1973 IC 392 rebuild to replace 304 in 78 Scout 2

[reptile0]

We have a 1978 Scout 2 with a 304 ci engine, 4 speed manual trans, new clutch, minor body resto nearly done. 4x4. Dana. It was a great buy considering body wasn't bad and guy thought more was wrong than a simple clutch job! Lee was excited to reclaim a Scout after a fully loaded beet haulin semi rearended his black one...and the Scout saved his life.
I am the camaro queen. I drive # 11 right now. Its a ddbut bein resurrected. I also love this Scout!
On to the story...
We bought a long block 1973 392 ic.
Its with a machinist and has been disassembled and checked for cracks.
It needs to be bored. 020 over or so.
Its supposed to be out of a truck not bus or grain hauler.
I am just learnin Scout. As well as have read tons of conflicting info.
Lee wants high compression power.
He keeps reading stroke this bb chev springs that. And so on.
I am not satisfied with hearsay! I have been placed in the position of gettin this done...which to me means doin it right
I want this jewel to last and be brute. He deserves this.
I need a specific plan to take to my machinist. This old guy loved IH rebuilds years ago and was excited to see me haul this to him. I trust his skill for stock, racing, custom builds etc.
I need all specs exact. I see michael and a few others are very wise.
Here's where I start?
3 angle valve job.
Line up cam bearings and rear for oil flow.
Smooth out oil passages.
True the heads. . but can we take it hair more ? ie . 020 for more compression
dui ignition
deck block . . How far?

"o" deck block vs. Offset grind crank to zero?
Oil pump kit
can we do. 040 over pistons with good results? Explain please.
Which: crank, springs, cam, carb/tuning and exact machining. Also read somethin about brass inserts somewhere into the 392. .
I have read and searched as well as gotten lost in these forums lol . this is a heavy task laid in my hands . if this was Chevy I would have the brass ones to just do it . .my machinist awaits my info..

 

[Scoutboy74]

Welcome to the forum. Robert kenney is the resident engine guru around here. If you search his name you will find all kinds of posts with relevant information. What I can offer you in anecdotal, lamens terms is that none of the IH v8 engines were designed with high compression, high revving, and high horsepower in mind. It isn't cheap or practical to achieve, though it can be done somewhat if the desire and pocketbook are nearly bottomless. These engines do make very good torque, especially the 392, and do so at relatively low revs with a flat curve across the power band. I have a stock 392 in my '74 Scout and it makes all the power I need and then some for the way I use it, which is mostly mild to moderate trail thumping with the occasional rallye opportunity here and there. Really, the kind of power a 392 makes is somewhat wasted in a Scout, as towing heavy loads is where this mill really shines the brightest.
There are things you and your machinist can do to "pep" up your mill, but you might do well to temper your expectations. I think you and lee will be far happier in the end if you set your goal to have strong runner, with good street manners that is capable of tugging your house off its foundation at less than 4k rpms and doesn't break the piggy bank to get it there.

 

[reptile0]

welcome to the forum. Robert kenney is the resident engine guru around here. If you search his name you will find all kinds of posts with relevant information. What I can offer you in anecdotal, lamens terms is that none of the IH v8 engines were designed with high compression, high revving, and high horsepower in mind. It isn't cheap or practical to achieve, though it can be done somewhat if the desire and pocketbook are nearly bottomless. These engines do make very good torque, especially the 392, and do so at relatively low revs with a flat curve across the power band. I have a stock 392 in my '74 Scout and it makes all the power I need and then some for the way I use it, which is mostly mild to moderate trail thumping with the occasional rallye opportunity here and there. Really, the kind of power a 392 makes is somewhat wasted in a Scout, as towing heavy loads is where this mill really shines the brightest.
There are things you and your machinist can do to "pep" up your mill, but you might do well to temper your expectations. I think you and lee will be far happier in the end if you set your goal to have strong runner, with good street manners that is capable of tugging your house off its foundation at less than 4k rpms and doesn't break the piggy bank to get it there.

I want the steadfastness rebuild as you speak of. Basically the standard rebuild. Lee wants more but I see nothing to use and as you say...finances are mild issue. We can afford stock style rebuild set and machining and a minor tweak here and there. I just need spesific standard specs. With minor maching ie: port, polish, truing, proper pistons, balance and so on. I need the info to talk machining to my machinist in an educated fassion. As in a print out I can hand him... As well as I will let him order the parts thru the place we want them from. (ihon) -so all communications are clear.

 

[Mark Pietz]

I've in the final phases of putting an ic 196 together, and enough of that project has helpful information for you (an ic 196 is an ic 392 literally missing one bank of cylinders , so the piston/rings/head/valves/bearing issues are identical). It's in this forum as the "limited disassembly of a 1980 ic 196". There are also other rebuilds on this forum that have great insight and information about handling what you are wanting to do.

 

[Robert Kenney]

We would have to ask a couple of pertinent questions first before I would even consider making any recomendations...

1) what is the intended use of the vehicle (eg towing, highway off road)

2) what fuel do you desire/are willing to put in it.

3) where do you want the bulk of the torque to be produced in terms of rpm.

4) desired cruise rpm

5) slush-a-matic or stick.

Keep in mind that any build will be a compromise.

Have a heart to heart with the guy you are doing this for.

 

[reptile0]

we would have to ask a couple of pertinent questions first before I would even consider making any recomendations...

1) what is the intended use of the vehicle (eg towing, highway off road)

2) what fuel do you desire/are willing to put in it.

3) where do you want the bulk of the torque to be produced in terms of rpm.

4) desired cruise rpm

5) slush-a-matic or stick.

Keep in mind that any build will be a compromise.

Have a heart to heart with the guy you are doing this for.

Snow. Mud. On road spare to work in really bad weather. Pull idiots out of ditch. Campin. Towing campers, trailers with vehicles and hay. All uses.
Mid to high grade fuel. Mid is only an option in a pinch honestly.
Our common roads are 55mph
4 speed manual . .11inch clutchplate
torque low to mid end... Tough s.o.b. At take off. I want what's best for this engine.
Stock rebuild with minor perks such as improving air and oil flows if possible
are headders a benifit here? We have dual 3" exhaust.
We do have good machinist.

Lee has decided I am in charge of getting this done right for this engine. He handed me full reigns in this project and you are my chosen wisdom scource. I want 200k plus out of it. We religiously maintain our stuff and take pride in it. But I know Chevy not Scout.. I appreciate your efforts and interest in this thread.

 

[jeff campbell]

Be ready to drop about $3k,I did on my '71-1210 392, .030,mild ( smallest comp cam u cud get at the time ) .440 lift exh & int.did all the assembly my self,saved about 6-900$.also included was a rebuilt 727 w/shift kit.most all parts from summit,at that time,it was the only place I cud get the piston's.rings were $200,hastings.if you're on a tight budget,just drop a good 392 an run it for now. Then do a rebuild? Jeff

 

[jeff campbell]

Port an polish will save a good chunk of $ ,it's really not needed,put that $$ elsewhere.also have a good tranny behind it,I learnt the hardway,my motor ran so good,it wasted my 727,8-1000 miles of driving after I put my motor in.ahh the feel of IH power was there,felt good,after the tranny got done,I was able to sit on my wallet,cause it was empty .lol,Jeff

 

[reptile0]

be ready to drop about $3k,I did on my '71-1210 392, .030,mild ( smallest comp cam u cud get at the time ) .440 lift exh & int.did all the assembly my self,saved about 6-900$.also included was a rebuilt 727 w/shift kit.most all parts from summit,at that time,it was the only place I cud get the piston's.rings were $200,hastings.if you're on a tight budget,just drop a good 392 an run it for now. Then do a rebuild? Jeff

We have priced it out and got machining quote.(our machinist is an old family friend). It will run around $2,000... Not counting headders and dui. Ive aready done the pricing leg work as well as other things. Trust me - I am tired and dizzy from researching this for months. I need the machining specks to do it right. We already have a running 304 in the Scout. I wont pull one old motor for puttin in another old motor. I strait up will not. Thats not my style. I always rebuild or open up and refurbish any engine before installing it. I have created plenty of awesome monsters that have stood the test of time as well as the people that have bought my chevrolet machines. I have built the reputation of doin it right the first time and have made good money doing so. As this is my man's prized project, he deserves no less than a perfect, fresh, clean rebuild to go into his baby. Lee gets his yearly bonus next month. Which will be plenty for the 392 project as well as his polaris 400 scrambler 2 stroke project.

There are no available drop and run 392's here.we looked and looked... Like findin a flea on a wooly mamouth..if there are some here no one will come off them. We had to drive over 3 hours to get the long block we could find.

Our trans is excellent. Syncros, forks and clutch are great.. Clutch has only a few miles on it.

I go to my machinist today and im lookin for knowledge so I can speak with him proper in IH language to build the most proper build I can for lee and this engine.

I am also stubborn and stand fast on never puttin an unknowen or untried part in anything. I just wont do it. That is also on my reputation. This is why I have the reigns in the project.

 

[Robert Kenney]

Reptile hold on till I have a chance to respond in a meaningfully way. Very few here except for sb74 and a couple of others have enough real world IH build experience to point you in a correct direction. I've build more then my share but with a busy life during the week it is tough to respond frok an iphone. I'll give you some good help on Saturday or maybe tomorrow morning.

 

[Scoutboy74]

Mr. Kenney, you are too kind. I'm gittin' guuder on the 727's, but when it comes to the engine builds, not so much. In retrospect, I probably should have kept my nose out of this thread entirely, but too late for that now. All I can say to reptile at this point is, when rk gives you his word, you can take it to the bank. What he tells you will be well worth the brief wait.

 

[Robert Kenney]

Sb74 less the bulk of knowledge but rather being able to censor out offering the bs that so many spew. Oh and don't short change yourself.

Now back to the project at hand.

Reptile0: from what you wrote above a stock 392 will be quite capable of delivering. Here are the items I would build in to it however to perk it up a bit..... The monetary limitations will preclude stroking much past 0 deck. The stock rod is the limiting factor. It will simply smack the cam above 3.75-3.8 stroke and you will need a custom piston at that. Don't think you want to go there. A 304 will yield a better engine and make more power @ 383 inches then the tall and heavy 392, but at a big cost, so we'll stay away from those combinations here in your thread.

Compression and cam choice are paramount in making this thing do what you desire. Since you are ok with mid and premium fuel you want some real compression. Definitely above 9-1.

So here are my recommendations.
0 deck by method of your choice.
Cam @ 392" = isky performance camshaft for IH v8 engines - International Scout parts


Cam @ 412"= isky performance camshaft for IH v8 engines - International Scout parts
412 inch = 3.781 (+ .125) stroke and .040 machined from the top of a stock replacement piston. .040 over bore. This will yield a 0 deck condition and require no deck machining. You'll be at about about 9.5 -1 cr depending on chamber volume. Before attempting this the block needs to be assembled and the piston tdc position verified as being in the hole .025. All build steps must be verified for adequate case and cam clearance. Possible that you will need to clearance the top inside edge of the big end of the rod to give it room at the cam. The crank work will require welding and a regrind. Only use a tried and true welder. The wrong guy will ruin the crank with to much heat. Cost will vary but easily $250-400.00 a standard offset grind is going to run you $150.00 with no welding. Make sure they mag the crank first,

both builds will benefit from headers, a 4 barrel carb and dual exhaust you have.
Port exhaust port as much as possible. Focus on valve bowls of both intake and exhaust.

Assume you have the latter studded cap rod that has studs and nuts instead of bolts. Those are strong enough. I would remove the big square knob of iron at the small end. This will reduce the reciprocating mass. The stroking will increase the recip loads, but removing the metal will help offset it. Balancing will go easier too.

With either cams you'll want 90-95# on the seat @ 1.850 and the comp springs in the store are good for this.

Other then that you seem to have a good handle on the other build steps.

 

[reptile0]

I didn't mean I was in super rush for info.I just had to talk with machinist before vacation. My only quam was the idea of throwin an unknown 392 used and untested when have good 304 . That's my pet peeve. No unknowns go in. It raised my hairs a little.(like tryin to tell me a light hindquartered mustang can out run my camaro style of hairs up...girl testosterone..trust me unless that stang has a very special engine it wont happen. . )
I too am usin new "smart phone" here . tough to use vs my laptop .
here's the status . : 2 valves are bad . magna flux showed no head defects . valve guides are needing replacement . rod boltz gettin replaced . lookin at cam kit on ihon . was lookin at comp cam kit . does isky come as kit ?
my list...give or take adjustments to what I've now read above:
oil pump kit
gasket kit
connecting rod bolts .
silvalite . 030 over pistons w ring set
valve guides
valves . . All 8.
Frost plugs. . all
rod, cam, main bearings
comp cam kit but can do isky..comp cam kit offered cam, lifters,springs,keepers,locks, and timing set .
I will show machinist post above this one . ya headders and all extras will take our price well over 2k but I feel its worth it . this is the info I needed to feel fed and satisfied .
oh and I don't know the guy whom would be doing cam work ie weld shave etc . would rather order one and work with it a bit as in not welding on it . my stomach got funny when my machinist mentioned process would be with some guy I don't know