Top end build l48
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
There are a lot of variables in this equation, man. We haven't even discussed pushrod length. Yup, that's right, you're gonna need to figure out the required pushrod length, and order new ones. And you can't do that until the heads are on the engine. That should be about it for surprises, though.
Scott
Last edited by scottyp99; Jun 13, 2013 at 08:12 PM.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Scott
Thread Starter
Racer
Joined: Apr 2013
Posts: 366
Likes: 0
Well, what some people do, is just order pushrods that are .100" longer than stock. I guess it's better to be a little long than a little short. I think it's a bad idea, though. If the engine is going to be out of the car anyway, it's not that big of a deal. What is going on here is that the pushrod length is basically the adjustment for rocker arm geometry. You want the rocker pushing straight down on the valve stem. If the pushrod is too long, the rocker pushes the valve stem down and toward the center of the engine. If the pushrod is too short, the rocker pushes the valve stem down and toward the outside of the engine. Either way, it wears out the valve guide, and once the valve guide is worn out, the valve starts to rattle around on the valve seat, which wrecks it.......well, you see where I'm going here, right? It's not good. You want the pushrod length to be like Baby Bear's porridge.........juuuuuust right.
Scott
Scott
Le Mans Master
Joined: May 2007
Posts: 5,031
Likes: 1,121
From: North tonawanda NY
And im guessing that pushing the valve stem into the engine does not wear it out as fast as pushing outside the engine? I think ill just order ones .1 longer then stock. Im doing it in a friends garage so I cant just leave it there for a week while I measure and order more parts.
If your going with roller rockers you don't want to guess.... it can get ugly quick I got lucky with my 7.900 length ones before I knew about the tool... you can olways order one push rod off say eBay and make sure it works well then order more..
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Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
And im guessing that pushing the valve stem into the engine does not wear it out as fast as pushing outside the engine? I think ill just order ones .1 longer then stock. Im doing it in a friends garage so I cant just leave it there for a week while I measure and order more parts.
Try to wrangle a deal where you can have the engine at your friends garage for a longer time. It's gonna take longer than ya think to assemble the engine, anyway. And, as my Granpappy used to say "An ounce of prevention is worth a pound of cure."
Scott
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
It should cost about 100-150 bucks to have the heads machined. They'll have to be disassembled, if the shop has to do it, they'll probably charge extra.
For your RPM range I would also recommend 180cc runners. That too may only be only be in the ball park, you could end up with anything from 175 to 205 cc runners.
Push rod length will change. I would not guess on this get a pushrod length checking tool and checker springs to get it right.
http://www.summitracing.com/parts/cca-7702-1/overview/
http://www.summitracing.com/parts/pro-66793/overview/
Le Mans Master
Joined: May 2007
Posts: 5,031
Likes: 1,121
From: North tonawanda NY
I got my Dart 64cc heads milled down to 61cc for $90. They do not have to dissasemble the heads to do this job. .030 is usually the limit without having to alter the intake manifold due to the changing geometry of the head manifold interface. Mine went together without an issue at .030 off the face. The real limit turned out to be the intake valve. You can only mill off so much before you start to hit the intake valve on one side. In my case that would have only been .007" more. The dart advertised 64cc's but were really 66.7 to 67.1cc heads so could only get down to 61cc's in the end.
For your RPM range I would also recommend 180cc runners. That too may only be only be in the ball park, you could end up with anything from 175 to 205 cc runners.
Push rod length will change. I would not guess on this get a pushrod length checking tool and checker springs to get it right.
http://www.summitracing.com/parts/cca-7702-1/overview/
http://www.summitracing.com/parts/pro-66793/overview/
For your RPM range I would also recommend 180cc runners. That too may only be only be in the ball park, you could end up with anything from 175 to 205 cc runners.
Push rod length will change. I would not guess on this get a pushrod length checking tool and checker springs to get it right.
http://www.summitracing.com/parts/cca-7702-1/overview/
http://www.summitracing.com/parts/pro-66793/overview/
Drifting
Joined: Mar 2009
Posts: 1,253
Likes: 4
From: East Wenatchee (2hours from n e where) WA
Big mistake. Get your self an adjustable pushrod. adjust it to the length that gives the right pattern on the valve tip. lock it down and send it to your valve train supplyer and they will ship you the right pushrods. If you need to move the car around with out push rods in it then thats what you need to do. If the original pushrods are right use them. If they are close use them to get the car home while you wait for the right ones. If you are using stock length valves +.1 pushrods will be way way off.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
*sigh* I never should have even mentioned that .100" thing. Here is a Car Craft article that explains why it is important to set pushrod length properly, and one way of doing it.
http://www.carcraft.com/techarticles...h/viewall.html
You're going to find that you get a lot of pushback from folks on this forum for not doing it. Maybe some peer pressure will help:
C'mon, man! All the cool kids are checking their pushrod length! What's the matter, won't your mommy let you check the pushrod length? What are you, too chicken to check pushrod length? Buck, buck, buck!
Ya know, years ago, a friend of mine didn't bother to check his pushrod length. Now he's dead. That's right, he's dead! He got hit by a bus while walking across the street. It didn't have anything to do with the whole pushrod thing, but still, it makes ya think.........you don't wanna get hit by a bus, do ya? Well then, check your pushrod length, and look both ways before crossing!
Scott
http://www.carcraft.com/techarticles...h/viewall.html
You're going to find that you get a lot of pushback from folks on this forum for not doing it. Maybe some peer pressure will help:
C'mon, man! All the cool kids are checking their pushrod length! What's the matter, won't your mommy let you check the pushrod length? What are you, too chicken to check pushrod length? Buck, buck, buck!
Ya know, years ago, a friend of mine didn't bother to check his pushrod length. Now he's dead. That's right, he's dead! He got hit by a bus while walking across the street. It didn't have anything to do with the whole pushrod thing, but still, it makes ya think.........you don't wanna get hit by a bus, do ya? Well then, check your pushrod length, and look both ways before crossing!
Scott
Drifting
Joined: Jun 2007
Posts: 1,404
Likes: 1
From: Ansonia/NYC CT
It comes down to this. How rich are you? Can you afford to replace the motor, or to tear into it to replace parts? Time something you got tons of?
Yeah, me neither.
Measure your pushrods, and order the right length. You don't want one cut corner at the back of your mind nagging you every time you consider winding the old girl out to 6k rpms.
By the way, I had the good off of my car doing the top end for about a month, and then another 2/3 months after that working out kinks.
It's gonna take longer than you think. This is your first time. The car is over 30 years old. Trust me, it's gonna take a while. Take your time. Mistakes cost money, and can be ruinous.
Yeah, me neither.
Measure your pushrods, and order the right length. You don't want one cut corner at the back of your mind nagging you every time you consider winding the old girl out to 6k rpms.
By the way, I had the good off of my car doing the top end for about a month, and then another 2/3 months after that working out kinks.
It's gonna take longer than you think. This is your first time. The car is over 30 years old. Trust me, it's gonna take a while. Take your time. Mistakes cost money, and can be ruinous.
Thread Starter
Racer
Joined: Apr 2013
Posts: 366
Likes: 0
Ok thanks guys lol but remember i wont be doing it. My mechanic friend will be teaching me. I will let him know to measure the pushrods and tell me what length to order. Im sure he will let me keep it in his garage. Would using the oem rocker arms on it atm be cutting a corner?
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Ok thanks guys lol but remember i wont be doing it. My mechanic friend will be teaching me. I will let him know to measure the pushrods and tell me what length to order. Im sure he will let me keep it in his garage. Would using the oem rocker arms on it atm be cutting a corner?
Scott
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Thread Starter
Racer
Joined: Apr 2013
Posts: 366
Likes: 0
Well browsing craigslist today someone put up the same lunati cam that I wanted. Brand new in the box never used w/lifters for $100 so i am going to pick them up saturday. Now my questions is can i install my cam, timing chain, intake, lifters, and keep stock heads for a little longer while I save up enough money to buy the speedway heads? Will the stock heads work with the cam?
Also with me buying a new timing chain. Do you guys have any suggestions on a good one to buy? or even a good drive gear? lol
Also with me buying a new timing chain. Do you guys have any suggestions on a good one to buy? or even a good drive gear? lol