302 rebuild suggestions?

Jardon · May 27, 2026

Ive got a 94 mustang gt and on cold starts or after letting it sit for about an hour or so, I hear what sounds like rod knock on startup that goes away after a few seconds. I do also have some engine noise around 3k rpm with light throttle and im thinking I might have pistons slapping cylinder walls or something going on in the valve train. Either way, I think its about due for a full refresh and rebuild. Are there any budget friendly (somewhat) brands i could go for? Im wanting to rebuild basically back to oem since its not being properly built just yet. Thanks!
Edit: my mustang has about 167k miles on her, and if it comes to a full tear down and rebuild, I'll end up buying a good block and building it mildly for street/daily with all new parts

Terrorist 5.0 · May 27, 2026

Jardon said:
Ive got a 94 mustang gt and on cold starts or after letting it sit for about an hour or so, I hear what sounds like rod knock on startup that goes away after a few seconds. I do also have some engine noise around 3k rpm with light throttle and im thinking I might have pistons slapping cylinder walls or something going on in the valve train. Either way, I think its about due for a full refresh and rebuild. Are there any budget friendly (somewhat) brands i could go for? Im wanting to rebuild basically back to oem since its not being properly built just yet. Thanks!

A little bit of knock on cold start is normal for these engines as they get older, especially when using the recommended 5W-30. Not for more than a second or two though.

10W-30 is more suitable for these motors. The noise at 3000 RPM is more concerning though.

Jardon · May 27, 2026

Terrorist 5.0 said:
A little bit of knock on cold start is normal for these engines as they get older, especially when using the recommended 5W-30. Not for more than a second or two though.

10W-30 is more suitable for these motors. The noise at 3000 RPM is more concerning though.

I do run 10w30. And occasionally the knocking on startup lasts about 5 or so seconds and sometimes a bit longer. Knowing some of the history its been through, id have to guess its either valve train or piston slap issues. Either way, im considering getting a good block off FB marketplace and doing a mild street built with everything brand new so I dont have to worry about anything other than suspension and rust

Daryl · May 27, 2026

No knocking here with straight 30w as per my engine builder, but my 302 is stroked to a 347.

Jardon · May 27, 2026

Daryl said:
No knocking here with straight 30w as per my engine builder, but my 302 is stroked to a 347.

I considered stroking mine to a 347, but I do want it to be able to be daily driven, so im thinking of keeping the stroke at the stock 3 inches

Terrorist 5.0 · May 28, 2026

Jardon said:
I considered stroking mine to a 347, but I do want it to be able to be daily driven, so im thinking of keeping the stroke at the stock 3 inches

If you want a reliable daily, a 347 can last for years, but keeping the stock stroke is the best decision.

These blocks were not designed for the forces of a longer stroke, and when pushed, they start to split. Also, a stroker by itself isn’t worth all that much power.

Keep the stock stroke, keep it at and under 6000 RPM (occasional blasts to 6500 are fine) and you shouldn’t have any issues.