| ||||
|
[ Post New Message | Reply | Edit Profile | Register | Search | Current Connections | Message Board FAQ | Lost Password? ]
Heads for a 1971 455cui block Posted By: winehippy On: 01-04-2008 @ 07:41:02 Reply | Edit I understand that many of the Pontiac D-port heads are interchangable. I have a 1971 455 motor out of a Bonniville with the D-port heads. What heads can I use and what heads can I not use? I don`t remember my casting #`s but can find out real quick.But are there any restrictions as far as the heads? Tanks, Tony Posted By: 76to70TA On: 01-03-2006 @ 11:53:19 Reply | Top | Edit A set of 6X's or 5C's from a smog era 400 will give you about 9:1 to 9.5:1 compression. They have about the best flowing ports of any of the D-port heads and can be ported out for more if necessary. Posted By: arcticz28 On: 01-03-2006 @ 13:51:53 Reply | Top | Edit Yes, 6x4 and 6x8 heads are the most common heads used. 6x4's will give you around 9.5 to 1 compression and 6x8's will give you around 9 to 1 on a 455. Stock 455 heads ( well it depends on the year) are usually big chambered heads with low compression. If you give me the casting # on the head I can find out if theyre good heads to use for your 455. -- 94Z A4 Snapped Crank at the time being. 
 Posted By: FlyingArrow On: 01-03-2006 @ 19:54:48 Reply | Top | Edit A 455 out of a 71 Bonny will most likely have the 66 casting d-ports and they are real low compression. The 6x-4 heads are the way to go for a nice pump gas 455 street engine. Posted By: winehippy On: 01-04-2006 @ 05:32:38 Reply | Top | Edit Will any of the older 426cui or even 400cui heads fit,say from the 1967-1970 pontiac motors? I am looking at many pontiac heads on e-bay and really need to know if there are any D-port heads that are not applicable. Posted By: winehippy On: 01-04-2006 @ 05:53:34 Reply | Top | Edit Does anyone know abot the 4xHcasting heads? Are there any more desireable heads than the 6x4 for the 1971 Pontiac 455 motor? Posted By: winehippy On: 01-04-2006 @ 06:32:48 Reply | Top | Edit Just checked the casting #`s on this motor. They are 6x on passenger side and 6H on drivers side.Front exhaust port has a 4 on it and can not determine if there is a letter or not. However the back exhaust port has another X on it.From what I can determine this is not a 1971 motor,but a 1973-74 455. Can anyone help me determine for sure what I have now? If they are a desireable head,I will go ahead and have them redone with some tricks. Tanks, Tony Posted By: OneOwner On: 01-04-2006 @ 11:18:15 Reply | Top | Edit I have a set of 6X 4 heads with some mild work done to them for sale if you are interested. I had them for 3yrs and they are in excellent condition. I put less than 5,000 miles on the motor while they were on I did not do the work, but can get the details from the machine shop if you are interested. Posted By: arcticz28 On: 01-04-2006 @ 14:18:31 Reply | Top | Edit If you can find out what kind of 6x head it is that would be some good info. A 4, 8, or 11 should be stamped on the exhaust side or the head. Looks like you have two heads that have different chamber sizes. It would be nice to get a matching set. 6H heads have about a 121-124cc chambers, not what you want. If you have a 6x11 head, it has around a 114cc chamber (still too big). You want your heads to have anywhere from 90 to 100cc's, that will give you a good compression ratio for a street motor with iron heads and no fear of detonation. 9.5 to 1 compression is the highest you should go with iron heads and pump gas. -- 94Z A4 Snapped Crank at the time being.
Posted By: 76to70TA On: 01-05-2006 @ 13:06:00 Reply | Top | Edit The pre-70 heads will fit but with 72cc combustion chambers you will end up with aobut 12:1 compression. Way too high. Posted By: quicksilver97ta On: 01-05-2006 @ 16:38:06 Reply | Top | Edit Look for 96's. They will give you the 9.5:1 like the 6x4's but have the larger 1.77 exhaust valve. --   
97 T/A 384 rwhp 354 rwtq http://quicksilver97.fbody.com Posted By: winehippy On: 01-25-2006 @ 00:51:33 Reply | Top | Edit Just bought a pair of 7K3 heads that are 96cc chaber heads,verses 121,or 114cc.These are large valves and have all crower roller rockers.Look to have double springs and dampners as well. Valves look in really great shape too.Not sure of the valve seats, but I think they also have a 3angle.I have a new set of long headers and will take all to a machinist to match exhaust ports and gaskets.Anyone have an idea as to what cfm exhaust flow this application may have? Have a Holley 750 double pumper and all msd ignition,2800 stall converter,4spd overdrive and a 373 rear. Trying to figure out a good cam to reach maybe 6000rpm. All input appreiciated. Tanks, Tony Posted By: 67bird421 On: 01-25-2006 @ 20:50:00 Reply | Top | Edit you cant bolt headers to 7K3's cause they dont have the bolt holes on the outside flanges. you have to remember that the heads you choose can not be decided until you have chosen what pistons you will use and what your deck height is.....not to mention your bore size. #96's would be great place to start on a 455 though. quicksilver97ta is right . the bigger valves are what you want...or find any 87cc head with screw in studs you can find cheap and pay the shop to enlarge the valves. Posted By: winehippy On: 01-26-2006 @ 01:17:15 Reply | Top | Edit I am taking the headers and heads to a machine shop to have all matched up. I am sticking with stock 455cui bore size and no work has been done to these heads to shorten the deck height. I currently have 121cc heads and 96`s seem like a good choice. Car runs like a raped ape now due to a 373 rear, a 4spd overdrive tranny which is all done up too along with a 2400 stall converter. All msd ignition,6a box,big wires,blaster 2 coil,Edelbrock perf.intake 750cfm double pumper w vac secondaries,as I have a auto tranny. All AArt Carr full race set up,with a mega shifter. Also,wanna do all allen bolts for the headers anyway. Does all this make sense? Posted By: 67bird421 On: 01-26-2006 @ 08:55:08 Reply | Top | Edit if you are willing to pay the machine shop to weld some bolt holes to the heads i guess that will work for the headers....otherwise i'd bet you will have exhaust leaks no matter what bolts you use. i meant to say in the reply above that any 96cc head will be good...you will want to ugrade to screw in studs and like i said i think any valve work you can afford is worth it ! not to mention some porting and port matching although i have read articles that say it is often not worth the expense and rarely done right. Posted By: winehippy On: 01-28-2006 @ 01:17:17 Reply | Top | Edit 67bird, Are you saying that the headers are longer at the flange than these heads and I need to have more metal welded to each end of these heads to be able to bolt up the headers or is it a matter of drilling the holes in both ends of the heads and having them tapped for either studs or bolts? 1972 heads should be able to accomidate headers as far as the length of the heads as far as I know. If I am wrong though please inform me in detail what needs to be done for these heads to accomidate headers. Tanks, Tony Posted By: arcticz28 On: 01-28-2006 @ 02:12:43 Reply | Top | Edit As far as I know all you need to do is drill and tap. The area is there for the bolt hole... just no bolt hole. -- 94Z A4 Snapped Crank at the time being. [ Edited on 01/28/2006 @ 02:13:10 ] Posted By: 67bird421 On: 01-28-2006 @ 05:31:49 Reply | Top | Edit good luck with that...i bought a set of 7k3's before i knew the difference (no manual or chart included the fact that they only accept cast iron manifolds) ,and mine did not have enough material to just tap and drill. i sold them to a person just looking for a numbers matching gig. in 72-3 folks were not as likely to be puttin headers on cause the trend was away from performance and more towards economy ! i saw a set for sale on ebay once that someone had modified to have the two end bolts added...it was ugly. in my opinion the $$$ spent modifying the 7k3's would be better spent on the right heads. Posted By: winehippy On: 02-02-2006 @ 01:15:32 Reply | Top | Edit Well,how good or bad these L-Brackets are, I did find a fix for this problem.I am hoping with some tricky machine shop work to recess the brackets just a little that they will work and not have exhaust leaks with the headers. Over all the 7k3 heads look to be about what I need for my application.Yes another set Of heads might work better like #15`s or 64`s.Hard to find though and usually alotta$$$s if you can find them. Gonna try to make this work as I got these heads for a real good price and they seem to be in real good shape.They have some mild porting,Got crane roller rockers,stainless valves w/double springs and I think dampner springs as well. Will let you all know in a few weeks how it all turns out. Tanks, Tony Posted By: max69 On: 11-09-2008 @ 09:41:10 Reply | Top | Edit Have a low compression 400, 77 TA, are 72CC heads or 96cc better? I would like to be about 9.5. Thanks, Max
|
||||
| If it looks (c) it probably is - All work done by James Hogan | ||||
