Guys, Looking to replace a small POS Comp cam 268H in a 455 with a TA 288-94H. The 268 has 0.469" valve lift. The TA is listed as 0.488" lift. The block still has the original stamp ID so I'm guessing it's not touched at all. I don't know about the heads. Stock rockers and appears untouched under the rocker covers. So am I safe to assume I can just swap it out for the TA without the valves hitting pistons? Thanks!
Hello Matt.There are a lot of other factors that effect valve to piston clearance.Duration,advancing the cam,smaller(tighter lobe separation),lift, etc.You will have to compare the 268 specs to the T/A.
Hi Tom, I've done all that and also talked with TA about this. I just overlooked any possible clearance issues.
Ahh, I got ya.I am sure Jim W can give you some good info and feedback on this cam.Good luck with your new cam.
If your running stock valves sizes 2.0 / 1.625 I would say, all good without thought. The TA 413 is .516"-235'/.516"-245',113'LS. and it will clear with Stage 1 valves. I recommend only .030" of pre load on the lifter. More can cause the valve to move further after rockers have been removed and re installed, until the lifter re adjust. So to be safe, .030 max. You should be fine, but the responsibility is on the builder, never hurts to check
Thank you! I really have no idea what was done to the heads or what valve size they have. I'm doing his swap in the interim. Working on another motor but that's st least 3 years down the road. So a cam swap will be a good learning experience for me.... I hope. I'll have to read up what you mean about lifter preload. Also, how does one check without removing heads? Matt
Keep the lifters in order if you can so you can sell them w/the cam & the buyer can just pop them in.
Good idea.... just by coincidence I'm doing that. I drilled a 2x4 out for everything. I wasn't even thinking about keeping it selling the old stock cam and lifters. More for future projects.
On second thought, I'd be really surprised if someone wanted a stock used cam and lifters of unknown background.
I wrote this in another thread and thought I would move it to your thread and remove from the other one that I thought was yours ; Don't worry about it like Larry said. The QM times you're running it is very doubtful that the heads were shaved at some point to raise compression, that's even considering the anemic cam you have in it. If they were and when it went back together chances are they used the Fel-Pro composite gaskets that lowered the compression back down because those are .020" thicker than what the factory gaskets are. So if they took .030" off of the heads and added .020" with the gaskets they didn't gain much. Its either going to work or its not. Seeing how you are in the process of building another engine to swap in a few years from now even if there isn't enough clearance the valves are only going to hit very lightly on a very small area of the raised outer dish section if at all and will self clearance the .005" it touches in that area if it does. If you were swapping in a roller cam with more than .500" lift then you should probably remove the heads and check the clearances. But with the cam you want to stuff in there you shouldn't have any problems and if you do you won't know you had any problems until you take that engine apart and go, oh look the valves did hit the pistons or oh look they didn't hit. GL The above info is for Matt's questions. Derek
