Piston ID and tight rods
March 25th, 2019, 05:56 AM
#1
Registered User
Thread Starter
Join Date: Aug 2010
Location: Economy, Nova Scotia
Posts: 987
Piston ID and tight rods
I've removed the crank from my previously rebuilt 71 455 and noted the number 961P on the underside of the pistons. I can't find any info on that piston. Any idea?
Secondly, I know this engine had a piston replaced a few years back due to a broken land and ring. I'm guessing due to pre -ignition, as it was pinging excessively when I tried it out. The dwell was only 20 degrees causing the timing to be far advanced. Combined with it running hot with an old two row rad, I can see why this happened. The piston was replaced with a Silvolite cast 1631 to match the other pistons dish, which I realized last night is a high compression piston, so no wonder pre ignition was more likely. Now I noticed on all but one of the other pistons, the rods don't move easily on the pistons. I'm surmising preignition has distorted the piston/pin area and I'm now into a full tear down. Probably? Oh joy.
Low compression or high comp pistons? If I go high compression again should one go with forged and stay away from cast? I'm looking for a nice smooth and quiet engine but would not like to lose power. It is in my 71 SX convertible, so just a nice cruiser with a 2:56 rear. I was reading good reviews about a Howard 510011-12 cam for a basically stock engine.
Opinions, comments welcomed.
Secondly, I know this engine had a piston replaced a few years back due to a broken land and ring. I'm guessing due to pre -ignition, as it was pinging excessively when I tried it out. The dwell was only 20 degrees causing the timing to be far advanced. Combined with it running hot with an old two row rad, I can see why this happened. The piston was replaced with a Silvolite cast 1631 to match the other pistons dish, which I realized last night is a high compression piston, so no wonder pre ignition was more likely. Now I noticed on all but one of the other pistons, the rods don't move easily on the pistons. I'm surmising preignition has distorted the piston/pin area and I'm now into a full tear down. Probably? Oh joy.
Low compression or high comp pistons? If I go high compression again should one go with forged and stay away from cast? I'm looking for a nice smooth and quiet engine but would not like to lose power. It is in my 71 SX convertible, so just a nice cruiser with a 2:56 rear. I was reading good reviews about a Howard 510011-12 cam for a basically stock engine.
Opinions, comments welcomed.
March 25th, 2019, 06:58 AM
#2
Registered User
Join Date: Sep 2011
Location: Plano, TX
Posts: 1,845
If you want to know what the pistons are, then post a picture of the top and the pin side and someone will probably recognize them.
As for compression, that's part of a the larger question of what setup you want. You gotta take the whole build into consideration or else you'll have big problems like you found. High compression, with the right cam and ignition, works wonderfully. We don't have as many options as the BBC crowd, so dialing in your combo requires a few tradeoffs.
What heads, intake, trans do you have? What's your performance target?
That howard cam is extremely mild. "cruiser" would be an understatement.
As a wild, and possible useless, bit of guidance, I'd say aim for 9:1 CR with iron heads and a moderate cam. A 455 will easily play with a cam in the 220-ish duration range.
As for compression, that's part of a the larger question of what setup you want. You gotta take the whole build into consideration or else you'll have big problems like you found. High compression, with the right cam and ignition, works wonderfully. We don't have as many options as the BBC crowd, so dialing in your combo requires a few tradeoffs.
What heads, intake, trans do you have? What's your performance target?
That howard cam is extremely mild. "cruiser" would be an understatement.
As a wild, and possible useless, bit of guidance, I'd say aim for 9:1 CR with iron heads and a moderate cam. A 455 will easily play with a cam in the 220-ish duration range.
Thread
Thread Starter
Forum
Replies
Last Post
cts-v
Big Blocks
10
January 10th, 2009 04:55 PM
