1973 Ford 302 Engine Rebuild Advice

[Joe hatton]

I am getting ready to rebuild my stock 1973 ford 302 with an automatic transmission. Assuming I will need to go .030 over and buy new pistons...is there any advice do's/don'ts, etc. I will also use the edelbrock performer cam as i already have the performer intake and carb and think edlebrock makes a good set-up for the daily driver. Last note is i have the mallory distributor and a duel exhaust set up with stock manifolds. I'd like to have a good solid daily driver with a little punch. Any advice before i waste money doing it the wrong way is greatly appreciated. Thanks in advance!!!!

 

[John Marinan]

I wouldn't just go 30 over, shoot for 10 and no more than 20, or find another a block.
My opinion.

 

[BRONCROB]

After breaking your engine down,take it to your machine shop and let them mic your cylinders before ordering your pistons and then bore to match the pistons.You want to bore as little as possible unless you're stroking it out.If you want to add a little power just change your cam and at least port your heads and intake to match your gaskets.While you're at it get them to mic your crank and turn it down if needed.I would also look into mods to make it run better on 10% ethanol fuel because it seems like that's what we're stuck with.

 

[Joe hatton]

If i change the pistons, are there better pistons for say 71 or 72? My understanding is the 73 dropped to 8.5:1 from 9.5:1? Also are the stock 73 heads OK for a daily driver given the porting suggeste above?

I know these sound like basic questions, but I have done a few chevy small blocks and know the some heads are just plain junk, while others are more than suitable for a daily driver with some spunk.

 

[cldonley]

69 had 9.0:1 (depending on who's data you look at) but I don't know if it was a change in pistons or casting that lowered compression. If it was pistons, (which I think it was because you use the same intake part numbers for all the models) then going back a few years on pistons would make a huge difference for you. Probably someone on here with more knowledge than me on this, maybe they'll chime in.
Always, always break it down and get it to the machine shop before you order parts! Don't take off any more material than necessary when oversizing pistons or undersizing crank journals! Good luck--rebuilding is fun!

 

[ENDLIFE]

When I pulled the engine in my Bronco I was mortified to find out my block was already bored .060 over, who ever built the engine did a pretty good job, so all I did was re-ring and replace all the bearings. I thought it would run like poo, but the little 302 runs STRONG with a mild cam. I have a 351 waiting to take its place, but it looks like it will be sitting in the crate for a while. My only advise would be to make sure you match everything to your engines compression ratio, and decent heads make ALL the difference.
Good luck in your endeavors.

 

[Joe hatton]

Thanks! Hope to get it under way soon and have it back on the road by thanksgiving

 

[baddad457]

Your 73 has huge dished centers in the pistons. You want to replace those with flat tops. But the problem here is not all flat top 302 pistons are the same. The pin height (aka compression height) varies from 1.585 to 1.620. You want the taller height to go along with your block's taller (by .020) deck height. You should have no problems boring it to at least .030. Some blocks will safely go to .060, depending on core shift (the cylinders beign off center in the block, you can judge this by looking at the bore cores from the bottom) You may also want to consider changing the stock pressed in studs in the heads to screw in, if you think there's a bigger cam in your future. Cam profile in these engines is severely limited by the stock pressed in rocker studs.

 

[SteveL]

Best thing you can do is order it all from the shop that does your machine work. tell em what you want it to do and they should know the best options for what you have..

 

[Joe hatton]

Thanks - i thought the pistons were dished...will print this thread out and take it with me. I really appreciate all the great help from all!!!

 

[blubuckaroo]

Best thing you can do is order it all from the shop that does your machine work. tell em what you want it to do and they should know the best options for what you have..

I think this is good advice. There are too many variables to just buy and assemble parts. Especially since the deck height changed somewhere around '73. I've found a local machine shop that sold me the kit. They did all the machining, fit the pistons on the rods, installed the cam bearings and freeze plugs. The assembly is good work. Not greasy work but good clean oil. I had a ball and it runs great! You really should get this book. It's a little old-school but so are these motors. http://www.summitracing.com/parts/hpb-hp89

 

[broncojo]

Didn't see it here but also have your shop check for hardened valve seats in your heads if you are using the stock ones, 72 or 73 was the turning point for hardened valve seats.