351 Windsor performance build
Laughing Gas
Joined: Apr 2014
Posts: 884
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From: Shreveport, LA
I think that's more for setting your ring end gaps exactly like you want them based on your usage or what type of build it is. So you would use file fit if you wanted to run a closer end gap. They are more labor intensive due to squaring and checking then filing the ends, deburring and so on. Plus if your gaps are too close and the ends butt up due to heat expansion it will cause damage.
Laughing Gas
Joined: Apr 2014
Posts: 884
Likes: 5
From: Shreveport, LA
Hopefully this isn't a violation of the rules. But check this thread out on a 351w build. FWHP estimation - Ford Mustang Forums : Corral.net Mustang Forum
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Senior User
Joined: Nov 2012
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From: Nashville, Tennessee
Still debating on whether to get file fit or prefit rings. I know I'll have to get someone else to file them if I get file fit. Will a 10.8:1 compression ratio make blowback more probable? Should I go with file fit?
Laughing Gas
Joined: Apr 2014
Posts: 884
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From: Shreveport, LA
This is the model I got for the timing chain set. Ford Racing Timing Chain Sets M-6268-A302 - Free Shipping on Orders Over $99 at Summit Racing The main thing you're looking for is the German "IWIS" chain. There is another brand that are considered better than most others and that's Rollmaster. The advance and retard keyways are not there because you may want to advance or retard it. They're there because you may need to adjust it due to degreeing the camshaft in. There are other features of timing set like Torrington bearings that you probably won't need though.
I've looked for polyurethane motor mounts and a transmission mount for these trucks. I haven't found any, but it's been awhile since I've looked. Someone may make some now. I swear by them for my Mustang.
I would not run 10.8:1 compression with cast iron heads. But to answer your question, it could make blowback more probable. Really, you're looking for good ring seal and that's in the final cylinder hone along with the rings you use of course.
I've looked for polyurethane motor mounts and a transmission mount for these trucks. I haven't found any, but it's been awhile since I've looked. Someone may make some now. I swear by them for my Mustang.
I would not run 10.8:1 compression with cast iron heads. But to answer your question, it could make blowback more probable. Really, you're looking for good ring seal and that's in the final cylinder hone along with the rings you use of course.
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Senior User
Joined: Nov 2012
Posts: 240
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From: Nashville, Tennessee
I've heard Cloyes timing sets are the best from a few people. One of the reasons was I can get Cloyes from my work with my employee discount. Which one would probably last longer?
Why wouldn't you run a 10.8:1 compression ratio on a cast iron head? I got a 10.5:1 with summits compression calculator using specs of what I have planned to use. I thought gt40p combustion chambers were 56cc for some reason. They're 59cc.
I'm going with perfect circle rings and a torque plate hone job.
Why wouldn't you run a 10.8:1 compression ratio on a cast iron head? I got a 10.5:1 with summits compression calculator using specs of what I have planned to use. I thought gt40p combustion chambers were 56cc for some reason. They're 59cc.
I'm going with perfect circle rings and a torque plate hone job.
Laughing Gas
Joined: Apr 2014
Posts: 884
Likes: 5
From: Shreveport, LA
Any timing set with the IWIS chain is going to last longer. Usually, people don't have trouble out of the gears, it's the chain that causes problems. If you can get the model that you like at your work and be able to look at the chain before you buy, then you could do that. I would get one that had some adjustability for degreeing the cam though.
I'll have to check my compression calculator and head specs for the cc's.
I'll have to check my compression calculator and head specs for the cc's.
Laughing Gas
Joined: Apr 2014
Posts: 884
Likes: 5
From: Shreveport, LA
Ok, so with p heads, they usually range from 58-61cc combustion chambers. With your pistons -4cc relief, a 60cc chamber, a .010 deck height, 4.100 gasket compressed to .047 and the 1.722 compression height on the piston I get ~10.6:1 compression.
Talking about the "IWIS" chain, read these descriptions. Rollmaster Timing Set SB Ford pre-EFI CS3031 - FlowTech Induction
Talking about the "IWIS" chain, read these descriptions. Rollmaster Timing Set SB Ford pre-EFI CS3031 - FlowTech Induction
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Laughing Gas
Joined: Apr 2014
Posts: 884
Likes: 5
From: Shreveport, LA
I don't know if I've sent you this link before but I was doing some reading about which brands offer the German chain. It seems a lot makers have switched from different things, back and forth. I know Fordstrokers will not cheap out on the gears or the chain. SA Gear Billet Timing Chain Set with Torrington Bearing
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Senior User
Joined: Nov 2012
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From: Nashville, Tennessee
With the calculations i used: 4.06 bore, stroke 3.5, 58cc combustion chambers, -4cc valve relief, deck clearance .025, compressed gasket thickness .041 gives me 10.78:1 compression. I wasn't trying to get a compression that high with the pistons I bought, at first I was struggling to get a 10:1 ratio that I needed to have with the cam I used to want. Is there any problems running that high of a compression ratio on a cast iron head? since i already have pistons, i would like to use them but the only heads I can afford right now is gt heads. So if there is a problem I need to figure out something else
Elder User
Joined: Nov 2009
Posts: 666
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From: Chicago area
If the heads have stock combustion chambers, that is "as cast" then you can polish the chamber to a smooth finish. This will lower the CR a bit and help it resist pre-ignition.
How much volume you gain is a guess but you can measure it before and after and recalculate your CR. Also there are thicker head gaskets available that can help as well.
How much volume you gain is a guess but you can measure it before and after and recalculate your CR. Also there are thicker head gaskets available that can help as well.
Laughing Gas
Joined: Apr 2014
Posts: 884
Likes: 5
From: Shreveport, LA
With the calculations i used: 4.06 bore, stroke 3.5, 58cc combustion chambers, -4cc valve relief, deck clearance .025, compressed gasket thickness .041 gives me 10.78:1 compression. I wasn't trying to get a compression that high with the pistons I bought, at first I was struggling to get a 10:1 ratio that I needed to have with the cam I used to want. Is there any problems running that high of a compression ratio on a cast iron head? since i already have pistons, i would like to use them but the only heads I can afford right now is gt heads. So if there is a problem I need to figure out something else
If your deck clearance is .025 and you only cut ~.006 off of the head leaving a 60cc chamber (hopefully), and a really common gasket (Fel Pro 9333 or 8548) is .047 compressed, I get 10.21:1 but that's with a .030 overbore. But that's doable and would make some NICE street compression.
But like Jim said, you can polish the combustion chamber, even cut a little bit of it out like unshrouding the valves for better flow. Ignore the red lines, I was trying to figure out how I could change the shape of the chamber.
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Senior User
Joined: Nov 2012
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From: Nashville, Tennessee
I talked to the machine shop the other day and he asked about the block being bored over before. He said it would be more to go to a .06 over from a 4.0 inch bore because he had to bore it to .03 and then again to a .06. I thought that was bull. Maybe not. But hopefully I can figure this out and get this below a 10.5:1 ratio. My goal is to get it down to a 10.3:1. It's not likely but it's what I'd like it to be at. I can get the combustion chambers smoothed out and some places smoothed out, hopefully add 3cc to the chambers and go with that felpro gasket.
Laughing Gas
Joined: Apr 2014
Posts: 884
Likes: 5
From: Shreveport, LA
If you can get with someone at Probe and try to swap your pistons for .030 over, that would be a better solution. The main reason is you don't want to go straight to .060 because that will be your last overbore. On the chambers, I'm showing a 58-61cc range they may have been in from the factory. The heads will need to be milled once just to ensure they're flat. Usually a .006 cut will reduce small chambers like these by a cc. The block deck will also need to be cut to ensure it's true, flat and 90° from crank centerline. So you'll lose a little material on both sides. BUT I don't know what deck clearance you'll end up with. How did you arrive at the .025 deck clearance?
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Senior User
Joined: Nov 2012
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From: Nashville, Tennessee
I don't know how I could swap pistons from probe. If I can't do that then I'll probably try selling mine and buying .03 pistons. if i can somehow get 60cc gt40p heads, and use a .047 compressed gasket I could get 10.38:1 ratio with .06 pistons. doing that with 4.03 pistons i can get a 10.27:1 ratio.