Very recently acquired a 68 barracuda and going to pull the current 318 for a 413 I've had for many years now in the barn just waiting for the proper vehicle to put it in. That time has arrived! Pulling 413 apart for rebuild and debating which heads to utilize. Have a set of 906's and 516's and have been pouring over the theads and websites and find myself leaning towards the 516's. Will of course need to use dish pistons to get to 10:1 compression as opposed to flat tops if using 906's. Other elements of the engine will be a 268/284 cam and a inline dual quad intake manifold. Pretty much building a 59 golden lion 413 with updated heads. My understanding is that the 516's have a better flame front, less prone to detonation and better low and mid range torque. Is this logic sound on this selection of heads to use? This project will most likely be the last that I can get in with my father(age) and want it to be our best and most fun!!
413 in the 68 barracuda
- Thread starter momo61
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No reason you can't. No different than any other big block in a 68 Barracuda. Post up lots of pics of your progress.
Will definitely post pics of the progress. The 383 and 440"s went into the formula s barracuda so my 413 will make it unique to say the least! Still working on the exhaust manifold solution...stock cast iron or custom headers, cross that bridge when it arrives. Any input on the head selection?
You might have heads you already want to use but if that was my project I would seriously be considering a aluminum Head just for the weight alone. 50 lb off the nose of that car would be a great performance improvement.JMO
I'm not up on big block heads but I would probably look at something with a closed chamber (or a small chamber) Check to see how far down in the bore your pistons are if you are using them. There's a member on FBBO right now that said his 440 is a "gutless turd" because it has 7:1 compression. Yep, it will be. LOL
This will be a 10:1 if I use 516"s or 10.5:1 if 906's are used. She'll have plenty of getty-up!
Have considered that option as well
Sounds like you have a plan. Start with compression and build around that is my motto.
Last time I looked, piston selection was pretty poor for 413s. Cast stock replacement pistons will end up .80 or so below deck at TDC. Aftermarket cast or forged? Last time I looked - a few years ago - there were none readily available. Of course Ross or the like can make some for you, but custom pistons ain't cheap.
For a street motor, milling the 516 heads .050-.060 or so will bump the compression up to mid 9s with stock replacement pistons. Upgrade the exhaust valves from 1.60 to 1.74. Won't have good quench, but would still run good in a street motor.
I'm not sure why you think your CR would be higher with 906 heads than with 516. I'd think the opposite. The 516s have a closed chamber, 906s open. If memory serves, 90 cc chambers for the 906, 78 for the 516s.
I have Edelbrock heads on my 413. They are milled .050. If my calculations are correct, CR is 9.5:1 or thereabouts.
For a street motor, milling the 516 heads .050-.060 or so will bump the compression up to mid 9s with stock replacement pistons. Upgrade the exhaust valves from 1.60 to 1.74. Won't have good quench, but would still run good in a street motor.
I'm not sure why you think your CR would be higher with 906 heads than with 516. I'd think the opposite. The 516s have a closed chamber, 906s open. If memory serves, 90 cc chambers for the 906, 78 for the 516s.
I have Edelbrock heads on my 413. They are milled .050. If my calculations are correct, CR is 9.5:1 or thereabouts.
Would be running flat top pistons on 906 heads, dished pistons on 516 heads..Working all the calculations to keep desired CR 10 to 10.5. There are still sources for both style pistons I've found but yes getting harder to find them!
Well, I'm not particularly up to date on what's available today, and I don't know how much you know, but understand that just because a piston is listed as a 10:1 piston doesn't mean that's what you'll end up with. (If you already know that, I apologize, but many do not.) The listing should give you a piston deck height, and then with that, your stroke, rod length and block height, you can calculate where the top of the piston will end up at TDC. A few years back, I did that calculation for supposed 10:1 413 pistons and I came up with they would be .080 below deck at TDC, which is where the pistons that are in my 413 are. (The motor was rebuilt before I got it.) That deck height, with .039 head gaskets and uncut 906 heads (or was it 516 heads?) ended up at about 8.5:1 as I remember. Steel shim gasket will get you up a bit, but nowhere near 10:1.
Definitely not going off any advertise on what CR would be based on that info. Using actual volume measurements and plugging them into CR=(VS+VC)/VC. The only measurements I don't have have yet is space from top of piston to block deck which I have later this week when we pull the engine out and pull the old heads. These preliminary calculations have got me insight into where im close to but not exact. I may very well find that a flat top piston may work with the 516s adding in the extra volume. Without that extra volume it's showing 11.7 cr.
PRH
Well-Known Member
I’m surprised that the 1.81 ex valve clears the small bore of the 413.
A low deck would ease some installation pain Iḿ sure.
Well, it is smaller than the 1.88s that came in max wedge 413s. I realize that those 413 bores were clearanced a bit next to the exhaust valve. Still, the 1.81s are .070 smaller. Plus my 413 has been bored .030 over, so its bore is only .030 smaller than a 426's bore. Or a 383's.
So, in other words your calculations have assigned a value of zero to that space?
PRH
Well-Known Member
I’ve test fit Ede heads on a std bore 383, and the exhaust valves contacted the bore at about .550” lift.
The side of the valve scraping the side of the bore.
Some were worse than others as with each cylinder and head casting there are varying amounts and directions of core shift at play.
The side of the valve scraping the side of the bore.
Some were worse than others as with each cylinder and head casting there are varying amounts and directions of core shift at play.
Interesting. Guess it's a good thing my 413's cam is only .504 lift. (That's not meant to be a smart-aleck answer.)
Correct at this point
I look forward to hearing what you find out when you pull the heads. Keep us posted. 
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PRH
Well-Known Member
Honestly, I never would have given the 1.81 valve on a 383 a second thought, but I was freshening a 383 that had ported 346 heads that had been fitted with 2.14/1.81 valves, and several of the ex valves showed evidence of contact on their OD, and corresponding marks on the bores.
I ended up relieving the bores to be sure they cleared.
At some point after that I did some mocking up and found that there wasn’t an excess of room there.
I ended up relieving the bores to be sure they cleared.
At some point after that I did some mocking up and found that there wasn’t an excess of room there.
Some of the earlier years required the oddball C body block with the front mount engine bracket. You might look into that. Driver's side
I had a conversation with a friend who's building a 69 barracuda formula s tribute car with a 440 and also mentioned that issue with the driver's side mount. He found a company that makes a bolt on conversion. Not sure if I'll go that route or weld in a new mount. That's still down the road a bit.
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