351W with broken rod

For anything machine shop / speed shop or engine specific. More technical than the range but not quite tuning specific.
efloth
Posts: 274
Joined: 2021 Feb 15, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: 351W with broken rod

Unread post by efloth »

Yeah, I can't see putting the motor back in without at least reworking the stock heads, which would cost about half as much as aftermarket heads. Being in California I have limited options though. The Edelbrock 50 state legal heads are not available but it looks like I could get a pair of afrs for around 2K. I didn't look extensively into trickflow but do they have emissions complaint heads?

Another curve ball is, after further inspection this camshaft has some pitting on one of the lobes. I believe the motor that I pulled out has a roller cam so I'm going to inspect that one hopefully it's good enough to use. If not it doesn't appear that cams are readily available right now.
red5.0fogger
Posts: 148
Joined: 2021 Mar 22, 15:58
Location: Newington CT
Vehicle Information: 1986 Mustang GT, Stock block, TFS 170 Heads , N41 cam, ported cobra intake, nitrous, T5 , 3.73s

Re: 351W with broken rod

Unread post by red5.0fogger »

I think some of the Trick Flow heads will comply for CA emission. Mine have the air injection fitting on either end that can be plugged if not used.
efloth
Posts: 274
Joined: 2021 Feb 15, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: 351W with broken rod

Unread post by efloth »

Do you guys think I should jump on these?

https://www.cjponyparts.com/afr-cylinde ... p/AFR1492/

Is the 2.020 intake valve an issue with stock pistons? Do you know if there is an aftermarket piston that will clear the larger valve? I am not sure if the larger intake valve is a good idea for low RPM performance anyway.
red5.0fogger
Posts: 148
Joined: 2021 Mar 22, 15:58
Location: Newington CT
Vehicle Information: 1986 Mustang GT, Stock block, TFS 170 Heads , N41 cam, ported cobra intake, nitrous, T5 , 3.73s

Re: 351W with broken rod

Unread post by red5.0fogger »

The piston to valve clearance will vary depending on the cam you pick and the cam timing. I went with the Trick flow heads because the valves have been moved/ rotated in the bore giving more room for bigger valves and cam timing. My 86 pistons have no valve reliefs so that influenced my choice.
wwhite
Posts: 313
Joined: 2021 Feb 16, 15:53
Location: Victoria, BC, Canada
Vehicle Information: 1994 Flarside, XLT, 351w E4OD
SD48b, Quarter Horse, Burn2

Re: 351W with broken rod

Unread post by wwhite »

WIth any head/cam swap you should be checking PtoV clearance regardless.
I'm putting 2.02 Eddys on, and PtoV on exhaust is fine, intake is super close, showing 0.050" radial valve clearance with stock pistons 1994 351, with 0.533 intake lift, 1.6 rockers.

Sooo, some might say I'm fine if not turning more than 6,000rpm.
I'm not taking a chance, going to cut .030 off the piston using a 460 intake valve I have laying around with some grit attached to the valve face.

Here is a picture of what I need to grind out for radial clearance.
This nick in the piston is from pushing valve down by hand. As I was checking clearances, from -10 to 0 to +10, this happened at about 8 degrees crank.
PtoV radial clearance
PtoV radial clearance
efloth
Posts: 274
Joined: 2021 Feb 15, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: 351W with broken rod

Unread post by efloth »

Thanks for that info! I ended up calling AFR and guy suggested the 165 intake runner head with the 1.900 intake valve. He said it would be better for a truck application and provide a bit more torque down low. Also no clearance issues. I got a pair of the smog approved afr-1472 for $1765 on Summit.

Planning on using the stock cam and scorpion 1.72 pedestal mount roller rockers. Should I buy new lifters for $100 or reuse? I will need new pushrods.

Block should just be a simple hone job. Will reuse stock pistons and rods if you guys think that is a good idea. Skirts look good.
efloth
Posts: 274
Joined: 2021 Feb 15, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: 351W with broken rod

Unread post by efloth »

I am interested in these pistons since they will work with the 1.90 intake valve. Will the stock rods need to be modified to support floating pins? Probably not worth the hassle if so.

https://www.summitracing.com/parts/slp-h336cp
wwhite
Posts: 313
Joined: 2021 Feb 16, 15:53
Location: Victoria, BC, Canada
Vehicle Information: 1994 Flarside, XLT, 351w E4OD
SD48b, Quarter Horse, Burn2

Re: 351W with broken rod

Unread post by wwhite »

If your not up to the task yourself, a machine shop can do it.
Then, after you pay the machine shop, you probably could have bought the correct rods for floating pins to begin with for the same price.
efloth
Posts: 274
Joined: 2021 Feb 15, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: 351W with broken rod

Unread post by efloth »

Any thoughts on using the stock 5.8 efi intake manifold? Seems to be some people say they're trash and other use them with gt40 heads no problem. I just don't want to hamstring my build.
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