Parts of 345 build

Well, that settles it... I'm going w/ the 262 isky and bumping the cr to 9.0.

I guess that sums up my build. Time to go to work.

Thanks for all the help guys.
 
A comment, not to change anybodie's mind....

I do not know much about cams, but I will relate a comment Jeff made when I talked to him about the choice of cam for my 392.

He stated that the IH power brakes were slightly less effective because of the slightly lower engine vacuum "produced" with the "more radical" cams.

Maybe this is why some people add "hydroboost systems" to their vehicle's brake system?
 
Robert,

don't want to disparage any of your talks with Jeff so I am speaking in general terms and from my experience from builds.

Your cam 202*@.050 is stock from a vacuum persective, 208* @ .050 is still a stump puller and will idle @ 15" + now this assumes it is in tune and dialed in.

These cams we put in our IH engines are for all intents and purposes dinky. Not a problem until you reach say 225* duration @ .050 and 110 lobe centers. Much tighter than 110 and more than 225* and you would be having trouble on an auto and a tight converter. A stick and you would still be ok.

If you can get 12 in/hg at idle don't worry about these cams.


Brake boosters are fine down to say 10 inches of vacuum. Yes pedal pressure May increase slightly at a signal but in decel you still have great vacuum.
 
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Robert kenney said:
Robert,

don't want to disparage any of your talks with Jeff so I am speaking in general terms and from my experience from builds.

Your cam 202*@.050 208* @ .020 is still a stump puller and will idle @ 15" now this assumes it is in tune and dialed in.

These cams we put in our IH engines are for all intents and purposes dinky. Not a problem until you reach say 225* duration @ .050 and 110 lobe centers. Much tighter than 110 and more than 225* and you would be having trouble on an auto and a tight converter. A stick and you would still be ok.

If you can get 12 in/hg at idle don't worry about these cams.


Brake boosters are fine down to say 10 inches of vacuum. Yes pedal pressure May increase slightly at a signal but in decel you still have great vacuum.
Click to expand...

Perzactly!

The average IH crapball running around out there right now in stock but crappy tune ain't even makin' 12"hg! But folks don't know that unless they hang out around here and try and lern shit!
 
600 cfm is to big for your application but since it is a vacuum secondary unit it will run fine... The 80457s has no fuel level adjustment screws. I don't like that. The other 600 cfm units on the same catalog page do. 0-80450- 0-80453. They are jetted leaner but are good units. Look into them.


My personal preferance would be in the 450-500 - 4160

they offer a 0-1848 465 cfm street performance carb that is also ok and cheaper then an avenger but not equiped with the GM throttle linkage for an auto.
 
Actually, I've installed many Holley list 80457 (including the shiny "s" version) on both stock 345 and 392 and are as close to plug and play as any carb out there. I run 'em on all my stuff and I have two here now to rebuild for customers that have been in service for years.

They do have adjustable needle/seats if the correct item is ordered. Stay away form the "no trouble" versions of any Holley carb, those do not have adjustable needle/seat assemblies.

The "truck avenger" is in no way a proper match for any IH sv application and I've wasted many hours trying to make one work, its super-fat and is not a proper carb for what you are trying to accomplish.

The list 1850 is near identical in setup to an 80457 (small difference in jetting out of the box) and does need to have some additional tuning work and jet swaps performed for most sv applications.

The electric choke 80457 is the best value for the dollar out of all the Holley carbs that are suitable.

For tuning info on a stock 392 with an rpt manifold and an 80457 that has been rebuilt 5 times in the last 11 years, see this thread. Even though I've installed a "quick-change" secondary vacuum pot top and played with all springs available, the oem spring is still the one I run. Typical range of operation is from sea level to 10,800ft. Pulling a 5500lb. Trailer:

http://www.forums.IHPartsAmerica.com/carb-tech/76-beer-can-maneefol-guapo.html
 
Update on the build:

I now have a 392... 345 turned out to be a 304 due to my ignorance. I was disappointed when I found that I was able to get a 392 for a good price.

The block has been machined. It was honed (no bore increase) and decked. I requested a zero deck but I guess the machinist thought that was too much. The piston is .015" in the hole. I measured the heads to be 87 cc's and calculated the cr to be 8.15 (w/ the decked block and .040" gasket... Would be 8.46 w/ shim gasket). He has yet to mill the heads so hopefully I can get the cr up by taking a little off the heads and locating some shim gaskets.

I went w/ the isky 262 (108 lobe center). I installed it and checked the centerline. It came out to be 113.5. I advanced the cam 1 tooth on the crank and rechecked it. It is now 105.5 (which seems correct given the # of teeth on the crank gear... 8*/tooth). I plan on leaving it here (2.5* advanced). Seem ok?
 
If you told your machinist that you're dead-set on rk's 0.022 steel shim gaskets it looks like you landed right on the tighter side of good quench allowance with 0.037". And apparently that tighter squeeze will help anti-detonation with your fancyazz hi-compression head milling, as long as heat of expansion doesn't kick yore butt when you get all leadfoot. I don't have enough experience to tell you how "close" you're really getting to be honest. If you were scurred, you could always toss performance out the window and use the composite gasket with your current mill for a whole 1/16" of safety or more.

:d some of us don't have to modify our pig iron to be happy!


Sounds like you got this all worked out, and if I remember correctly that bit of breathing advance should play nice offroad. I sure hope you have a video camera to capture a few glory moments later on, cause this sounds like a worthy build. Don't leave us hanging!
 
Ic or non ic 392?? Iirc only non ic 392's had the steel hg's. The ic vintage used a composite hg's from the factory.

104-105 in/lc will be ok.

Get the compression up with that cam and absolutely achieve proper quench distance. A .060+ qd and 9-1 is at risk of chronic detonation. So don't just mill the heads to bump the cr, also zero deck or find the shim hg's
 
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