valve to piston clearance

289 - 351 cid Small Block Performance

valve to piston clearance

Postby Kingspeedy2 » Wed Jan 02, 2019 9:27 am

I want to start putting my motor together and I am starting from scratch with a machined 85 ish 302 Roller block stroked to 331.
AFR Aluminum Heads ,Howards cam 221145-10 cam

A necessary check will be valve to piston clearance and push rod length determination.
I have a couple of questions.
FYI I do have an adjustable pushrod length Tool,and will get light weight check springs

1) do I need to temporarily substitute a solid lifter for the hydraulic ones or modify a sacrificial pair of hydraulic ones So that I don't have to worry about the hydraulic lifter compressing and perhaps causing an error in pushrod length? and valve clearance
2) there is lots of different info about clearance .I have seen .125 for both and .125 for exhaust and .060 for Intake.(this is a street motor ) with 380 Hp as a goal
3) do you check 1 piston each bank to ensure the deck heights are machined right? or 4 corners?
4)I kind of know the answer to this one already ,but the Felpro 1011-1 Gaskets specified by AFR is $71 Canadian .Can I use the gasket for clearance checking and then re-use it for final build or should I get on extra to sacrifice for clearance checking?

As always your thoughts are appreciated
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Joined: Tue Mar 31, 2015 12:36 pm

Re: valve to piston clearance

Postby bigdan » Wed Jan 02, 2019 2:56 pm

Pretty much exactly ther engine i'm running, 91 roller block, AFR185's.

Lifters - i'm using the motorsport stock style rollers, so I picked an extra pair up at Auto Zone and modified them "solid." It's hard to explain, but if you take a height measurement, then remove the guts there's a spring plate I flipped over, removed the spring and it worked perfectly. Pretty cheap at AZ - $7?

Not sure what pistons you're using, but the Mahle's i'm using have large, deep reliefs and I ended up around .200I and .190E with an XE274 and 1.6 rockers. I checked with clay, and checked every cylinder, which were all the same. Would have been alot closer with 1.7's.

Felpro 1011-1 - I'm currently fighting a coolant leak on the rear passenger side studs. A quick web search shows problems with leakage with studs and that gasket. I just spoke to them today at AFR, they also recommended a Felpro 9333pt1. Not sure if it was the 1011, but i'll find out in the next few days.

Hope some of this helps -

Currently diligently patiently trying to complete my 65 Futura long term project. . . . .

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Location: Eastern TN

Re: valve to piston clearance

Postby Kingspeedy2 » Wed Jan 02, 2019 9:46 pm

Thanks Dan ,good to know about the gaskets as I was about to order a set and
I know exactly what you mean about making a set of solid lifter out of a hydraulic one.
I am running Probe forged photons with reliefs only because they came with the striker kit
Posts: 250
Joined: Tue Mar 31, 2015 12:36 pm

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