achalmersman stroker 4.1 build (291 block)

[David Husek]

I can do the machine work on the rods. Having the crankshaft, rods, and rod bearing on hand, I resize the big end of the rods to set correct bearing clearances. The rods get machined for side clearance. Only one rod really needs work for camshaft clearance. If you purchase the pistons and rings from me, I can pin fit the pistons and rods which so often gets overlooked. I can balance also for a drop in assembly. You will need to set main bearing clearances, final hone cylinders and file ring gaps. Usually final main bore size is done in the line hone with bearing and crankshaft on hand to set proper clearance of the main bearings. I have designed the pistons and camshaft in TType6's engine and this would be a excellent starting point as his engine has many similar parts.

I will be starting a 4.1L build very soon also. I have a complete 25,000 mile motor as a starting point. May be built for E85, but not sure yet. Attached are 4.1L stroker pistons....

 

[earlbrown]

I

No I didn't grove the block but I used TAs coated dual grove bearings and they are installed correctly. There are 2 groves on the back side of the cam bearings that does the same thing right?

PS. Keep an eye open regarding pistons. Once I know what length rod I'm using. Probably 6.350" unless somebody like Bison tells me I would be better off with a shorter rod for velocity / cylinder fill.

Yeah, the grooved on the backside of the bearing will share oil to the DS lifter galley, so you're good there.


Pistons are easy whatever rod you want to run. I had a set made last week that are for a E85 4.1 stroker with a 6.500" rod. If fits just fine but does require a support ring for the oil groove. Not that big of a deal. Going with a shorter rod just means the pin is lower on the piston and can possible leave out the support ring.

 

[achalmersman]

At the good advice of T-Type6 I mic'ed myself the closest combo of paper I could get to 0.027" to use as torqued head gasket simulation.

I then screwed in 4 studs and set my heads on my block using the 7 sheets of paper (just under 0.027"). I dont have intake bolts so I used a little Crisco to try to hold the Felpro 1200 intake gaskets in place. Idk if that ruined the gasket or not but really I don't care. I expect to have to waste some materials for mock up purposes.

Point of this was to check intake to head port alignment with my current deck height / prospective head gasket combo. Looks pretty good to me esspecially considering its just laying on there. Nice port work from Nick Micale.

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

 

[earlbrown]

That looks like 26 and 8 tenths.


I usually use feeler gauges when I need to shim my heads like that.


but then again, you're probably having fun with the new mics, so have a blast!

 

[achalmersman]

That looks like 26 and 8 tenths.


I usually use feeler gauges when I need to shim my heads like that.


but then again, you're probably having fun with the new mics, so have a blast!

I don't have any feeler gauges here at my house. I have some at work and also at father's shop lol.

My new Shars 0.0001" bore gauge kit comes tomorrow. More playing [emoji1]

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[earlbrown]

I just realized someting... Why are you going with .027" gaskets. Those Cometics are harder to seal than conventional gaskets. When I did my 54.1 I had to deck the crap out of the block and use .027" to get quench. The side effect was having to mill my intake (twice) to make it fit.

That's one of the things I put into my slugs was the ability to move the crown up to avoid all the machining, the additional machining from the first machining and then having to buy a pair of non-shelf $100 gaskets.... that are harder to seal.



You might be happier with some Fel-Pro 1000's in the long run. Something to consider.

 

[Reggie West]

Subscribed

 

[achalmersman]

I like the idea of the Felpros that are easy to seal, but I don't want to take any chances of blowing them because of cylinder pressure and wishing I had used MLS gaskets. Maybe I'm lazy but I really don't want to pull the engine back out wishing I had used MLS. I know cometics are a pain but Bison and others have shown how to place a little smear of RTV around ports to help with sealing.

Maybe I'm thinking about it wrong but with the 0.027" gaskets and large chambers I will have room for change if my heads need decked in the future and the chamber volume changes. I will have the option to go thicker on the HG and it not be ridiculous. I'm going to buy a burett that has 0.1cc resolution because I don't feel confident in my syringe method accuracy / consistency. But so far it looks like I was off and my chambers are actually around 53-54cc

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[Ttype6]

Cometics are very easy to seal when you use Hylomar spray. They absolutely will seep if you don't. I don't care how flat the heads and decks are. They absolutely won't if you do. If a 1000 gasket is used,it will raise the heads and mess with the port alignment. Now that we know what gasket it takes to align the ports,piston dimensions can be chosen. Most importantly,compression height and dish cc.

 

[Undercover87T]

Used that on my Cometics and after two years and 6000 miles they just started to seep slightly. 291 block with two billet mains, 4in bore and stroker crank, 6.3 Molnar rods, Diamond pistons, 220/220 roller, topped with M&A heads and a 7168. Definitely a fun combo and loads of torque make it a great street motor. If your goal is mid 10's you can probably get there around 20psi and the motor will last a long time. First time out I went 10.60s@128 at 19psi leaving around 5psi.

 

[achalmersman]

I'm not going through all this for mid 10s. At least I hope not. I plan to push it much harder than that. I hate hearing cometic seepage stories. Is yours leaking externally water or oil? Do you guys remember seeing the post where Brian circled the areas where he put a "U" shape of thin RTV? I assume between the layers too?

I wish RJC made a gasket for the 4.1

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[Undercover87T]

I'm not going through all this for mid 10s. At least I hope not. I plan to push it much harder than that. I hate hearing cometic seepage stories. Is yours leaking externally water or oil? Do you guys remember seeing the post where Brian circled the areas where he put a "U" shape of thin RTV? I assume between the layers too?

I wish RJC made a gasket for the 4.1

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Haven't had a chance to turn mine up yet and will probably need injectors to do so. Has a trans brake now so in decent weather with no changes should be able to go 10.30's-10.40's. Oil is clean, its seeping external on the back side dripping on the crossover. Need to deal with it here shortly.

 

[earlbrown]

If you plan to make some SERIOUS cylinder pressure, MLSs are needed. Slight seepage takes a back seat at that point.

My Cometics don't leak at all. In fact one gasket has been torqued twice and once has been used three times. I filleted my layers and copper coated the hell out of them.

I also decked my block and heads myself and dressed the machined faced with a diamond stone along with bevelling the hell out of the head bolt holes.

I just wish someone would have invented my pistons before I had to do all that stuff to my engine. It would have saved me a bunch of effort and time and I could have bought plain ole 1000s and not had to thin my deck.


With your syringe method it's probably plenty accurate. If you can repeat your readings with what you have, odds are you're pretty accurate. If you can get repeatibility from a .1cc burette, you'll find none of your 6 chambers match. If they're close that's easy enough to fix with a rotary tool.

 

[marleyskater420]

Hey Man, you're totally using that C-Clamp the wrong way!



(but srsly- great thread. Very informative. Wonderful way to waste my morning at work "working on new bids"....shhh don't tell the boss!!)

At the good advice of T-Type6 I mic'ed myself the closest combo of paper I could get to 0.027" to use as torqued head gasket simulation.

I then screwed in 4 studs and set my heads on my block using the 7 sheets of paper (just under 0.027"). I dont have intake bolts so I used a little Crisco to try to hold the Felpro .

 

[achalmersman]

Sooo after work I tried to learn how to use a Dial Bore Gauge. A 0.0001" gauge actually and my OCD was quite challenged. Setting it up is a real PITA to get zeros especially not having something to secure my Mic in. I think the process will go much faster after some practice. I didn't write my bore measurements down but they varied more than I expected. I know this block was honed with torque plates installed. I hope that explains my varations measured. The line bore was MUCH more consistent. I measured 2.6872" to 2.6874" . I know temp makes a difference and I know my block, mics, and bore gauge were all at different temps. Just practicing for tonight [emoji2]

On a side note the shars bore gauge seems pretty nice for the money. I was able to get repeatable readings and I have never used a bore gauge before (I have used dial indicators before).

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[earlbrown]

Sooo after work I tried to learn how to use a Dial Bore Gauge. A 0.0001" gauge actually and my OCD was quite challenged. Setting it up is a real PITA to get zeros especially not having something to secure my Mic in.

Dude, you're new at mics so don't egg about bore gauges being a jerk.



Mics are a 'feel thing' and bore gauges are waaaaaaay worse. Just keep on keeping on and if you can get a same reading over an over again, you're gravy.



Also, I've been drinking all night.... and forth, isn't precision measuring tools fun.

 

[ek02]

Try gently mounting the mic in a very soft jaw vise or in some soft rags after you adjust it and lock it to size. Holding the mic to set the dial bore gauge is too hard to get a consistent reading.

 

[Mr.Spool]

My Cometics don't leak at all.

neither do mineand haven't been off the car in 6 years.cometics take a serious beating

 

[Ttype6]

neither do mineand haven't been off the car in 6 years.cometics take a serious beating

Before I installed mine,I had a cold rolled steel plate ground flat. I put strips of auto body sand paper on the plate and sanded the decks with it. It became immediately apparent that the decks weren't flat and the highest portions of the deck were the portions between the cylinders. I sanded until there were no high spots. I then sat the plate on my bench and ran the heads across it. It became immediately apparent that the heads were very flat. I installed the heads and within a couple of days they leaked oil and coolant. I took the heads off and removed the rivets from the head gaskets and sprayed both sides of each of the layers with Hylomar spray. They don't leak now.

 

[Mr.Spool]

Before I installed mine,I had a cold rolled steel plate ground flat. I put strips of auto body sand paper on the plate and sanded the decks with it. It became immediately apparent that the decks weren't flat and the highest portions of the deck were the portions between the cylinders. I sanded until there were no high spots. I then sat the plate on my bench and ran the heads across it. It became immediately apparent that the heads were very flat. I installed the heads and within a couple of days they leaked oil and coolant. I took the heads off and removed the rivets from the head gaskets and sprayed both sides of each of the layers with Hylomar spray. They don't leak now.

Well done!you prepped everything and sprayed the cometics are just slap on gaskets but they work so damn good.