Pontiac V8 engine
From Crankshaft Coalition Wiki
(→Bore and stroke) |
Terry Petty (Talk | contribs) m (→Pistons) |
||
| Line 661: | Line 661: | ||
In 1967 the 400 4bbl engines went to new valve angle and placement and all Pontiac V-8's 1968 and newer. Newer valves don't line up correctly with the 67 2bbl, any 326 or all 1966-back piston valve reliefs (and obviously vice-versa), the correct piston has to be used if any sort of aftermarket high lift cam is used, or else there may be destructive valve to piston interference. There are 8-valve relief pistons available to fit all the valve angle differences used through the years on Pontiac 400 engines. While these pistons will get the job done, from a high performance standpoint they are not desirable partially due to the lower compression. | In 1967 the 400 4bbl engines went to new valve angle and placement and all Pontiac V-8's 1968 and newer. Newer valves don't line up correctly with the 67 2bbl, any 326 or all 1966-back piston valve reliefs (and obviously vice-versa), the correct piston has to be used if any sort of aftermarket high lift cam is used, or else there may be destructive valve to piston interference. There are 8-valve relief pistons available to fit all the valve angle differences used through the years on Pontiac 400 engines. While these pistons will get the job done, from a high performance standpoint they are not desirable partially due to the lower compression. | ||
| − | |||
| − | |||
Pontiac went to an advertised 7.6:1 compression in about 1975, due in part to the design of the top of the pistons. Pontiac pistons from the low compression years have a 45 degree machined outer edge of the piston top. | Pontiac went to an advertised 7.6:1 compression in about 1975, due in part to the design of the top of the pistons. Pontiac pistons from the low compression years have a 45 degree machined outer edge of the piston top. | ||
Your Privacy Choices