A minor mystery
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Mountain Pass
Joined: Oct 2004
Posts: 119
Likes: 5
From: SW Washington State
A minor mystery
Hi guys! I'm back. I was here awile back asking questions about my truck. Well, now it looks like I've got a buyer, and I've got MORE questions to ask. (And since I'll soon be building ANOTHER truck, I don't mind asking!)
My truck is a 78 supercab 4x4 with a 428. It's the motor I need to find out about. I know from the rebuild it's a 428 long block with 390 heads (it had 428 heads, but one was cracked) The guy who is interested wants to know if it's a "real" 428. How do I answer that!?
I'm going to spout some numbers at you. You tell me if they make sense and what it all means, okay? Some of this comes from notes I took while talking to the company who rebuilt the motor, so bear with me. k?
Camshaft Milling MtF4 (or maybe M+F4?)
484 intake lift
510 exhaust lift
duration at 50 (mph???) 204 intake 214 exhaust
Block casting number 352
Crank casting number IU
I dont have the head casting number, but I could sure pull the valve cover and look, if you insist!
Okay guys, fill my head with knowledge!
My truck is a 78 supercab 4x4 with a 428. It's the motor I need to find out about. I know from the rebuild it's a 428 long block with 390 heads (it had 428 heads, but one was cracked) The guy who is interested wants to know if it's a "real" 428. How do I answer that!?
I'm going to spout some numbers at you. You tell me if they make sense and what it all means, okay? Some of this comes from notes I took while talking to the company who rebuilt the motor, so bear with me. k?
Camshaft Milling MtF4 (or maybe M+F4?)
484 intake lift
510 exhaust lift
duration at 50 (mph???) 204 intake 214 exhaust
Block casting number 352
Crank casting number IU
I dont have the head casting number, but I could sure pull the valve cover and look, if you insist!
Okay guys, fill my head with knowledge!
Post Fiend
Joined: Sep 2004
Posts: 5,231
Likes: 1
From: Near Fresno, California
duration at 50 should be 0.050 - measures the time your valve is open in degrees. Starts when the valve opens 0.050 inch, stops when it closes to 0.050.
Valve lift is how wide the valve opens: 0.484 intake, 0.510 exhaust.
Block casting number "352" is not important. Crank casting number "IU" is for a 66 to 68, some early 69, 428 cranks.
You can read the head casting numbers near the center spark plugs without removing the valve covers. You might as well get it and post it again, your buyer will want to know.
The only way to know for sure if it is a 428 is to measure the bore or there is a special number behind one of the freeze plugs that ids the 428 blocks. I guess it is possible that it is a 390 block with a 428 crank (making it 410 cu inch.)
If it were me, I would tell the guy that it was sold to me as a 428, and I beleive it to be one. I would give him whatever receits I had and hope he was satisfied.
The big thing is that you have proof that it has a 428 crank.
Valve lift is how wide the valve opens: 0.484 intake, 0.510 exhaust.
Block casting number "352" is not important. Crank casting number "IU" is for a 66 to 68, some early 69, 428 cranks.
You can read the head casting numbers near the center spark plugs without removing the valve covers. You might as well get it and post it again, your buyer will want to know.
The only way to know for sure if it is a 428 is to measure the bore or there is a special number behind one of the freeze plugs that ids the 428 blocks. I guess it is possible that it is a 390 block with a 428 crank (making it 410 cu inch.)
If it were me, I would tell the guy that it was sold to me as a 428, and I beleive it to be one. I would give him whatever receits I had and hope he was satisfied.
The big thing is that you have proof that it has a 428 crank.
Last edited by WillyB; Nov 29, 2004 at 02:00 AM.
Thread Starter
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Mountain Pass
Joined: Oct 2004
Posts: 119
Likes: 5
From: SW Washington State
Re: Re:A minor mystery
duration at 50 should be 0.050 - measures the time your valve is open in degrees. Starts when the valve opens 0.050 inch, stops when it closes to 0.050.
So, if the measured duration is .204-.214 and should be .050, what does that mean?
I'm going to be crawling around looking for numbers today. I'll post back with whatever I find. And I think you're right about what to tell him (whichis what I've done so far) but my natural curiousity got to me. Besides, I'm learning a lot that I can apply to another truck!
Thanks.
So, if the measured duration is .204-.214 and should be .050, what does that mean?
I'm going to be crawling around looking for numbers today. I'll post back with whatever I find. And I think you're right about what to tell him (whichis what I've done so far) but my natural curiousity got to me. Besides, I'm learning a lot that I can apply to another truck!
Thanks.
Post Fiend
Joined: Sep 2004
Posts: 5,231
Likes: 1
From: Near Fresno, California
Almost - from what you have posted I would say that your cam has the intake valves open 204 degrees, and the exhuast valves open for 214 degrees.
Remember that each stroke in a 4 cycle engine is 180 degrees - likely your cam is opening the exhaust valve towards the bottom of the power cycle, leaving it open through the exhaust cycle, and for a short bit at the start of the intake cycle.
Crane cams has a camshaft Q and A page on their website which helped me understand the different cams and the terms used.
Remember that each stroke in a 4 cycle engine is 180 degrees - likely your cam is opening the exhaust valve towards the bottom of the power cycle, leaving it open through the exhaust cycle, and for a short bit at the start of the intake cycle.
Crane cams has a camshaft Q and A page on their website which helped me understand the different cams and the terms used.
Thread Starter
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Mountain Pass
Joined: Oct 2004
Posts: 119
Likes: 5
From: SW Washington State
mystery
Okay, I'm begiing to catch on here, I think! *grin*
I'll check out the crane cams page. Thanks! And please read my posting to the other post (education) I've got more casting numbers to ask about. And something else.
I'll check out the crane cams page. Thanks! And please read my posting to the other post (education) I've got more casting numbers to ask about. And something else.
