351 pistons
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8th Gear
Joined: Dec 2024
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351 pistons
So I'm putting this 1985 351w back together I want to put new pistons in but leave everything else stock, for the time being. Then later down the road I'll put different heads on retro fit rollers ect.
I have picked pistons and heads that will give me the right compression ratio for both heads, I want to know if my valve reliefs are the right ones.partes linked below.
https://www.summitracing.com/parts/UEM-KB151KTM-STD
https://www.summitracing.com/parts/afr-1388
If you think I need to pick different heads and pistons let me know.
I have picked pistons and heads that will give me the right compression ratio for both heads, I want to know if my valve reliefs are the right ones.partes linked below.
https://www.summitracing.com/parts/UEM-KB151KTM-STD
https://www.summitracing.com/parts/afr-1388
If you think I need to pick different heads and pistons let me know.
Super Moderator
Joined: Apr 2004
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I moved this from the General Performance forum as this is a better place for the questions.
Free bump to the top.
As to your question, IMO only a test fitement with clay will tell you your true clearances and is the best way to make sure you don't have interference troubles.
Free bump to the top.
As to your question, IMO only a test fitement with clay will tell you your true clearances and is the best way to make sure you don't have interference troubles.
FTE Community Team
Joined: Dec 2023
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From: sussex county, nj
sorry for the late reply
those or like flat top pistons with those heads will be a very nice combo. good street ratio compression ratio, do you know if the blocks bore is still standard or if it has ever been over bored, you need to know that before buying, cam if your planing on a retro roller , beware that it's a lot of work to swap cams inframe down the road, i would personally leave that motor on the stand till the funds were in hand rather do the job 2 times. .IE assemble the collection of parts till complete do the work 1 time only ,heads have you looked at the other brands? ie edelbrock, summit, flotek, blueprint, those will save you some nice dollars,
as 85 wrote the only way to know for sure if the valve relief pockets are deep enough is claying them , cam 1 and cam 2 will most likely have different lifts ,either way those pistons have deep pockets
those or like flat top pistons with those heads will be a very nice combo. good street ratio compression ratio, do you know if the blocks bore is still standard or if it has ever been over bored, you need to know that before buying, cam if your planing on a retro roller , beware that it's a lot of work to swap cams inframe down the road, i would personally leave that motor on the stand till the funds were in hand rather do the job 2 times. .IE assemble the collection of parts till complete do the work 1 time only ,heads have you looked at the other brands? ie edelbrock, summit, flotek, blueprint, those will save you some nice dollars,
as 85 wrote the only way to know for sure if the valve relief pockets are deep enough is claying them , cam 1 and cam 2 will most likely have different lifts ,either way those pistons have deep pockets
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8th Gear
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Thank you for the reply makes me feel more confident that the pistons might work. Especially seeing I already ordered them 😂
I'm not worried about pulling the motor again. I want to get it together so I can makeup some motor mounts transmission ect...
Ik this swap will be expensive and a lot of work so pulling to motor once it's more done to do some performance upgrades doesn't scare me.
Thanks again
Update: forgot to say I have measured the bore and checked the block casting number. It is out of the 85 and I will be trying to retro fit a roller cam eventually
I'm not worried about pulling the motor again. I want to get it together so I can makeup some motor mounts transmission ect...
Ik this swap will be expensive and a lot of work so pulling to motor once it's more done to do some performance upgrades doesn't scare me.
Thanks again
Update: forgot to say I have measured the bore and checked the block casting number. It is out of the 85 and I will be trying to retro fit a roller cam eventually
FTE Community Team
Joined: Dec 2023
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From: sussex county, nj
1985 block is it by chance set up and drilled for factory rollers, as 85 was the first year ford used them in mustangs and some cars,
85 IMMO please ,i'd measure the bore with a bore gauge and check for wear.out of round
85 IMMO please ,i'd measure the bore with a bore gauge and check for wear.out of round
Cargo Master
Joined: Oct 2020
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One thing that you have to really watch on these later Ford Windsor blocks are the bore sizes. The engine can be factory but that does not mean it has a 4 inch bore. I've seen them that are 4.004, not from wear that's just how they are made sometimes. So even if the block is worn very little a "std" piston won't really work because the clearance will be too big. Measure the bores before you open your pistons.
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Laughing Gas
Joined: Jul 2009
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From: NE Ohio
I used a '92 block when I built my 393W, because finding a roller cam block was next to impossible waaaay back in 2006. Initially, I used a hydraulic flat-tappet cam, but I later modified to a retrofit roller cam, using a conversion kit that used factory 5.0 spider/dog-bones/ OEM Ford roller lifters. I had to drill and tap the block with the two 1/4-20 holes to bolt down the spider. It is best to do that when the block is being machined since those bolts go down into the camshaft bearing journals. I cheated a bit and only drilled and tapped down very shallow - maybe three threads - then put in a threaded rod that was coated in JB Weld, installed a jam nut, and coated that jam nut to the block with more JB Weld, essentially epoxying the studs in place permanently. When that cured, I installed the spider and held that in place with nylock nuts. That spider stud install has been holding there for the last 14 years! The factory spider isn't under any sort of stress - it just holds the 'dog-bones' down.
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FTE Community Team
Joined: Dec 2023
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From: sussex county, nj
funny as i had a 85 351 block that was drilled for the spider, if it was done by someone or was a factory is who knows the block was freeze cracked beyond stitching so it became a dock anchor at the marina
Laughing Gas
Joined: Jul 2009
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From: NE Ohio
Easy to tell - the roller block has raised bosses to allow the drilling and tapping for the spider hold-down bolts - and the lifter bosses extend higher above the valley than the a non-roller block since the hydraulic roller lifters are taller - the oil groove in the lifters would come out of the lifter bore - hence the 'reduced base circle' retrofit cams. One more slight detail - the tops of those taller lifter bores will have a machined surface, not cast like a standard block.
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8th Gear
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One thing that you have to really watch on these later Ford Windsor blocks are the bore sizes. The engine can be factory but that does not mean it has a 4 inch bore. I've seen them that are 4.004, not from wear that's just how they are made sometimes. So even if the block is worn very little a "std" piston won't really work because the clearance will be too big. Measure the bores before you open your pistons.
FTE Community Team
Joined: Dec 2023
Posts: 8,692
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From: sussex county, nj
Easy to tell - the roller block has raised bosses to allow the drilling and tapping for the spider hold-down bolts - and the lifter bosses extend higher above the valley than the a non-roller block since the hydraulic roller lifters are taller - the oil groove in the lifters would come out of the lifter bore - hence the 'reduced base circle' retrofit cams. One more slight detail - the tops of those taller lifter bores will have a machined surface, not cast like a standard block.
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