Engine size - Off-Road Forums & Discussion Groups
IH Scout & Trucks Discussion of International Harvester, 4-Wheel Drive Truck and Scout Vehicles

LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 08-23-2000, 06:08 PM Thread Starter
Join Date: Jul 2000
Location: Las Cruces, New Mexico
Posts: 25
Thanks: 0
Thanked 0 Times in 0 Posts
Engine size

I have posted once before concerning gas milage of a Scout, and I thank you for your help (your milage figures did not deter me, they were as I expected.) This time it is about engine size. How much difference is there butween the 304 and the 345 in terms of ammount of power, torque and gas milage? Also is one of the two more reliable or eiser to work on? I would appreciate all your help on the matter.

Buck is offline  
Sponsored Links
post #2 of (permalink) Old 08-25-2000, 11:28 AM
Posts: n/a
Re: Engine size

I can't give any real world impressions since I've only driven one 304-powered Scout, and it had different axle ratios
and different sized tires than my Scout. But if you look at the numbers, there is only a slight difference in power
and torque between the two. I would expect the gas mileage differece to be fairly slight as well, and I doubt there's
any difference in reliablity, etc. There's a much bigger jump in torque when you jump up to the 392, but the 392s
don't seem to last as long either.

Hope this helps.


post #3 of (permalink) Old 08-25-2000, 10:06 PM
Posts: n/a
Re: Engine size

The 304's use a smaller block than the 345's and 345's use same block as the early 392's (later ones are same except those 392's are "increased cooling" and are different in that expect than the 345's)... It all depends on you, some people like the 304's, others the 345's, I have never actually driven a 304 powered scout, just ours with a 345... what I can tell you is that when I was working on the spedometer and put the wrong geared reducer in (20 mph slower than actual)... I went off and left my dad in our '91 z71 (350), he was supposed to be checking the speed calibration...

Sponsored Links
post #4 of (permalink) Old 08-28-2000, 12:45 PM
Join Date: Aug 2002
Posts: 71
Thanks: 0
Thanked 0 Times in 0 Posts
Same block??

FYI, the 266, 304, 345, 392 (IC and non-IC) all use DIFFERENT blocks. They are similar, but all different.

The 266/304 share the same overall physical size, just like the 345/392 do, but the block castings are different for each one.

The 266/304 have different bores, while the 304/345 have different strokes, and the 345/392 have different bores.

Thus, a 304 is a bored 266, the 345 is a stroked 304, and the 392 is a bored 345. You could also claim a 392 is a stroked n' bored 304.

Too bad the "bored" is a full 1/4"! And the "stroked" is somewhere around an inch as well. Thus you can't turn one into the other.

Any of the IH V8s seem to be a good choice for your typical Scout. My 1977 has had a 304 (before I got it), 196, stock '72 304, stock 345, and built 345 in it. The built 345 is a whole different monster from the stock 304, but the stock 304 ran just fine. I used the Scout (with 33s, 4.09s, and lift) to flat-tow my race Scout II long distances without a problem (as well as several other new-purchase Scout IIs). It would accelerate up a grade while towing a spare Scout behind it.

The fresh 345 just does all that and a little better - but it'll turn over 5,000rpm, cammed, more compression, ported heads, blah blah.

BUT.. as potent as my 345 seems to be.. I have a 304 that puts it to shame - built a little "more" by Gryphin Racing. It's setup for all-out racing though.. and to turn 6500rpm, and push out 350+hp and approaching 400ft-lbs.

of course, to make a 304 do that cost nearly double what it took to build the pretty-potent 345.

Bottom line - if I had a stock 304, would I swap it out to put a stock 345 in? If the 304 ran well, I probably wouldn't (I did this swap, but only after I burned up the 304).

A "built" motor is an entirely different debate.

Allan Ericson used his '68 Travelall with a 304 to pull a 30' Airstream travel trailer from Arizona to Fairplay, CO for RMIHR last year - and said the 304 did just fine up n' down the passes up to 10,000' elevation.


tsm1mt is offline  
post #5 of (permalink) Old 08-29-2000, 09:18 AM
Posts: n/a
Re: Same block??

If you don't mind me being nosey, what do you have into your built 345, both monetarily and part wise. I'm prepping the 345 to go into my scout and wouldn't livening it up a bit while I'm at it. My scout will probably end up being a daily driver/ AZ rock crawler, but will definately do a lot of towing. Any help would be appreciated. Thanks

So many Jeeps... So little time[img]/wwwthreads_images/icons/crazy.gif[/img]
post #6 of (permalink) Old 08-29-2000, 09:53 AM
Join Date: Aug 2002
Posts: 71
Thanks: 0
Thanked 0 Times in 0 Posts
Built 345

I think my total is around $2500 into the 345. Including a used Holley ProJection unit. I still need to buy some headers though.

345 block, 392 rods. Punched .030, decked .040, heads milled .010 (with the new style head gaskets, that results in a NET "milling" of just .030 for the roughly 1/2pt compression boost). H997CP Federal Mogul hypereutectic teflon-coated skirt pistons. Single moly rings.

I ported the heads (removed the "hump' in the exhaust ports, and barely touched the valve pocket - should've done more, but this was my first port job). I had a valve job done on 'em, and had Chevy LS6 454 big-block valve springs installed (keeps the valves from floating at 4500rpm.. it HAS turned 5500+, and should do 6,000)

I used an Isky 262/262 cam (purchased from www.GryphinRacing.com) and new lifters.

The reciprocating assembly was balanced. I used a recurved Pertronix equipped points distributor set around 7deg initial advance.

More details are available at http://www.4x4play.com in the International Tech section, as well as my own web-site under FAQ/Tech Tips at http://www.tmcom.com/~tsm1/scout/

I used the Dana Perfect Circle valve stem seals - I would NOT use them on the exhaust valves again. I've broken 4 rocker arms since I put the motor in, and I'm not sure if it's because they're running a little too-dry (too good of a seal) or if I just had some bad rocker arms that I used.. I haven't broken the same rocker arm twice, which might indicate bad rocker arms that have now been replaced.. but it would be safer to just use the stock O-rings, and just remember that the white puff at startup is a GOOD sign (it's a sign that your motor's going to last a long long time)


tsm1mt is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome