Don Terrill’s Speed-Talk

The quality and condition of the front disc brake line FLEX hoses makes a difference also.
I replaced these on my old Firebird. Like night and day.

If i is determined that the valve stems are indeed BENT you will probabily have to cut the stems off to get the valves out.
I bet that the keeper grooves got pounded. Don't force it. Take corrective action.

Valve stem lock groove distortion. This engine was very likely OVER REVED, causing the valves to BOUNCE and springs to surge. This beats the hell out of the valve locks and the lock groove on the valve stems. You may need to hand file the groove on the stem to remove any raised up metal on the edge ...

Variable valve timing and direct injection is not what saves the modern latest LS engines. Its the ability to sense detonation and retart timing on the fly. YUp when that occurs these engines ALL Make REDUCED in car engine power. Again NOBODY road races these engines on pump gas. They run on 98-100 ...

F-Bird, this is a gen2 LT1. They start at 10.5:1 with god awful quench from the factory and a tiny cam and have no problem running on crap 87 octane fuel. Factory cranking compression is 185-200psi on these engines. With aluminum heads and reverse flow cooling these things break the rules of conven...

You are into further head machining costs to go to these larger valves. If the valve stems are not worn I'd just re grind and reuse the stock valves. Since covid nothing is cheap anymore.

Your cranking compression test may have been fubared by the lifters BUT the truth does not change. 11.5:1 is excessive for street pump gas. If you run it balls out with full power WOT timing it will be a very SHORT car ride. Bring cab fair. You can and will make a TON of POWER ( reliabily) with a re...

Ir reguardless of the crankiing compression test if the compression ratio is 11.5:1 it is not going to operate on street pump gas without retarding the timing at least some.... THis engine needs 98-100 R+M/2 octane fuel. 92 octane is not going to work without retarding the timing. On a street car an...

If you use a "heated "O2 sensor, It does not need to be in the hottest spot on the pipe. If you want the sensor to read O2 content at idle and off idle part throttle then you need a long extenstion of exhaust pipe AFTER the sensor. If there is water injected in the exhaust stream I'd think...

Those Isky .450" lift circle track hyd cams punch way above their weight.

I would use one of the cams I suggested ( or stay with the current Isky hyd cam) VS that Summit 256/264 camshaft with the TFS Super 23 * aluminum heads also.

A return style fuel pressure regulator will work a lot better, as the fuel is always circulating from tank to carb back to tank to keep it cooler. You will also what to use a carb heat shield between the holley carb and intake. This keeps the fuel blowls cool from the heat of the intake manifold run...

I switched from my fully ported 4416 heads 1.94x1.60 to a set of fully ported GM 062 vortecs and the differnce was significant. My 305 heads were not shabby at all but the Vortecs are just a lot better design. Your TFS heads should rock. These can be inproved further with soome hand porting. But for...

I'd say its the heads that are the cork in the system. U did a nice job on what you did but they really need bigger valves (1.94x1.60 at least) and full effort porting to match. These 305 heads really need opeining up to get them to flow. 2.05"x1.60 valves even better. You'll have tro decide if...

I stand by what I posted re: tuning for when pump gas and agressive compression ratio. The bit of (high speed) retard on real world conditions, on pump gas is not nessessarily a bad thing. They do not pay you for the MPH. They pay you to get there first, in a race. And do it again next round. If you...