Because you're not taking more off one side than the other. You're taking the same amount all the way around so the stroke stays the same.

 

1 the bearing shell is thicker
3 I like the stock rods in my 455 engine is pretty stock but i think they get out of round at higher performance builds then you are left with the chinese steel rods

 

ok so the rod cap is just is closer in clearance to the rod journal. Now I wan't to open another can of worms to make sure my math is correct. So my stroke is 3.385 and Bore is 4.087 which nets me approx 355CI. I have a stock 6" connecting rod. If the rod journals are cut down to the diameter of a 350 chevy (no stones please, just trying to learn ) I can go with a 5.7" connecting rod and have a 3.685 stroke- 386 CI. is that accurate? Is it that simple?

 

The journal needs offset ground, material removed from the underside. Factory Olds cranks can go 3.6" stroke with 1.88" Honda journal, you can get 390 ci if you can bore to 4.185". Another option is the 2" small journal sbc rod which gives a 3.5" stroke and can hit 385 ci with a similar bore. Most go less on the overbore, 4.125-4.165" and hit 380 and 385 ci with easy to find sbc 400 pistons and 6" to 6.2" long sbc aftermarket rods in the 1.88" to 2" journal size. Hope this helps.

 

Very helpful.
Few questions.
1- Increasing the length of the connecting rod increases or decreases stroke?
2- When you say 1.88" Honda journal is that the size of the diameter or an actual part? I'm failing to see the honda connection.
3- To clarify (the old man was over for a visit yesterday and we were having a spirited debate) I maintained that I can use chevy connecting rods if the rod journal is cut to the correct diameter. Can they be used with a the 4.087 probe pistons? The debate was- a piston is a piston regardless of chevy or olds , you're buying a bore size.
4- Are the comp roller tip rockers worth the money in a mild build? My build is getting very expensive (which I am ok with) as long as I get ROI. in the form of power.

Thanks

 

[QUOTE=1BOSS83;796533 If the rod journals are cut down to the diameter of a 350 chevy (no stones please, just trying to learn ) I can go with a 5.7" connecting rod and have a 3.685 stroke- 386 CI. is that accurate? Is it that simple?[/QUOTE]

How do you get to that? With all due respect I think you need to quit while you're ahead.
Jmo

 

The 1.88" is just a Honda journal size with the common .927" piston pin. You can use the Probe piston with a large journal sbc rod. The crank needs ground .025" undersize and the journal widened slightly with the pin size enlarged to the Olds .980" piston pin size. Still equals 355 ci.

 

Well, I'm not going to learn if I don't ask questions. I'm not afraid of looking stupid for a moment as long as I don't remain ignorant forever. I understand the error in my thinking now with the length of the connecting rods, my math was incorrect when I was using a displacement calculator.

 

Alright, so there is no reason to monkey with the existing rods as I wont gain anything, just didn't know. My math was off.

 

Neither. The length of the rod has no effect on stroke (though if you change the stroke you will have to change the length of the rod or the height of the piston).

Stroke is determined by the throw of the crank. Stroke is the distance from the center of the rod journal when the piston's at TDC vs when it's at BDC.

If you grind the rod journal to a smaller diameter but leave its center in the exact same spot, you haven't changed the stroke. But if you offset-grind the rod journal so that the center moves further away from the crank centerline, then you've increased the throw that same amount, which in turn increases the stroke 2X that amount.

 

$455.38 purchase price from WA to PA. Summit was out of stock. Anybody ever get summit to match a competitors price?

 

I need a popcorn eating smiley......

 

Summit has good customer service. As long as you have a listed price from another site, they should match the price. I buy a lot of non Olds parts, other than Jegs, no one comes close to matching their inventory and selection.

 

Your engine builder can buy the pistons through a supplier cheaper than you can get them from Summit. Summit is great for back yard builders, but most Machinists have a supplier such as Motor State or EPWI... The more they buy the cheaper it gets. Summit does not offer volume discounts to businesses.
Too often guys want to buy their own parts instead of letting the Machinist/Builder put in the parts that he/she likes or trusts. Which is fine, but for most internals, builders develop preferences. It's probably not the first time this builder has built an engine especially if he is in business. I don't worry about other builders doing a good job. I worry about customers who don't understand what is going on trying to second guess the guy who knows what he is doing.
Seriously, how about some advice..... your builder is in business to build engines, tell him what you want to do and let him do his thing. If you are building it on the cheap, let him know. He will pick reliable components at a better price. Not everyone needs Egge or Arias or JE pistons in their daily driver. As far as Cams go, you told your builder what you want the car to do. He's no dummy, he will call his favorite cam guy and together they will put together a profile that fits your desires. You will end up happy if your Machinist/Builder is a decent reputable experienced guy.

 

The above statements aren't necessarily true. If I had a dime for every guy that's told me he was disappointed in his build for one reason or another I could change my name to Donald Trump. Too many machinists/builders simply look in a book for piston and cam specs/descriptions, not taking into account different displacements, combinations etc. All too often the customer assumes. It's your money, ask questions.

 

Exactly......in fact, it was the builder of the OP who wanted to put in pistons that would yield 7.5:1 compression, which is detailed in the earlier pages of this thread. The builder thought he could simply deck the block to get desired compression, which showed he obviously never took the time to research this build by using a simple compression ratio calculator.

 

I could see your point if we were discussing this with the builder.... but frankly, the discussion is taking place with a customer, not the builder.... we are making the assumption that the customer is clear on the build process and what rotating assembly he is buying as well as valve train parts. He has little understanding an is wishing to be educated. I don't think that telling him he needs a new builder is a good choice. I rather think that asking more questions to determine really what is going on is more helpful. It will let the builder know that he wants to learn about the process and make an educated decision. Not alienate a good builder from the customer.

 

I've never met a machinist who was doing a custom build that didn't ask questions and determine exactly what the customer wanted. Customers become unhappy when there is not VERY clear communication and expectations are not verbalized. My statements are mostly true and exceptional circumstances occur is all situations. Please, don't change your name to Donald Trump.... he's a cad

 

You bring up an excellent point. That being that it takes an educated customer to yield fruitful results. The customer does not have to be a rocket scientist (no pun intended) but has to have a basis for making good decisions with the build while working with the builder.

Unless, the customer says "here is my pile of money, I want a streetable engine that can make 350hp on the dyno"......to which case the builder says "need more piles of money to do it" or "I can start on it yesterday".

I don't know the full story, but I do know that the builder in this case said he could deck the block to get the desired compression ratio with the pistons that were selected......to which it is virtually impossible to do unless they mill the heads into "unsafe" territory, which would be after they already zero decked the block.

The customer is obviously interested in learning more about the process and the fundamentals of engine operation. It does take time to learn this stuff, it cannot be expected that a 15 minute visit with the machinist will bring someone up to speed if they have very little basis to start with.

 

No machinist in his right mind would zero deck a block for a street car without careful planning. The customer said the machinist said, we have yet to hear from the machinist himself and you are right, milling and decking for compression is an exact science, not a "thereabouts" wack job and pray for the best. Lets help this guy open a meaningful dialogue with his machinist. We will be better able to assess what this customers knowledge needs are by asking and listening....

 

I think you missed my point. Even after zero decking the block, and milling the heads .060", they would still be unable to attain the 9.67:1 compression the machinist said they will establish......and it is because of the pistons the machinist recommended, it has too big of a dish to get that compression, and from what I gathered here, the machinist did not seem to understand this fact.

Here's a quote from the OP on page 1 referring to what his machinist said:

"When I inquired about flat top pistons the engine builder said the car would run like **** with flat tops because of the poor quality of the gasoline today."

If the machinist truly did make that statement......well, then I don't know what to say except that I would not have this guy building my engine......maybe he is a good machinist, and I'd have him do my machine work, but thoughtfully planning out the build does not seem like his forte if the information the OP is giving us is in fact correct.

Did you read this whole thread? We are giving the OP lot's of advice. He is a lot smarter when it comes to building compression in a SBO. I can say for a fact we certainly saved this gentlemen from having a turd of a motor, which was the route the builder seemingly was taking him based off the information given.

 

[QUOTE=80 Rocket;799993]

Unless, the customer says "here is my pile of money, I want a streetable engine that can make 350hp on the dyno"......to which case the builder says "need more piles of money to do it" or "I can start on it yesterday".

Put ' r ' ther

 

I do understand your point. I also think that supporting communication between the builder and the customer would yield the same fruit. They both need to be on the same page. Trying to understand what the builder is trying to say in his over simplified terminology is difficult as best. He said, he said is a tough way to give advice correctly.

 

So when the builder said he could get 9.67:1 compression with those 24cc pistons......you think the problem was communication between the customer and builder?

Or when the builder said flat top pistons don't work with todays crap gas, that was a communication problem as well?

 

I will say this again differently. The machinist did not say this to you, it's what the customer heard and repeated to us. The "telephone game" has been around for years...... we shouldn't play it here.... guys are trying their darnedest to do things on their own. It a right of passage. we all want to say we did it ourselves.
Ask more questions until the customer has enough knowledge to understand what the Machinist is trying to say.....

Here is what I get from your concerned statement.. When the builder says "flat top pistons wont work with todays crap gas" I interpret that as, "If I zero deck that motor the compression ratio will be too high to run well on 91 or 92 octane with flat top pistons and small chambers".

Does that make more sense to you???? no one is right and no one is wrong... it's perception and reception.....

 

I don't know about you, but a builder should say with flat tops, and your desired compression ratio......"heres what I can do".

Why does the builder say that? Because he has a compression ratio calculator and is actually tryin to help the customer with facts. It's not that hard. I'm not even the builder and I can do that from miles away over the internet with simple math equations.

Do you have a compression ratio calculator?

Download this one and get back to me so you can help out the OP:

http://cochise.uia.net/pkelley2/DynamicCR.html

ps- your wife said its the right way to do things

 

I think you're missing Dons point as well. And I believe I mentioned, "flat top pistons" is a broad term. It seems to me the machinist should have kept his mouth shut until he really knew what he had to work with. He didn't, and exposed himself, at the very least, as uninformed on this type of build.
Imo the customer needs to find another machinist.

 

You are both correct. If the machinist actually thinks that he is incompetent. And you are basing that judgement on what the customer said.
I have an AERA calculator that works just fine for many different calculations and I know how to use them. I have even been known to apply the theory in to practice once or twice. I have micrometers, bore gauges, calipers and many other precision tools (and some antique ones that are for sale) and I use those as well.
I guess I feel the machinist is getting thrown under the bus. Is this because we choose to show prowess and make the customer feel like he can come and share his woes??? Perhaps, but without hearing from the machinist I am not willing to potentially send this guy into the machine shop loaded for bear. I'm just asking for a little more effort on the part of the well doers to be sure we are sending this guy a clear message. Buyer beware and take the time to educate yourself. Understand the basic of internal combustion engines and how they can be affected by compression, duration, overlap, long rod, short rod big bore and stroke. We can help him with that.
Oh.... And I am the wife.... Stretchmarks and all....

 

Will somebody please get the OPs machinist an account on here!


I have all those precise measuring instruments as well. I used to work for a performance machine shop. And I build my own race engines that go very fast down the dragstrip.


No, it's because the machinist has shown a lack of knowledge on these types of builds. And if the OP is giving us all false information on what the machinist really is saying, well that's his own fault and he will get what he deserves. That's usually how life works. Kinda like a reap what you sew type of thing.

However, the OP never started this thread to share any woes, he was simply looking for a cam recommendation, and we found some things that were not right.......and being the stand up citizens we are, we educated the man and pointed him in the right direction with his build.

Again, can someone please get the machinist an account over here!!!


More effort? What do we gotta do, send this guy to a tech school? Why don't you take the lead where we all failed and start educating this guy about the internal combustion engine then?


That makes sense.

 

I'll look for this poor machinist guy under your car....

I'm not sure why I try.... but I just have to stop feeding the trolls...

 

Why would you look there? He is most likely at his machine shop machining the OPs engine. Why is he doing that? Because we educated the OP on the subject of compression ratios and such, so he was able to communicate better with his builder (which communication with builder, and knowledge on the subject are both things I advocated early on in this thread). The OP is still working with the original machinist, and the OP is thankful for the knowledge he was given from us.



You tried to say we should tell the OP to communicate better with his machinist.......that's all you did (and we did that already) . Meanwhile, a few of us spent time formulating posts to help the OP on the subject matter.....and your first contribution to this thread is:

"I need a popcorn eating smiley......"

Tell me again who the troll is........

 

Here is a perfect example of what Don and Mark are referring to,
https://classicoldsmobile.com/forums...gine-woes.html
He ended up with an un-driveable 11.3 to 1 iron-headed "pump gas" engine because he relied solely on his builder to achieve his goals. Also, while engines are engines, Olds engines DO have their little quirks. I worked for a guy who built engines On Gant's NASCAR team in the 80's, been building race engines for years. But, he is a Ford guy and was unaware of some of the differences. Cams that work well in Chebbies don't always work as well on olds and Buicks. The rear drilled oil galley plug is another example that can be catastrophic if left out. ETC.

 

I hope to shout that I never encounter a builder like the one you think this guy is. If he is as bad as you say he is, it's hard to imagine how he has stayed in business for 44 years without you to correct his math.

80Rocket, you should go into business for yourself. You clearly have the desire to see things done right.

This whole conversation is PURE CONJECTURE. It's unhealthy, confrontational and counterproductive. Done.

 

Im not ready to throw that engine builder under the bus yet either. The builder did the bottom end and the customer installed the top end. Too many variables there and no diagnostic evidence of either. If the engine builder did zero deck the motor KNOWING that the customer had 64cc heads, shame on him.... but again, things need to be checked. measurements need to be taken. Careful disassembly and evidence gathering needs to been done. Even if the engine builder did zero the deck, the heads must have been clearanced in order to not smash valves into pistons. It's just not that easy to screw up. Something is amiss and more questions need to be asked.

Frankly, I don't expect anyone to see it my way, I come from a dry, sterile profession where nothing is assumed until all the facts are in. I'm trained that way. I understand that it is difficult for some people to remain neutral. And that is why I was good at what I did.

 

Thank you. I am self employed in fact.

 

speakfordadead, if you don't have anything to contribute to OP's build please stop, and start your own thread about engine builders. You are arguing with very reputable guys in Olds community whose opinion is highly respected.
Do you have any clue how many people have been pointed in a right direction by them?
It's obvious that OP's builder is not as competent as OP hoped for. He told him what he wanted and almost ended up with something he didn't want. This is not the first time CO guys are saving the day.
Not sure what you are trying to accomplish here.
Please just stop arguing and let this thread get back on track.
Thank you

 

I dont see anything wrong with him adding his point view, also very reputable men are not the words of God

 

Her point of view was criticism of their attempt to help save somebody's build, no valuable information added.
They are not word of god, but they sure proved many times that they know what they are talking about, at least when it comes to Olds engines.

1BOSS83 Good luck with your build.

 

Does anyone know what this means?

 

AMEN! 70cutty))))


Adam/OP...LOL!
How's your build going? I got all my parts for my machinist accept new rod bolts, but as soon as I get them ......off to machine shop and then all that he needs to do is install cam bearings, cut new valves in, and balance crank. I'm still trying figure out the best cam? These guys have helped me big time and I thank them for there input and I thank you for starting this thread Hopefully some of the BS above hasn't kept you from posting? Maybe this post will get you talking again and stop the arguing above...LOL!
Anyway....I can't wait to start assembly and here her purrrrrrr!!! or should I say growllllllll )))))))))
Eric M