[ponyakr]

I don't have a dog in this hunt. But, I'm always interested in the cam threads. Sometimes they go on for a LONG time. And they sometimes seem to get quite heated, with guys disagreeing on cam specs, especially the LSA.

For HFT street cams, just as some prefer Crower, I've noticed that well respected Pontiac engine builder Paul Carter prefers & recommends Lunati Voodoo cams. And he has done LOTS of engine builds & dyno testing.

Also, I remember one very well known Pontiac engine builder who recommended CC XE series cams for most of his builds, which many here really badmouth. This particular builder has since "fallen from grace", with most of the Pontiac community.

There are several here who recommend an 068 cam for LOTS of different street builds. I assume the Melling SPC-7 is the most popular 068 clone. The Meliing SPC-8 is a popular 041 clone. So, I assume the Melling cams are OK.

Lots of others have used & recommend Summit cams. So, I suppose they are OK, too. I don't recall reading that any one brand uses cam blanks that are better than those that all other brands use.

Bottom line is: I can't see that any one particular brand of cam is better than all others. But, that's just my opinion. And I'm a nobody. Everybody is entitled to their own opinion.

[TransAm 474]

Originally Posted by Cliff R

"I've never used a Crower cam. Just wondering if they are really so much better, in some way, that they are worth the price difference, over another brand with similar specs."

I'll answer your question with a real World example.

Recently we helped a customer with his 400 engine build. Ported #62's, low 10's for compression, iron intake, Q-jet, TH350, one of our custom built converters, 3.73 gears. He wanted to run pump gas, good street manners and run well at the track with DOT's, car is a 1968 Firebird..

I recommended the Crower 60243 cam, Harland Sharp high ratio rockers and Rhoads lifters.

The engine idles nearly smooth, just a slight "attitude" at idle, strong power off idle, drives good on the street, very mild at a glance.

At the track....and this is NOT a typo....it runs high 11's over 114mph! Nothing really fancy going on anyplace, just a good solid 400 pump gas engine build using iron heads and a stock intake/carb/distributor.

He did have the heads professionally ported, and the block zero decked with aftermarket forged rods/pistons.

The Crower cams work, been using them for quite a while. I like them because they have a lot of seat timing for the .050" numbers, wide LSA, ramps aren't overly aggressive, very little spring pressure over stock required, and they make the dyno and track numbers we look for in these engines.....Cliff

Cliff, after reading this, and how mild it sounds like the 60243 is in this particular 400, maybe we should be looking at it instead of the 60916 Lol. I was just trying to be a bit conservative, because I want to make sure I dont install something that is a bit too big for the customer, since this is a basically stock restoration build. He will want to stick with a basically stock converter as well, maybe 2000 stall at max. The 60243 with Rhodes would probably work even better, but I'm not certain that he would like the tick of those either.

[Lee]

I'm missing something here, I guess. What exactly is broken with this engine?

From what I've read, the owner is just going to cruise in it. If it doesn't NEED a rebuild, then I'd leave the block alone, and reuse the rods & pistons. Maybe stick a 744 type cam in it, like a Howard's 417251-15, and slide in a quality torque converter with 2200-2400 stall.

[ponyakr]

"...744 type cam in it, like a Howard's 417251-15..."

https://www.summitracing.com/parts/h...RoClv8QAvD_BwE

I assume the Melling SPC-3 is exactly the same cam, probably made by the same company. Anybody know, for sure ? I know that sometimes the same cam will show slightly different specs, depending on the brand. But, I reckin some brands grind their own version, with slightly different specs.

https://www.ebay.com/itm/Engine-Cams...5.c10#viTabs_0

Lunati changed the specs of their version quite a bit.

https://www.lunatipower.com/factory-...8-301-313.html

Howards also changed the specs of their version of the 041, quite a bit.

https://www.summitracing.com/parts/h...w/make/pontiac

Would be very interesting, at least to me, to some way find out EXACTLY how much difference there is in performance, of some of these very similar cams. But, as I've said before, that won't happen 'til I win a big lottery. Til then, I suppose we'll just have to rely on how a cam performs in a particular build, as reported by owners, builders, dyno results, or drag strip results.

[TransAm 474]

Originally Posted by Lee

I'm missing something here, I guess. What exactly is broken with this engine?

From what I've read, the owner is just going to cruise in it. If it doesn't NEED a rebuild, then I'd leave the block alone, and reuse the rods & pistons. Maybe stick a 744 type cam in it, like a Howard's 417251-15, and slide in a quality torque converter with 2200-2400 stall.

Lee, he told me he wanted us to go through it, and would like to upgrade it some internally, for a little better power, while remaining numbers matching and stock heads on the outside, but we had no idea (or him either) that it had 8 eyebrow pistons in it and .040" in the hole until we tore it down. So naturally I would like to do this correctly, with the right parts while we are building it, but I will just have to see if he gives us the go ahead to do it.

[Cliff R]

Go back to my early response.

CC the heads and compute the true static compression ratio. Most #48's and 12's that I've used here had pretty small chambers in them.

Once you determine what the compression ratio is going to be, then you can proceed with a cam choice.

Folks who make statements about bigger cams not being street friendly are NOT well experienced with picking them for the CID and static compression ratio.

A 400 (for example) with 6X-8 heads on it will LOVE a 2800 or a 204/214/112 "RV" cam, or even a 256XE (if you like really pulling some power in early). The same engine with 9 to 1 compression woln't like either one of those cams much, and run much better with the larger 214/224/112 or something close to it

BOTH engines will idle about the same, similar street manners, but the one with the larger cam will make more upper mid-range and top end power.

Kick the compression up another full point or so, and the 214/224 cams become to small (dynamic compression too high for pump fuel). They will like and run fine with a cam with about 10 more degrees duration. Have done gobs of engines here, and not just Pontiac's.

One of my favorite builds is to take a 1987-up 350 roller cam block and top it with Dart Sportsman, Iron Eagle, or very well prepared SBC heads with at least 170cc intake runners and small/efficient combustion chambers, plus very tight quench. Install the Speed Pro CS-179R camshaft (327/350hp clone) with 1.6 rockers or the LT4 "Hot" HR cam. I like to see at least 10.2 to 1 compression, 10.4-10.6 even better.

That little combo will rip your head off, plus relatively smooth idle, strong low end power, and excellent street manners. With correct timing/fuel curves perfectly fine on currently available pump fuel. Depending on the heads/cam combo you'll end up around 385-435hp, smooth/broad/flat torque curve, and a really nice street SBC engine.

A Pontiac isn't much different, applying the same techniques, tight quench, decent flowing heads, optimum compression ratio, well chosen cam they make great power and fine on pump gas as well.

[Stan Weiss]

Originally Posted by TAQuest

I think you will be in the 10.5 range.
For pump gas I would like to be in the 9.5 to 9.75 range.
If the customer wants the 12's then they want the 12's.
If it detonates on pump gas you could tell them why and give them a plan B with the other heads I recced.
They would work fine with everything else you suggested.

Or if when everything is measured before assemble, the CR is a little to high he could have a small dish milled into the pistons so the customer could still use his 12 heads.

Stan

[TAQuest]

Originally Posted by Stan Weiss

Or if when everything is measured before assemble, the CR is a little to high he could have a small dish milled into the pistons so the customer could still use his 12 heads.

Stan

Thanks sounds like a winner.

[Formulajones]

Originally Posted by TransAm 474

Thanks guys, but it is a must to retain the Numbers Matching 12 heads, so we are going to talk with the customer and see what he is willing to do to get this built correctly. I'm thinking of doing a set of the 5140 rods, a set of SpeedPro l2262 flat top pistons, and having a little taken off the deck to get the piston to around .005" in the hole, and use the Felpro 1016 .039" head gaskets, that should put it around .044" quench. I'm not exactly sure what compression it would have, but I would think it should have close to 10-1 or maybe a fuzz over? I'll know exactly what it is after the heads are cc'd. We then would use the Crower 60916 camshaft and convert it to an adjustable valvetrain. We will get a carb kit and Jets/Rods from Cliff for the numbers matching 7040270 qjet. This is what our plan is, depending on what the customer will allow us to do with it.

That right there sounds like a solid little engine. Should come in very low 10's for compression, tight quench, and the cam combo should work well with pump gas, the quench helps. It'll be a strong runner. If you decide on the 243, I'd use that with the bleed down lifters in a 400, as long as the owner doesn't mind a pinch of valve train noise, hardly a big deal.

[Formulajones]

Originally Posted by ponyakr

There are several here who recommend an 068 cam for LOTS of different street builds. I assume the Melling SPC-7 is the most popular 068 clone. The Meliing SPC-8 is a popular 041 clone. So, I assume the Melling cams are OK.

I only use the 068 because of rules and wanted to see how quick I could make the car go under that package. I don't necessarily recommend it. Matter of fact I was only suggesting it for this build early on because there was talk of keeping the non adjustable valvetrain and leaving the rest of the engine alone with it's pistons sunk in the bores.

Now that the owner seems willing to do this right, all bets are off, I'd ditch the 068 idea all together

And yes the Melling cams are excellent pieces (what I've used in 2 engines) as they seem to measure much closer to factory specs, and is also the popular brand to run for many of the PS guys just for that reason (least the ones that are following the rules ) Some of the other copies seem to measure a pinch short on lift and/or duration.

[unruhjonny]

incase this helps the OP or his client, I did some quick calcs;
I used a nominal 69cc for the #12 heads - this needs to be verified, but I should be close;
I calculated these with a 0.030" overbore;
I used piston valve relief from Jegs listings of speed-pro (formerly TRW) pistons;
I used the compressed thickness for the two head gaskets;
I used the smaller of the two bore diameters for the two head gaskets.

Going with any more of an overbore, will creep the compression up.

Hopefully the jpg's load up to be readable.

[Stan Weiss]

Originally Posted by unruhjonny

incase this helps the OP or his client, I did some quick calcs;
I used a nominal 69cc for the #12 heads - this needs to be verified, but I should be close;
I calculated these with a 0.030" overbore;
I used piston valve relief from Jegs listings of speed-pro (formerly TRW) pistons;
I used the compressed thickness for the two head gaskets;
I used the smaller of the two bore diameters for the two head gaskets.

Going with any more of an overbore, will creep the compression up.

Hopefully the jpg's load up to be readable.

Increasing the deck height while reducing CR can cause other problems. Leave the deck height @ 0.005" and mill the pistons so that the valve reliefs and dish total 13.4 cc's and you will have 10.0:1 CR

Stan

[unruhjonny]

/\ you may be correct, but iirc Pontiac built them about 0.040" down the hole;
So I show theoretical compression numbers at 0.005" increments from 0.005" all the way through 0.040".

I also believe that the readily available head gaskets compress to about the same as OEM head gaskets;
I would wager that when the Royal cars were set up, that 99% of the time only a thinner head gasket was used - which left the slugs 0.040" down the hole.

Is there any difference from pistons down 0.005" and a 0.040" compressed head gasket versus an engine with the slugs 0.040" down the hole and a 0.005" head gasket?

I have understood that it's all the same - the combustion chamber surface is still 0.045" from the piston tops;
The only variable might be the head gasket inside diameter, and where it is in relation to the piston/combustion chamber.

[Stan Weiss]

Originally Posted by unruhjonny

/\ you may be correct, but iirc Pontiac built them about 0.040" down the hole;
So I show theoretical compression numbers at 0.005" increments from 0.005" all the way through 0.040".

I also believe that the readily available head gaskets compress to about the same as OEM head gaskets;
I would wager that when the Royal cars were set up, that 99% of the time only a thinner head gasket was used - which left the slugs 0.040" down the hole.

Is there any difference from pistons down 0.005" and a 0.040" compressed head gasket versus an engine with the slugs 0.040" down the hole and a 0.005" head gasket?

I have understood that it's all the same - the combustion chamber surface is still 0.045" from the piston tops;
The only variable might be the head gasket inside diameter, and where it is in relation to the piston/combustion chamber.

Not very much. But we are talking about 0.038" and 0.040 down.

Originally Posted by Cliff R

Go back to my early response.

CC the heads and compute the true static compression ratio. Most #48's and 12's that I've used here had pretty small chambers in them.

Once you determine what the compression ratio is going to be, then you can proceed with a cam choice.

Folks who make statements about bigger cams not being street friendly are NOT well experienced with picking them for the CID and static compression ratio.

A 400 (for example) with 6X-8 heads on it will LOVE a 2800 or a 204/214/112 "RV" cam, or even a 256XE (if you like really pulling some power in early). The same engine with 9 to 1 compression woln't like either one of those cams much, and run much better with the larger 214/224/112 or something close to it

BOTH engines will idle about the same, similar street manners, but the one with the larger cam will make more upper mid-range and top end power.

Kick the compression up another full point or so, and the 214/224 cams become to small (dynamic compression too high for pump fuel). They will like and run fine with a cam with about 10 more degrees duration. Have done gobs of engines here, and not just Pontiac's.

One of my favorite builds is to take a 1987-up 350 roller cam block and top it with Dart Sportsman, Iron Eagle, or very well prepared SBC heads with at least 170cc intake runners and small/efficient combustion chambers, plus very tight quench. Install the Speed Pro CS-179R camshaft (327/350hp clone) with 1.6 rockers or the LT4 "Hot" HR cam. I like to see at least 10.2 to 1 compression, 10.4-10.6 even better.

That little combo will rip your head off, plus relatively smooth idle, strong low end power, and excellent street manners. With correct timing/fuel curves perfectly fine on currently available pump fuel. Depending on the heads/cam combo you'll end up around 385-435hp, smooth/broad/flat torque curve, and a really nice street SBC engine.

A Pontiac isn't much different, applying the same techniques, tight quench, decent flowing heads, optimum compression ratio, well chosen cam they make great power and fine on pump gas as well.

I am with Cliff.

Stan

[scott70]

Originally Posted by unruhjonny

/\ you may be correct, but iirc Pontiac built them about 0.040" down the hole;
So I show theoretical compression numbers at 0.005" increments from 0.005" all the way through 0.040".

I also believe that the readily available head gaskets compress to about the same as OEM head gaskets;
I would wager that when the Royal cars were set up, that 99% of the time only a thinner head gasket was used - which left the slugs 0.040" down the hole.

Is there any difference from pistons down 0.005" and a 0.040" compressed head gasket versus an engine with the slugs 0.040" down the hole and a 0.005" head gasket?

I have understood that it's all the same - the combustion chamber surface is still 0.045" from the piston tops;
The only variable might be the head gasket inside diameter, and where it is in relation to the piston/combustion chamber.

I thought I remembered reading somewheres that the average Pontiac engine from the factory what's about .020 in the hole? also when the Piston is in the hole the cylinder wall becomes part of the combustion chamber which can cause overheating and other undesirables.

[scott70]

Originally Posted by TransAm 474

Lee, he told me he wanted us to go through it, and would like to upgrade it some internally, for a little better power, while remaining numbers matching and stock heads on the outside, but we had no idea (or him either) that it had 8 eyebrow pistons in it and .040" in the hole until we tore it down. So naturally I would like to do this correctly, with the right parts while we are building it, but I will just have to see if he gives us the go ahead to do it.

My game plan was also the same when I did the engine in my GTO. Original block,heads ,intake and carb so it looks stock on the outside but get the internals upgraded into where you want them as far as quality and specs. Get rid of those cheap Pistons and put some quality ones in with a better compression height so it's closer to zero deck. If compression calculates out a little too high for you then like was said you can get a slightly dish piston. You can always shoot for about 9.5-1 and pick a cam that goes with your combo.

[72projectbird]

Originally Posted by unruhjonny

Over the years, I have had people repeatedly say that me that my 1970 YZ RAIII was too much compresssion for pump gas, but I was able to pull it off.
I am not sure how far down the hole my TRW's were, but when I pulled it apart to freshen (I had the deck milled for good measure), it was already at 0.030 over.
I had it brought to 0.040 over.
I still have stock rods with ARP bolts, when I pulled it apart, I found a 067 cam was in there(!?), and I opted to replace it with a 744 (I had an M22 behind it).

Formulajones is running his car's original 1970 YZ RAIII, with exactly what you hope your customer to allow you to do, and he is running pump gas.

It can be done.

Good luck, and please keep us posted!
(If the customer ok's everything, maybe you can share a couple pictures of his car too!?)

As long as everything is dialed in, you can run a high compression iron headed Pontiac on pump gas.

There's a lot of individuals who feel like their Pontiac needs to be a low compression turtle to be streetable, but it's not really the case.

[tom s]

The amount of CR all being equal can really change depending on where you live and the quality of true buy anywhere pump gas.Out here in SoCal the quality sucks!Our 91 piss gas is hard pressed to work well with iron heads at 9.5.Really hot days,bumper to bumper traffic can be a deal breaker.FWIW,Tom

[TransAm 474]

Originally Posted by tom s

The amount of CR all being equal can really change depending on where you live and the quality of true buy anywhere pump gas.Out here in SoCal the quality sucks!Our 91 piss gas is hard pressed to work well with iron heads at 9.5.Really hot days,bumper to bumper traffic can be a deal breaker.FWIW,Tom

We are located in S.W. Missouri. Most of our stations have "alcohol free" 91 octane, and even a few still have 93 octane, although I wouldn't want to rely on them to always have it Lol

[TransAm 474]

Ok, we got the go ahead from the owner to do whatever we had to do to build it to where it is correct, while maintaining a reasonable budget. So, this is what we are thinking...

Stock YZ 400 block +.030 4.150" bore
Block Zero Decked
Stock N crank
Eagle 5140 forged rods 7/16" ARP capscrews
Speedpro L2262 Flat Tops
Sealed Power E299K Moly rings
Stock R.A. III #12 Heads(not sure of chamber volume yet, waiting on tool to cc them)
Ferrea F5143/F5144 Stainless valves
We will have hardened seats put in the heads
Compression "probably" 10-10.5-1 area(depending on what the chambers measure)
Felpro 1016 .039 gaskets for .039" quench
Summit 2802 Camshft or Crower 60916 depending on what works best with pump fuel with whatever final compression figures out to be, right now leaning towards 2802
Crower 68404 springs
Hylift-Johnson lifters from Paul K.
Stock rockers with adjustable valvetrain
Stock 1970 cast iron intake
Stock RA III exhaust manifolds
Have the distributor recurved by somebody to limit total advance
Original 7040270 RA III Qjet with Cliffs parts and recipe


Right now, the camshaft is what we are most concerned with getting right, so that it doesn't give problems with running pump fuel for the customer. I'm awaiting a head cc kit to measure the chamber volume, so we can get a close idea of what it will be, before we make a final decision on the camshaft. Ive researched this a bunch here the last couple days, and at this time, we are leaning towards the Summit 2802, it seem like it has great reputation for working with high compression in a pump has 400. Its definetly budget friendly at $76, but in the end, we want the camshaft that will work best for the combination, while still being compatible with pump gas.