Pistons for a 434 sbc
Thread Starter
Racer
Joined: Oct 2000
Posts: 491
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From: Los Altos Hills, CA
Pistons for a 434 sbc
I am trying to dial in a 434 combination but cannot seem to find pistons. Hard to believe that piston manufacturers are ignoring this engine. Here's where I'm at...4.155 inch bore, 4 inch stroke, and pistons at deck height, .041 inch head gasket to set quench at .041. This set-up requires a total of 90cc of head and piston combustion volume for 10:1 compresssion. That is, if the head has a combustion chamber volume of 76cc (AFR for instance), the piston would have to be dished 14cc for 10:1 compression. Likewise a 64cc head would need a dish of 26cc.
The only pistons I can find are -5 or -6cc flat-tops (JE, Wiseco, Mahle), and a -20cc Mahle. Are there other stock pistons out there that I am missing?
The only pistons I can find are -5 or -6cc flat-tops (JE, Wiseco, Mahle), and a -20cc Mahle. Are there other stock pistons out there that I am missing?
Race Director
Joined: Sep 2000
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From: The Top of Utah
I just visited the J&E web site. Their "Automotive" PDF catalog is from 2002. The "Sportman" catalog shows the dish you want, but not the part numbers you're going to need. I have a set of J&E's for a 4.125" bore with a 4.00" stroke for 5.85" rods and a 16 cc dish. Give them a call (and probably the others, too). They'll come up with what you want.
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Race Director
Joined: Sep 2000
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From: The Top of Utah
I bought the engine, built, new. I've torn it down to check it all out. I don't, for sure. know the compression height of the piston. I believe it IS .150. I had to have another .007" shaved from the top of the block to get my zero deck. The rods are Crowers. OH, by the way, the ring pack fits above the pin. There is no encroachment of the oil ring into the pin bore.
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Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
10:1 is to low IMO for a performance motor. That's why I have flat milled heads to bring the -20 cc dished Wiseco pistons up in compression.
Aluminum heads work fine in the 10.5 - 11.2 range if your running a cam in the mid 230@.050 or bigger range. These big 427+ ci motors like lots of cam.
Aluminum heads work fine in the 10.5 - 11.2 range if your running a cam in the mid 230@.050 or bigger range. These big 427+ ci motors like lots of cam.
1st Gear
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Right now Im building a 434 6" rod motor. Compression is 10.6:1 but when I bought my rotating assembly I had to stress the compression to them for pump gas. So it took a couple days more but they sent me a custom set of Lunati forged pistions to go with what I want. These pistions were set for 76cc heads but I about to get a set of Pontiac 867 heads which are I think 64cc (have to inspect them myself). So I can either try to dish mine or just get another set.
Thread Starter
Racer
Joined: Oct 2000
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From: Los Altos Hills, CA
gkull:
I wasn't aware that Wiseco made a -20cc dish. Is that an off the shelf part? I was also getting nervous about getting up towards 11:1. Nice to hear of someone who has a working combo in that range. Do you run mechanical rollers? This is another area I can't get good info on. Can a mechanical roller live on a street/weekend race car?
NewmanGTP:
How much dish do you have on the Lunatis? I assume the 76cc heads were the AFR's. I can't seem to find a fit with the AFR's, they only recommend the 210's for street use and I think the 210's would be a little small for a 434. The 227's have offset rockers and they don't recommend those for the street without shaft rockers (read $$$). I also don't like hearing all the reliability issues with AFR's.
I'm looking at the Brodix M2 T1's. They've got a 68cc chamber so a bigger dished piston is needed.
I wasn't aware that Wiseco made a -20cc dish. Is that an off the shelf part? I was also getting nervous about getting up towards 11:1. Nice to hear of someone who has a working combo in that range. Do you run mechanical rollers? This is another area I can't get good info on. Can a mechanical roller live on a street/weekend race car?
NewmanGTP:
How much dish do you have on the Lunatis? I assume the 76cc heads were the AFR's. I can't seem to find a fit with the AFR's, they only recommend the 210's for street use and I think the 210's would be a little small for a 434. The 227's have offset rockers and they don't recommend those for the street without shaft rockers (read $$$). I also don't like hearing all the reliability issues with AFR's.
I'm looking at the Brodix M2 T1's. They've got a 68cc chamber so a bigger dished piston is needed.
Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by gkull
Aluminum heads work fine in the 10.5 - 11.2 range if your running a cam in the mid 230@.050 or bigger range. These big 427+ ci motors like lots of cam.
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Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Originally Posted by Cris
gkull:
I wasn't aware that Wiseco made a -20cc dish. Is that an off the shelf part? I was also getting nervous about getting up towards 11:1. Nice to hear of someone who has a working combo in that range. Do you run mechanical rollers? This is another area I can't get good info on. Can a mechanical roller live on a street/weekend race car?
I wasn't aware that Wiseco made a -20cc dish. Is that an off the shelf part? I was also getting nervous about getting up towards 11:1. Nice to hear of someone who has a working combo in that range. Do you run mechanical rollers? This is another area I can't get good info on. Can a mechanical roller live on a street/weekend race car?
My last motor ran fine for a total of 25,000 miles with 11.2 compression and solid rollers. I really think that with prior proper planing you can get 20,000 miles out of roller lifters. One set of mine that failed were right at 20,000. It was a no big deal, bearings in on wheel failed and beat up the billet cam.
If your not going to run over 6200 rpm H-rollers will work fine. I even think that h-rollers and S-rollers make simular power if they are ground the same.
Right now my 427 has a H-roller cam only I'm running S-rollers on it. I was instructed to run .010 - .012 lash. It makes the valve train so quiet compared to my older cams that has anywhere from .018 to .022 hot lash. I'm running solids because the H-roller cam I have makes great power out to over 7000 rpm in my combo.
Thread Starter
Racer
Joined: Oct 2000
Posts: 491
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From: Los Altos Hills, CA
gkull:
I could live with 20,000 miles. How much spring pressure do you run? And whose mechanical rollers?
My guess at a cam right now is about .600" lift with around 240 ish at .050. Am I on the right track?
Sorry for all the questions, but getting info on 434's is not easy. Even the manufacturer's tech lines are a little unsure on what to put in these motors.
I could live with 20,000 miles. How much spring pressure do you run? And whose mechanical rollers?
My guess at a cam right now is about .600" lift with around 240 ish at .050. Am I on the right track?
Sorry for all the questions, but getting info on 434's is not easy. Even the manufacturer's tech lines are a little unsure on what to put in these motors.
Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I'm using 1.65 intake rockers to get my net lifts at .620 The reason is: most common heads have near max flow at .600 The gain to .700 is minimal. So you just want to hold the valve at over .600 for the longest time.
I'm not saying that my cam is the greatest. But it's 242/248 110 I also installed 4 degree retarded to help the top end. I figured that if I didn't like it all I have to do is pull the water pump off and the top of the two piece cover. and rekey the cam a few degrees.
I've run seat pressure anywhere from present 180 to 225 pounds.
Seat pressure is not the number to worry about. Open pressure from spring rate determines if your lifters can follow your cam profile at high rpm. So I run about 560# open at .620
I'm using the Crane pro lifters Vert bar. Crane billet chain set.
I'm not saying that my cam is the greatest. But it's 242/248 110 I also installed 4 degree retarded to help the top end. I figured that if I didn't like it all I have to do is pull the water pump off and the top of the two piece cover. and rekey the cam a few degrees.
I've run seat pressure anywhere from present 180 to 225 pounds.
Seat pressure is not the number to worry about. Open pressure from spring rate determines if your lifters can follow your cam profile at high rpm. So I run about 560# open at .620
I'm using the Crane pro lifters Vert bar. Crane billet chain set.
Last edited by gkull; Apr 14, 2005 at 10:30 AM.
Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
You want to have heads that flow in the low 300 cfm range for a 434ci.
For street use. You have to think about what big blocks have. They often have 300+ cc intake heads. You can't look at it the same because of the valve arrangement. CFM is the key and your intake manifold size of the runner. Single planes and the whole intake track has to matched to your rpm.
The best single planes are IMO are the world products or an off shoot with custom fuel rails with on the low end FAST injections. That is where you can really spend the money. The $8000 computers if you really want it to run .
Mine runs nice I only have so many miles on it so i have not tested it.
I can tell you that the difference between a mid 500 hp 383ci and 427 is great. It's instant spin of my tires at a stop light. my 3500 9.5 inch and 4.11 with a racing 700r4 add to it
For street use. You have to think about what big blocks have. They often have 300+ cc intake heads. You can't look at it the same because of the valve arrangement. CFM is the key and your intake manifold size of the runner. Single planes and the whole intake track has to matched to your rpm.
The best single planes are IMO are the world products or an off shoot with custom fuel rails with on the low end FAST injections. That is where you can really spend the money. The $8000 computers if you really want it to run .
Mine runs nice I only have so many miles on it so i have not tested it.
I can tell you that the difference between a mid 500 hp 383ci and 427 is great. It's instant spin of my tires at a stop light. my 3500 9.5 inch and 4.11 with a racing 700r4 add to it
