Need some engine advice....

[wyrmrider]

the only way that open chamber works is with race gas and a trailer queen with any compression at all 8:1 up
Dish pistons, tight quench makes life much easier
match the compression to the cam and load (truck, motorhome, marine have to go lower)

 

[33 IMP]

Can you point me in the direction of the compression ratio calculator you are using? When I hung up with him, he still mentioned that it was at 9.9 now. I want to have all the numbers in front of me for the next time I talk to him.

The numbers i came up with in post#46 were from the Wallace Racing calculators. I find it very easy to use. It doesnt require the calculation between cc and cubic inches, it does that for you .
If you change the numbers in #46 to eight for the valve reliefs, and four for the miscellaneous space (i really have no way of calculating this misc. number, but it is the space around the piston head above the top ring. It would depend on bore size and top ring placement), the numbers still come out the same. The calculator explains what it considers "other additions".
If you ignore the "other additions", wallace says what you have now, 4.35, 4.15, 76cc, .080 thick cometics with a 4.38 bore, .010 deck, 8cc valve reliefs, is 10.52. Toss in 4cc for "other" and you get 10-1. This kind of variation is why actual measurement is so critical.

 

[hunt2elk]

The numbers i came up with in post#46 were from the Wallace Racing calculators. I find it very easy to use. It doesnt require the calculation between cc and cubic inches, it does that for you .
If you change the numbers in #46 to eight for the valve reliefs, and four for the miscellaneous space (i really have no way of calculating this misc. number, but it is the space around the piston head above the top ring. It would depend on bore size and top ring placement), the numbers still come out the same. The calculator explains what it considers "other additions".
If you ignore the "other additions", wallace says what you have now, 4.35, 4.15, 76cc, .080 thick cometics with a 4.38 bore, .010 deck, 8cc valve reliefs, is 10.52. Toss in 4cc for "other" and you get 10-1. This kind of variation is why actual measurement is so critical.

He does have .004 piston/cylinder wall clearance on the sheet. Would that be what you are referring to?

 

[Nate S]

Can you point me in the direction of the compression ratio calculator you are using? When I hung up with him, he still mentioned that it was at 9.9 now. I want to have all the numbers in front of me for the next time I talk to him.

I have a spreadsheet I use. Here are the details.
Piston up:
Combustion chamber: 76cc /(2.54^3) = 4.6378 in^3
Piston below deck volume: (bore^2*pi/4)*distance = (4.35^2*3.1416/4)*.01=.1485in^3
Head gasket volume: (bore^2*pi/4)*thickness = (4.35^2*3.1416/4)*.08=1.1883 in^3
eyebrows: 8cc /(2.54^3) = .488 in^3
Total = 6.463

Piston down = piston up + cylinder volume
Cylinder volume (bore^2*pi/4)*stroke = (4.35^2*3.1416/4)*4.15=61.644in^3
Total = 68.108

68.108/6.463=10.538

 

[hunt2elk]

the only way that open chamber works is with race gas and a trailer queen with any compression at all 8:1 up
Dish pistons, tight quench makes life much easier
match the compression to the cam and load (truck, motorhome, marine have to go lower)

I just told my buddy about the conversation I had with Brian. He is also adamant that the pistons should be replaced to get a quench. I was happy thinking we could just change the gaskets here, but he says that is not happening. His reasoning is that if head gaskets are changed, pushrod length needs to be adjusted, cam degree should be checked, and put on a dyno. If anything goes wrong with anything, Brian will be able to wash his hands on the whole deal.

 

[Nate S]

I just told my buddy about the conversation I had with Brian. He is also adamant that the pistons should be replaced to get a quench. I was happy thinking we could just change the gaskets here, but he says that is not happening. His reasoning is that if head gaskets are changed, pushrod length needs to be adjusted, cam degree should be checked, and put on a dyno. If anything goes wrong with anything, Brian will be able to wash his hands on the whole deal.

You're talking .03" to get to 9.9:1, If you need new pushrods after that, you need them now too.

 

[33 IMP]

He does have .004 piston/cylinder wall clearance on the sheet. Would that be what you are referring to?

No, what wallace refers to as "other additions" (in cc.s) is quote: chamfer on piston outer edge, (on certain old trw's that was huge!) Ring land volume, (that is the space around the head of the piston above the top ring) the extra volume in head gasket where the bore is not a perfect circle, and the valve chamfers on a cylinder bore of block, (as were typically found on max wedge blocks, and always on 409 chevy truck blocks).
Just google Wallace Racing Calculators. Its an amazing resource and its free!

 

[33 IMP]

Lets see...... fix it right, maybe two or three thousand bucks, lots of work, and down for a month. (Six months, if it was me!)
make it work, free parts and a days worth of head pulling.
I know what i would choose.
Did you look at IQ52s no-quench 440 build on FABO? Mopar made MILLIONS of engines with no quench! You are making way over 550 hp now with no quench, how bad do you want it?

 

[HEMI-ITIS]

This is Brians build,pull the engine and send it to him. He said he will make it right and in the 10 years or so I know of IMM I have never heard a bad experience with him. Many great suggestions you guys but the path of least expense and resistance is Brian making his minor adjustment and sending the engine back

 

[wyrmrider]

millions of engines and they all suck
open chamber smog heads suck worse
the 361-413 truck heads had wedge chambers and the spark plug up top like a SM or FE ford
whoever thought of the plugs way over to one side with no water around them
what were they thinking?
There is NO WAY to get a even burn - flame front all the way to the intake side
if the intake side does not light off on it's own

 

[451Mopar]

I agree with Hemi-Itis. The builder is in the best position of knowing how the engine was built, and why he chose the parts used in it.
He will also be able to spot any other issues like pushrod lengths, intake manifold fitment, and then dyno test (and tune?) the engine.
I know it will cost Brian money and you time, but if you do the work and there are still problems, you will spend alot of time on the phone trying to sort it out, and may end up shopping the engine back anyway.

 

[Nate S]

millions of engines and they all suck
open chamber smog heads suck worse
the 361-413 truck heads had wedge chambers and the spark plug up top like a SM or FE ford
whoever thought of the plugs way over to one side with no water around them
what were they thinking?
There is NO WAY to get a even burn - flame front all the way to the intake side
if the intake side does not light off on it's own

So not a single factory big block Mopar is worth the powder to blow it to hell? Other than a truck engine. Bummer. Those closed chamber engines had the piston .060-.080 down the hole with a .020 gasket. No quench there. Guess I’ll need to build a 396 Chevy for my Plymouth.

 

[HEMI-ITIS]

Me thinks the OP wanted somewhat a budget build, discussed what he wanted out of this build and recieved an engine making almost 600 HP. That's not chicken nuggets. Different builders do things differently and if you feel you could do it better,,,,,just do it. IMM has built dozens & dozens of BBM'z with great success.
Brian will do the right thing and the OP will be happy with the end result.
Let me make one thing clear,I do not know Brian personally nor have I used his service. When someone get phucked we hear about it on the MOPAR forums. IMHO the OP has NOTHING to worry about!

 

[hunt2elk]

Me thinks the OP wanted somewhat a budget build, discussed what he wanted out of this build and recieved an engine making almost 600 HP. That's not chicken nuggets. Different builders do things differently and if you feel you could do it better,,,,,just do it. IMM has built dozens & dozens of BBM'z with great success.
Brian will do the right thing and the OP will be happy with the end result.
Let me make one thing clear,I do not know Brian personally nor have I used his service. When someone get phucked we hear about it on the MOPAR forums. IMHO the OP has NOTHING to worry about!

Well I surely wasn't looking for a budget build. If that was the case, I would have had it done locally for 1/2 the cost. And would have gotten what I paid for.....
I know Brian will take care of it. I have made the decision to pull the motor and send it back to him. Today he did admit that he didn't calculate the compression ratio correctly. From what I have been reading, it probably would have been ok if it would have been built with a quench, but like I said earlier, he doesn't build them with quench. I surely don't know enough about these things to know why, but he has put together a lot of big block Mopars and has a stellar reputation (which is why I ended up going with him in the first place).
Sure is great to have all you racers on here weighing in on subjects like this, I personally have learned a bunch.

 

[69 GTX]

I was wondering if he made a mistake on the math.....

 

[wyrmrider]

The plug location on the Truck/ Industrial heads makes a big difference
Open chambers work better on gas we can't get anymore
The BBM can be fixed with quench dome pistons or different heads
your other option is to always keep the revvs above peak torque

 

[451Mopar]

As I mentioned earlier, it is easier to lower the compression than increase it.
When wiring Mikes car, told him it is easier to shorten a long wire than make a short wire longer.

Building an engine to have quench with a closed chamber head is pretty straight forward, usually a flat top piston or "D" style dish piston is used.
With an open chamber head, building a quench engine is alot of work to get the "quench" pop-up / dome to be the same distance from the "quench" area of the head, and the small area of "quench" you get with a quench dome piston is almost not worth all the hassles.

My original 451" stroked 400 block was 11:1 compression and the pistons were dished all the way around, not a "D" style dish, so I had no quench, and the only time I heard pinging with that engine on pump gas was on a really hot 100+ degree day, but to be safe at the drag strip I would run 25% or more 110 leaded race gas. The car has a 20-gallon fuel cell and I would dump 5-gallons of race gas in to top off the tank that had pump gas in it.
That engine ran a 251/251 @ 0.050" solid roller cam.

 

[beanhead]

...When wiring Mikes car, told him it is easier to shorten a long wire than make a short wire longer...

You don't own a wire stretcher?!

 

[hunt2elk]

His plan is to replace the .080 head gasket with a .110 to get to 9.65:1 cr. Does everybody agree that should be enough to take care of the problem?
And another option I guess would be to pay him extra to replace the pistons to get a quench, or would that also mean a cam change? Is a quench really that important for what I am doing with the car and worth the extra cost since it is already put together and making good power without one? Or would this be another debate similar to running ported vs manifold vs no vacuum advance?

 

[Nate S]

The plug location on the Truck/ Industrial heads makes a big difference
Open chambers work better on gas we can't get anymore
The BBM can be fixed with quench dome pistons or different heads
your other option is to always keep the revvs above peak torque

Interesting with the truck heads. A guy is giving me a truck 440? 413? With tranny and it has those heads. I’ll give them a look to educate myself. I don’t think they fit any good manifolds or headers though. Meanwhile I’ll be content with my stockish engine and 9.25:1. Does what I want it to.