Thank you Gary.

 

Interesting notes on my rebuild. I am going to have to dig a lot deeper into this discussion and educate myself a bit more thoroughly.

From what I understood at first, there was a maximum acceptable compression ratio to run X octane pump gas.

However, after reading through your post a couple of times, it seems as though it's not that simple and there are several other factors that play into how the compression ratio and octane of gasoline interact.

One thing I'm fuzzy on - what do you mean by 0.035" squish?

 

Squish is a term that describes what happens when the distance between the top of the piston and the flat part of the head. If that distance gets down to .040" or less then magical things happen as the gas gets squirted at high speed around the cylinder. And that can dramatically decrease the detonation tendencies.

And you are right that it isn't simple. As FMJ was saying, there is the static compression ratio, which is what is traditionally calculated via bore, stroke, combustion chamber volume, etc. And then there's the dynamic compression ratio which adds in the open/closing timings of the intake and exhaust valves. And a the wilder the cam the lower the dynamic compression ratio.

Plus, the type of the head makes a difference - open chamber, closed chamber, cast iron, aluminum, etc.

 

Hmm, just more stuff to read up on I guess haha.

Oh, and to answer a previous question - yes I'll be running a Melling Oil pump. The machine shop uses ONLY Melling pumps when rebuilding - anything else and they'll try to sway a customer back to using strictly the Melling pump.

 

Melling is good. Just don't use a high volume or high pressure pump. Do Tim's mod's, inc his cam bearings, and a standard pump. That was Tim's guidance to me.

 

LOL, Squish also made me fuzzy when I first learned about it.

Google squish, quench, and DCR, but look at technical sites, not forums.

There should be drawings, so that will help a lot to understand it.

With regard to piston ring end gaps, look at KB's site below, and click on installation guides half way down the page on the left :

https://www.uempistons.com/index.php...8d31f00ad4dda2

Good choice with the Melling !

 

While I remember, can your engine run unleaded gas ?

If yes, great, end of.

If not, change the valve guides(or is it seats ? I've forgotten) to hardened ones.

In addition to your Google homework (LOL), google the definition of engine ''blue printing'' coz in effect, that's exactly what's going to happen, and then some.

Given your enthusiasm, and attention to detail, book the day(s) off when the engine is being built. That way you can learn big time, but more importantly, you can ensure that it is built perfectly.

And lastly, if you're **** like one of us is (LOL), you can see if they use an internal micrometer to check the valve guides, ummmmm, like one of us did.

 

A couple small updates fellas.

I was away for hernia surgery for the last 3 weeks, hence no postings on progress until today.

Machine shop called back. Block is in fantastic shape for its age - no cracks.

I order Tim's KB2347 pistons + rings, ordered his special F26g cam bearings, and a couple of thermostats to try out (180 degree, and 195 degree).

Question: What length are the dowel pins where the timing cover goes?

I talked with Tim on the phone regarding them, apparently they're just common 5/16" steel dowel pins - nothing special - something I can fabricate on my own if needed.

But what length are they? Anyone know the proper dimensions for these dowel pins?

 

I don't know the length. But if Tim is shipping you pistons and rings, could he include the dowel pins? He must have them as he put some in my engine.

Anyway, congrat's on the block passing the tests. And I hope the surgery recovery is going well.

 

Although the optimum quench distance is often quoted at .040, anything less that .050 works. So anywhere between .040 and .050 is a good target. tighter isn't necessarily better, but you do need and want quench. Anything over .055 doesn't provide enough squish to provide quench and the open chamber heads of the 400 don't have much flat surface for the piston to work off of, so take that into account. Also pay attention to DCR. Compression is great, until you have to much and it pings on even premium fuel. Choose a cam that provides enough duration to lower DCR enough to work with the grade of fuel you want to run and provides power in the RPM range you wish to operate you motor in. A lot of things need to work together so take it slow and match your components well.

 

Turns out I needed both dowel pins and a new water pipe tube for the block.

I got both from Tim. He's been very accommodating and friendly to work with, chat with and order from.

If I lived in the states, I'd be asking Mr. Meyer to rebuild my motor. Unfortunately.. he's 14 hours away from me lol.

Quench and DCR. Great suggestions for research topics, and great advice.

I've found a few places online (credibility yet to be checked lol) that state 0.035 to 0.045 are the target areas for quench. The general consensus online is that 0.040 is the target (as far as I can tell - but I aint no engine builder, still learning here ).

Since my shop is waiting on the pistons, and waiting to deck the block, this is something we'll definitely talk about when we get to that point.

Now for DCR... This is one area I understand very little about. It seems to be a much more difficult discussion to have than quench.

Any suggestions on reading material for DCR? Links? Previous posts?

I've come across a few DCR calculators online, but they might be difficult to use since I don't know for 100% sure what my static compression ratio will end up being (yet). I could make some assumptions, but since the heads, the deck, and the pistons haven't been assembled/machined/decked/etc, it's difficult to determine exactly what my static ratio will be.

 

Stole this from George Pence,

"dynamic compression
July 9 2011, 10:24 PM

how much compression any motor can tolerate depends upon the fuel octane, the combustion chamber design and camshaft timing.

Lets cover these things one at a time:

Fuel Octane: Most of the world rates gasoline octane based upon the research octane number (RON). The US and Canada use a number that is the average of the RON number and another testing procedure called motor octane number (MON). The MON test is a more difficult test, the MON octane rating will be 8 to 10 points lower than a RON rating for the same gasoline. Since the US and Canada use the average of the two (RON+MON)/2 our octane numbers tend to run 4 to 5 points lower than the rest of the world for the same gasoline. Gasoline rated 91, 95 or 98 octane in Europe or Australia are equivalent to gasoline rated 87, 91 or 93 octane in the US or Canada, respectively. Our 91 equals their 95!

Combustion Chamber Design: The iron 4V heads are fairly detonation resistant, much moreso that wedge designs like the SBF (Weezer) or SBC, and they are better with gasoline than hemi heads like the hemi Chrysler (which does well with alcohol). Folks don't realize that the combustion chamber design was just as important in the Cleveland head design as the intake port, it was not an after thought, it was in fact quite advanced for its day. I've always found 8.0:1 dynamic compression to be a safe limit for iron Cleveland heads and premium pump gas available here in southern California (91 or 92 octane).

Modern high swirl combustion chambers (like those found on the Trick Flow heads) combine elements of Harry Weslake's combustion chambers with Cleveland combustion chamber geometry, the result is an even more efficient combustion chamber. A combination of a better combustion chamber combined with alloy construction enables those heads to tolerate at least at 1/2 point more dynamic compression than the iron Cleveland heads, i.e. 8.5:1.

Camshaft Timing : Dynamic compression is supposed to more accurately represent how much the mixture within the cylindervof an operating motor is compressed. Dynamic compression is calculated using the SEATED intake valve closing spec, in degrees after bottom dead center. Hydraulic cam events based on duration at 0.004" tappet lift are "close enough" to use in computing dynamic compression. 0.004" tappet lift is reasonably close to how much a hydraulic lifter collapses in operation. The problem is the advertised duration of some hydraulic cams is based on 0.004" tappet lift, but others are based on 0.006" tappet lift. When we are comparing cams, or computing dynamic compression, we must be careful to notice what spec the advertised duration is based upon, because it makes a big difference. Although it doesn't sound like much difference, specs based on 0.006" tappet lift will have much shorter duration figures, and will not give accurate results when computing dynamic compression.

If somebody has only the camshaft duration figures they cannot accurately compute dynamic compression, they have to assume too much camshaft data regarding to cam timing. On top of that, duration at 0.050" tappet lift is useless for computing dynamic compression ... not enough information ... we need to know when the intake valve hits the valve seat.

After all is said and done, keep in mind if you push the limit of dynamic compression, the compression ratio needs to be consistant among all 8 cylinders, i.e. the decks must be very level, the combustion chambers cc'd, etc. If these things aren't done, then it will be prudent to back off a little in the compression to allow for a margin of error.


-G "

Note he is talking about 4v closed chambered heads, not open chamber heads.

 

Here is some good info on the 351C from George Pence, note he is talking about the 351C, the engine that fathered our 400's. A 400 is essentially a tall decked stroked Cleveland

Sticky #3: 351C Basics and Performance Tuning - Topic

 

George talks about the 400, Sticky #1: 408 Cubic Inches Using All Ford Parts - Topic

 

This is all extremely interesting.

I've searched and searched and searched and have never come up with a comprehensive threads such as these on the 335 series motors. Thanks for shining a bright light on the dusty/dark corner of the internet!

That second link is very encouraging for my build... I assume it's the baseline for all our builds actually...

Thanks for the links - finished reading both of them just now. Big reps for the info. There's one line that really interested me in the second link...

"The heads with 78cc combustion chambers may need to be milled 0.015" to reduce the chamber volume by 3cc (1cc per 0.005" milled) depending upon your choice of pistons." Sticky #1: 408 Cubic Inches Using All Ford Parts - Topic

That gives me a pretty good idea for what will happen to my heads when they're milled by the shop - which was originally a big concern for me since 91 octane is the highest around. Gotta keep that DCR at or below 8.0:1 if I want to drive this thing without any pinging.