May be interference though depending on pistons and valve springs. All readable in Dave Bean catalog

[EWEuropa]

Sorry I was not clear. I am replacing both cams.
Eric

[Billmack]

Good. Probably go for springs that are designed for the extra lift. I had had an engine out of here that used just the one inlet cam and a sprint exhaust cam and ran very well. Horsepower in low 150's

[bitsobrits]

Steve,
Thanks for the information. What carburetors are you running?

Eric 72 Europa TC

Dellorto DHLA 45C with 35mm chokes. Similar to Webers but have a very nice 6 hole progression circuit that helps make the engine a sweetheart on the street.

[jonesa62]

I am running QED 420 cams (285 deg, .416 lift ) which are not dissimilar to the BLF14's in broad terms. My engine starts and idles easily and runs superbly. Tuned correctly, I wouldn't hesitate to install the BLF14's provided the rest of the valve train can handle the clearances. The 420's are very tractable around town and when I want to get it up on the cam they never disappoint.