Cam Questions

[neilca]

I have a 914-6 race car with a 2.0 liter I built from my least desirable parts in inventory. This includes some stock pollution cams from a 1975 2.7CIS. The engine puts out 110hp with a fair amount of torque and no top end (redlines at 6000 rpm). This motor has been useful while I work on chassis setup and other systems checks.

The motor will need to come out soon due to oil leaks so I thought it may be a good time to change cams. I have a set of Solex center lube cams and a set of E cams that could be used.

Another part of this equation is my plan to build a good 2.4L engine to replace the 2.0.

Should I put the Solex cams in the 2.0 and have camgrinder regrind the E cams?
Put the E cams in the 2.0 and save Solex cams for the 2.4L?
Put the E cams in the 2.0 and have camgrinder regrind the Solex cams to something else?

I use the car to race in SCCA in Special Production Under 2.5L (SPU). The car weighs 1700 LBS and has a close ration gearbox. I do run 9.5x23x15 slicks.

The engine has a 10:1 compression ratio and Zenith carbs with 27mm chokes. I have some 32mm chokes available too.

What do you all think?

[aws]

You need to answer a couple of questions to answer your questions. What pistons? What heads and port size? Are you using the stock 66mm 914/6 non counterweighted crank? Mag 914/6 engine case? Headers? The early Solex and E cam profiles were very close and not really enough (but certainly better than 2.7 CIS cams) for a dedicated race engine depending upon heads and port size. The center-lube cams are desirable but not absolutely necessary. The 32mm chokes would probably help your current engine as far as top end.

aws

[neilca]

The pistons in the 2.0 are the forged "S" pistons with birel cylinders. The ports have been opened to 36 mm intake and 34 mm exhaust. Valves are 42 mm intake and 39 exhaust. Non counterweighted crank, mag case, 1 5/8 header supertrapp mufflers.

[aws]

With that parts combination you need at least a early S cam. My guess is you will gain 10-15hp with cams and venturis with the 2.0. If you are limited to 2.5 you should probably stick with the 66 crank and go to 90mm cylinders rather than a long stroke 2.4. The short stroke crank is more robust than the 70.4mm 2.7 crank. If you decide to do that you need to upgrade to 2.2 rods and ARP bolts because of the increased weight of the 90mm piston and higher redline.
It might make more sense to sell the Solex/E cams and try to buy a used set of early S cams.

aws

[kenikh]

Another option to consider...John can grind E and Solex cams to DC30. A far better grind than either and they perform nearly on par with an S cam on top end, with a much meatier torque band. They work great with 32mm AND 36mm ports...the bigger ports give the cam longer legs, but my 2 liter car with DC30s screams to 7000 RPM (then falls of fast w/ 32mm ports).

I talked at length with John about using these cams with S pistons and S ports and he said they'd be one hell of a match. I decided to keep my small ports and Normal pistons for originality reasons, but haven't met the '67S yet that can walk away from my car.

[kenikh]

Originally Posted by neilca

The pistons in the 2.0 are the forged "S" pistons with birel cylinders. The ports have been opened to 36 mm intake and 34 mm exhaust. Valves are 42 mm intake and 39 exhaust. Non counterweighted crank, mag case, 1 5/8 header supertrapp mufflers.

BTW, BAD header choice for your motor...waaay too big. Those are for a 3.2! You really need 1.5" or you are losing buckets of torque and would need to spin over 8K to take advantage of that size.

[mike the snake]

Wow, 1700 pounds is REALLY light? How you do that? Got some pics?

[neilca]

Here is a picture from Road Atlanta test day. I have a lot of carbon fiber and honeycomb body work from Composite Technologies.



I also changed the engine mounting. This makes it real easy to drop a motor.


I did not scrimp on the cage. 1.75 diameter .095 DOM tubing, because I worry about the fat boy behind the wheel.