Cam Lift and duration

[holywood3645]

QED make a thin cam .03 platform and I have read about taking .04 of the spring retainer. My question is 'If both these mod's were performed, What is the highest lift i can use with out spring bind' I do not want to recess the seats.
James
Any cam recommendations for a mildly+ tweeked 1700 cc twin cam. I was thinking the old L2 profile

[elansprint71]

Ask QED?

[rgh0]

With the right springs you can go to 0.500 lift with the standard retainers. This requires smaller cam base circles of around 1.00 inch in order to provide the space for longer valve stems and long spring installed height. You also need the smaller cam base circle so the bigger cams still fit on the buckets surface OK.

The L2 profile is to low in lift and to long in duration. You want a short duration around 280 degrees seat to seat and as high a lift as you want to spend money on getting. There are are number of Cams in 0.410 to 0.440 lift range that are good and can easily be fitted with the right valves and springs and cam followers.

cheers
Rohan

[Rob_LaMoreaux]

As Rohan said don't go too long of duration.

I had a Dave bean 112 cam (3.75 lift 300 duration) in my old engine and it was too long of duration, especially for the Stromberg carbs.

With the weber headpartly due to Rohan's advice, I went with John McCoy's 0.440" lift 290 duration cam and it is quite nice. I ended up sending the whole head to John and he ported it and replaced the valvetrain so it could get the lift. He even got stem seals in.

It cost me around $1500 US three years ago, but might be a bit cheaper now that he has a CNC program to do the porting. That was new valves, followers, retainers, springs, stem seals, porting, and cam grind with hard facing.

I'm quite happy with it even though I haven't gotten the carbs tuned to the optimum.

Wow, I just realized I've owned the car for 10 years as of this month.

Rob