First, I would like to say what a great site this is even though I dont own a chevelle I do own 3 chevy trucks.I'm building my first BBC. I have read that the TRW pistons will have valve to piston problems. How much lift can you run with these pistons?

454 .030 over (std deck ht.)
trw 2465? ( have not got pistons yet so I have many options)
781 heads, stock valves
Edel. air gap intake
comp soild roller xe280r
242/248 @.050
.646 .653 lift
if i use the trws will i have to fly cut them?
should I just use srp pistons?
I know alot of different variables come into play with piston to valve clearances but I need somewhere to start.
Thanks for all you input !!!!!

grande,
It varies from piston to piston and depends on what heads you have and what size valves. There is no cut and dry rule as to how much will work. You MUST check it ... thats the final say.

that cam has a lot of lift I would bet they will hit mabe even with dished pistons

So what pistons do I start with ? I want to stay around 9.8-10:1 ratio with this cam. I know I will have to check them when I install them but I'm sure some pistons can only be cut so far. The new probe pistons claim to have a larger vavle reliefs should I start with these?

thanks

i'm running a 468 with a roller cam .685 lift with domes that take up 50cc of my chambers........big domes more then most run.....and even on this motor there was no need to cut for nothing.....with a compression of 13.5 to 1 .......

for most street applications there is no problems with valve to piston clearences.......it must be checked on any engine anyways......just to be sure the timing event is ok to the location of the piston....meaning a cam to far advance or to far retarded my cause problems......

more then likely you will be just fine, check it with clay. then go from there.

That's a lot of lift for a street motor. Check with the piston manufacturer but I'd think you're gonna need the exact right piston for that combo assuming all else is normal. Anything with a standard deck, flat or dished pistions, nl stroke and rods with nl pin height and less than .575 is probably ok. You're actually probably ok to 600 but you really should check your clearance. At speed and a hot motor clearances change. Pistons hitting valves are a terrible thing to waste. Playdough or wax on just number one is all you need. Use a gasket and torque it properly.

I used a JE/SRP piston with an 18cc dome in my 489. Cam lift .625/.640, and I had nearly .200 clearance on both intake and exhaust. I dont' think that just looking at the lift will tell you if you have a problem, the cam timing and lobe separation play a big part too.
Steve

I don't really consider .650 gross as all that much lift for a Rat.
Also, the size of the dome has nothing to do with piston to valve clearance.
It is the piston notches which will be cut in basically the same configuration regardless of dome height.
Even a flat top needs a valve notches on a SB for both valves & the intake for a Rat.

As was mentioned above, you need to check it as there are no set rules & it has very little to do with total valve lift, except for the fact that higher lift cams usually have more duration & are open further on overlap,,

It is the rate of lift off the seat, lobe separation & how the cam is installed not total lift.
The valves are only close to the pistons on overlap not any where near max lift.
Also, the SRP's generally have more clearance than the TRW's & they are generally also lighter,, both good things ;)

All that said Steve, Bill & Dennis are right, you will probably not have a problem with that cam if you decide on SRP's as I have run over .700 net with SRP's with a 112 LSA without cutting but you still need to check,,,, ;)
I can't really speak for TRW's, I don't use them all that much but some don't have a ton of valve clearance.
Bottom line,,, check everything,,, twice :D

Wolfplace, do you think this is too much cam for a 454 street engine.
Could I run this cam with a little lower Comp like 9.1-9.5:1.
I already have the cam but have yet to build the short block. I could get the cam reground if I have to.
Also what size headers will I need?

Its going in a 3750lb Truck (weight with SBC)
Turbo 400trans 2800 stall
Ford 9in 3.50 gears
31 tall tires

Thank you very much for your input !!!

Don't use the TRW 2465's, with .549 lift lunati I had to cut .050 valve reliefs in mine, & run the cam only 2 deg advanced(would have liked more). I called Fed Mogul & they said don't cut anymore than .050 out of the top of the piston.

Go with a performance piston with nice big reliefs built in.

Originally posted by grande rojo:
Wolfplace, do you think this is too much cam for a 454 street engine.
Could I run this cam with a little lower Comp like 9.1-9.5:1.
I already have the cam but have yet to build the short block. I could get the cam reground if I have to.
Also what size headers will I need?

Its going in a 3750lb Truck (weight with SBC)
Turbo 400trans 2800 stall
Ford 9in 3.50 gears
31 tall tires

Thank you very much for your input !!! The cam is a little big for 9.0 & you are asking the wrong person about running that cam as I will not put a cast solid roller in anything I build & that is a cast cam.
Don't like them, had too many problems with them & know too many people who have had problems with them :(
It will work if you keep the spring pressure at or below 400 open but I prefer more spring than this on a roller.
Also, I am pretty sure Jason is correct about those pistons not liking a lot of cam but again total lift has very little to do with p/v clearance, it's separation & duration.
I think the engine will run a lot better with less cam unless you are planning at least 10.0 or better in a 454.
Of course if you built a 496,,, things change slightly :D
Also, if you get it reground with a less aggressive lobe than the XR series it will be happier with less spring.
I would say in Comp the 274 should make the engine happier.
On the cast core you might look at Comp's 1474/1476 lobes, they are less aggressive then the XR stuff & will run with a lot less spring.
If you contact Delta Cams they probably have the masters for these lobes or something very close.
web page (http://www.deltacam.com/)
1 3/4" on the headers ;)

I thought about doing the 496 but changed my mind ($$)
I guess the real question I should have asked was what would be a good combo for a 454 street engine.

I have a 454 2 bolt block, truck rods and stock 781 heads where do I start. Like I said before this is my first BBC so I'm kinda dumb
what would be your suggestion.

once again thanks for your time.