[tc]

Originally Posted by 65sport

You are missing a part of your equation. You have to add for piston dish (valve reliefs in this case), head gasket and deck clearance.

Read my post #12, you did not mention piston volume so I did not add that in.

[65sport]

Originally Posted by tc

Read my post #12, you did not mention piston volume so I did not add that in.

Oh so you thought I was running no valve reliefs, and zero piston to head clearance.

OK

[tc]

Originally Posted by tc

You should not need to mill anything to get 9 to 1 compression with 6X heads. 6x-8-100cc's, deck clearance-6cc, gasket-10cc's. 116cc's with a 455 is 9.0 compression.

You can't read? OK, post # 12 see above.

Deck clearance is your stated .025, see your post #11. How many cc's are in that .025?

Put some 6X-4's on if the valve reliefs are too many cc's. This isn't the f-ing race section where forum members put other member down!

[Lee]

TC, 65 is thinking you are saying he will have 9.0 with his 66 heads. That is how I first read your post.

65, TC is saying you'll have 9.0 with 6X-4's.

The English language can be rather ambiguous, causing such confusions.

[65sport]

Originally Posted by Lee

222/242 @ .050", .443"/.435" valve lift, 116 LSA, ICL target was 111 but it ended up at 112.

The motor had a .454" lift cam in it, when I got it. There was no wear on the cam or lifters, so I knew that whatever the springs were, they were fine for up to .454" lift.

My engine came with a Crane 278, more cam than I want. It too is in great shape, no sign of wear. I plan on going with a small cam like a 204-214 or a 214-224 on 112 LS. I'm running factory air, power brakes, stock torque converter. Want to keep the RPM's down if I keep the stock rods. Also planning on running the Edelbrock Performer Pontiac. I've heard that will limit RPM's as well.

If I reach my target of 9:1 CR, how do you think my 455 will idle with the 214-224-112 LS ?

[Jay S]

If I reach my target of 9:1 CR, how do you think my 455 will idle with the 214-224-112 LS ?[/QUOTE]


I have, and have had that cam in a ton of engines. Slight, very slight lope at about 500- 600 rpm in 9:1 bigger cid engines. Above 700-800 has a smooth idle.

I will mention this, since you mentioned having rebuilt 6x-4, and a good crane 278. That is a good combo in a 455. A 455 probably has a about equal vacuum comparing the 214/224 at upper 8:1 with the 66s as the 278 crane would with the 6x-4 (est 9.4:1 compression. That crane is an asymmetric profile, the 214/224 is symmetrical on the ramps. That crane is a well design modern cam. It would run all your vacuum accessories.. just an opinion if your doing the screw in studs, the 6x-4, crane 278, in a lower 9s 455 is a really nice combo. 214/224 would be better with the 66s imo in that 8-9 compression range. The 214/224 seems to like 9:1, I have not seen any reason to go beyond 9 with that cam in bigger engines. Pressed in studs bolt neck studs should be ok with the 66s and 214/224. 204/214 is a stock cam, smaller than some of the mild OEMs. If you want a stock cam, it is fine too.

[77 TRASHCAN]

Originally Posted by Jay S

If I reach my target of 9:1 CR, how do you think my 455 will idle with the 214-224-112 LS ?

I have, and have had that cam in a ton of engines. Slight, very slight lope at about 500- 600 rpm in 9:1 bigger cid engines. Above 700-800 has a smooth idle.

I will mention this, since you mentioned having rebuilt 6x-4, and a good crane 278. That is a good combo in a 455. A 455 probably has a about equal vacuum comparing the 214/224 at upper 8:1 with the 66s as the 278 crane would with the 6x-4 (est 9.4:1 compression. That crane is an asymmetric profile, the 214/224 is symmetrical on the ramps. That crane is a well design modern cam. It would run all your vacuum accessories.. just an opinion if your doing the screw in studs, the 6x-4, crane 278, in a lower 9s 455 is a really nice combo. 214/224 would be better with the 66s imo in that 8-9 compression range. The 214/224 seems to like 9:1, I have not seen any reason to go beyond 9 with that cam in bigger engines. Pressed in studs bolt neck studs should be ok with the 66s and 214/224. 204/214 is a stock cam, smaller than some of the mild OEMs. If you want a stock cam, it is fine too.[/QUOTE]

X2, yes!!!

[65sport]

Thanks Jay !

[65sport]

Thanks 77 TRASHCAN !

[lust4speed]

I'm a little surprised that you wouldn't use your Crane 278 cam. It's 222/234 @ .050" is about the same size as the Crower 60916 that measures 221/229. I was going to install the Crower in my Bonneville project but ended up selling it to a club member for the 455 build in his '66 GTO. Idle was very mild and worked with the stock converter. His car has a very good mid-range punch. We kept compression at 9.1:1 with dished pistons and his #93 heads.

I had a Crane 214/222 HR cam (114 LSA) in my 8.6:1 low compression 400 engine in the Cruiser. Even with the 400 I always wished I went one size larger on the cam. With Dougs headers and a very decent exhaust it still sounded stock.

[65sport]

Originally Posted by lust4speed

I'm a little surprised that you wouldn't use your Crane 278 cam.

I labeled each lifter individually so that I could re-use it if I want to but I've never built a 455 before. You guys have experience and I'm certainly going to consider it now that I've heard from several of you.

My engine is a recent rebuild in regards to how very little wear on it but I've never been able to talk to the last person that ran it. A guy stored it in my friend's garage and he decided to sell it. He didn't even know it was a 455, he thought it was a 350. I actually told him but he did not raise the price.

My main concern is the rods. My machinist told me I could bring the rods with the pistons still on and he would recondition them and put on ARP bolts for $180. If I do that, I might be more willing to go with the Crane 278-2 cam.
222-234-114LS with .467-.494 lift. According to Crane this cam wants 9.5-10.75:1 CR so my 6X-4's would put me right there.

OR

I can break open the billfold, get 30 cc dish pistons use my ported 670's, buy some Eagle rods, get the thing balanced and not worry about RPM's.

What I'm gleaning from these conversations is that the 455 engine tolerates a larger cam, something I'm not experienced with.

So, thanks to you all for sharing the experience.

[65sport]

[QUOTE=lust4speed;6053442]I'm a little surprised that you wouldn't use your Crane 278 cam.

I also have a new, unused Elgin E-1221-P. It's 224-234-114 and .466-.488 lift. Was given to me with an intake I bought, just needs new lifters. I like the Crane grind better it's a little less than the Elgin.

[Jay S]

Thunderstorm alarm woke my up. So I will guess i will get to go first, lol

Crane compression ratio ranges are good for a 350 cid engine. Very accurate actually for a 350 cid engine. But not for the bigger 455. For the same compression the compressed volume is more on the 455 than the 350 (350 is about 24% smaller). Look at it this way, there is more volume in the cylinder for the overlap area of the cam on the bigger engine, 455 has more air to be diluted by the intake and exhaust mixture. It takes more overlap to effect the 455. Most cam mfg ratings are based on 350 cid, unless they say otherwise.

Elgin grind would be absorbed by the 455 too, also a small cam in a 455. Elgin is the same cam profile as the 204/214 and 214/224, just the next step up, exhuast profile on the 214/224 is the intake profile on the 224/234.

We have never rebuilt a Pontiac that did not get arp rod bolts. Something that gets done here even on a stock build.

[steve25]

Folks with a motor of under 10 to 1 comp you would be giving up a good amount of much needed low lift Exh flow by bolting up a set of stock 6X heads without at least fitting them with 1.77" Exh valves with a 30 degree back cut.

Your giving up some 22 cfm of Exh flow at peak lift as compared to the 66 casting and between .050" lift, .100" lift and .150" lift your giving up a total of 15 cfm minimum!

You don't need a duel pattern Cam to crutch up the flow ratio any more with the above rework if your keeping the Intake ports about stock.

[65sport]

Originally Posted by Jay S

Thunderstorm alarm woke my up. So I will guess i will get to go first, lol
We have never rebuilt a Pontiac that did not get arp rod bolts. Something that gets done here even on a stock build.

Agree with all you said, and appreciate the explanation on the over-lap. Knowing the why makes a person more secure in a decision.

I'll take the piston/rods out and have the bolts installed, rods honed. .

[65sport]

Originally Posted by steve25

Folks with a motor of under 10 to 1 comp you would be giving up a good amount of much needed low lift Exh flow by bolting up a set of stock 6X heads without at least fitting them with 1.77" Exh valves with a 30 degree back cut.

Your giving up some 22 cfm of Exh flow at peak lift as compared to the 66 casting and between .050" lift, .100" lift and .150" lift your giving up a total of 15 cfm minimum!

You don't need a duel pattern Cam to crutch up the flow ratio any more with the above rework if your keeping the Intake ports about stock.

Agreed, whatever heads I end up using will get the 1.77" exhaust valves.

[dmac]

Originally Posted by tc

One cylinder volume is 932 cc's. 455 cu in is 7456 cc's
116 + 932 = 1048
1048 ÷ 116 = 9.03

Not accurate, but it is how the factory specs always overstated CR in the muscle car era.

[65sport]

Originally Posted by dmac

Not accurate, but it is how the factory specs always overstated CR in the muscle car era.

So true ! My engine 71 455-325 HP was supposed to have 8.2:1 stock compression, that's with the big head gasket, stock deck, approx. 6 cc valve reliefs. In reality that would be around 7.86:1.

[65sport]

Update
Found a bare set of 6X-8's on craigslist for $40. Wasn't expecting much, but after all only $40 bucks.

Magnafluxed-good
Flatness-good
Valve guides-tight

I'm astonished at how good the condition is on these heads. I plan on taking the valves, retainers, push-rod guides and rocker arms off the #66 heads and using them. Just need to get some new springs, seals, 7/16" rocker studs and friction nuts.

I used the used the valves from the #66 heads to check the fit in the 6X-8's and remarkably good.

I got lucky.

[steve25]

Nice find no less nice price!

Machine work wise do not forget to have all the guides cut for .530" seals and then grind off the remains of the machine lip on the short turn of each Exh valve bowl then blend and polish out the bowl.

Also grind off the casting nub on the crown of each Exh port short turn.

Next gasket match each Exh port to a factory steel gasket on the top / roof only, and blend this in for 2 inches.