Comments on these chambers' burn pattern?

General engine tech -- Drag Racing to Circle Track

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BradH
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Re: Comments on these chambers' burn pattern?

Post by BradH » Sat Apr 13, 2019 8:50 am

Mummert wrote:
Fri Apr 12, 2019 4:17 pm
There is pretty good burn coverage, we play with old 50's motors as well and have seen some things that help them.

...

I was curious to why the engine is apart.
What sort of "things" have you done or seen that have helped? I've seen a few builds where the heads were offset towards the lifter valley to help move the valves away from the cylinder walls, but was wondering if there were other approaches, as well.

Pulled heads back off after finding water on some of the plugs. My Mr. Gasket MLS (Must Leak Somewhere?) head gaskets didn't seal, despite their claims that the coating they use would keep that from happening.

arlancam509
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Re: Comments on these chambers' burn pattern?

Post by arlancam509 » Sat Apr 13, 2019 12:16 pm

Mummert wrote:
Fri Apr 12, 2019 4:17 pm
arlancam509 wrote:
Fri Apr 12, 2019 8:55 am
Mummert wrote:
Thu Apr 11, 2019 9:39 pm
... and the chamber being bore crowded.
i am young and naive, so please forgive the ignorance of my question -

what does "bore crowded" mean? the bore on this engine is 4.34, which seems big to me.
Essentially 180 degrees of the chamber is sitting on the bore. Very common to many 50's designs. No squish on the plug side.
Looking at the "burn pattern" all the fuel is directly beside the intake valve. Virtually none around the cylinder side or directly out in front.
There is pretty good burn coverage, we play with old 50's motors as well and have seen some things that help them.
Aluminum heads with bigger modern ports flow better but the architecture (valve proximity to bore) is what it is.

I was curious to why the engine is apart.
Thank you for the explanation!!! It all makes sense to me.

Mummert
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Re: Comments on these chambers' burn pattern?

Post by Mummert » Sat Apr 13, 2019 5:15 pm

BradH wrote:
Sat Apr 13, 2019 8:50 am
Mummert wrote:
Fri Apr 12, 2019 4:17 pm
There is pretty good burn coverage, we play with old 50's motors as well and have seen some things that help them.

...

I was curious to why the engine is apart.
What sort of "things" have you done or seen that have helped? I've seen a few builds where the heads were offset towards the lifter valley to help move the valves away from the cylinder walls, but was wondering if there were other approaches, as well.
Work on fuel atomization. Looking at it you can see the fuel hangs a 90* turn and tornadoes over the exhaust valve. Burr finish you intake manifold and intake ports. (DO NOT sand or polish them) defined angles on the intake valve job (no radius) this is basic stuff.

"Advanced" is to angle mill the and move them away from the cylinder wall. Those work well together for hp and tq. Also gains material to correct the intake flange.
Pushrod clearance can be a problem with heavy angle milling.
Mummert Machine and Development 4 stroke hp
Mummert Y-blocks

Newold1
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Re: Comments on these chambers' burn pattern?

Post by Newold1 » Sat Apr 13, 2019 6:40 pm

Not sure why Mr. Gasket MLS gaskets are labeled by some as must leak somewhere. If the heads and block deck a straight square and of a proper RA , RK and RVK finish as MLS gasket manufacturers recommend I don't ever see MLS gaskets leak unless the head is not properly torqued or the gasket finish is damaged or gone from to many reuses.

I would suggest that before this engine goes back together you check the heads and deck surfaces for finish and straight level surfaces. I think its a good idea to use something like a Stant coolant pressure tester and put 20-25 psi in the coolant system closed and see how fast it bleeds down if at all to make sure the coolant system is really sealed. Then try a compression test and leak down test on all cylinders before its ever fired off. Then if all checks good you've got a good place to start and find how the engine is doing just from a fuel and timing and the plugs should give a more accurate reading when things are close to right.

To take an engine down for multiple problems is a a bit of a problem in that it's hard to identify the overall condition when you've got multiple problems to start.
The Older I Get, The Dumber I Get :wink:

BradH
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Re: Comments on these chambers' burn pattern?

Post by BradH » Sun Apr 14, 2019 10:02 am

The block had no issues with holding pressure or leaking prior to being re-honed. Previous builds using DG "race" composition-type gaskets had no seaing issues.

Head & block surfaces are level. Head surface is MLS compatible; perhaps block's isn't quite smooth enough. These were new gaskets installed dry, torqued to spec, etc. Mr. Gasket says their MLS coating makes surface finish less critical; doesn't look that way to me.

If I reassemble it with new Cometic MLS, they'll have the same sealer that Chrysler specified when they were doing MLS conversions under warranty. My other option is to use the DG composition gaskets, again, but I'd wanted to use MLS for this rebuild.

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Re: Comments on these chambers' burn pattern?

Post by BradH » Tue Apr 16, 2019 12:45 pm

Here's a pic showing the no-longer-available DG "race" gasket. My experience with them was that they sealed very well, but were also a total PITA to get the orange coating off of the head & block surfaces when disassembled.
.
72 cc 77929 Hughes CNCchmbr w_IMM vj.jpg
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In-Tech
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Re: Comments on these chambers' burn pattern?

Post by In-Tech » Tue Apr 16, 2019 4:52 pm

Hi Brad, they were a bit of a pain but probably the best composite gasket I have ever used. Sucks they are gone. :(

p.s. the fuse was the fel-pro then I put DG in and split the block, gasket was fine. :shock: :lol:
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl

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Re: Comments on these chambers' burn pattern?

Post by Newold1 » Wed Apr 17, 2019 10:43 am

I pretty much do only chevy stuff and I have been using the Cometic MLX gaskets for those versus the older MLS gaskets. You should check with Cometic and see if they have the MLX gaskets available for your engine in your bore size.

If your block deck is out of RA range for a good MLS-MLX seal then you either resurface the deck or use a different form of gasket that will seal in a rougher RA finish. Soft copper might be your friend.
The Older I Get, The Dumber I Get :wink:

BradH
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Re: Comments on these chambers' burn pattern?

Post by BradH » Wed Apr 17, 2019 12:28 pm

Just checked and no MLX series for Chrysler products; lots of bore & thickness options for the standard MLS series.

Re the long-discontinued DG "race" gaskets, years ago I found a Mopar Performance vendor who still had some left over from when MP sold them in a 2-pack. I bought the last 4 pairs in his inventory and have rarely come across them since.

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