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Discussion Starter #1
Has anyone tried comp cams pn. 51-224-4? Preliminary research tells me I may need to machine spring pockets but doesn't say whether it's a diameter or depth issue. It's going into a 67' GTO with the original 72cc combustion chamber, casting # 670 heads with ARP screw in rocker studs.
 

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IMO, that is NOT a good cam choice, for a high compression pump gas 400 engine.

Please post all your engine specs, gear ratio, & expected driving details.

Example: Cubic inch, compression ratio, rear gear ratio, what trans, all street driving, street/strip, lots of high speed highway cruising, etc.

Unless you're looking to make max hp, I don't see needing more cam than a Summit 2802, for a high CR 400.

In fact, a 2801 is probably enuff cam for most daily street duty 400's. But, there are quite a few decent cams, between the 2801 & the cam you listed.
 

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Discussion Starter #3
From the top - the carb is factory Qjet 680 advertised cfm and rejetted. Factory intake. Casting 670 heads. 400cid bored 0.030 over to 406cid. Factory rods and crank with advertised 10.5 Wiseco forged pistons. Exhausts through Hedmen full lenth headers and Flowmaster 50s
Tranny is Ford 3 spd toploader, also factory installed. Rear end is 3.55 gears. Will not see the track. She's a daily driver from late spring to early fall, and she's not babied. Running Shell 91 with STP octane boost. The cam currently in is comp cams pn 51-223-4 and in 10 yrs I've not heard any pinging or detonation.
 

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Looks like you just wanna move up 1 step, but stay with a CC XE series cam. CC recommends 995-16 springs for both cams. Those springs are rated for 1.70 installed height. Most stock length valves are said to have aprox a 1.60 installed height. That's probably why spring seat machining is recommended.

COMP Cams Catalog - Pontiac 265-455 8 cyl 1955 - 1981

https://www.amazon.com/Competition-Cams-995-16-Valve-Spring/dp/B000CEM5DY/ref=asc_df_B000CEM5DY/?tag=hyprod-20&linkCode=df0&hvadid=265987795869&hvpos=1o1&hvnetw=g&hvrand=10836921369215849751&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9025480&hvtargid=pla-624911874189&psc=1

I don't like the idea of a steep ramp cam, like the XE series, in a high CR pump gas street engine. But, if you want aprox 230° @ .050 lift, there are a couple of slower ramp cams that I'd prefer.

The Howards 410051-14 is one of 'em.

https://www.summitracing.com/parts/hrs-410051-14/overview/make/pontiac

And, an 041 clone, such as a Melling SPC-8, is another.

https://www.ebay.com/itm/Engine-Camshaft-Stock-Melling-SPC-8/292730769197?epid=76634348&hash=item44281d0f2d:g:tdUAAOSwtAtboHby

If I ran an 041 clone, I'd definitely run Rhoads lifters. They'll provide a smoother idle, more vac, & more low rpm torque, below 3000 rpm. Most 400 street guys don't like a cam this big in a street driven 400.

https://www.summitracing.com/parts/rhl-9518/overview/make/pontiac

https://www.summitracing.com/parts/rhl-9518l/overview/make/pontiac

Here are a couple of slightly smaller cams that might be a little more streetable than the 041 clone types.

https://www.summitracing.com/parts/crn-283951?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-crane-cams&gclid=Cj0KCQjwhrzLBRC3ARIsAPmhsnU0u54qydmvH3kgPclzar4EixRF9nyONKDNg0eySh9VIuf6FmIYCaIaAusEEALw_wcB

Crower seems to be real proud of their products.

https://www.summitracing.com/parts/cro-60243?cm_mmc=ppc-google-_-search-_-brands-_-keyword&gclid=Cj0KCQjw4s7qBRCzARIsAImcAxYGI6sdOmnmmmrM6BouVjZZRx6Xja7fFtin26GErOuW-yH-P0SUop0aAuxzEALw_wcB

If I did go with a steep ramp cam, it would be a Lunati Voodoo. They're similar to the CC XE cams, but close the valves more gently, where as the XE cams are said to slam the valves shut, in many cases enuff to produce a very noticeable ticking sound, which many don't like. Many also don't like the ticking sound Rhoads lifters produce.

https://www.lunatipower.com/voodoo-hydraulic-flat-tappet-cam-pontiac-v8-268-276.html

Most consider cams with 230° or more dur @ .050 lift, much better suited for a 455 than a 400.
 

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Im a fan of XE cams. I have an XE288hr-10 in my 10.5:1 zz4 stock headed 355 chevelle motor over 10 years, thousands of street miles and hundreds of track passes. Yeah its slightly different as its a roller but it screams and has a ton of torque with less cubes. (236/244).

Just put an XE268h cam in a 69’ 351w. Has a mild lope, a ton of vacuum and idles great (224/230)

I dont see any reason why a 10.5:1 400 motor wouldnt run great with an XE274h cam (230/236). Yes they have more aggressive ramp rates but properly setup they will last forever. The faster ramp rates allows the motor to have more vacuum then a similar spec cam with a slower ramp rate hence you can get away with more duration. This cam should have enough vacuum for power breaks, should idle with a great sound and good lope, and have tons of mid range power. Plus you’ve got 3:55’s... If you’re only gonna go 1 size bigger than your current cam then why bother. Go with something like this or equivalent, have some fun and make some noise.

Now this cam in a high compression 455 would not be a good choice. Also remember you’ll need a mild converter. In terms of machining the heads they make note of... I did a little research real quick and found something along the lines of using a behive spring will eliminate the need for machining the heads based off another forum thread. If you are really thinking about this cam, call comp and ask them. Also Lunati does make great cams similar to XE line.

Just dont short yourself if you’re a driver and like to beat on it. A 10.5:1 400 can take some cam.
 

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Discussion Starter #6
Thank you very much for your time and effort. My engine builder has ordered the CC 51-234-4. I will definitely run our conversation by him. What especially interested me is the valves basically slamming shut with the CC 51-224-4. Obviously not keen on that. Did talk with CC by phone and email and was told the 234 would work fine. Regarding vacuum, I have standard drums all way round so not really a big deal I think. Only external power robbers are water pump and alternator. Learned, not the hard way, last year about lifter differences in Pontiacs. All in all not so much a learning curve as a steep incline this last year.
 

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Discussion Starter #7
Satisfied with the research and especially help from BigD and went with a custom grind with specs from the '068' cam. Next up is repairing the limited slip 10 bolt.
 

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Satisfied with the research and especially help from BigD and went with a custom grind with specs from the '068' cam. Next up is repairing the limited slip 10 bolt.
"...My engine builder has ordered the CC 51-234-4..."

https://www.summitracing.com/parts/cca-51-234-4/

WOW, that's a change I wasn't expecting, from a 230° @ .050, .480 lift, single pattern, to an 068.

The Melling SPC-7 is supposed to be a close copy of an 068.

https://www.autozone.com/internal-engine/camshaft/melling-camshaft-spc-7/107135_705947_0

And the popular Summit 2801 is a cheaper & similar but higher lift version.

https://www.summitracing.com/parts/sum-2801

So, I'm just curious as to why you bought a "custom", with 068 specs. Does that mean exact 068 specs, or just something similar, but slightly different, in some way ?

I'm also curious as to the cost of this "custom". Most of the HFT customs I'm aware of cost around $200.

The 068 was a very popular Pontiac factory cam, being used in 350, 389, 400, 421, 428, & 455 engines.

Wallace Racing's Pontiac Engine Search

In a high CR 400, an 068 should have a fairly smooth idle, make good low rpm torque, and make decent power to at least 4000-4500rpm. Will probably begin to fall off some as it hits 5000 & above. But, 99+% of street driving is probably done UNDER 4000 rpm.

Very few Pontiac engine builders recommend single pattern cams for Pontiac engines, unless the exhaust ports have been extensively ported to increase their flow. Most recommend around 10° or so more intake duration than exhaust duration.
 

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Discussion Starter #9
I don't have all the specs yet but am assuming it will be slightly different than the 068. My engine builder also races and after getting 2 bent cams from Comp he went with his supplier for the race cars. Cam Motion out of Baton Rouge. Expect it will be @ $300 CAD. They were made aware of all pertinent specs, so hopefully getting the ideal cam.
 

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So here are my cam specs from Cam Motion. From what I've learned here in the forum this is a reasonable profile and LSA. If pic didn't make it please leg me know. First time sending pictires through this forum.
Well, I have to be honest and say I don't know how to read that spec sheet.

First, here is the spec for the factory "068" cam, the SAE standards used to provide the cam specs on factory cams was measured at .006" off the seat:

Pontiac "068" cam

LSA - 116
Intake Centerline - 113
Valve Overlap - 63

Intake Opens - 31 BTDC
Intake Closes - 77 ABDC
Exhaust Opens - 90 BBDC
Exhaust Closes - 32 ATDC

Intake Duration - 288
Exhaust Duration - 302

Valve lift - .406"

Here is a further explanation on cam spec by the guy who specs/grinds them:

"Re: Cam Duration: Advertised vs. .050

I always hate it when this bag of snakes gets dumped on the floor......
There is one place to rate hydraulic cams according to the SAE, the Society of Automotive Engineers, and that is at .004" ramp height. That equates to .006" valve movement with a 1.5:1 rocker, .007" with a 1.7:1. This movement allows for valve train compression, etc, and supposedly gives a .001" lift off the seat.
Companies do not all use this number, because customers are always looking for that shorter and shorter seat timing coupled with a lot of lift. But valve trains MUST follow the Laws of Physics, and there are limits to how fast a valve can be opened.

Here are some duration numbers and how they can change based on how the cam manufacturer lists their numbers:
UltraDyne Cam 272 @.0045", 266 @.006", 217 @.050", 127 @.200", .454" lift -1.5 rockers
VooDoo Cam 256 @.00?", 213 @.050", 125 @.200", .454" valve lift with 1.5
CCC 267 @.004", 259 @.006", 213 @.050", 126.4 @.200", .454" valve lift with 1.5
CCC 273 @.004", 265 @.006", 219 @.050", 132 @.200", .470" valve lift with 1.5 "


I have a Dyno 2000 engine analyzer program I like to play with and just for chuckles, made an attempt to input the numbers on your cam card. Using 10.5 compression, 750 carb, dual plane intake, big valves, good flowing exhaust. My input numbers are seat-to-seat. I cannot input any of the negative numbers, so I used the next closest whole numbers, ie "0" for the Intake and "1" for the exhaust. This also altered the LSA & Intake Centerlines slightly, but not much. What I got out of the program was miserable - no power but it had torque. Peak HP was 285 @4,000 RPM and all done at 4,500 RPM's. Peak TQ was 495 @2000 RPM's and down hill fast from there. Almost has the feel of a 455 - big TQ, low HP, but it'll be good at the lower/cruising speeds. Do you tow a 38 foot house camper? LOL

But the good news was this. I used some of those numbers to come up with a killer cam :yesnod: on my engine program (which is not 100% like many of the highly evolved dyno programs). Cam specs on the program are again set to seat-to-seat values.

LSA - 112.2
Intake Centerline - 107.2
Valve Overlap - 43.6

Intake Duration - 264
Exhaust Duration - 272

Intake lift - .443"
Exhaust lift - .442"

Intake Opens - 24.8 BTDC
Intake Closes - 59.2 ABDC
Exhaust Opens - 73.2 BBDC
Exhaust Closes - 18.8 ATDC

The RESULTS:

Peak HP - 417 @5,000 RPM's
Peak TQ - 487 @3,500 RPM's

The graph showed a nice steady power & torque line, so it was a good looking cam. In this spec, it is a big increase in HP over the original inputs, and pretty darn close on TQ at a higher RPM value.

So I am not saying your cam is a bad spec, as I honestly am not sure how to read it or how it converts to what style of cam specs I am more familiar with. So my inputs into the Dyno2000 program could be way off or, you are going to have a torque monster at low RPM's and not the HP a Pontiac engine has the potential for.

So do keep us posted on the results once you get it installed and up and running. It should be interesting and would be a great hands on comparison with the Dyno2000 results.

:thumbsup:
 

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Summary of those cam specs (rounded)

214/222
.443/.443
On a 112 LSA with a 107 ICL
 

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Discussion Starter #14
I printed off stock spec sheet that Pontiac Jim posted to compare and the negative numbers are screwy, never seen that. I'll talk to my builder tomorrow to try to better understand the numbers but man I hope your HP # is off. With that short a duration there seems to me to be a real danger of running lean as well. BTW carb is rochester qj bench tested at 695cfm and rejetted larger than stock. Will get that # tomorrow as well.
 

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Here is Cammotion's response to my question about negative numbers. Crower has a part number 60918 with similar specs. Short story is I'll try the cam and see/hear and feel it out.
OK, like I said, I am not a cam expert by any means and my Dyno2000 program is far from perfect in its determinations, but is fun to play with.

The Crower 60918 has been recommended as a good cam. I am using the Crower 60310 in my 455 build which is a solid lifter cam.

Crower specs look a little better, @.050" - Intake 288/Exhaust 298. Lift - Intake .444"/Exhaust .467". Power range 1,750 - 4,500, Redline 5,750 plus. Delivers impressive mid-range and top end power.

So give it a whirl and report back on your impressions. :thumbsup:
 

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Discussion Starter #18
This is what i pulled from crower web site. Numbers jive with the Cammotion piece. That and that you said that Crower has been recommended gives me some confidence. Will definitely pass on the experience in the forum. Thank you for your time and help. Much appreciated.
 

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It sure does look the same. But, the differences are the 1,800-5,000RPM range and it is listed as a "Smooth idle, low midrange power" which is more in line with what my dyno program showed, but the Crower site says, " Delivers impressive mid-range and top end power."

And this is why cam selection is so confusing. LOL

Hopefully we will get a first hand impression and we can decide if it is a good cam to recommend or a dud. :yesnod:
 

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I'm no cam guru, either, but I've been around the block. The most important things to consider when selecting a cam are: rear gear ratio, transmission type, and driving conditions. The choppy, low vacuum, high lift, long duration Sig Erson stick I have in my manual brake, 4 speed, tripower, header-equipped 3.36 geared '65 GTO would be a terrible choice for my automatic, 2.56-geared, four barrel, stock exhaust '67 GTO. Apples and oranges. The 068 cam in my '67 does just fine, producing plenty of low end and mid range power needed to get the car moving....and plenty of vacuum for it's power brakes. A stiff rear gear, stickshift trans, and manual brake car will tolerate a much more radical camshaft than a cruiser type car with an automatic, stock stall converter, power everything, and AC.
 
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