420 rebuild thread

1slow95

Founding Member
May 16, 2002
1,797
3
48
ohio
In case you missed it, I killed the #8 piston last fall at the drag strip. Here's the destruction pics...

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After some researching on the net, I think the problem was that I didn't get enough clearance on the file fit rings. It seems like the #8 cylinder runs hotter than the rest and the rings expanded too much and didn't have anywhere to go but up when the ends met. I also may have damaged the piston from running lean.

I sent the heads to Fox Lake for repair. They fixed the damage, replaced two valves, cut all the valve seats, clean and grind the valves, and installed all new valve seals. Here's the finished product.

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I picked up a '74 351w block locally. Clearanced it for the stroker crank dropped it off to the machine shop. I read that it should have at least .060 clearance between the rod bolts and the block, and the closest I measured after I was finished was a little over .070.

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I was told the block was .030 over, but the machine informed me that it's .040 over. Of course they didn't tell me that until they were checking piston clearances with my .030 over pistons. :( So instead of 418ci I have 420ci.

I went with Ross Racing -31.20cc forged pistons for 9.5:1 compression. I had 10.5:1 previously so I'll probably lose a little power, but I can make up for that with a turbo next year. :)

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Old pistons removed from the rods
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Ed Curtis @ FTI says my current cam will work great if I install it at a 110 centerline. I thought I had it at 112 centerline last time, but when I degreed it this time I came up with 110 installed exactly like it was before. I did it with the heads off this time, put a dial indicator on the #1 piston and when it stopped moving I set the degree wheel at tdc.

I got everything back from the machine shop last friday and started putting it all together. I got the rotating assembly installed, then the cam wouldn't go in. :fuss: Had to take it all apart and go back to the machine shop for new cam bearings.

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Got it back, painted, and 7 pistons installed. Broke a ring installing the #1 piston. It came out of the ring groove and I crushed it with the ring compressor. :bang: Called the manufacturer and they sent me a new one for free. :) Installed it last night, and installed the heads after checking piston to valve clearance. And that's where I'm at right now. Hoping to drop it in the car tonight and have it fired up by monday.

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You threw me with your username, I'm used to your other one. Anyway, it's nice to see that you are getting it back together. Its a shame you have a 351 block as I'm considering selling my single T76 setup since I'm having so much luck NA.
 
You threw me with your username, I'm used to your other one. Anyway, it's nice to see that you are getting it back together. Its a shame you have a 351 block as I'm considering selling my single T76 setup since I'm having so much luck NA.

same here lol...the new name threw me off before i opened the thread.


Which hotside do you have paul? Im sure it could still fit a 351 with a few changes.





So did you have to buy new pistons? Im assuming so:(
 
I should also be dittoing on all the people that should be saying Paul you WILL put the turbo on your car.

Lol i cant blame him for not wanting to put it on. If i was him i'd hold onto the turbo stuff, and see what i can get out of the combo n/a wise with a new cam perhaps. Then in a few years if he grows to be bored with it...he can toss the turbo stuff on.:shrug:
 
My profile got messed up in the last stangnet update so I just changed my user name. :) Should have put Low-5.0 in the thread title...

Anyways, got the engine and transmission set down in the car tonight. :rock: I just need to get rockers installed and adjusted, dizzy (EPM) installed, and upper intake on and the engine is finished. The rest is just bolting the accessories and exhaust back on and wiring. Also got an Innovate LC-1 wideband I need to install. Hoping to have it fired up monday or tuesday. I'm heading up to Columbus in the morning to help my cousin finish his 4.6l kenne bell build, so I won't have time for mine til monday.

Here's some pics from tonight. This was a bare block on monday btw. Been working on it every night.

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same here lol...the new name threw me off before i opened the thread.


Which hotside do you have paul? Im sure it could still fit a 351 with a few changes.



So did you have to buy new pistons? Im assuming so:(

Yeah, all new pistons and new block. The rest is from my old setup.


I have a welder and I'm getting decent at it. I was planning on building my own hot side, so modifying one to fit a 351 shouldn't be too much trouble. How does the T76 compare to the S475 turbo? That's what I was planning on going with. Need to get my credit card paid down first though. :(
 
Rebuilding and engine is always fun until there is a setback.:nonono:

I just rebuilt a 460, It was fun when there was progress to be made but when your waiting on the right parts:mad:.

Hope you get it up and running without any more issues.:nice:
 
I really don't like the look of that head....even after the repair. Seems to me like they should have spend a little more time on that section above the exhaust valve...especially knowing that you're going to be running any sort of forced induction with the engine? :shrug:
 
Yea Brian i noticed that too. I thought they coulda been filled in a bit more. I had a similar repair done by Brian at ADPerformance....it looked spectacular. If i didnt tell u what happened u wouldnt have guessed.
 
i was fooled by the name too Mike. Gotta give us a heads up next time!!

great progress so far. that's cool that Ross just exchanged the pistons and you didn't have to buy fresh ones and try and offload the .030s.
 
I'm anxious to see your dyno results after its all buttoned up. I'm running that same intake on my 408 but I'm considering getting a super vic..I would like to keep the victor efi cause it would be cheaper. Decisions
 
I'm anxious to see your dyno results after its all buttoned up. I'm running that same intake on my 408 but I'm considering getting a super vic..I would like to keep the victor efi cause it would be cheaper. Decisions

It made 449rwhp/475rwtq with 10.5:1 compression.



I got the rockers installed and adjusted, starter installed, and headers installed last night. Hoping to get all the wiring done tonight, except for the wideband. I'll put that off til last. Should be ready to fire tomorrow or friday.