What are 4X Pontiac heads?
What are 4X Pontiac heads?
The 4X head was the 49-state casting used on all ’73-74 400 and 455ci engines. Since Pontiac offered the 400 2-barrel, the 400 4-barrel with both manual and automatic transmissions, and the 455 4-barrel for 1973 and 1974, separate applications of the 4X head were required to meet such broad usage.
What CC are Pontiac 6X heads?
Pontiac Heads
| PONTIAC HEAD CHART | ||
|---|---|---|
| CASTING NUMBER | YEAR & FACTORY APPLICATION | CHAMBER VOL# CC’S |
| 6X | 75-79 350 & 400 ALL 75-76 455 | see chart below |
| 5C,5X,5G | 75-76 455, SOME 350 | 93-114+ |
| EDELBROCK | PERFORMER RPM ALUMINUM | 72 or 87 |
What is the bore and stroke of a Pontiac 400?
With a 4.12-inch bore and a 3.75-inch stroke, Pontiac’s 400 had similar bore and stroke to Chevy’s big-block 396 (even when the Chevy actually displaced 402 cubic inches).
What is the bore size on a 455 Pontiac?
4.151
Pontiac Blocks- Bore and Stroke
| PONTIAC ENGINE CHART | ||
|---|---|---|
| ENGINE | BORE | |
| 455 CU. IN. | Stock Bore | 4.151 |
| 30 over | 4.181 | |
| 60 over | 4.211 |
What size is a 455 bored 30 over?
Stock 455 bore is 4.3125″. 0.30″ over is 4.3425″.
How much does it cost to port a set of heads?
That could be a $1,000 question, if you go the fully ported route. On the low-end, you’re looking at around $200 for a professional three-angle valve job with the existing 1.94/1.50 valves. Add bowl-porting and a set of big valves and you move up into the $500-$700 range.
What cubic inch is a 455 bored 60 over?
Pontiac Blocks- Bore and Stroke
| PONTIAC ENGINE CHART | ||
|---|---|---|
| ENGINE | BORE | |
| 455 CU. IN. | Stock Bore | 4.151 |
| 30 over | 4.181 | |
| 60 over | 4.211 |
What kind of engine does a Pontiac 455 HO have?
The 455 H.O. was carried over for 1972 without any major changes, but the gross output rating was dropped in favor of net values. It was rerated at 300 hp at 4,000 rpm and 415 lb-ft at 3,200 rpm. Despite only two years in production run, the 455 H.O. is regarded by many Poncho experts as the most versatile street engine Pontiac ever produced.
Are all Pontiac heads interchangeable?
All Pontiac V8 cylinder heads from 1955 to 1976 are essentially interchangeable. Except for some special heads the bolt pattern, the bore spacing, and deck heights are the same. Pontiac heads produced PRE 1968 used a closed combustion chamber design while heads produced from 1968 on used an open chamber.
What is the difference between pre 1968 and 1968 Pontiac heads?
Pontiac heads produced PRE 1968 used a closed combustion chamber design while heads produced from 1968 on used an open chamber. The high output heads produced by Pontiac after 1967 used bigger intake and exhaust valves and a 14-degree valve angle. These heads flow better producing more power than the heads produced pre-1967.
What kind of valves are on a 1972 455 HO 7F6?
The 1972 455 H.O. 7F6 cylinder heads with oversized intake ports and round-shaped exhaust ports were completely rebuilt using bronze valveguides, stainless-steel Ferrea valves in 2.11/1.77-inch, and a multi-angle valve job. Intake and exhaust airflow at 28 inches measures 223 and 177 cfm, respectively.