5.7 300 H.P. engine supplier recommendations

Looking to purchase a 5.7 300 H.P. long block.(new or reman) All suggestions about suppliers would be appreciated.

Try Michigan Motors. Speak with Roger or Loren.
They are willing to build, on a custom basis, a Quench Effect built 5.7L or 6.2L SBC for us now.

Just as with drugs..........., say NO to these

i would go with jaspermarine motors

i have fixed more than 10 Michigan crap motors

That's fine.... even if going with Jasper Engines, see if they'll build you a more true SBC Marine engine by steering clear of the fully dished pistons.
These pistons should NEVER be used in a SBC Marine application....... Period!

There are better choices, and choices that won't break the bank!
Any good builders, that know the SBC, will understand what I'm speaking of.

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thats funny because every motor i have seen has the dished pistons from the factory

thanks for the input, still undecided

justintime said:

thats funny because every motor i have seen has the dished pistons from the factory

Click to expand...

Yes, that is true, and they should be ashamed of themselves for using these in the Marine version.
The fully dished piston was a product of the 70's when emmissions control became important for automotive.
The use was continued when the small chamber cylinder heads came along as to control C/R.

If not familiar with the Quench Effect (aka Squish Effect), you can find many articles on the Internet regarding the topic.
Many are related to automotive, but the principle nicely crosses over into the Marine environment.
However, the Quench dimension can be tightened up some for Marine use.

Here's a great article by Jeff Smith

Here's one by Charles Borrini. see section 3.0.12

Another by John Erb.

Here is an explanation of the differences between Detonation and Pre-Ignition of which the Q/E build plays a role in re; Detonation potential reduction.

And one that I cannot link you to, would be Dennis Moore, the author of; "Small Block Chevy Marine Performance".
In order to read what Dennis has to say, you'd need to get your hands on a copy of his book.


I'm personally no expert on the topic, but I've been involved with the SBC since the 60's. I have never used the full dished piston in any SBC that I have built.
It's simply the wrong piston to use, and if you have any concerns for detonation, this piston should be avoided for Marine use in particular!
It has to do with a more ideal LPCP (approx 14* ATDC) and detonation control.
We can't do this with the full dished piston when used underneath the wedge area of the SBC cylinder head.
It renders zero quench or squish effect.

All that having been said, marine engine builders will no doubt continue using the full dished piston in the SBC Marine Engine line.
It's cheap, and readily available!

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but if it was fuel infected motor with the knock sensors, i think it would have no effect

mainly these articles are for carb motors

thanks for the info

Whether FI or Carbureted, Detonation remains a potential, and in particular when the full dished piston is used.

And yes, you are correct. With ECU's and ECM's using knock sensors, we do cut back on ignition TA..... and this is precisely why the full dish piston is not a good choice.
Look at some OEM ignition advance curves and compare between an engine using the full dished piston and one built using a Q/E or Squish Effect combustion chamber.
We can throw a few more degrees TA at a Q/E built engine, getting our PCP (aka LPCP) more precisely located at what works best (again, approx 14* atdc) ...... and that genarally means better performance!

(we'll see PCP or LPCP at/near anywhere from 12* to 15* ATDC, depending on the study, I suppose)

A Quench Effect built engine can also use one or two points greater on C/R without having any ill effects re; Detonation Potential.
The dynamics of it are quite interesting.

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