"Stock style, improved implementation" engine build

As Lamune so wisely indicated at the beginning of his engine build discussion, I am also an engineer and come with all the stereotypical traits. Those traits, IMO, can be very useful in things like engine design in regards to attention to detail and such, but some will certainly find them overkill

The whole purpose of this engine is to use the ideas that GM had for the Buick RMW that worked well while at the same time attending to the things that could have made those ideas work a bit better. That makes this a stock style torque curve shape engine, but with higher output levels, better detonation control, and better cylinder to cylinder consistency, with improved reliability. Wagon will have a 1600rpm stall and 3.23 gear with Trutrack limited slip, on 235-60-17 touring tires. It is my retired life daily in the summer and our fun cruiser at the same time, so gets limited miles but not super low.

I am using a local, very good, mostly race engine, shop to do the machining and such that can't be done at home. Certainly not on the low cost end of the scale, but quality is worth paying for to me. It is really nice to deal with such totally knowledgeable people who always understand everything they do and say.

I got the heads back today, which was the first step in the process. I wanted to make sure they would be able to cut the heads adequately to give the most uniform chamber CCs and at my desired 60.5cc. The shop says they got them very close, with only a tenth or two variation between all 8 chambers. If I choose to a touch them up to perfect, which I may or may not, it would be easy to get them all the same.

They got a competition valve job and the guides replaced as they were all at about .002. They were brought down to .0012 with hard cast iron inserts. At the recommendation of the shop, the springs I had chosen to use to match the cam choice, were not used and a switch to LS style beehive springs, keepers, and locks was done. They say they are doing that on essentially all small block GM engines now as they see much better guide, seal, and valve life with them. Cam is fast ramp hydraulic roller, custom grind, with about .480 lift so the springs are selected to match that setup. They are in a 1.700" and give 145# on the seat and 285# open, which is about what I had chosen open but higher on the seat. I won't be doing a lot of port work beyond deflashing if there is any flash and maybe smoothing the valve boss area a bit.

I dropped the block off when I picked up the heads and we went over the work for it, which will be pretty straightforward things like any high output motor would use also. Deck to zero to .002, bore and hone with plates to fit pistons at .0012 clearance. Pistons will be bore specific. It is getting a new Scat cast crank in normal weight balance and full weight Scat forged, floating, rods, plus KB flat top two cut hyper pistons and Mahle moly full width rings at standard tension. They will be file fit when I assemble. New stock style ductile iron damper. Full balance of rotating assembly, rods, and pistons.

If new crank, and new pistons... why not stroke it?

jayoldschool wrote:

If new crank, and new pistons... why not stroke it?

I would ask the same thing. shouldn't be much difference in cost at this point for added power.

I mostly just didn't see the need to stroke it, which I think would require some notching and few other things. Not trying for max hp or anything so kind of similar to not going to a bigger cam. The good about using the stock stroke, at least on Chevies I found out (I am new to GM engine builds as was always small block Mopar), is that the most commonly found and most reasonably priced parts fit kind of into a cookie cutter formula. In this case it is stock bore and stroke (.020over), zero deck, 60.5cc heads, flattops at +7cc, and .039 head gasket equals 10.5 to 1 and .039 quench height. This is a near perfect combo for a pump gas street engine IMO, and power curve can be set from cam selection. It was a bit tough to find flattop pistons with only the two reliefs, as most seem to be 4 relief. 4 relief isn't my first choice if you are going for tight quench and high turbulence on a two valve engine.

Sounds like you're doing it right - spec'ing the combustion chamber geometry and going from there.

[You must be registered and logged in to see this link.] is a great cookbook for 383 and 396 LT1 builds.

The stock motor is coming out of my wagon soon and since it sat outside partially disassembled for several years, I'm very tempted to take the iron heads and clean up the throats, short side radius and a few other little things, make it a 355 with an appropriate cam and see what it'll make. But.. I have way too many other more interesting projects between now and then.

sherlock9c1 wrote:

Sounds like you're doing it right - spec'ing the combustion chamber geometry and going from there.

[You must be registered and logged in to see this link.] is a great cookbook for 383 and 396 LT1 builds.

The stock motor is coming out of my wagon soon and since it sat outside partially disassembled for several years, I'm very tempted to take the iron heads and clean up the throats, short side radius and a few other little things, make it a 355 with an appropriate cam and see what it'll make.  But.. I have way too many other more interesting projects between now and then.

Yep, it is very handy when there are very proven "cookie cutter" things to emulate, and then just tweak to your personal preferences and application. There are lot of them out there for various engines and brands and they usually make for more reasonable parts costs because they are higher volume of sales.

I used to start out with a plan which included CCs, deck height, quench, compression, piston style, etc and than start on all the stuff at the same time, but after a couple of times of finding out too late that the heads couldn't be angle cut or faced enough to get the CCs I wanted to match the rest of the system, I started doing the heads first so there was still time to compensate the other items to get the right end point.

This time I have the advantage of using a shop that in the old days of scraping by to feed the car habits was out of reach cost wise. I am super picky on details and this puts off a lot of engine shops and hotrodders in general. How many times have we all heard it is good enough for this use, or no need to be right on, etc etc? You would never hear that at this shop and even their street engines get very good detail work, just like their race engines. When I asked if he honed everything with torque plates and matched the bores to individual pisiton, all he said was "every engine we do". Cutting the heads on angle in either or both directions is normal for them so they got my CCs right on, even checking them as they cut to confirm.

Booster, do you have the tops of the bores chamfered for easier ring installation or do you request not?

Also, head gasket diameter - the Felpro 1074 is a 4.125" bore; you can buy custom [You must be registered and logged in to see this link.] for around $80 that are made for 4.040."  I've run the compression number and it's 0.02 or so difference which is insignificant mathematically, but does it make a difference in real life?  Or just fill with carbon?

BTW anyone wanting to dig deeper on engine building ought to check this out:
[You must be registered and logged in to see this link.]

sherlock9c1 wrote:

Booster, do you have the tops of the bores chamfered for easier ring installation or do you request not?

Also, head gasket diameter - the Felpro 1074 is a 4.125" bore; you can buy custom [You must be registered and logged in to see this link.] for around $80 that are made for 4.040."  I've run the compression number and it's 0.02 or so difference which is insignificant mathematically, but does it make a difference in real life?  Or just fill with carbon?

The norm that I have seen is a light corner break to deburr the edge, I have never requested or needed more than that. A good ring compressor is essential and using ductile iron top and second rings can minimize chances of breaking one.

Not too concerned about gasket dimension on this motor. If I was boosted or sprayed and using o-rings and receivers, the gasket needs to match them and stay close to the bore, though. As you say minimal compression change and the same on all cylinders so no real harm, I think.

bit late here but my real world experience may offer a different perspective,.
3.23 gears are better than 2.56,.   after having a lot of ratio's in my cars right up to and including 5:13's
my personal experience is this,. 3.73's, a 2800 converter with a tight stall torque ratio,. I often notice an increase in mpg over stock,. and driving experience is much nicer. The wagons will cruise up a grade at highway speed without sagging,and all without unlocking the converter and heating up the tranny
People seem to get ocd on low rpm,. economy etc,. thats fine if you live in kansas,. but its a small block chevy, not a diesel. Tuning plays a huge part in fuel economy more so than rpm ,.
I've had close to 20 B+D body's over the years,. i've modded them extensively, sometimes its been a waste of time, and other times people have told me it can't be done or it wouldn't work, and they've been quite surprised to find out i've already done it a few years earlier.
There is no substitute for cubic inches for easy driving, and going with a 1600 stall converter will choke your combo cosiderably.
carry on, blue printing any engine is the key to smooth running longevity and good power,.
Making poor financial decisions is what the car game is all about!! like $6000 engines in 2500 cars!  something i have been guilty of many times,.
Over the years tho i have learned to start at the rear end and work forward,.

DWYWYGA

phantom 309 wrote:

bit late here but my real world experience may offer a different perspective,.
3.23 gears are better than 2.56,.   after having a lot of ratio's in my cars right up to and including 5:13's
my personal experience is this,. 3.73's, a 2800 converter with a tight stall torque ratio,. I often notice an increase in mpg over stock,. and driving experience is much nicer. The wagons will cruise up a grade at highway speed without sagging,and all without unlocking the converter and heating up the tranny
People seem to get ocd on low rpm,. economy etc,. thats fine if you live in kansas,. but its a small block chevy, not a diesel. Tuning plays a huge part in fuel economy more so than rpm ,.
I've had close to 20 B+D body's over the years,. i've modded them extensively, sometimes its been a waste of time, and other times people have told me it can't be done or it wouldn't work, and they've been quite surprised to find out i've already done it a few years earlier.
There is no substitute for cubic inches for easy driving, and going with a 1600 stall converter will choke your combo cosiderably.
carry on, blue printing any engine is the key to smooth running longevity and good power,.
Making poor financial decisions is what the car game is all about!! like $6000 engines in 2500 cars!  something i have been guilty of many times,.
Over the years tho i have learned to start at the rear end and work forward,.

DWYWYGA

It all depends on what your purpose and use wants are, I think. High stall, deep gears, is going to also need a higher rpm cam, although probably not bigger heads unless you want to go over 400 hp from what I have seen in flow numbers for iron heads. That is just not for me. I have had a twin turbo 340 Mopar small block in a 1970 Challenger that I built several engines for, which the early on being higher rpm versions and the later being lower rpm versions. Had it nearly 30 years. The high rpm ones would make a bit more peak hp, but not torque, and would be quicker at the dragstrip, but the low rpm versions were far and away more fun to drive on the street and cruise in. I have had the Buick for 8 years with the 1600 and 2.56 gears with an unoptimized engine and been very happy with the range of where the power is and how it feels on the street. The new engine will have a very similar torque curve, but higher, so not much will change in the range of torque curve by rpm except it should be somewhat higher, but speed will a bit of course. The engine is the primary setter of the converter stall need as they should match, which with the 1600 still will. Lower stall converters will run much, much cooler on the street at low cruise speeds around town than high stalls. I have a tuner so I will be able to change the shift points and lockup points if I want to tweak what the tuner does when you enter a gear change.

Economy is nice but not a primary consideration aside from being interested in what it is when all is done. I am retired, no commute, salt free weather only, and have been doing 2-3K miles a year, but that will probably go up some once it all is done this spring.

I never know for sure if I will like a car, so I usually start with mechanical things to make it to my liking, as I really want a well handling car, whatever it is. Steering, suspension, brakes, etc. If it turns out I do like it, the Buick has been my favorite from the start that way, I continue after that first stuff with body and interior, then running gear. I see lots of hotrods for sale that have had $10K of custom engine and trans sitting on pallets for a decade or more, with car still half finished. They finally figure out they are in over their head and think it is worth what they have in it, when a 10+ year old engine and trans, unused or not, of unkown quality to a buyer, is probably not worth even 1/4 of what it cost. I did the Buick body and paint last winter, and this winter it is trans, engine, rear, Hellwig swaybars, and general stuff like ABS delete, power steering hose change and routing with AN fittings, add gauges.

I am relatively certain that the combo I am doing will fill my want list based on what the car has showed me in the past. Some light/moderate towing, town cruises, through the twisties country drives, cool running and reliable. The guess is that it will probably spin the tires without a brake stand, and beyond that no more initial hit is really usable, and if it doesn't that is OK to as that is low on the list of wants.

So whatever floats your boat, it is a free country although not much for old cars comes free!

you need to investigate todays stall converters more,. i feel from your comments its something you are not current on,.
The modern stall converters can be built with different stall torque ratios,
You comment regarding what you think,. runs contrary to what i am telling you from experience,. a 2800 stall converter with a tight stall to torque ratio is very easy on the street,. it does not act like the old style loose converters that sound like an old gm flyer revving up to go anywhere.
your comment regarding larger cam and heads and 400 hp to match the converter is also twaddle,. a stock engine will rev easily to 5500 rpm,. and a stock motor with bolt ons performs exceptionally well without the need for much camshaft,. You are not blazing a new trail,. and i don't think you've researched enough yet to be making sweeping comments,.
You are constantly pushing your twin turbo as a certificate of expertise,.
It is no where near the combo you are attempting to build, in any shape or form,.
One of yhe quickest wagon ever was naturally aspirated 350 lt1 had a baby cam in it, about 100 hrs on the aluminum heads, this was over 10 yrs ago, and the car now has an LS7 in it,.
There are people like my self who have been doing b body's for over 20 years,. that was a 2200 rpm right out of the GM parts bin for about $100 back then.



You can always tell an engineer,. but you can't tell them much.

Good luck,.i'm sure it will turn out to be exactly what you want,. and if it doesn't i'm sure you'll be the only one to know.
As i stated before my opinion is irrelevant,.carry on!

ps,..for shits and giggles perhaps read up on the S10 converter swap info from 20 yrs ago,.
2200 rpm for $100 right out of the GM parts bin.