4.1 stock block build

[kurt24]

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[Dlynch1130]

Cam bearings are in stock nowshould be on the web site today. Pistons are being made will be about 2 weeks. approx 9 to 1 with 48CC head, 2618 alloy, good pins and rings, pressure ring, bowls mapped to combustion chambers, good stuff.
Mike

Mike: Thank you, this helps me decide which block I will build up, the 109 or 4.1

 

[ek02]

Glad you are doing a 4.1. I agree with the 4" bore. Rings are a problem with anything over the stock bore. Your block prep is right on, but don't forget to countersink the head bolt holes after it is decked, and be careful with stud length if using studs. One of your stroker cranks would really be nice if you are having pistons made.

 

[Mike Licht]

stroker would be fun and that may be phase two but this one is a budget friendly driver like most of our customers would build. I have an end mill ground with a pilot to knock a couple threads out of the head bolt holes I use in a drill., works great
Mike

 

[Ken Adams]

Mike, are the 484 blocks usable for this build?

 

[Mike Licht]

The 484 is the last design and has the best oiling of al the 4.1 blocks, The 291 has a little more meat around the head bolt holes in the water jacket areas. This is the place they usually crack so in theory that one should be better but that has never been proven that I know of. I am using a 484 so we will find out

 

[TurboCrazy]

A 484 block is what I built 18 yrs ago. Didn't know there were different blocks at that time. Put center steel caps on it way back then also(cut down 4 bolt caps I managed to procure). 4" forged pistons from Duttwieler on beam polished stock 4.1 rods, hung on a .010/.010 stock crank. Oh, & filled the water jackets with hardblok to the top of the water pump opening(used modeling clay to keep the port open). Beat the ever living snot out of the thing for years. Went 11.0s with junk iron heads. It would have went 10.50s with good heads, no problem. It even saw 7400 RPM once & lived. It might still be around if I hadn't screwed it up trying some things on a freshin up job.

 

[TurboCrazy]

Oh, if you fill the water jackets as far as I did. You need to drill the steam holes between the cylinders! Guess how I figured that one out? Ran fine on the street then without any issues. I think the HardBlok is necessary to stabilize the 4.1 block. I loved that motor. Wish I hadn't screwed it up. It had goood heads on it when I freshened it up. Oh well, live & learn.

 

[threerail]

Got me curious mike, what heads, rocker ratio and cam lobe profile and specs??? Turbo choice??

 

[Nick Micale]

Got me curious mike, what heads, rocker ratio and cam lobe profile and specs??? Turbo choice??

That is actually determined by the owner's goals, use and budget.

We have six 4.1's in the build process right now and every one is different to meet the owner's performance wants. There are many variables just with type of use which can be for pump gas, alky injection, e-85 or?

The many 4.1 builds before these all were different as well.

 

[Mike Licht]

Got me curious mike, what heads, rocker ratio and cam lobe profile and specs??? Turbo choice??

Heads? not sure I was actually hopeing you still had your M&A's I will find something keeping with my "budget commonman theme here" As soon as I find something I will post up. As far as the cam goes I am going to use our new XR5 roller which is a 214/214 with a very big .200 duration and lots of lift. This acts like a much bigger cam without the overlap. rocker will depend on the head but roller rocker are needed with this cam. I will set the car for E-85 but will have tunes ups for that pump alky and race gas for the SD2 set up, 120 lb injectors should cover me and turbo wise I am not sure, I did make a deal on a 71GTQ with a customer we will start there but likely end up with something smaller for more "fun factor" on the street.

 

[Mike Licht]

MACHINE SHOP UPDATE caps are done, decks are measured this block was decked on one side at some point in its life and the final deck height ended up 9.510 so we had to move the wrist pin in the piston some, we will have pistons in two weeks I had the 4.1 pistons done with the GN1 shape bowls so if a guy wants to use a big valve aluminum head he is good to go. Iron heads work fine with them too.
Mike

 

[boostmaster]

Oh, if you fill the water jackets as far as I did. You need to drill the steam holes between the cylinders! Guess how I figured that one out? Ran fine on the street then without any issues. I think the HardBlok is necessary to stabilize the 4.1 block. I loved that motor. Wish I hadn't screwed it up. It had goood heads on it when I freshened it up. Oh well, live & learn.

Steam holes? Never noticed that, explain......what size drill bit?

 

[TurboCrazy]

I had pretty close to a half fill of HardBlok. When I first got it running, it wanted to overheat if it sat & idled. I was pissed, cause I thought all that money & work to get the 4.1 together was wasted!! Then I got to thinking, 4.1 StageII motors don't have this problem? Started reading my Power Source book, & figured out why. The Power Source book has a section in it on drilling the steam holes. I think I remember using an 1/8" drill bit. This isn't necessary if you don't use the HardBlok.

 

[Mike Licht]

Sounds like a nice version 2 project, hard block steam holes and stroker crank hmmm.......... need to get back on track here

 

[TurboCrazy]

I would really like to see how that turns out, Mike. I had M&A heads & a big cam on mine after the freshen up. Unfortunately, I didn't get to see how that was going to turn out on mine.

 

[kidglok]

whats the general consensus on the amount of power these blocks can handle? (if kept detonation free of course)

 

[Nick Micale]

whats the general consensus on the amount of power these blocks can handle? (if kept detonation free of course)

Back in the 90's before the advent of "boards", a turbo Buick owner by the name of Fred wanted an answer to that question as well.

He was a member of the GN/TTYPE list and had access to an engine dyno. He built a production 4.1 block over a period of many months as he accumulated the necessary parts which was not an easy task back then?

The rotating assembly was all stock parts, none of them forged, he just hand picked the best available.

The real challenge was finding and obtaining the supporting parts to develop enough power, as the goal was 700 HP.

He did reach that goal and barely surpassed it when the block let go and ended the project.

Based upon his efforts, I built my first 4.1 with a girdle and hard block and this was before affordable forged cranks and rods were available. I ran this at the track for a few years in the low 10's, and sold the engine. Second owner used it hard for a few years and sold it to a person that beat the hell out of it but never hurt the block.

With the advent of forged cranks and rods, we no longer used girdles or hard block on stock blocks, but we do install 2 steel center caps.

At the time Fred did his testing, very little data gathering info was available, and do not recall details on his fuel supply or injectors, as there was very few supporting parts available.

My experience has show the 700 HP level can be reliable with the current tuning and data products available.

A street driven GN with 700 HP available is very hard to recon with especially if this power/torque can be utilized with proper traction.

 

[regalracer1987]

im using a 484 block and some home ported 8445 heads in my t type and it dynoed at 526hp at the the wheels on the mustang dyno at bushers with 21# of boost. i still got some more room left to get some more power out of it but seems to be holding up great and im not easy on it at all

 

[John Wilde]

Mike, Thanks for the great thread!