Found a 4 bolt main Mark IV block to replace the one I sold ..
Going after it this evening ...
Photos of it looks really good, soon to see it up close ..
It's also the last year for the Mark IV's .. 1990
Will be doing another 496 cid stroker with it ..
Been on the hunt for a 4 bolt for a long while, thinking I got super lucky finding this one so close to home ..
Still hadn't got around to taking the Gen VI (L-29) and Gen VII (L-18) apart yet ...
Don't have a need for them, although I might have a need for the Gen VI heads to use on a Mark IV block ??
Spec's on the L-29 Vortec BB head vs a peanut port BB head (PPH) ..
L-29 intake ports = 233.2(S) and 239.5cc (L).
PPH intake ports = 192.4(S) and 198.0cc (L).
L-29 exhaust port = 81.2cc.
PPH exhaust port = 101.3cc.
Chamber volumes. L-29 = 100 cc and PPH = 118. cc.
Approx. CR's on a regular stock, small domed 502, PPH = 8.74CR. and L-29 = 9.74CR.
For a flat-top piston 502, the L-29 would make 9.3CR.
For a stock 454 flat-top P/U truck motor PPH = 7.9CR. and L-29 = 9.0CR!!
Valves = the same for both heads at 2.065"/1.72".
NOTE: Use Fel-Pro headgasket 1017-1 to use L-29 heads on the early IV BB blocks AND check coolant holes CAREFULLY!!!
A VERY GOOD WAY TO UP YOUR OLD P/U MOTOR's POWER, imho !!
Going to put the 88 motorhome 2 bolt 454" motor up for sale ..
Will be a long block with having Gen VI heads ..
Want $2,500 .... Any takers ?