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Discussion Starter #1
Hi all!

I am going to rebuild my Chevy 350 and I need some advice.
Hope you can help me!

What do I have and/or want to re-use:
1) Stock Chevy 350 (4-bolt, 010 020 high nickel) from 1972. It's at the machine shop now to bore and hone (.020 or .030).
2) Stock crankshaft. Is polished and in good condition.
3) Standard piston rods. In good condtion.
4) Double hump (Mickey Mouse) 64cc heads, stock springs, rockers.
5) Edelbrock 2101 intake

What do I (not) want with the engine:
5) More power (torque) than stock; Need not to be >300HP.
6) No high rpm (<5500)

Some thoughts:
7) I live in The Netherlands, so what I buy in the USA, is at least times 2 (or 3) due to shippin, tax and import rates. Therefor I do not want to buy eg. forged pistons, Edelbrock camshaft etc.
8) It's a 'hobby' car, I have a decent car. I can spend money on it, but reasonable... no, no, the misses is not complainig :D.
9) I drive on natural gas / LPG (not sure how it's called in the USA), with a Impco 425 (gas) carburator. High octane.

So... I have to buy:
10) A camshaft and lifters. I have a Edelbrock 2102 in my current block. It's okay, but maybe a little more torque. But idle must still be okay, rather no new springs, rather no new rockers, rather no new push rods. Please explain if it needs to be updated/changed. I know there are brands like Melling (ccs-2) and.... what is a good brand/replacement, please also give a partnumber?!
11) Pistons and rings. I was looking around and found some decent prised (Ebay, Summit) brands eg. Speed pro, Enginetech. I have no experience with pistons. The 'old' pistons had valve reliefs. What do I need (no dome please)? Flat Top, w valve reliefs? The size will probably be .020 or .030 over size. I guess Moly rings?
12) Timing set. Prefereably a double roller; have this on my current engine also.
13) Gasket set, full engine. Which gasket set? FelPro? What kind of head gasket -> thin steel or the blue ones with the steel rings? I have NO clue what deck heigh means or should be calculated, I do read a lot, but I don't understand (also I'm not native English speaker...).
14) HEI ignition.
15) Main bearings and piston rod bearing.

Hope you can give me some good advice on which parts to buy!

Best regards,
Rudy



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natural gas plus turbo will make lots of power, even with Mickey Mouse heads. Steal a couple turbos from hot 4 cylinders in your country.
Fabrication time.
Don't need to spend money in North America
 

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Since you want simplicity and need new pistons I would go with a dome and get as close to 12:1 as you can get...typical rules for engine building are used with tight quench a given.

11.5:1 is fine but its cheap torque to use as much of that propane octane with high compression since your restricted in your cam selection to low overlap which is required for propane, you will need hardened seats in the heads also.

Why do you not want a dome piston?
 

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Discussion Starter #4
Ok, I try to keep an open mind as possible...

@vinniekq2:
Nice idea, but maybe for a next project!

@4 Jaw Chuck:
Ok, dome is an option maybe. Not sure what the disadvantages are of a high compression (need special piston/push/connecting rods??). Need special requirements? Engine breaks down easily?

So, open mind (no turbos...), but need an idea for a setup with partnumbers.
 

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First off, I have no knowledge of LPG and compression and cam specs for it, so no recommendations. Second, don't buy any parts until the machine shop is done with the block and heads. Regarding quench distance, once the machine work is done, block decking if needed, then the machine shop can measure the deck height for you and then you can get your stack of parts and head gaskets to get the desired quench distance of .040" +/-.005". The same goes for the heads. I would assume you'll need some new valve springs as those old heads' springs are probably whipped (in need of replacement.)


Regarding the LPG, assume it is readily available? How do the octane ratings compare to our gas, E85, methanol, race gas (if you know)?
 

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Discussion Starter #6
The cylinder heads are on my truck now. When the 'new' block is finished, the heads will go to the machine shop to place hardened seats, if needed. I bought the heads as 'revised', but the machine shop will have to take a look to be sure.

I want to buy parts as soon as the machine shop is done, but want to gather as much information as I can in advance.

LPG is widely available in The Netherlands (and in Europe, except 2 or 3 countries). This is also a finacially choice...
LPG = 'cheap' -> $3,29 / gallon
95 oct = 'expensive' -> $6,67 / gallon
98 oct = 'YouDontWannaKnow' -> $7,29 / gallon

Octane rating is approx. 108-110. May vary a little, I guess, in the winter it contains more propane, in the summer more butane.
LPG is a mixture of butane and propane.
 

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Since you want simplicity and need new pistons I would go with a dome and get as close to 12:1 as you can get...typical rules for engine building are used with tight quench a given.

11.5:1 is fine but its cheap torque to use as much of that propane octane with high compression since your restricted in your cam selection to low overlap which is required for propane, you will need hardened seats in the heads also.

Why do you not want a dome piston?
X 2... you want high compression for good MPG... (Miles per Gallon of fuel)

Valve springs are cheap ($30/16), don't re-use ones with over 100 KM and risk dropping a valve into the engine...
 

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Discussion Starter #8
Hi, I try to answer this posts, but this website states that my posts need to pass the moderators. Also asked the moderators why I can't post messages, but no answer. Can't answer until this is fixed, because have to re-type my messages multiple times.
 

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Discussion Starter #9
New try:

I'm gathering information right now to see what parts I need to rebuild my engine. When the machine shop is done, I will order my parts.
My current heads are bought as 'revised', but I will have them checked by the machine shop when they get of my truck. I think it's a smart thing to replace the springs!

Regarding the LPG, it's widely available in Europe (except for 2 or 3 countries), so this is no issue for me. I have a Impco 425 gas carburator, so no gas carburator anymore. So far no troubles. LPG has a octane rating at about 108 - 110 (E85 at about 102 - 105).
The choice for LPG is economical... see why:
Euro 95: ~ $6,50 / gallon
Euro 98: ~ $7,20 / gallon
Nat.gas: ~ $2,90 / gallon (10-15% less economical than Euro95)

But what are the risk of higher compression?
Which parts do I need? Or brands?
Can you give me an idea which combo of camshaft/pistons/rings/gasket?
Also do I need special bearings, because of the higher compression?
 

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-Speed-Pro #H618CP20(.020" overbore) or 30(.030overbore) is a 3.5cc dome volume hypereutectic that will work and gives 11.4:! compression in with your 64cc heads, an uncut block deck(piston .025" down @ TDC)and .020" thick gasket giving you a .045" piston-to-head clearance(total quench distance).
-Speed-Pro #H617CP20 or 30 has a 11.8cc dome, gives 12.8:1 compression ratio with the same deck and gasket spec.
-Keith Black #9904HC-020 or -030 is a 4.0cc dome hypereutectic that comes in at .020" down at TDC and with the previous mentioned gasket spec gives a .040" piston-to-head clearance and 11.6:1 compression ratio.
-Keith Black #9905HC-020 or 030 is 10.0cc dome and gives 12.65:1 compression at .020"down and .020" gasket..
The Keith Blacks are $60-100 lower cost than the two Speed-Pro's. Quality is equal, so choice is yours.

Raising compression to go with the increased octane of LPG equals better low rpm power and increased fuel mileage with no downside or problems.
Downside to higher compression only comes if you raise it beyond what the fuel octane will support, which is why I did not list any pistons with a 13.0:1 or higher compression ratio for you.

Use any basic stock replacement or claimer performance moly ring of your choice, no need for the more expensive Plasma moly rings racers use. All the piston I listed use the common 5/64'-5/64"-3/16" ring widths.

higher compression doesn't need anything special as far as bearings, just use any suitable stock replacement in the size you need to match your crankshaft.

As far as camshaft selection goes, we will save that for another post after asking a couple questions:

-Do you want a glass smooth, stock type idle....or a slightly hot rod noticeable lope at idle,...or a very noticeable shake and lope at idle speed??
-What is the approximate engine RPM at you highway cruising speed??

Valvespring specifications need to match with camshaft choice, so we need to determine camshaft spec first.

Hopefully this was understandable enough to help you out. :)
 

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Discussion Starter #11
Thanks ericnova72! Very clear!

Do you want a glass smooth, stock type idle....or a slightly hot rod noticeable lope at idle,...or a very noticeable shake and lope at idle speed??
Pfff, okay:
-definitely NOT a 'a very noticeable shake and lope' (is it going to brake down?, or: will it keep running?)
-and not glass smooth... that's performance wise.
-hm, not stock... performance wise

So, that leaves:
-slightly hot rod noticeable lope at idle. I think that's okay when I know it will give a slightly hot rod noticeable lope at idle ... :cool:

In my truck I have an Edelbrock 2102 cam, I guess it has a pretty 'stock' type idle...

What is the approximate engine RPM at you highway cruising speed??
Not, sure, but I would guess 1800-2000 rpm @60mph
 

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You need high compression of 12:1 with propane just to get the power and MPG of gasoline at 9:1...

And as Bogie mentioned, you need a wide LSA/narrow overlap to keep the propane from escaping... similar to the requirements of a blown engine...

Propane and natural gas are also available all over the USA, but our gasoline starts at $2/gallon... and is more convenient...
.
 

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Which cam you use really depends on your mixer, if you have the typical mixer used on most propane conversions they are really low volume/cfm and won't support high rpm well because they go lean.

You can run long overlap cams but this requires special attention so you don't sneeze the intake which can blow the mixer apart and can lift the intake off and shear the intake bolts or crack the casting. Not a scenario you want to happen if everything isn't perfect.

I recommend you build for low rpm power, high compression (Keith Black #9905HC-020 or 030 is 10.0cc dome that gives 12.65:1 compression is ideal) a mild RV style cam and keep it under 5000 rpm where you make your power.

I built a Ford 390 on propane 25 years ago when it was more popular and it powered a 1 ton truck, the high compression really woke the truck up and I could run any timing it needed even at 12:1...I think we could have run 13:1+ at the time but piston selection is what it is. The engine had the torque of a much larger diesel engine, if I had to guess I would say over 600ft pds of torque which totally impressed me at the time. The truck actually carried a 5 ton crane drum which was way overloaded and we had to block the springs to keep it from collapsing. The clutch barely held the load but the engine was unstoppable and lifted the front tires off the ground getting the load moving, pretty impressive for what was basically a stock engine with high compression running propane. Pretty lucky we didn't break the axle but they built trucks differently back then and the truck was none the worse for wear after that ill advised move.

I've always wanted to build another propane engine with perhaps 15:1 compression with dual mixers on a dual carb short ram intake to see where the limit is and get some top end performance out of it. One thing I noticed is propane does not need much ignition lead like gasoline does, 6 degrees was plenty and adding more just made the 390 run hotter. Getting a proper ignition curve might need some experimentation on a dyno to get it right.
 

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Discussion Starter #14
I have the Impco E and Impco 425 mixer setup. No need for high rpm! So <5000 rpm is just fine.

Currently I have the Edelbrock 2102 cam, this is a mild cam, right? If so, is there a cheaper substitute for it? Or do you recommend another?
What kind of springs will go with 'the' cam? Just stock?

I assume 'the' cam will limit the rpm?!

Ok, I will check the domed pistons eg. KB, you and ericnova72 proposed!
 

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Natural gas is Methane, LPG is Propane. LP is higher energy content than Methane (natural gas). I work on furnaces so I use both.
 

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Discussion Starter #16
Ah sorry for the confusion! I have to check the interweb for translation sometimes... LPG is Liquid Petrol Gas and is a propane/butane mixture here in the Netherlands. More propane in the winters and less in the summer.
 

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Discussion Starter #17
Any suggestions for a cam for my setup?
KB9905 pistons for high compression approx. 1:12 and running on LPG (propane) only.
 

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Discussion Starter #19
Unfortunately no answer yet.

Question A.

Does anyone know if a camshaft needs special requirements if used:
1. High compression domed pistons, say 1:12,5
2. LPG / propane only
3. 64cc heads
4. <5000 rpm

Just need an insight, machine shop will start on the block after I purchase the pistons.

Question B.
Can I use a stock camshaft or an Edelbrock 2102 cam, with the above spec?
 

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Discussion Starter #20
Ok, after some research the cam will be a mild cam Edelbrock 2102.

Any suggestions for a full engine gasket set? Fel-pro KS2600 ?
Can the head gaskets (of KS2600 set) handle compression ratio of 1:12,5 to 1:12,9 ?
 
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