80 Rocket

I actually looked up the specs of that cam and it looks like it should work. Didn't mean to scare ya. I would run premium in it though.

cutlassefi

With 9.5:1 or better I'd do an Erson Viking 100H. Duration is 222/222@.050 with .478 lift on both. A little tone, great midrange and it'll bleed off a bit more cylinder pressure than that Comp cam.

1BOSS83

THAT is really helpful. Thank you. I just want to gather as much information as possible because I need to make sure I have the proper understanding before I go to a guy 30 years in the business basically telling him I don't see the vision. So what I'm hearing is if I switch to the flat top pistons I will have a significantly better motor overall? I'm going to call on Monday. This calc was done with the speed pro pistons listed before?

80 Rocket

Yes, this was done with Speed Pro pistons. I do think it is important for you to be educated on the subject as well. It makes it easier for you to communicate with your machinist and have a build that is closer, if not exactly what you want.

You can download this calculator for free (scroll to the bottom of the page):
http://cochise.uia.net/pkelley2/DynamicCR.html

olds 307 and 403

My 350 needed 55 cc cylinder heads on a 76 short block. Pistons .030" in the hole with a 14CC dish, glad you see how it effects compression, even those specs drop it a lot. Get the Probe pistons better pistons for not much more.

1BOSS83

Thank you. I am always trying to educate myself on the finer point I'm going to call on Monday and let the machinist know I want to go with the flat top pistons, if we stuff those dish pistons in there it's going to suck the life out of that motor.

1BOSS83

Also (as this is an invaluable spot to learn the nomenclature better) what exactly is the "head gasket bore"? Also- in reading the calculator you entered .030 for piston to deck clearance. Is that the measurement from the top of the piston @ TDC to the surface of the deck?

80 Rocket

Head gasket bore is the diameter of the open area of the head gasket that goes around your cylinders. All Olds head gaskets have a 4.250" bore except for the 403s that have a 4.400" bore.

Yes, you are correct on piston to deck. The .030 I used was an assumption, but most Olds I have seen with Speed Pro pistons come out to around .030.

Everything should be verified when the engine is being built so you have exact figures, especially if you are running a lot of compression (near or over 10:1). You don't want to assume you have 10:1 compression when it is really 10.6:1 because you did not take final measurements on everything.

1BOSS83

That article was really excellent thank you. If I understood the material correctly It looks like I can answer my own questions in regards to piston to deck clearance. In my proposed set up with L2320F30 pistons: the quench distance is .069 the gasket used is a .039 in thickness thus leaving .030 between the top of the piston and bottom of the head/deck. Meaning--- I could only mill the deck .030 before the piston @ TDC was flush with the deck and if I keep these dish pistons we'd have to chop the deck down quite a bit and use a razor thin gasket to achieve the CR I need with that cam, now I'm really following my potential error.

80 Rocket

That's good you're getting it. You have to remember that you want to keep the piston about .040" away from the head because of piston rock, and the possibility of some parts stretching slightly. Having the piston getting intimate with your head is a bad idea. It would be like in the movie Gremlins where you don't give that thing chicken after midnight, otherwise you got a big mess on your hands.

Now that you are following......if you use .040" as your minimum distance, you should be able to clearly see that with the dished piston, it is almost impossible to get over 9:1 compression.

Also, for small block heads, every .006" milled off equates to about 1cc taken out of the combustion chamber. I have always followed the rule of no more than .060" milled off an uncut head, but I have always erred on the safe side of that. Some say .100" and you are good. But, .060" milled would be 10cc s you can take away for your calculation. So, you would go from 69cc's to 59cc's. As you can see, with a zero decked block, and .060" milled from your heads, coupled with a .039" head gasket.....you still cannot achieve 9:1.

Now let me open up another can of worms here. If you go with the Speed Pro flat top, you are in another predicament........too much compression. You really want to be at 10:1 or less on pump gas with iron heads. Some even say 9.5:1 is the limit, but I have gone 10.3:1 and lived......as well as others.

If you zero deck, use a .039 head gasket, and do not cut the heads and keep them at 69ccs, you are a touch over 10.5:1 compression. If you have the machine shop set up your piston to deck at .020", that puts you at 10:1. Your tune better be good on this car otherwise you could have detonation issues.

Another option, that others have chimed in about, is the Probe piston. This has a 3cc dish (which alleviates the higher compression of the Speed Pro), is of better quality, and as others mentioned......they use a thinner ring pack.....which is less drag and more HP. Free HP if you just pony up the extra $100 they are over the Speed Pro varieties.

I hope you realize you will probably waste more time than you would like to admit on that compression ratio calculator. Wait til you start using the dynamic compression feature......

1BOSS83

Ha! I can't get the CR calc to load but I am looking forward to all the adjustments


Questions of course!
-If you aren't trying to bump CR, why mill the deck? Even .010?
-When you say zero the deck, you mean mill the deck down so that TDC equates to the piston aligning flush with the deck. Our best best is to be .040 "in the hole" correct?
-Assuming it is; that means it's best to err on the size of caution and consider the probe -3 dish or SP -5.8 dish with my set up?

80 Rocket

Well, you don't have to mill it, you could just touch it up to straighten it.......or leave it alone if it is fine.

Yes, zero deck means .000" piston to deck clearance, which means it will be flush.

No, the piston to head clearance is different than piston to deck. The head gasket adds distance between the piston and head at TDC. Piston to head clearance is piston to deck plus head gasket thickness.

1BOSS83

According to summit racing CR calc (for what that is worth) Probe -3dish, .039 gasket, .040 deck clearance yields 9.16. Is it better to go with a .017 gasket in this case (lets assume I'll talk myself into 500 dollar pistons LOL) ? I guess what I am wondering is what is more important; gasket thickness or deck clearance?

cutlassefi

The answer is yes, to both. Ultimately the gasket thickness is directly related to the final deck clearance.
If you're considering the Probe piston, that's a good thing. That piston with a .017 gasket would be getting a little tighter on squish as it's .013 taller than the Speed pro.

olds 307 and 403

The Probe pistons are taller as Mark said, lighter and have the modern, thin 1/16", 1/16", 3/16" ring pack. If you shop around they can be had for less than $500. With the taller compression height, 9.6 to 1 won't be hard to hit. They also both require the same .005" piston to wall clearance, don't go any amount less! Also makes sure he adds the extra clearance on the center exhaust valve guides or bad things happen.

1BOSS83

.

When you say piston to wall clearance; I am picturing the space between the piston and cylinder wall. If we are already .030 over bore does this mean we need to bore another .005?

80 Rocket

.030 over is a generic term. The Probe pistons might be 4.083" from the factory. A stock bore on a 350 is 4.057", which means .030 over is 4.087". This is something you shouldn't have to concern yourself with as long as your machine shop is competent. If they say they can bore/hone your block without the pistons in hand, tell them you want all of your stuff, pay them for the work they did, and find another shop. I am dead serious on that, there is no compromise after that.

It might end up that the pistons you get are 4.084", which means to have a .005" clearance, the bore needs to be 4.089". That is determined when the machine shop has pistons in hand, and they measure them to get the precise bore size to tailor the piston to wall clearance.

olds 307 and 403

Agree completely above. He needs pistons in hand to measure for the final bore and hone size. It is kind of like ordering bearings for the crank without seeing it, you have to measure it to know what undersize it will go to. I don't know the specs on the valve guides for sure, seems to me .0025" clearance is needed on the center exhaust guides. Please correct me on the number if wrong but people on this site have had valve stick because Chevy specs were used. Not a good thing, can cause mass destruction. We just want you to be happy with the final outcome and not have to pull it apart unessesarily. The Olds 350 really was GM's best 350, just has different specs than the sbc everybody builds.

1BOSS83

I phoned this morning and explained that I wanted to go with a different piston. He offered to look for both the Probes and Speed Pros to see if he can secure a price below MSRP (314.99/492.99 respectively). Once a decision is made on pistons and they have been delivered to the shop and measured I will inquire about the final bore/hone since we will be using a different sized piston (as an FYI the block has already been through the machine process so I'll have to inquire about wall clearance and final bore measurements along with how far in the hole the new pistons will be) when we were speaking about deck clearance he said that this is all theoretical until he has the pistons in the block which was a sign of relief. I was put in contact with another CO user who has his 350 at the same shop and explained to me that the workmanship is good but they aren't Oldsmobile motor specialists so I will have to manage the build closer than I thought. 1- It's good to know another user has had success there. 2- I will be very active on this thread 3- Shame on me for writing a check and assuming a bad *** motor was on the way without having a more intimate understanding of the actions, but thats why I am here.

thanks again,

Convertcrazed

Hey Adam, Glad to here you've got her under control So which piston did you choose? I've learned even more from this thread thanks to Mark and 80 Rocket I hope you all know that I wasn't trying to butt in on Adam's thread, just thought he was building the same motor I am and would benefit from what I'm doing? Anyway Adam, are you keeping your heads stock? I've decided to go with 442 valves instead of w-31 $$$$$(Melling v1457 and v0974) One step up from the stock non OAI valves I haven't had my heads cc'd yet(but will) My block is done+30 and my crank and rods are being cut this week....so I need to purchase parts next week. So I'm still planning on the Speed Pro flat tops, comp xe268h, comp 1441 roller tips, clevite bearings, double roller chain, felpro gaskets and heads recut for above valves.....hoping for 9.5/1 CR and 325 HP? ( but will recalc once heads are cc'd) Stock Intake and exhaust mans with duals and 650 Q carb, 342 posi rear and rebuilt th350 with B&M 2500 stall. Looking for a peppy driver..... not a drag car with rough idle and want to run on pump gas. Adam, I would love to know what your final #'s are? Thanks Everyone! Eric M

1BOSS83

Eric, good morning. I havn't heard from the machinist since Monday (we had some weather here yesterday). I'm waiting to hear on pricing for both still but it's the Speed Pros of the Probes. The heads are staying stock. Steel bridges, new valves, springs and rockers are being replaced. Rest of set up will be Performer RPM, Quick Fuel 750 OR Eddy 750 (still on fence), HEI, hedmans, xpipe, flowmaster 40s, 200-4r w/shift kit, eaton 3:73 rear and stock 2400 stall. No final numbers yet but will post as soon as I have them, Shooting for 9.5 but I will move to 9.8 if the math dictates. I've learned more in this thread than you could imagine but I digress. Eric, what are you doing for cooling....? Thanks for checking in on the build and feel free to join in the fun!

olds 307 and 403

Going to the W31 2"/1.625" valve sizes would add little cost. Just get him to use a bowl hog when he cuts the seats bigger. For cooling get a heavy duty water pump, Flowkooler or Milidon aluminum pump or an A/C heavy duty cast iron pump. The Griffin F body dominator series rad is affordable and will cool your car no problem, big dual 1.25" cores. Believe it or not the A/G body Dominator rad is too wide.

cutlassefi

Cam? And I'd do the Quick Fuel over the Edelbrock anyday.


jmo.

olds 307 and 403

Either Quickfuel Slayer series 750 or Street Demon 750, if maximum mileage is a concern. Alot of people have bog issues with the Edelbrock 750.

1BOSS83

Bog is a big concern of mine. I have a 1406 on the 307 and with the bigger accell pump and all arm adjustments I can't stop the bog at WOT. I had planned to get the needle kit and ratchet and turn until I fixed it but just took this as a sign the universe was speaking and started the 350 instead, but I digress.
- When you say "max mileage" I assume you mean MPG? I just want the best street performance in terms of fun, I rarely take this car more than 30 miles from my house.

-I spoke to the machinist today and he cannot get pricing better than summit for either piston. I thought about it all day and I'm gonna buy the probes and set the little lady on a hunt for the best internet deal (she already saved me 90 dollars on 2 car batterys this year). I mentioned it to Jim and he said "it's no problem but we will have to remeasure and maybe re hone the block" and the credit of the old pistons will help in overall price point.

Mark- I'm going x268 for camshaft. (I'm also going to sell the xe262 that was in the motor already if anybody is interested out there)

1BOSS83

http://www.buydart.com/oldsmobile-sm...8-p-15361.html

423.99 is the lowest price I can find.

cutlassefi

No problem but why, curious as to what your builder told you.

coppercutlass

You got a bog with 1406 on a 307 ? I had a 650 double pumper on a 307 all I need to do was a pump cam adjustment to fix a very minor bog . The 750 is fine for a 350. I'm running a 3310 750 vac. Secondaries holley on my 350 . No bog off the line .

1BOSS83

Had the 262 in there and he actually wanted to stick with that cam as it made power in a lower RPM. I wanted something a little more aggressive and one step up seemed like the most logical choice.

1BOSS83

Mark , that does lead me to a question I have. These heads have a 1.567 exhaust valve size and the intake is 1.880 (this is according to 442.com/faq). Those numbers are the diameter of the valves in it's seat, correct? In my head it seems that stepping up to a cam with more lift 0.490 and duration 280 on the exhaust side made more sense to compensate for a smaller valve running concurrent with a very low restriction exhaust system considering the compression ratio we are aiming for with the probes. Also, the probes are listed as "press fit" or floating style pin. Is press fit the style I want to run with considering I am using the stock connecting rods? I'm going to do some research myself because I need a more advanced understanding of duration numbers but I am sure I will have questions when I am done.

Thanks

cutlassefi

I'd use something with more off the seat time like a Comp Dual Energy or the Erson stuff. Stock sbo heads don't flow well approaching .500 so there's no hurry to get them there, especially if you're using a stock valvetrain.

Thanks.

Convertcrazed

Hey Adam, Well I bought the Speed Pro's(Summit $315 shipped) I'm all about the bottom line$$$) So I can't see spending an extra $150 on Probe for maybe 3-5hp(wild guess) and less CR...which you commented about the thin head gaskets to get back up there?...another $100 Felpro's are only $75 for whole engine kit w/head gaskets...anyway just my .02 worth. Also my machinist said no to the Melling valves, so still searching....w-31 or 442??? Any thoughts? You gotta trust your machinist Anyway Mark. with my proposed valve train(w-31 valves and comp 1441 roller tips) do you think I'll be ok with the xe268h? Still trying to figure this whole cam thing outI sure don't want to over cam or under cam? What do the Erson cams run $$ 100H that you recommend? Stock Q-jet, intake and exhaust mans w/ duals, 2500 stall and 3.42 gears Planning on some long road trips (so mileage will be a plus) Just looking for a peppy driver with a cam that most will notice Well, thank you all for the help with our builds!!!!! Eric M

1BOSS83

Morning Eric, glad to hear you are making progress. After seeing what the machinist was going to stuff in my engine I'm now 100% in Don's camp of "not every machinist is a great engine builder" and I'm differing to the experts here. I'm going probes (and believe me I'm a bottom line guy), I'm sure the speed pros are an awesome product but another 150 dollars into a 4k build is peanuts to me. I'm going Comp because its available and it's a good product, I could (and prob should) split hairs and get a custom grind but I'm getting too close to the ceiling of my price point. I'm 3:73, 2400 stall and a very aggressive/low restriction exhaust system. I'm not modifying the heads, just replacing the stock equipment. My goal is to build a 2015 version of a 1970 factory motor, the drive train/ignition/intake/exhaust are all an upgrade to factory so big HP/Torque should be no problem at all. As far as my opinion goes I'm still a student of process so I would differ to the wisdom dropped into this thread as it has served EXTREMELY valuable to me (the QandA portion of this probably netted me 100hp!).

Good luck sir!

cutlassefi

Cam and lifters is $265.00 to your door. The Viking 100H would give you strong midrange and most likely a more noticeable idle.


Thanks!!

1BOSS83

Mark, I have more some more questions please.
1- You said SBO heads don't flow as well near .500 lift so getting them there isn't a priority. I'm going to explain my line of thinking so I can find the error so bare with me because I may have a facile understanding.
According to my research on the xe268 the exhaust vale (which we identified as smaller and thus more restrictive than the intake) holds a duration of 280 degrees (opening at 74 BBDC and closing at 26 ATDC +180)= 280. Meanwhile the lift of that valve is .490

Here are the things I'm not understanding:
1)The erson you mentioned is 222/222, is that at .050 or the advertised? Also the duration I'm using for the xe 268 is 268/280 but @ .050 we are at 224/230, at .050 the numbers used to obtain the advertised duration become obsolete as duration is a measurement of a constant circle of 360 not ticking time so where can I find the measurements of valve opening/closing @.050 for an apple to apple comparison? Or is there a math step I'm missing that simplifies the process?

2) How is head flow measured? In my novice understanding I think larger lift equates to more pent up pressure/air flow able to enter (like a double door at a store vs. a single door) and the longer duration equating to that larger door being open longer and thus more people (or air in this case) being able to enter before the door slams shut. Even if the heads don't flow very well I can't understand how bigger lift +bigger duration doesn't equate to more air flow total. I understand the juxtaposition of the argument where as you can open your "door" as long and as wide as you want but if you have no customers running in than it's irrelevant. So to summerize when you said something with more "off the seat time" how is a 222/222 cam off the seat longer than a 224/230 cam @ .050? More over is .500 is the ceiling for a stock valve train/head design that isn't .490 as good as it gets?

3- Finally. According to the fact sheet this xe268 advertises 110degrees of lobe seperation. My math says intake opening at 28 degrees BTDC + exhaust opening at 74 degrees BBDC = 102 degrees total. That void of 8 degrees tells me I'm measuring wrong OR is that 8 degree difference the difference between advertised vs. .050...?

Thanks again, I really can't express how valuable this has been.

80 Rocket

He's talking @ .050. So for comparison, the Erson cam mentioned is 222/222, and the Comp cam is 224/230.

cutlassefi

Correct. And Adam when I mention off the seat time I'm talking about from .006 of tappet lift (normally referred to as "advertised"), not just the @.050.
You can call it a slow ramp cam if you like but in essence it's just a "slower" ramped cam, with more time in the lower to middle lift ranges. If you don't have real efficient ports/heads in the upper ranges then you won't gain much by yanking the valve open real quick, especially if you have the compression to support a "larger" cam.

Hope this helps!

1BOSS83

When you say .006 of lift- Is that the distance from the vavle to the seat or is that the distance the lobe on the camshaft has lifted the lifter? Also- my head plan at present is to stay stock #6. Factory ratio rockers, steel retainers will be used and hopefully I can re-use the beefier springs that are in there already but that is measurement pending. How to my heads stack up for this build? Is there something I SHOULD be reviewing/considering by am not?

cutlassefi

[QUOTE=1BOSS83;795441]is that the distance the lobe on the camshaft has lifted the lifter? [QUOTE]


Yes

1BOSS83

In regards to the crankshaft. The machinest had recommended cutting .010 from the main journals and rod journals and I have some questions about that.
1- How does cutting .010 from the diameter of the crank and rod journals NOT change the stroke length? The way I look at it is- You have a stroke of 3.385 inches. That is the travel from the top of the piston at BDC to TDC, correct? If the journals then measure 2.115 in diameter at the rod journal and 2.49 diameter on the main would that not change the overall stroke?
2-Is this a prophylactic measure or a must have in a rebuild?
3- Stock rods are being reused and am I missing any dos/don't in regards to bearing selection?

Thanks