N/A 4.1 builds?

jdpolzin

Well-Known Member
Joined
Dec 5, 2004
I've been searching for some good reading on a production 4.1 build but haven't really come up with anything yet. Any good reads out there? I'm curious on what pistons people use with stock rods and N/A cam choices to work with higher compression pistons. My next build is going to be an N/A 4.1 for a 65 Skylark to replace the original 225. It'll need to run on pump gas and will be non CCC. Planning to run a mild build CZF 200r4 with 3:73 rear gear. Not wanting anything crazy but I'd like to get the most out of the motor.
 
When you say you'd like to get the most out of the motor what do you mean exactly? A .040" over 4.1 is similar in cylinder size to a 350 chevy. What works on one will work on the other. Head flow is very limited with production heads. 200hp would be a good goal for an 9:1 engine. 225hp would be a high goal that would be more attainable with higher CR and better valvetrain components. The cam matters a lot for peak power. Having a good usable power band would be most sensible. 3.73 is probably ok with most of the smaller emissions type cams


BPE2013@hotmail.com
 
Well mainly looking for piston possibilities. I know I can use Chevy pistons but will that require a custom rod? I built enough motors to know that everything isn't cut and dry as far as components but how about head gaskets? Valve clearance on pistons at what max lift etc. Wondering if someone's already done one that can give some specifics. I'll be using ported irons. Needs to be as budget friendly as possible. I'll be trying to make it look as close to original as the 225 so stock 4.1 intake and manifolds will be used. I'm hoping for 9.5 compression. I know there aren't many options for head gaskets aside from felpros and cometics and I know the cometics will be thinner than felpros but felpros are more cost effective.
 
Another note would be that this is going to be a driver car and will be driven on the power tour yearly once complete. That's why I'm wanting a 3:73 matched up to a monte SS trans. I'll probably be using a stock d5 with the combo as well. Can choice is going to need to match those parts for more mid range power over high rpm power.
 
Trans will be a very basic rebuild. No high dollar parts, only basic parts to help make it last.
 
You won't have enough gear or engine to have to worry about running out of lift since you'll be dealing with small lobes. I've ran higher CR with a 3.8 and had plenty of piston to valve clearance. 46cc heads require a dish no matter what to be under 10:1. Id build it with long intake runners and small hyd roller just like the 3800 engines. Id use steeper gears if it was my car for sure. 32% drop in OD is a lot. Even cruising with 4.56 it's about the same as 3.23 rear in OD. That will make it a lot of fun to drive.


BPE2013@hotmail.com
 
I've got a 4.1L build which is almost done but a bit more than you are looking for. I will talk in generalities of things I know or have learned. Bore the block to .035 over and you have a 4" bore. This will allow a huge selection of piston ring packages. The pistons will almost for sure need to be custom. Believe me, it will be the most cost effective way in the long run. Been there have the very expensive T-shirt. Ported irons will work but they will leave some performance on the table compared to a set of aftermarket heads. Same for a stock intake manifold. With a build on the milder side it will perform well but it won't be a barn burner. Don't be afraid of carb cfm. Get a bigger carb than you think you need and it should be good. For yours a Q-jet will probably be the choice so shoot for one in the 600 to 750 range. The bigger carb work better with no downside I can detect. This will not be budget friendly, a Buick V6 done right isn't cheep but it is really cool. Select all the parts first, have the deck height figured out and THEN have the pistons built. You can get them perfect this way and the engine can be optimized as much as possible. For a cam I think I would be somewhere near a 224 at .050 lift. There is a ton of room for a big lift cam as long as the heads are set-up for it. Custom pistons help here too. I would for sure go roller. Oh, almost forgot, this will not be cheep.

This is the Cliff's notes version of the thousands I have spent on building my N/A 4.1. ek02 has builds closer to your goals so maybe he will chime in. Hopefuly this will help a little.
 
Oh yea, gear the wee out of the car. I have 4.30 gears, 26" tall tire and about 2500 pound car. It was quick-ish with a fairly stock build but certainly nothing to get really excited about.
 
What trans are you running and hows it do for mileage? Also, where would I get a custom set of pistons made? Are you using a stock rod with a Chevy piston?


One other thing, whenever I play with gearing on a 200r4, shift points seem to be way off. I know I can adjust governor weights to make it right but I'd rather not do that. This is the reason for choosing the CZF and 3:73 combo. But, if it needs to be up there to keep the RPM's in range, that's ok with me. Just rather not have to hassle with the trans much. With the taller gear, how's it shift through the gears before OD kicks in during in town driving? Id imagine it wants to shift quick?
 
Anybody know what rears ends work in a 65 Skylark? Or, anybody know what size rear is in a 65? I know its got a 2 speed glide so it's going to be a granny gear but I don't know what size rear end it is.
 
flat out for that size car your gonna hate an NA v6. It may have been fine when it was built and speed limits were 55mph... but times have changed.

Fuzzy has tons poured into his machine to get where he is at. There is simply no room to even mention budget when trying to make any kind of power and be NA.

You need compression......... every darn point you can literally get. so throw pump gas concept out of the window. 225 horse power in a 3800lb car will be totally lame.

All of us who have gone down the NA route at some point in time had small light bodys. in the end, all of us spent considerable money moving up from the lack luster performance of a build your describing exactly. Fuzzy went for extreme buick NA, EK02 Went for cubed Buick NA, and I went screw it and moved to turbo.

so dont waste a dime on trying. you will be dissapointed. other guys who has come in here and asked the same question, few have actually done it, and more have said i should have gone turbo in the first place.

Just speaking from experiance.

you want bang for buck? build a cheap LC2 long block and give her the blow thru. problem solved, all parts off the shelf, and reasonable cost to boot.

do the research...... besides Brian, Fuzzy, EK02, Myself, who else has successfully touted any results from NA... That alone should be your deciding factor.

Im not trying to be a dick, or sound mean, or any of that... 100% love here... but I dont want you to make the mistake many of us had. We only do what we do now because were all trying to prove some kind of point. a Point only madmen and crazy people attempt.
 
Well, since AJ brought it up, my combo is almost 100% custom. I have a stock block but it is partially filled, Oliver 6" rods, full custom 13:1 pistons, a solid roller cam which is 260 @ .050 and about 630 lift with 1.6 roller rockers, aluminum heads, TH-350 trans with a 5200 stall (yes, for real) and what is fuel mileage? I can't even fathom what I have spent on this engine. My probably very low guess is 8 grand and this includes some parts I originally got for free and others for a complete steal. A set of aluminum M&A heads with valve covers for $250 bucks? Off the bottle I might make 400 HP. There was really nothing left to do to this engine and still keep it N/A. I don't think I left anything on the table. Now, even a mild 109 based turbo engine can make 400HP. My GN at 13 psi boost made almost 400 to the ground. Like I stated earlier this is not a cheep project. Be prepared.
 
I guess I should have explained the car a little more to give you guys a little better idea of what I'm doing.

This car was bought new by my great grampa and now my grampa has it. It's a very low mileage car. My grampa and I spent a lot of time together making this car driveable, and getting it cleaned up. My grampa drove this car from IL to New Hampshire to go to a Pharmacy, which used to be the dealership that this car was old originally. Took a picture. Then he drove it all the way back home.

My grampa is not in any real condition to work on the car or really even drive it any longer. When he was more mobile, all he wanted was a trophy from a car show. He never got it. This car is a 225ci v6, glide, granny gear rear. My grampa also told me stories of when he was younger. Him and his buddies used to have straight sixes and they would split the manifold and run "true duals" because it sounded cool. Well when he was too old for his motorcycle, he shipped it down to Florida to my Uncle, who then trashed it. This bike was my grampas baby. My grampa drove all the way to Florida because he was pissed and brought the bike up here and gave it to me. It was too far gone though. I talked with my gramma and sold he bike so I could take his Buick in to have dual exhaust and turbo mufflers put on it. I parked it back in his garage and he never knew it was gone. Then one day I got a phone call from him and he was SOOOOOOOOOO PUMMMPPPPED!!!!!!! He said it brought him back to his high school days. The next year, I bought a set of 14" Buick ralleys from another board member here. My grampas car had white walls and some crappy looking center caps on it. So I put new tires on the ralleys and put them on his car without him knowing it. Well this didn't make him happy when he saw it. "How can I run in an Original Restored class with these rims on the car?" "Put the other wheels back on the damn thing!!!" Well I assured him that these are period correct and he'll like them once he goes to the show, which was a Buick only event. Well, when him and my gramma got there, he noticed that all the 64-65's had these same ralleys and he thought it was cool!

So, back to the motor. I'm not looking to make 300HP. I'm not looking to make 200HP. I'm looking to keep the engine bay as close to original as possible by looking at it with a naked eye. I don't want a V8 and wont ever be putting a V8 into this car, once it's handed down to me. I just want to put a 4.1 in it to help a little and while I'm in there, do as much possible to the 4.1 as I can as far as pistons, heads, and cam. I'll more than likely save the turbo crank out of the block for a turbo build and use an NA crank. If I need to get custom pistons, I'll do that but I'd like to know my options there. I do need it to be pump gas friendly. I'd like the OD so I can drive it across the country to the same pharmacy he did. I just want to do this simply. I don't care about making a bunch of HP. I know it would be easier to put a Chebby V8 in it. That's not the goal. I just want to know what pistons will net me a 9.5:1 ratio? What rods will I need or do they make a set of pistons for a stock rod? What cam and what specs would work? Things like that.

I'd like to win him that trophy he never got.
 
hmm... ok i see what your after.

custom pistons will be your best bet for this instance. simply because anything off the shlef for the 4.1 wont be in the compression area your looking for. Id consult with Earl Brown or Mike Licht to see if they have there 4.1 piston program running yet. keep it on stock rods, rarely hear of failure and might as well keep the oddball/ custom stuff to a minimum.

cam im not to sure about... ive never cammed an NA motor looking for good drivablity charcteristics rather then max power, I had a bunch of good luck back in the day with plain ol comp cams 268H but there are much more modern grinds available. Id consult with Brian and pay for his time to set you up right to maximize what your doing if you want every ounce of power to be squeezed out.

other then that, do the oiling mods you would for a turbo motor.

with a good set of pistons, proper cam like Brian says, 225-250 isnt too far out and fairly resonable for a daily driven style machine. but anything past that... its a huge uphill battle.
 
Are there any companies out there with NA Buick cams? I remember back in the day I had an old Jim Ruggles cam for an NA set up but I don't remember much about it.
 
hmm... ok i see what your after.

custom pistons will be your best bet for this instance. simply because anything off the shlef for the 4.1 wont be in the compression area your looking for. Id consult with Earl Brown or Mike Licht to see if they have there 4.1 piston program running yet. keep it on stock rods, rarely hear of failure and might as well keep the oddball/ custom stuff to a minimum.

cam im not to sure about... ive never cammed an NA motor looking for good drivablity charcteristics rather then max power, I had a bunch of good luck back in the day with plain ol comp cams 268H but there are much more modern grinds available. Id consult with Brian and pay for his time to set you up right to maximize what your doing if you want every ounce of power to be squeezed out.

other then that, do the oiling mods you would for a turbo motor.

with a good set of pistons, proper cam like Brian says, 225-250 isnt too far out and fairly resonable for a daily driven style machine. but anything past that... its a huge uphill battle.
225-250 is going to take a lot of rpm. Rpm will require duration and more overlap which won't be good for his gearing. He's not looking to spend a lot on the valve train and heads. 180-200hp with typical small hyd roller lobes is what I'd expect. Torque will be higher than hp


BPE2013@hotmail.com
 
Tell you what Jeremy, I've got a Schneider cam you can have if you pay the shipping. It's new in the box. Lobe separation is 110, lift is .450 intake and .495 exhaust (1.6 rockers), and duration is 204/224. Should give you a decent driver without to many issues.

As far as guys that have done NA builds go, we've got 1 member that's been racing one but he hasn't been on in a long time. He did post everything in the B4black section and if I remember his name I'll tell you.;)
 
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