Clearance limits w/GT40 P heads ?

[Katmandu]

I'm planning on installing a set of GT40Ps on my 91 stock short block. I also plan on using the old B-Cam (advanced 4 degrees) and some 1.7RRs.

Do I need to be concerned with and Valve-Piston clearance issues ? :confused:

[dedpedal]

Id check it first just to be sure.

[YouGotJunk]

I have regular gt40 heads...they have 1.94 valves in them and they have been on my car the whole time i've had it...along with the b cam that's in it..and i've never had any problems out of it. I have a completely stock shortblock..I dont think you'd have any problems at all.

[Katmandu]

I have regular gt40 heads...they have 1.94 valves in them and they have been on my car the whole time i've had it...along with the b cam that's in it..and i've never had any problems out of it. I have a completely stock shortblock..I dont think you'd have any problems at all.What ration are your rocker arms ?

I'll probably be going with 1.7s (if the seller ever gets back with me on them :rolleyes: ).

I also have TFS springs (rated at .540"). That should be more than enough with the B Cam.

How much more lift would 1.7s give with the B cam ? :confused:

[dedpedal]

.480/1.6=.300 lobe lift
.300*1.7=.510 at the valve

Im assumung a b cam is .480 lift

[Timido]

You should allways check piston to valve clearance when making changes. The lift is not what makes the valves hit it is the duration. By advancing the cam 4 deg you are changing the timing events. If you have not installed the heads yet checking Valve clearance with clay is no big deal. If you have installed the heads you can replace 1 intake and 1 exhaust sping with a checker spring and then move the engine to 10-15deg BTDC and check the exhaust clearance on the valve with a dial indicator then push the valve in. I was told you should see at least .100 clearance on the exhaust. Then turn the engine to 10-15 deg ATDC and check the intake it should be at least .050

[blueoval4ever]

Im assumung a b cam is .480 lift

correctamundo

[Katmandu]

You should allways check piston to valve clearance when making changes. The lift is not what makes the valves hit it is the duration. By advancing the cam 4 deg you are changing the timing events.Roger that on verifying via Clay method.

Around what Lift #s would there be expected clearance issues with GT40P heads ? :confused:

[Timido]

The Valve is not at full lift till the piston is pretty far away from the valve. You have to look at more than the lift you need to keep in mind the cam timing and duration. The thing that causes the valve clearance problem is how long the valve stays open. I dont know what specific cams clear the P heads.

[YouGotJunk]

i'm running 1.6 RR on mine. I think you would be fine, but thats just me.

[RyanR]

I have a decently bigger cam than a b with 1.7 rockers and I have no issues. You will be fine.

[Gregg@TFS]

and the winner is....................Timmay!!!

[aperacer]

i am running 1.6 rockers with an x cam... and the block i zero decked. no problems here.