Pontiac V8 engine

[[File:Pont twin turbo eng.jpg|right]]<br style="clear:both"/>

 

 

 

The Pontiac engine has long been recognized as being a good engine for making a lot of torque at a relatively low RPM. Recent advances in aftermarket parts in general and cylinder heads in particular have given new life to this venerable platform. While turning your Pontiac 400 into a fire-breathing BBC eating machine can be accomplished given enough dedication and money, the Pontiac engine remains a viable ''economical'' option for building a lot of torque using basically stock castings, including blocks, heads and cranks.

 

As for the current (ca. 2000-up) aftermarket support given to the Pontiac engine, suffice to say that a Pontiac engine- much like a BB or SB Chevy- can be assembled using basically NO factory production parts whatsoever. Never before has the Pontiac engine enjoyed such aftermarket support, and it can truly be said that the golden years for building a Pontiac is... NOW!

<table border="2" cellpadding="2" cellspacing="0" >

  <tr align="center" bgcolor="#DDDFFF" valign="center">

     <td>'''CID'''</td>

     <td >'''BORE''' (in.)</td>

     <td >'''STROKE''' (in.)</td>

     <td >'''MAIN''' (in.)</td>

     <td >'''ROD''' (in.)</td></tr>

  <tr align="center" valign="bottom">

     <td>'''265'''</td>

     <td >3.75</td>

     <td >3.00</td>

     <td >3.00</td>

     <td >2.00</td></tr>

  <tr bgcolor="#F1F1F1" align="center" valign="bottom">

     <td>'''287'''</td>

     <td >3.75</td>

     <td >3.25</td>

     <td >2.50</td>

     <td >2.25</td></tr>

  <tr align="center" valign="bottom">

     <td>'''301'''</td>

     <td >4.00</td>

     <td >3.00</td>

     <td >3.00</td>

     <td >2.00</td></tr>

  <tr bgcolor="#F1F1F1" align="center" valign="bottom">

     <td>'''303**'''</td>

     <td >4.120</td>

     <td >2.840</td>

     <td >2.50</td>

     <td >2.25</td></tr>

  <tr align="center" valign="bottom">

     <td>'''316'''</td>

     <td >3.9375</td>

     <td >3.25</td>

     <td >2.50</td>

     <td >2.25</td></tr>

  <tr bgcolor="#F1F1F1" align="center" valign="bottom">

     <td>'''326*'''</td>

     <td >3.71875</td>

     <td >3.75</td>

     <td >3.00</td>

     <td >2.25</td></tr>

  <tr align="center" valign="bottom">

     <td>'''347'''</td>

     <td >3.9375</td>

     <td >3.5625</td>

     <td >2.623</td>

     <td >2.25</td></tr>

  <tr bgcolor="#F1F1F1" align="center" valign="bottom">

     <td>'''350***'''</td>

     <td >3.875</td>

     <td >3.75</td>

     <td >3.00</td>

     <td >2.25</td></tr>

  <tr align="center" valign="bottom">

     <td>'''366**'''</td>

     <td >4.153</td>

     <td >3.375</td>

     <td >3.00</td>

     <td >2.25</td></tr>

  <tr bgcolor="#F1F1F1" align="center" valign="bottom">

     <td>'''370'''</td>

     <td >4.0625</td>

     <td >3.5625</td>

     <td >2.623</td>

     <td >2.25</td></tr>

  <tr align="center" valign="bottom">

     <td>'''389'''</td>

     <td >4.0625</td>

     <td >3.75</td>

     <td >3.00</td>

     <td >2.25</td></tr>

  <tr bgcolor="#F1F1F1" align="center" valign="bottom">

     <td>'''400'''</td>

     <td >4.12</td>

     <td >3.75</td>

     <td >3.00</td>

     <td >2.25</td></tr>

  <tr align="center" valign="bottom">

     <td>'''421'''</td>

     <td >4.09375</td>

     <td >4.00</td>

     <td >3.25</td>

     <td >2.25</td></tr>

  <tr bgcolor="#F1F1F1" align="center" valign="bottom">

     <td>'''428'''</td>

     <td >4.12</td>

     <td >4.00</td>

     <td >3.25</td>

     <td >2.25</td></tr>

  <tr align="center" valign="bottom">

     <td>'''455'''</td>

     <td >4.15</td>

     <td >4.21</td>

     <td >3.25</td>

     <td >2.25</td></tr></table>

<br>

 

===6X heads===

Casting 6X heads and similar heads from the "smog era" generally all have hardened exhaust seats, screw-in rocker studs and guide plates, with 2.11" intake x 1.66" exhaust valves. See [http://www.pontiacstreetperformance.com/psp/6XheadID.html '''''How to Identify Pontiac's Small Chambered 6X Head'''''] for more info on ID'ing 6X heads.

<table border="2" cellpadding="2" cellspacing="0"><tr><td colspan="5" align="center" bgcolor="#DDDFFF"><font size="4"><strong>CYLINDER HEAD APPLICATIONS</strong> </font></td></tr><tr><td bgcolor="#FFF8DC"><strong>Casting</strong></td><td bgcolor="#FFF8DC"><strong>Secondary ID</strong></td><td bgcolor="#FFF8DC"><strong>Valve diameter (in.)</strong></td><td bgcolor="#FFF8DC"><strong>Chamber volume</strong></td><td bgcolor="#FFF8DC"><strong>Original application</strong></td></tr><tr bgcolor="#F1F1F1"><td>4X</td><td>1/1H</td><td>2.11/1.66</td><td>112 cc</td><td>1973-'74 455ci 4-bbl</td></tr><tr><td>4X</td><td>3/3H</td><td>2.11/1.66</td><td>98-99 cc</td><td>1973-'74 400ci 4-bbl manual trans.</td></tr><tr bgcolor="#F1F1F1"><td>4X</td><td>4/4H</td><td>1.96/1.66</td><td>98-99 cc</td><td>1973-'74 400ci 2-bbl</td></tr><tr><td>4X</td><td>7/7H</td><td>2.11/1.66</td><td>98-99 cc</td><td>1973-'74 400ci 4-bbl auto trans.</td></tr><tr bgcolor="#F1F1F1"><td>4C</td><td>5/5H</td><td>1.96/1.66</td><td>96 cc</td><td>1973-'74 350ci 2-bbl w/A.I.R.</td></tr><tr><td>4C</td><td>8/8H</td><td>1.96/1.66</td><td>98 cc</td><td>1973-'74 400ci 2-bbl w/A.I.R.</td></tr><tr bgcolor="#F1F1F1"><td>46</td><td>6/6H'''*'''</td><td>1.96/1.66</td><td>96 cc</td><td>1973-'74 350ci</td></tr><tr><td>5C</td><td>4</td><td>2.11/1.66</td><td>92-94 cc</td><td>1975 350ci</td></tr><tr bgcolor="#F1F1F1"><td>5C</td><td>7</td><td>2.11/1.66</td><td>99-101 cc</td><td>1975 400ci w/A.I.R.</td></tr><tr><td>5C</td><td>8</td><td>2.11/1.66</td><td>99-101 cc</td><td>1975 400ci</td></tr><tr bgcolor="#F1F1F1"><td>5C</td><td>9</td><td>2.11/1.66</td><td>92-94 cc</td><td>1975 350ci w/A.I.R.</td></tr><tr><td>6X</td><td>4</td><td>2.11/1.66</td><td>92-94 cc</td><td>Mid 1975-'77 350ci; 1977-'79 W72 400ci</td></tr><tr bgcolor="#F1F1F1"><td>6X</td><td>8</td><td>2.11/1.66</td><td>99-101 cc</td><td>Mid 1975-'78 400ci</td></tr><tr><td>6S</td><td>7</td><td>2.11/1.66</td><td>99-101 cc</td><td>Mid 1975-'76 400ci w/A.I.R.</td></tr><tr bgcolor="#F1F1F1"><td>6S</td><td>9</td><td>2.11/1.66</td><td>92-94 cc</td><td>Mid 1975-'76 350ci w/A.I.R.</td></tr><tr><td>51</td><td>6</td><td>2.11/1.66</td><td>124.5 cc</td><td>1975 455ci</td></tr><tr bgcolor="#F1F1F1"><td>6H</td><td>6</td><td>2.11/1.66</td><td>124.5 cc</td><td>Late 1975-'76 455ci</td></tr><tr><td colspan="5">'''*'''Some reported to have a secondary stamp of "'''2'''"</td></tr></table>

[[File:Pont stk stud.jpg|thumb|500px|Stock type Pontiac bottleneck stud]]Pontiac heads like the 6X and practically all other production Pontiac heads likely to be used in a performance-orientated build originally had screw in ''bottleneck'' studs and steel guideplates. There are some exceptions to this, like heads having pressed in bottleneck studs, and the Ram Air IV and "Ram Air II" round port heads, which used a straight 7/16" stud with an adjuster nut/lock nut arrangement.  

So if any of the above changes are made, the stock Pontiac bottleneck stud/net lash set-up may no longer preload the lifter properly. Unless the studs are changed to allow for an adjustable valve train, different length push rods may be needed to set the lifter preload- but changing the length of the push rod can adversely affect the '''[[valve train geometry]]'''. For that reason it is advisable to use straight studs to replace the bottleneck studs. A good replacement is ARP '''p/n 190-4003''' w/hex nuts, or p/n '''190-4203''' w/12-point nuts. Be aware that there can be clearance issues between the polyloc and valve cover if polylocs are used. Check the clearances carefully; you might be able to use a shorter polyloc. If possible (and the valve cover are so equipped) keep the oil drippers. The oil drippers are a separate piece from the valve covers on the RA II/IV engines.

Round port heads were long favored for high performance. But they are scarce (read ''expensive''), and don't flow all that well, at least when compared to aftermarket heads.

But now that Edelbrock and others have come out with affordable aftermarket aluminum heads, the round port heads are all but ignored by the performance crowd. But to restorers, they are still highly sought after.

*Best low compression D-port head:  No.96(1971)

*Best low compression post-1972 head:  No. 6X

*Most under-cammed:  1963 SD, 1971 455 HO, 1973-74 455 SD (tie)

*Most under-exhausted:  1964 GTO (No.9770716)

With the D-port heads, unless they've been heavily ported, an RPM intake is a good choice. It will hit harder off idle and gives up nothing to a single plane at the modest peak rpm the 455 is going to be turning (5000-5500 rpm in street trim), built as described here; harnessing the torque by using sticky drag radial tires will give the maximum all-around performance. There might be an argument made for a single plane to "tame the torque". But that might be better left until all other avenues have been exhausted.

 

 

;[[Pontiac V8 engine #Parts interchangeability|Return to Parts interchangeability]]

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.  

This info on crankshafts is from the www.pontiacpower.org site.  

 

[[File:BCA-7109.jpg|thumb|150px|BCA p/n 7109 pilot bearing]]Pilot bearing is BCA p/n 7109 (available from Summit and Ken's Speed and Machine, among others). The GM part number is 15533265. The dimensions are 1.3780" OD x 0.5906" ID x 0.3543" wide (35 mm OD x 15 mm ID x 9 mm wide). According to www.pontiacpower.org, the cheaper p/n 6202 bearing may be used, but the crank opening may need to be machined 2 mm deeper. The p/n 6202 is 35 mm OD x 15 mm ID x 11 mm wide. The 6202 is available with shields on both sides to keep dirt out.

 

[[File:Pontiac firing order.jpg]]

 

 

;See [[Hot rodding the HEI distributor]].

 

 

 

 

 

 

 

 

 

 

 

 

==Parts interchangeability==  

<table border="2" cellpadding="2" cellspacing="0">

<tr valign="center" align="middle"><td bgcolor="#DDDFFF"><font size="4"> <strong>PART:</strong></font></td>

<td bgcolor="#DDDFFF"><font size="4"><strong>INTERCHANGE YEARS/NOTES:</strong> </font></td></tr>

<tr valign="center" align="middle"><td ><strong>Block:</strong></td>

<td >1955,1956,1957,1959-'60,1961-'64 (full size V8), 1964-'69 (Tempest/Grand Prix V8), 1970-'79<br> '''Note:''' No block mount starter holes on pre-1964 blocks</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Bellhousing:</strong></td>

<td >1955, 1956-'57, 1958-'60, 1961-'64 (fullsize), 1964-'79 (all except 1964 fullsize)</td></tr>

<tr valign="center" align="middle"><td ><strong>Oil pump:</strong></td>

<td >1955-'58, 1959-'79; all use the same oil pump shaft</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Oil pan:</strong></td>

<td >1955-'58, 1959-'60, 1961-'63, 1964, 1965-'71, 1972-'79<br>'''Note:''' Same pan can be used from 1964-on with proper rear pan seal</td></tr>

<tr valign="center" align="middle"><td ><strong>Windage tray:</strong></td>

     <td >1955-'58, 1959-'60, 1961-'62, 1963, 1964, 1965-'72<br>'''Note:''' #2 and #4 main cap holes are for windage tray mounting. After 1972 some blocks have no provision for windage tray mounting. Center main cap holes (#3 cap) are for lower dipstick bracket</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Oil filter:</strong></td>

     <td >1955-'59, 1960-'79</td></tr>

<tr valign="center" align="middle"><td ><strong>Oil filter mount:</strong></td>

     <td >1955-'59, 1960-'62, 1963, 1964-'70 (straight), 1967-'79 (tilted)<br>'''Note:''' There are basically two different oil filter housings: Pre-1970 straight mount and the later angled housing mount. Also special adapter for a rearward facing oil filter housing to clear RA III and IV exhaust</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Crankshaft:</strong></td>

     <td >1955-'56, 1957-'58, 1959-'66 (3" main), 1967-'78 (3" main), 1962-'76 (3.25" main).<br> For all engines after 1964: 326, 350, 389 and 400 use the 3" mains. 421, 428 and 455 use the 3.25" mains.<br>{{!}}More at '''[[Pontiac V8 engine #Cranks|Cranks]]'''</td></tr>

<tr valign="center" align="middle"><td ><strong>Harmonic balancer:</strong></td>

     <td >1955-'62, 1963, 1964, 1965, 1966, 1967, 1968-'79<br> '''Note:''' Some 1977-up 400 and 301 use a crankshaft hub without a rubber torsional ring</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Flywheel/<br>Flexplate:</strong></td>

     <td >1955-'57, 1958-'60, 1961-'62, 1963, 1964-'79<br>'''Note:''' There are two different diameter flanges used on the 400 crank after 1975: 2-1/2" and 2-3/4".<br> All 350/389/400/428 and 455 with same flange will interchange.<br> Also watch the pilot ID on early pre-1964 389 Armasteel cranks when using an automatic<br>{{!}}More at '''[[Pontiac V8 engine#Modern GM transmission behind early Pontiac engine|Modern GM transmission behind early Pontiac engine]]'''</td></tr>

<tr valign="center" align="middle"><td ><strong>Connecting rods:</strong></td>

     <td >1955-'79<br> '''Note:''' Before 1962 forged rods were installed, but weaker then the later cast rod unless heat treated and prepped. Swapping to the earlier lighter forged rod requires re-balancing<br>{{!}}More at '''[[Pontiac V8 engine#Rods|Rods]]'''</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Pistons:</strong></td>

     <td >Must match the bore, stroke, and head series<br> '''Note:''' 455 SD piston use SD rod unless the pin boss is internally milled. <br>{{!}}More at '''[[Pontiac V8 engine #Pistons|Pistons]]'''</td></tr>

<tr valign="center" align="middle"><td ><strong>Wrist pins:</strong></td>

     <td >1955-'57, 1958-'62, 1963-'65, 1966-'79 Some SD pins are longer</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Heads:</strong></td>

     <td >1955, 1956-'60, 1961-'66, 1967-'79<br> '''Note:''' Valve centers were widened in 1967 for larger valve diameters.<br>{{!}}More at '''[[Pontiac V8 engine #Heads|Heads]]'''</td></tr>

<tr valign="center" align="middle"><td ><strong>Rocker arm:</strong></td>

     <td >1955, 1956-'60, 1961-'64, 1963 (421 HO)-'64 (GTO Tripower), 1965, 1966, 1967 (326 only), 1967-'79<br>'''Note:''' Ram Air IV engines used a 1.65 ratio, the pushrod holes were factory enlarged for this.<br> All other heads have to be modified to use 1.65 rocker arms</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Pushrods:</strong></td>

     <td >1955-'60, 1961-'66, 1967-'76 (except longer Ram Air IV)<br> '''Note:''' Match pushrod to year of head</td></tr>

<tr valign="center" align="middle"><td ><strong>Valve covers:</strong></td>

     <td >1955-'57, 1958-'60, 1961-'62, 1963-'66, 1967-'79</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Lifters:</strong></td>

     <td >1955, 1956-'79</td></tr>

<tr valign="center" align="middle"><td ><strong>Camshaft:</strong></td>

     <td >1955-'79 (except Ram Air V/455 Super Duty).<br>{{!}}More at '''[[Pontiac V8 engine #Cams|Cams]]'''</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Intake manifold:</strong></td>

     <td >1955, 1956, 1957-'58, 1959-'60, 1961-'62, 1963-'64, 1965-'71, 1972-'79<br>{{!}}More at '''[[Pontiac V8 engine #Intakes|Intakes]]''' and '''[[Pontiac V8 engine #Heat cross over|Heat cross over]]'''<br></td></tr>

<tr valign="center" align="middle"><td ><strong>Exhaust manifolds:</strong></td>

     <td >1955, 1956, 1957, 1958, 1959-'79 (D-port); 1968-'74 (round port)<br> '''Note:''' While the manifolds physically fit the engine, the oil filter mount, steering box, and chassis configurations all need to be considered if using a non original manifold</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Distributor:</strong></td>

     <td >1955-'79 (except Ram Air V/455 Super Duty)</td></tr>

<tr valign="center" align="middle"><td ><strong>Starter:</strong></td>

     <td >1955, 1956-'60, 1961-'64 (fullsize), 1964 (Tempest/Grand Prix)-'79</td></tr>

<tr bgcolor="#F1F1F1" valign="center" align="middle"><td ><strong>Timing Cover:</strong></td>

     <td >1955-'59, 1960, 1961-'62 (inc. Tempest "Trophy" 4), 1963, 1963 1/2-'65, 1966-'67, 1968, 1969-'79<br>The only difference in the 1968-up timing covers are the timing indicator markings.<br> Some late model 400 and 301 covers have a plastic bolt-on tab.<br>{{!}}More at '''[[Pontiac V8 engine #Timing covers|Timing covers]]'''</td></tr>

Jim Hand has been a prolific writer on the Pontiac scene for decades. The following is a few articles by him; others can be found on the web:

*[http://en.wikipedia.org/wiki/Pontiac_V8_engine Pontiac V8 engine] Wikipedia page