I have looked in vain for the intake/exhaust valve diameters for a 1978 LF-8. Specs I have found have everything but the valve diameters. Any help????

 

What's an LF-8?

 

4bolt 454

 

Maybe u should try using the casting number. Since there were no 454 engined corvettes in 1978 u need to to provided better identification. Google shows a lot of trucks used the LF-8 454 under code TRB (77), TRC (77, 80), TRD (77), TRF (78), TRH (78), TRK (78), TRM (78), TRR (79), TRS (79), TRU (79), TRW (79), TRX (marine 79), TRY (78), TRZ (76, 77, 79), TSA (76, 77), TSB (78), TSB (78), TSC (77), TSD (77), TSF (78), TSH (78), TSJ (78), TSK (77), TSL (76, 77), TSM (77), TSR (77), TSS (78), TST (78), TSU (78). All these were used in 454 engines with the VIN S and 20 or 30 designations.

Now for 454 heads there was mostly only 4 castings used on the 454 powered trucks but some where light duty and some heavy duty. The 20 or 30 designation with the LF-8 blocks would be heavy duty and leaves only 343771 and 343772 head casting numbers for those trucks/blocks. All i can find for those are some forum posts so u can take those or leave them:

Big block head casting number 343771 where used on top of 1968-85 366/427/454 tall deck truck motors. They have an open combuston chamber that has 113 cc's. They have flat bottomed small valves (2.07"/1.72") and hardened seats. They are peanut port heads. They are called that because the have the smallest intake port of any of the big block heads cast, ever.


Hope this helps.

 

I have used the casting number. That gave me the engine designation. I need the valve diameter for the 1978 454 used in a one ton truck. Your valve specs are the first I have seen. Thanks

 

Please tell me did I have the correct casting number for your head? Curious.

 

Front block is T0601TST (TST is the suffix for 1978 HD truck)
back block number is 361959. I ran a fiber optic scope thru the oil drain plug hole and confirmed it is a four bolt main. Lots of low end torque, moderate high rpm power like you would expect from a truck engine. At idle it sounds like there is a moderate performance cam in it, but not sure. I have not removed the valve covers yet to check the casting number on the heads. The stamped number on the head is C81 194932. My listing is for the casting number, but almost all of them are small valves: 2.19/1.88 is the biggest I found for 1968-70 427s.


I rebuilt a 454 from a 1978 truck twenty years ago, before I had my Corvette and before I wanted to know the valve size. Can't remember valve size and all of the parts bills are long gone. None of the spec sheets I found list the valve size for the LF-8.


The PO put the LF-8 in my 68 convert and I have no info on the internal components, except what I see with my fiber optic scope- flat top pistons with valve reliefs and the 4 bolt bearing caps. I suspect the heads are the ones from the stock motor and am trying to decide whether to put just a different cam in it or to put aluminum Brodix heads also, with larger valves. If the small valve size is correct, there is a big difference from the 2.30/1.88 valves in the Brodix.

 

Don't these truck blocks have a taller deck and often referred to as "Tall Blocks"? No experience, I just remember hearing they were difficult to get higher static compression ratios and were used a lot for a Blower motor?

Anyway just trying to reconcile what I had heard in the past.

 

Most of the tall blocks were 366 or 427 cu inch truck engines. I have not found any list that has 454 tall blocks, however that is part of my problem. There are various lists that have been copied and re-copied, so I don't know how accurate they are for 40 year old info.