Differences between 302 and 302 HO engines...

[Stangman]

Refresh my memory if you would... What I have is a non-HO 302 that came out of a grand marquis, what were the differences between the HO and non-HO engines? Rick just got his Marquis engine and it turned out to be a XXX block, so from what ive been seeing with the grand marquis motors... mine is more than likely a XXX block. It went into my '89 GT as it was, with the exception of the mustang upper and lower intake. Well, my plan for this engine now, is to rebuild it and put it in the '88 with the addition of GT40P's and the explorer upper/lower and TB. SO basically what i need to know is what size pushrods do i need to run when running an E-cam. I know that I need to upgrade my timing chain to the double roller, the E7's are being replaced by the GT40P's, the non-HO cam is being replaced with the E-cam... What else am i missing that would get this motor up to par?

[85_SS_302_Coupe]

The biggest difference is the firing order and the cam that works with the firing order, but there may also be crank/rod/piston differences that i'm not sure about. The main thing is the cam and firing order though....as you can swap out the cam with an HO cam and do the firing order to match and it'll run just like an HO, so i guess the rest probably differs between years as to whether it's got forged pistons or hypers or whatever.

[Gearhead]

Refresh my memory if you would... SO basically what i need to know is what size pushrods do i need to run when running an E-cam.

6.272 inches is the stock pushrod length, 6.25 will work, but it wouldn't hurt to measure....

[Stangman]

Oh, i forgot, I am planning to replace the pistons to get rid of those non-dished/valve reliefed pieces, that E-cam will bring me back to the HO firing order. as for the crank and rods... the same?



6.272 inches is the stock pushrod length, 6.25 will work, but it wouldn't hurt to measure....


Wont i have to put in different pushrods when I add the E cam? to prevent Piston to Valve issues?

[85_SS_302_Coupe]

Oh, i forgot, I am planning to replace the pistons to get rid of those non-dished/valve reliefed pieces, that E-cam will bring me back to the HO firing order. as for the crank and rods... the same?





Wont i have to put in different pushrods when I add the E cam? to prevent Piston to Valve issues?


You really only come into PTV clearance issues when you get into the low to mid .500 lift cams, like i think the X303 is one of the biggest you can run with stock valve reliefs. You wouldn't change the pushrods...that would change the lift (shorter rods would equal less lift). You would want pistons with more valve relief to make up for the extra lift. You should be totally fine with an E, but it's ALWAYS a good idea to check PTV clearance anyways because you never know....


Also you can use stock length pushrods with GT40P heads as well.

[Timido]

Regular 302 and 351 (1981 and older) is 28 ounce imbalance crank ballancer and flywheel. 302HO is 50 ounce imbalance Crank ballancer and flywheel. <<Fixed it cause I was wrong!

[PaulFiveOh]

This was really interesting!

[85_SS_302_Coupe]

Also i've never heard any explanation of what the XXX signifies....anyone know? I know they're pretty common blocks, mine is and it's an '85.

[Stangman]

Regular 302 is 28 ounce imballane crank ballancer and flywheel. 302HO is 50 ounce imballance Crank ballancer and flywheel.

Strange... I had a HO flywheel on my non-HO 302 and it ran just fine :dunno: it had a large balancer on it too....

Also, Ive looked up both reman and new cranks for the two... same part numbers...


Also i've never heard any explanation of what the XXX signifies....anyone know? I know they're pretty common blocks, mine is and it's an '85.


Well, ive heard that the XXX blocks are stronger... may just be hearsay... i think that the common block is a YYY, i could be wrong...

[85_SS_302_Coupe]

Strange... I had a HO flywheel on my non-HO 302 and it ran just fine :dunno: it had a large balancer on it too....

Also, Ive looked up both reman and new cranks for the two... same part numbers...




Well, ive heard that the XXX blocks are stronger... may just be hearsay... i think that the common block is a YYY, i could be wrong...


Could be...i've seen the YYY blocks as well. Maybe it's something to do with being an HO or non HO block?

[Stangman]

Could be... but my friend Steve just bought a 5.0 HO and its a XXX block... so i dont know...

[Timido]

Maybe it is just the old 302 no HO motors that were 28 ounce.

[Timido]

I looked it up 1981 and older 302 were 28 ounce imballance. Everthing after 82 is 50 ounce.

"Q.: What is the crankshaft balance factor of my 302 or 351W/C engine?


A.: 1968-80 302 engines were built with a 28-ounce imbalance factor.
1981-2001 302 engines were built with a 50-ounce imbalance factor.
1969-97 351W engines were built with a 28-ounce imbalance factor.
1970-74 351C engines were built with a 28-ounce imbalance factor.

Note: Severe engine damage will result if you use the wrong flywheel or damper on your engine. "

[Stangman]

I looked it up 1981 and older 302 were 28 ounce imballance. Everthing after 82 is 50 ounce.

"Q.: What is the crankshaft balance factor of my 302 or 351W/C engine?


A.: 1968-80 302 engines were built with a 28-ounce imbalance factor.
1981-2001 302 engines were built with a 50-ounce imbalance factor.
1969-97 351W engines were built with a 28-ounce imbalance factor.
1970-74 351C engines were built with a 28-ounce imbalance factor.

Note: Severe engine damage will result if you use the wrong flywheel or damper on your engine. "

ya had me worried there for a sec...:)