354 Compression Test!

Travis

Travis

Member
I ran a compression check on my 354 and it has about 90-95psi per cylinder. My buddy said it should be 150 give or take. If so is it worth rebuilding or jumping ship to a 350? Thanks for you input.
 
A "target" hot compression onna sv motor is 120 minimum. Yore buddy must screw with chevs.

Why do a motor swap when you can rebuild what ya have...over...and over...and over...and...

Every part is available right here on ihon for any level of IH motor rebuild, stock to wild.

Better yet, do a complete diagnostic regarding your engine's internal condition and then determine what to do, might be a simple ring and valve will bring it back to life just fine.

For engine parts/kit info, look here:

http://www.forums.IHPartsAmerica.com/gas-engine-tech/2468-152-rebuild.html

The engine rebuild process for both the I-4 and the sv engines is exactly the same!
 
Your right about him being a Chevy man. He is the one that told me its a rod knock last year when we first revived the beast from the field. And it was a lifter and doesnt knock any more. Well what about finding a good 354 on the side and doing a build over time and swaping it in. Would that be simple enough.
 
Learning to build up a motor that is not a "must have" for a dd is always preferable!

Lottsa non-runners around to use for "practice" and we can certainly help ya with a process. The purpose behind documenting the motor build for sonja's rig I'm doing now is to provide a step-by-step approach that anyone can do once the machine work (if needed) is done by a pro.

I'm just like anyone else around here, all this stuff I do is "projects" and some float to the top on occasion between must-do assignments! We're working towards having documentation and "how-to's" for any common diy issue that might arise when dealing with this old junk.

So find a motor that is not frozen and been under water, gitta engine stand, and git busy!
 
And don't lose too much sleep looking for 354 engines. You won't find any. What you want is a 345. I know that's what you meant. 304's aren't too shabby either. Or if you really get a wild hair, go big and get a 392.
 
Well I found my "345" already. It was totally rebuilt I guess and heads are off to see cylinders. He want $500 for the long block. I guess thats not to bad.

I would go for a 392 if I could find one. Another guy told me that only the 392 came factory with 4bbl. I know 304 never did but did the 345. He also said thats what most travelals came with. I have a few sitting in the pick and pulls up here and they have 4bbls on them so this guy clames they have to be 392. I didnt think that sounded right.
 
travis said:
well I found my "345" already. It was totally rebuilt I guess and heads are off to see cylinders. He want $500 for the long block. I guess thats not to bad.

I would go for a 392 if I could find one. Another guy told me that only the 392 came factory with 4bbl. I know 304 never did but did the 345. He also said thats what most travelals came with. I have a few sitting in the pick and pulls up here and they have 4bbls on them so this guy clames they have to be 392. I didnt think that sounded right.
Click to expand...

Lottsa urban myth surrounds "which engine/which platform"!!

A Scout II did not use a 392 though there is no doubt some were swapped in at the dealer level...even when the rig was new.

"some" 345 California emissions Scout II did use a 4v carb, a spreadbore carter thermoquad.

Fullsize stuff could have a 392/4v, but a 2v/392 was only available in medium duty trucks, governed or non-governed. Again, over time...those motors get swapped around.

266/304 was a 2v manifold only, there was never a 4v version produced. The rpt aluminum manifolds for the 266/304 are a full custom casting

the "late" '73>'75 392 in fullsize stuff used a spreadbore thermoquad in some applications, others used a squarebore Holley, those two manifolds will interchange but of course the carbs are dedicated to each manifold.

'74>'75 were bastard years for fullsize stuff as some received an amc 401 motor, others received a tq-equipped 392. The shortage of 392 engines in those years did not affect Scout II production since the sii platform never was built with the 392.

Confused???

304 or 345??? Either one is a good choice for ya! And either one will get the job done with a 2v carb just fine...it's all about the state of tune and internal engine condition!

You do have to pay attention to the motor mount positions on the various blocks as not all are machined for the variations in mounts as used with medium duty, Scout II, and fullsize stuff. Same for the oil pans and oil pumps, the Scout II 4x4 oil pump/pan is the bastard of the bunch and is application specific...but any of those engines May be fitted with an sii pan/pump combo. Dipstick location will also vary but there are ez workarounds for that.
 
Thanks as always michael. So whats the difference between the 392 and 345. I know the intake manifolds swap. I guess the cams are the same "as advertised by isky". Well same part used for either. Another urban myth here, the crank is the only real differnce, the blocks the same pretty much. Just what I was told and I ask ask the experts as usuall. Anyway thanks again. I really want this trail ready so I can attend some functions soon.
 
Stroke is the same , same cam , same con rod, but a about it for internals. Crank May swap but I would hesitate with out a Bob weight and balance check, block different, bore bigger, heads different but will swap on non ic 392.
 
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