Engine rebuild...need ideas

[Benm109]

That engine sounds like a great deal. A Pontiac 400 engine for around $1100 is a great deal. If I had the money I would buy it!

About your questions:
About him calling it a 400 and a 406 block, I don't know

You can still buy performance parts for your 400. Everybody has different opinions on what is better than what. Do your own research and pick what you want for performance parts. Everybody will tell you something different.

You usually have to reset valve lash after you run the engine for a while (especially on flat tappets lifters, not so much on hydraulic lifters) since the rockers move so much and can't be adjusted in the best position without the engine running or turning for a while (somebody can explain this better than me, I'm still a newbie to certain aspects of engines).

When he says 10-10, he is saying that the crankshaft was ground down .010" on the main and rod journals. This is pretty typical for an engine rebuild.

I would go for the roller tip rockers and cam, too. It is also worth it, in the long run. Good luck!!

[70formula400]

I talked to some guy on another forum...and I posted the same thing about the engine and this guy I talked to said he didnt like the looks of it at all. This is what he said about it...

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In my opinion, I'd run for the hills! Several comments that he makes scare me. To keep it short as possible, I'll just list them:

1. Boring the engine will not increase the compression ratio.
2. "No increase w/Performer intake" - I've never checked the flow numbers compared to a stock 4bbl but I find this hard to believe.
3. "Lessor performing aftermarket carbs" - Then I guess all of those racers (myself included) have just been throwing away our money on aftermarket carbs? Ill admit, a properly built and tuned Q-jet can outperform many stock aftermarket carbs but off the shelf comparisons between the two and I think most aftermarket will win.
4. What's a "good Pontiac" Q-jet? Weren't they all built by Rochestor?
5. He has a degree wheel to "properly degree in" the cam. Okay.
6. The rods have been resized and are not going to knock - well, that's a reassuring statement.
7. There "should" be no leaks. Well, I would hope not.
8. The rear main seal was installed "properly". If this guy knew anything about Pontiac engines, he would have tossed the factory rope seal and installed a BOP seal.
9. It's possible to get an oil leak on a rebuilt engine. I guess I'm bragging here but I've built countless engines and have NEVER had an oil leak. (knock on wood).
10. He's willing to bet that the crank is only 10-10. First off, to type that properly, it should be .010/.010. Sorry, a little anal at times. If a good machine shop had turned the crank, it should be written on his receipt. If he did it, he should have made a record of it somewhere.

By the way, he's referring to machining the crank down 10 thousandths of an inch on the rod and main journals. Each number represents the rod and mains: .010/.010.

If it were anymore than .020/.020, I'd toss the crank unless it were being used in a stock motor. That's just my opinion, though.

Hope that helps and in my opinion, you should stay away from this guy completely.
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What do you guys think of what he said above? Do any of you have bad feelings about the guy trying to sell the engine or not?

[Benm109]

I don't know now. I see the other guys points on the sellers wording. I personally think he was just trying to give as much information as he could about the motor and reassure the buyer. Not everyone knows everything about rebuilding an engine (for example, me, I rebuilt my motor about 3 months ago and I don't know everything about engines and it was my first time but mine has turned out fine). I'd say that as long as he has all the receipts, bills, etc. to back up everything that he did, it should be fine. If he doesn't have any receipts or proof of some kind, don't buy it. If he can prove he did all the things he said he did I would buy it from him.

Just talk to the seller some more and see if he knows his stuff or not or acts like an (you know)hole or treats you like an (you know)hole. Basically, if he has proof, it should be a fine motor.


Also, the guy who is selling the engine sounds like a newbie to me. His wording hints at being a newbie (trust me, I know, I'm one). All they ever seem to say is what the hear "professionals" say. You know, stuff like, nitrous will explode in your car if you ever try to use it, Edelbrock parts suck, platinum spark plugs are always better than regular stock spark plugs, stuff like that although they haven't actually tested or had these parts. They just hear it and repeat it. Maybe his suspicious wording is him just being a newbie.

[markd79ta]

Personally, I would find a 400 candidate and a good Pontiac engine builder in your area. The 406 is just a .30 over 400 block (not sure about his math)...no big deal. However, I am not too sure about what this guy put into this engine. Depending on the 400 you get, you will need to choose your piston size based on the CC of your head. Some of the 6x & 5C heads had very large chambers thus reducing the compression ratio. I went back and looked again and I misspoke earlier. The '77-'79 W72 400 had the 6x-4 head with the smaller 89-95 CC chamber while the early heads in the RA engines had CC chambers in the 70s and the standard 6x and I believe 5c were in the 100+cc area. The difference is the compression ratio you net from 11:1 to 7.5:1 depending on which set of heads you have. Now, you can very that with piston size to increase or decrease the compression ratio. Many of the early Pontiac heads had 2.11 intake and 1.77 exhaust valves while the later ones had 2.11/1.66 valves. The flow rates very depending on head. Some were balanced between intake and exhaust, some overflowed exhaust, some underflowed...there are too many tests to read with varying results. Another factor is cam size and intake. If you are going to use a stock grind, stay with the stock intake. If you want to get a little more wild, go with an aftermarket or single plane intake. The stock cams and intakes were great from idle to about 5,000rpm. However, you can change that. I don't agree with the earlier statement that a W72 is not a good builder. Yes, it did have lower compression approx 8.2 to 8.5. However, the 6x-4 heads have decent flow numbers and pistons can be changed to net you in the 9.x:1 ration perfect for a daily driver. Additionally, the Stock HP ratings were based on the new HP scale along with the fact that the cam was a 274/298 total duration low lift cam with .364/.407 of lift, one of the cast manifolds had a butterfly for a heat riser, small y-pipe, a single pellet style convertor(absolutely horrible) dumping into duals from there. If you put in a better cam, headers, duals, a better intake, the engine rumbles (loudly). The W72 was not just another smog engine and what many in the Pontiac circles consider a great sleeper.

Anyhow, I know there is a lot to absorb. If I was in your shoes, I would be looking at a good 400 builder with either the Ram Air heads(see cast numbers I sent on the following website), 6x-4, or aftermarkets, 9.5-10:1 compression pistons, single plane Torker Edelbrock manifold (since you don't have the shaker, go with the single plane), Edlebrock Performer 800cfm carb, and a good 1,500-6,000rpm Comp Cams grind. Anyhow, these flow-numbers along with the stamped number may help you with your engine selection. http://www.wallaceracing.com/ultimateflow.htm This also tells you what compression ratio the motor had with this head. Also, remember, those 11:1 compression ratios were possible with leaded high octane fuel not exactly in abundant supply these days. You need to build you motor based on what fuel you will be running through it.

[70formula400]

When you say a 400 candidate...you mean a rebuildable 400 engine that looks to be in good shape? How exactly would I find a good Pontiac engine builder in my area? I heard a few people on this site saying that there is a guy in San Pedro...about 1hr 20 minutes from me who has built some engines for some of the guys on this board, and he says he is great.

[markd79ta]

Originally posted by 70formula400
When you say a 400 candidate...you mean a rebuildable 400 engine that looks to be in good shape? How exactly would I find a good Pontiac engine builder in my area? I heard a few people on this site saying that there is a guy in San Pedro...about 1hr 20 minutes from me who has built some engines for some of the guys on this board, and he says he is great.

Correct. Give the guy a call and ask him about 400s, whether he has done any, what he recommends, etc. ...get a feel for him. I usually talk shop with somebody before I trust them with my car or any part there of. If they appear to be a dork, I find somebody else. Even for $1,100, the engine you are looking at is nice. You can always make adjustments later, have somebody go through it before install, etc. I would make sure he tells you the casting number on the heads so you know exactly what they are so you can hold him to it. If he bored it .30 over, find out which brand (type) pistons he used along with compression at what CC size. He apparently used the stock cam. I would be inclined to change the cam along with the carb/intake of my choice. You can change the cam later, but it is nice to break in the engine as one unit and stick with it. However, you can go with it stock, see how it goes, save some money, and go crazy later. His comments about aftermarket intakes and carbs make sense ONLY in that if you mismatch your carb, intake, cam, or if you downgrade from what you have stock, you will likely have a mess. It kinda all works together...Pontiac big blocks are little temperamental. Personally, I would pull the pan and heads, mic everything down, and check the bearings, and rotate through the valves after buying a built engine...just to be sure I got what I wanted and it was done right. My buddy just bought a motor where the builder managed to bend one of the valves...what a mess...my friend pulled the head and brought it back to them...got a new one.

[N20LT4Bird]

I think your buddy on the other board was a little nit picky about the sales pitch on the engine. He twisted ALOT of what the guy was trying to say. I would ignore your buddy on the other board as he sounds like hes trying to be a hot shot. I agreed with most of what the engine seller had to say. He has his opinions about the intake and carbs....thats O.K. THere are differing opinions. I happen to like the quadrajet carb myself as well.....someone else may like a holley....whatever.

The guy is absolutely right about it being a 300 horse version of the 406 (400 bored .030). He is right in saying that compression will increase with a alight overbore (duh). He is also right in warning you about the possibility of the Pontiac rear main leak. It is very common for these to leak - its a rope style seal and just about every one leaks. Yes, there is a differnent type of seal that could be installed, but just because he used a rope seal doesnt mean he doesnt know Pontiacs!

I think its a good buy at 1100. As long as its built well, its a good buy for what he has. I would just get a guarantee in writing as it is going to start and run well. For the money, even if there was a problem, and he stiffed you, you could have it fixed and still be ahead of the game. Like I said, I have about 1800 into my GTO motor and there is nothing fancy done to it. Pontiac engines are expensive. It a little gamble to take as you dont know the guy, but I think your getting your money's worth just in parts.