Thread: Engine Building Question

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I have a similar 350 awaiting a rebuild. It has one split piston skirt that will have to be delt with. Not sure if one piston can effectively be replaced, or if a new set is a better idea?

What was the cam suggestion?

Originally Posted by SBC

I have a similar 350 awaiting a rebuild. It has one split piston skirt that will have to be delt with. Not sure if one piston can effectively be replaced, or if a new set is a better idea?

What was the cam suggestion?

o yes better look at your piston to wall sounds loose for cast pistons they will not hold up to loose piston to wall if you had a split piston?????????

Thanks Pat - didn't realize the split piston was probably indicative of a bad/excessive clearance.

Hey Tech - would you please PM the cam you suggested? Still trying to leaning the theory behind cam selection based on static CR and other variables. Thanks -

Originally Posted by SBC

I have a similar 350 awaiting a rebuild. It has one split piston skirt that will have to be delt with. Not sure if one piston can effectively be replaced, or if a new set is a better idea?

What was the cam suggestion?

Nova, While I am no expert as witness my asking for advice on this subject. I believe that there is a lot that should go into "cam selection". The cam that Tech advised me on will work in my motor, may not be the one for you. now with that said "TECH's" advice was this, and was based on the following.
350 4 bolt block .030 over using the "existing" TRW cast pistons and with heads casting #3927186, with 2.02 intakes/1.60 exhausts, Ported and polished, bowls blended, gasket matched screw in studs and guide plates these heads are 64cc and have been milled .010 and the cc volumn NOW is a verified and matched 63 cc's. The cam was a http://www.compcams.com/Cam_Specs/Ca...x?csid=87&sb=0

That is a link to the spec sheet of the cam. Now also this cam was going into a realitive heavy car (55 Chevy) with a Turbo 350 and stock converter. Tech advised me that this cam would tend to load up some with the stock converter and a 2200 stall was recommended, however I do have a 4 speed swap planned for this car this winter and it will be fine with the 4 speed.

I have purchased this exact cam and sense Comp Cams does not recommend using the stock valve train components I bought the complete cam and kit that comes with springs, retainers, and timing chain and gears. The cam came in on Friday and I am looking forward to getting it into the motor and making this swap.

I have decided to go with the cast pistons and just freshen everything up with the exception of the cam and kit. I'm going to drive it till it quits and then do a proper rebuild from the ground up.

Roland

Thanks Roland. For the benefit of others on the board, I also recommended paying attention to this list of failure points with a flat tappet cam. Oil formulations have changed and extreme pressure lubricants are no longer part of the formulation in off-the-shelf motor oils, so we must use extreme caution in the installation and wear-in of valve actuation components. The Extreme Energy camshaft series is particularly prone to failures due to the additional loading involved with the lifter coming up off the base circle onto the opening ramp very quickly. It's nothing you have to be really afraid of if you pay attention to all the cautions I have laid out and pay attention to using all the matched components that the cam grinder recommends. I recommended to use only 1.5 rockers arms with this cam and also advised Roland to adhere to the list I provided. Here's the list....
http://www.crankshaftcoalition.com/w...ips_and_tricks

There are numerous offerings of extreme pressure lubricants on the market. Here, for example, is one from Crower that I would trust. Just add one of these 4 oz bottles to the oil on break-in and one with each subsequent oil change.
http://www.summitracing.com/parts/CRO-86092/

Bottom Line: Use all components that the cam grinder recommends for the cam you are purchasing, pay attention to the tips and tricks listed above for installation of flat tappet cams and lifters and use an aftermarket oil additive in your off-the-shelf oil or use a dedicated racing oil in which you can verify the content of extreme pressure lubricants.

This information is applicable only to small block Chevies and other "valve-in-line" type motors. I suspect that Pat McCarthy has built more big block Chevies than all of us combined and he will not use a flat tappet cam in a BBC. That's good enough for me, so be advised. Use only a roller cam in a BBC.