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400 build

  
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400 build

 
zman123 zman123
Enthusiast | Posts: 531 | Joined: 06/08
Posted: 03/28/13
07:57 AM

I have a 400(+.030) stock replacement dish pistons, 64cc World Sportsman II iron heads, comp extreme 4x4 cam (210/218 @ .050), edelbrock intake, MSD dist and ignition. I had this engine in a 77 3/4 ton 4x4 with a 700R4, 3.73 gears and 33 inch tall tires. After about 20,000 miles one of the pistons gave up due to detonation. I'm assuming because of the high gear ratio and lockup converter the engine was always lugging in OD at lower speeds. I pulled it and put in a 350 and 4.56 gears, the 350 runs good but now I think I'd like the extra torque back the 400 would give me. Same heads and dish pistons maybe a different cam. Any suggestions?  

76Skylark 76Skylark
Guru | Posts: 853 | Joined: 12/11
Posted: 03/28/13
08:22 AM

I would think the 4.56 rear gear has fixed the lugging Problem   but 33's are kinda tall. If in driving down the road you are under 2200 rpm or so... drop it into 3rd. but the low rpm lugging isn't what caused the Detonation, I wouldn't doubt it is the Fuel or timing set to high.  

redneckjoe69 redneckjoe69
Addict | Posts: 2337 | Joined: 03/10
Posted: 03/28/13
09:38 AM

out of curiousty, do the heads have the steamholes drilled?  just wondered if that could effect detonation?     i agree, the 4.56 gears have probably helped stop the lugging issue.   cam seems about right.   do you remeber what the total timing was on the 400?  

68scott385 68scott385
Guru | Posts: 1990 | Joined: 10/09
Posted: 03/28/13
10:36 AM

I have to concur with fuel/timing being the main concern in regards to the detenation.

I had a truck w/31" tires/4.11 gears/700r4, remembering its characteristics, I'd think the 4.56 gears/33" tires would work together well.

IMO, go for the 400 rebuild but pay extra attention to the timing & fuel curves.  
68scott385 68scott385 68scott385

zman123 zman123
Enthusiast | Posts: 531 | Joined: 06/08
Posted: 03/29/13
06:56 AM

I'm thinking it was the gearing combined with the lock up converter. Total timing was 34-36 degrees. Yes, I had the steam holes drilled in the heads before I put them on. I don't think the 64cc heads were out of line for compression with the dish top pistons.  

68scott385 68scott385
Guru | Posts: 1990 | Joined: 10/09
Posted: 03/29/13
08:49 AM

I wouldn't toss the converter yet. In my experience the lock-up feature only reduces rpm by 200 but it reduces heat in the trans by being locked up. A good auxillary cooler correctly plumbed into the system could eliminate the additional heat of a non-lock-up converter.  
68scott385 68scott385 68scott385

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 03/29/13
04:57 PM

Icon Quotezman123:
I have a 400(+.030) stock replacement dish pistons, 64cc World Sportsman II iron heads, comp extreme 4x4 cam (210/218 @ .050), edelbrock intake, MSD dist and ignition. I had this engine in a 77 3/4 ton 4x4 with a 700R4, 3.73 gears and 33 inch tall tires. After about 20,000 miles one of the pistons gave up due to detonation. I'm assuming because of the high gear ratio and lockup converter the engine was always lugging in OD at lower speeds. I pulled it and put in a 350 and 4.56 gears, the 350 runs good but now I think I'd like the extra torque back the 400 would give me. Same heads and dish pistons maybe a different cam. Any suggestions?

Zman: With the experiences I've had with the 400s and its quirts. Do you remember if the passemger side was the side the was detonantig. The reason I'm asking that when the heat riser stuck or over time became frozen, the heat in that heat was high enough the gall the valve in the guide and sometime would move the guild the in the bore. Then you would hear a click, click, click. and it was the the guide,valve, spring and the whole assembly banging up and down. But because the steam holes wheren't there made more heat.

My buddy bought a 1 ton with 4:56 gears ans we had the coolingsystem all flushed out with a 4bbl.400 redid a set of heads. He installed a nice set of heads. He pulled he show car all over New England It was running fine.

Bob  

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 03/29/13
05:12 PM

I might add at the first sign of the temperature starting to rise , pull over and let it cool down. If you are running an automatic, install the largest trans cooler you can fit between the fenders. Use a 50/50 coolant/water mix. Or a 70/30 coolant water mix. Use the temperature pickup in th e intake manifolfd. Using the temperature probe in the cylinder head will show a higher temp.
 
Bob  

zman123 zman123
Enthusiast | Posts: 531 | Joined: 06/08
Posted: 03/29/13
07:54 PM

Bob, I've never had a heat issue with the truck, already had a trans cooler, driver's side (#5) piston was the one that gave up (top ring groove broke), no heat riser, headers, Edelbrock EPS intake with Holley 670 carb and World sportsman II heads (200cc) it gets plenty of air (and gas) I'm running 87 octane with the 350 and get absolutely no knock at any speed with the same set up except flat top pistons.  

redneckjoe69 redneckjoe69
Addict | Posts: 2337 | Joined: 03/10
Posted: 04/02/13
12:19 PM

how does the bore measure in that pistons hole?   i saw you mention the motor was bored.   wondered if somehow they didnt get that one perfect?  especially up top?  

zman123 zman123
Enthusiast | Posts: 531 | Joined: 06/08
Posted: 04/02/13
07:43 PM

Joe, the bores are good. It only took one look at the pistons to figure out the cause. Definately the detonation. In fact, I will probably just run a hone down the bores before putting new pistons in.  

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 04/03/13
05:16 PM

I remember back in the early years GM installed a heat rise on the passengerside exhaust pipe. As it became older it either froze up or it rattleted to best the band.
  But there was a nother problem with it. GM installed a double wall exhaust pipe. That pipe would collapse and you didn't know it.

The biggest problem it caused was over-heating. You could go to the corner and it would over-heat.

Let it idle for 2 minutes and it over-heated.

Guys changed everything they normally would change. My brother had a 1970 chevelle. I was the last person they called. They did the whole nine yards. I told him to drop the front pipe and see if the overheat power goes away. Thats what it was.  

zman123 zman123
Enthusiast | Posts: 531 | Joined: 06/08
Posted: 04/03/13
08:00 PM

No overheating issues ever with this motor. Headers and dual 2 1/2" pipes.