[73_Lemans_350]

There is a 400 for sale near me on Facebook marketplace. Based on the info in the ad... What's everyone's opinion?

https://www.facebook.com/share/18djpzfHEr/

I currently have the original 350 in my 73 LeMans, and have been casually searching for a decent 400 (or larger) for it.

Let me know what you think and if it's worth asking any questions and looking further into it.

Thanks!

[HWYSTR455]

Not enough info to know if it's worth it, you would need the engine code and year.

Just to say though, that doesn't look like a 10k mile rebuild, or wouldn't accept it as one. You would have to go through it if you plan to run it.

It obviously has been open and exposed for a while by the looks of that valley pan.

But, if it's a desirable casting, and it's usable, it's worth that money just for the block.


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[HWYSTR455]

I see now, has a casting of 481988 on the block, which I think are in the 71-74 year range.

Those pistons look to be TRW forged ones, .030 over, were good pistons at the time, better choices are available these days.

Heads appear to need a complete rebuild IMO. You would be better off to just buy some aluminum replacement ones.

Could probably use the intake with a good cleaning up, had to say about the carb & distributor.



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[grivera]

Seems like an OK price - I wouldn't use those heads on a 400 even if they didn't need a rebuild as they are either 6x4 (94cc) or 6x8 (98-101cc) which makes for very low compression in a 400. Could sell them for $200 and put money toward aluminum or a set of ready to run big valve heads of the late 60's variety.

[steve25]

Looks like a back yard rebuild of a already .030” over motor since you can tell that a ridge rimer was used and the cylinders just likely ball honed.

Depending on how badly the cam failed enough grit may have got into the motor to get into the piston skirts.

If there dash 4 heads then it could be rebuilt to make 380 hp without much effort.

[73_Lemans_350]

Thanks for the input. I got another pic of the head to confirm they are -8 heads.

I'm not looking for a real scorcher of an engine, but just about anything would be a good step up from what I have. Also, as many people are, I'm not looking to pour too much money into it. 300hp would feel like 600 compared to what I have now. 😂

I do have a four barrel intake and Quadrajet that I put on the 350 that I could use on a future engine.

[steve25]

You could put your current higher compression 350 heads on that 400 block for now once you check it out or rebuild it.

Down the road swapping on a better set of heads is just a afternoons worth of work.

[grivera]

Originally Posted by steve25

If there dash 4 heads then it could be rebuilt to make 380 hp without much effort.

How much shaving of the heads to get to this point? What compression are you thinking?

[HWYSTR455]

Yeah, backyard build is what comes to mind with me too. That's why I mentioned it's really only worth a block core. It's a waste to attempt to use the rotating assembly without having it machined, IE, full rebuild. Who knows what it looks like once you crack it open.

If you're doing a full rebuild, stroker kits are cheaper than machine work to old parts. Or are very close.

You would be better off just freshening a running engine, like the one that's in your car now if you want to go cheap. Do backyard rebuild on it, so to speak.


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[John Milner]

It looks like it may come with a Trans Am shaker air cleaner base. If a Pontiac shaker base, you could probably sell that for around $300 and be into the engine a lot cheaper. Since the cam went flat, you can count on tearing the engine down and cleaning everything up good and hope the pistons are ok and the crank isn't all scratched up. If all is good and the bores measure good, I wouldn't be afraid to clean it up and do a cheap overhaul on it if you are looking for a driver engine. Offer him $500 and if he takes it, you'll be into everything at a very good price in my opinion.

[jwcfbd]

Originally Posted by John Milner

It looks like it may come with a Trans Am shaker air cleaner base. If a Pontiac shaker base, you could probably sell that for around $300 and be into the engine a lot cheaper. Since the cam went flat, you can count on tearing the engine down and cleaning everything up good and hope the pistons are ok and the crank isn't all scratched up. If all is good and the bores measure good, I wouldn't be afraid to clean it up and do a cheap overhaul on it if you are looking for a driver engine. Offer him $500 and if he takes it, you'll be into everything at a very good price in my opinion.

That's what I was thinking.

[77 TRASHCAN]

Ask if you can look it over, first. Look for vertical scratches in the bores. I would want to spin the engine over to look deep into the holes. Crank bolt takes a 15/16 socket.

Pull some lifters out, look at them. See if they are all scratched up.

THEN, make your decision.

I'd buy it if it was close to decent. As mentioned, you'll need to completely take it apart, clean it up.
Those -8 heads are the lower compression of the 6X heads. They look like they need surfaced any way. Many here say you can take .030 without any other mods needed to anything else.
My stock 77 TA had the lower HP engine with the 6X-8 heads.. It was fun to drive. It has a 350 in it now, not so fun to drive...

My thoughts...

[steve25]

Milling a 6X-8 head only .030” for use on a 400 is a waste of one’s money, you need to go at least.045” to get any usable gain in compression.

You would be better off milling the blocks deck surface to get the pistons to stick up .005”.

[HWYSTR455]

Cometic makes a .027 gasket, not sure how much that would help without running the numbers though...


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[HWYSTR455]

Like I mentioned before, those heads would need to be completely gone thru, and would be better off switching to an aluminum head.

Out of box pair of SpeedMASTERS ARE like $1800, but my understanding is they need at least some minor work. Could probably get away with running them out of box, but there's risk involved.

Not sure you can get the iron heads for that or not, it looks like they need everything, and at that point would make more sense to at least go to a better casting.



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[67Lemons]

Speedmaster heads are an excellent choice for a low buck head BUT require round port manifolds or headers which add to the cost. I’ve been eying them for a few years now and the pricing on Black Friday is pretty tough to beat. Also some vendors sell a set with better components and carefully inspected/set up for a few bucks more.

https://pontiacspeedshop.com/speedma...eads-complete/

[73_Lemans_350]

Well guys, thanks for all the input! It turns out the guy selling it is the husband of a co-worker. I talked to her this morning and she said he sold it last night, so someone wasn't as hesitant as I was about it. Wish I would have gone and talked to him after finding out about the connection to him.

The search continues. Thanks again!