Visual difference in 302 vs 347?

Not too uncommon for the rings to need a good reseat after sitting that long and I would be more worried about "puffs of smoke" later on once you've refreshed the carb and filters along with frsh fluids and driven her hard a few times.

Also check to be sure it has positive type seals on the valve guides and get rid of the antiquated umbrella style seals if that's what's on there now.

 

Okay, yeah. Good idea. Once it gets swapped into the '73, going to drive it a while and go from there.

 

I doubt they'd have done all that and kept the rail rockers. Seen half assed stuff like it though. It had poly locks, but couldn't tell if it had screw in studs in the pics.

 

Domed pistons and 68 heads equals: you're gonna need race fuel to run it. That combo will be around 11 to 1 ratio. The std 289/302 popups netted about 12.5 to 1 with 54 cc heads. Get the "list" number off the choke housing, that'll tell you what Holley it is. Probly a std run of the milll 1850 600 cfm carb though. Two valve cover caps = they skipped running a PCV system. I used to have a set of chrome 302 covers with two grommet holes in each cover. That allowed me to run a dual PCV system out of the front holes.

 

Oh, man. Racing fuel to run it? Wasn't expecting that. What is the difference? Might it be why it was traded off and not taken care of over the years? If I knew a quarter of what you know about engines, I'd be set. You are an encyclopedia. I'm glad you are a part of this forum.

 

This ain't the 70's and 80's no more and there are many types of pistons and the domes available these days.. and CR will be quite different on many of them for all the various combo's out there. Smaller domes could easily bring you down to only 10.5 to 1 if the piston to deck height is negative(and it likely is if they didn't want to really spend the coin to parrallel deck it).

Look at it like this. Was the car a racecar only?.. or was it used on the street before? Most who hotrod these things(especially those who use rail type rockers when cuting corner) can't afford to go full race only so it has to take fuel from the local station.

And FYI.. you can fairly easily run 11-1 compression with iron heads on the street with many larger cams(they bleed some of the static compression down low and build as they rev). I know this to be fact because I've done it many times(I've run 11.5 to 1 on my 429SCJ and well over 12 to 1 with aluminum heads) and if you think back.. that's all we used to be able to do at one time. You just run dual tunes, is all.. one for the street with premium.. and one for the track with race or avgas. I will however mention that you need to be running a fiarly tight tune and keeping up on maintenance and making sure you get consistently good gas.

And although that cam doesn't sound very aggressive from the little that I heard so far.. some detuning of the advance curve and a tad bit of extra fueling(it will be slightly rich.. but will help cool the charge and reduce the chance for detonation) will likely let you squeeze by with premium fuel.

If you really want to know how that motor will fare with premium fuel?.. you need to make sure the rings are seated again and take a compression test to see where you're at right now. Anything around 200lbs will require a fairly tight.. and consistent tune.. and anything well over that will likely have to be detuned a bit with less advance and more fueling(cooler plugs will probably become mandatory as well). You could also run thicker head gaskets to bring compression down too.

 

I was going to say... Get the thickest head gasket you can find. You could also polish the chambers a bit while the heada are off to add a little volume and get rid of any sharp edges that would promote detonation. And if you're real careful you could smooth any sharp edges or lines on the tops of the pistons which would do the same. Every little bit adds up.

 

Great ideas everyone. Was planning on borrowing a compression tester kit very soon. Just from trying to get the #1 up on TDC, I noticed the compression was extremely tight/powerful when it turned over.

 

Yea, this isn't the 70's or 80's but the motor is. And judging from the overall build I've seen here, it's a pretty good bet those will turn out to be the old 12.5 to 1 popups in there. At a minimum, it'll likely require 93 octane only, and a good bet nothing less (in octane) will do. I've run 10.5 to 1 on 89 octane in a 390 with stock heads. My 331 likes only 93 with 10.4 and aluminum heads. My side oiler 427 required mixing Avgas and leaded regular for 11.5 to 1. Whatever he's got there, it ain't something he'll want to drive everyday. It would be a prime candidate for swapping a set of aftermarket aluminum heads on with 64 cc chambers and a bigger cam to match the comp ratio.

 

Oh yeah. Definitely not an everyday car. Going to be a weekend special.

 

Pop those heads off, determine what pistons those are, then hunt down some good aftermarket aluminum heads and a better cam to replace what's there now. The intake can stay (looked like an Edelbrock RPM there) Those stock heads look like someone spent too much money reworking them, and at the same time, not enough to make em worthwhile. They've likely got new springs, definately good one piece retainers and poly-locs on the studs (I'm betting those are pressed in though) Of course, if they've been ported, then they might be worth keeping, provided the studs are screwed in. The cam didn't sound like anything to write home about.

 

You are correct. It is the RPM Performer. Any brand of heads you recommend?

 

Any of them are better than what you've got now. Pick one. I bought the Canfields on my 331 purely because the price was right. I was just about to buy a set of Brodix heads for a 302 I was running when I stumbled on these on ebay for $1100 shipped. They were new in the box, one of those "divorce sales" you hear about (the seller was a woman) The chambers were too big for the build so I had my machinst mill them .060 to get them to 57 ccs. I ran them on the 302 for 4 months then used them a few months later on the 331. Never been happier with any parts than these. They're the equivalant of AFR165's (1.94/1.60 valves) If you've got popup pistons then you'll do well picking a set of 64 cc chambered heads to reduce the compression a bit.

 

Got ya. Thanks!

 

Finally had a chance to get the numbers off the carb. Turns out it's a Holley 4160.