aftermarket engine block questions

DukeGnarley

DukeGnarley

Member
Apr 2, 2003
597
2
19
Auburn/Ellensburg, Wa
#1
ok, I'm new to engines, and i'm trying to figure out what to do for my next one. I've been toying with the idea of running a fair ammount of boost, and i'm worried about the longevity of the production 5.0L blocks. I do not want to upgrade to a 351 due to clearance issues, and i also don't want to have to ever worry about the production block cracking. from what i understand this leaves me with either a dart block or an R302. Now for my questions.

#1. what is the difference between the R302 (link) and the new boss302 (link)?

#2. I noticed that there are two different deck heights to work with. 8.7" and 8.2". both of the ford racing blocks are 8.2" and i believe the production block is 8.7". How does this change how the engine is built? can i still use all the same parts?
 
#2
The 8.2 is the stock deck height.
the R302 block is ment for racing and not street, this meens that if you not going to race this car all the time then dont spend the extra money because you dont need it, but if you have gobs of money then the R block can be bored and stroked to 360 CI and the Boss only to 347 CI.
The Boss is a very good steet and race block, steet run and weekend race.
It is stronger than the original Boss block which was one of fords strongest at that time. The Boss block looks just like the original for the restorers that dont have there original block. Call Ford racing and ask them these questions before you buy.
 
#3
DukeGnarley said:
ok, I'm new to engines, and i'm trying to figure out what to do for my next one. I've been toying with the idea of running a fair ammount of boost, and i'm worried about the longevity of the production 5.0L blocks. I do not want to upgrade to a 351 due to clearance issues, and i also don't want to have to ever worry about the production block cracking. from what i understand this leaves me with either a dart block or an R302. Now for my questions.

#1. what is the difference between the R302 (link) and the new boss302 (link)?

#2. I noticed that there are two different deck heights to work with. 8.7" and 8.2". both of the ford racing blocks are 8.2" and i believe the production block is 8.7". How does this change how the engine is built? can i still use all the same parts?
Click to expand...

1. I'm assuming the R302 would use Windsor heads and the Boss302 would use Cleveland heads.
2. 8.2 is production deck hight. 8.7 use a special intake (wider) and they are usually race intakes and very expensive.:nice:
 
#5
Ideally, you want a non-siamesed block for best cooling, so long as it can handle the power adder. The World/Dart/R302/Boss blocks are all siamesed. Being in WA, you may not have worries about overheating. That's nice. I would go either Dart Sprotsman or Boss. If Dart, go for the 4.125" bore, which will add cubes and help unshroud the valves.
 
#7
TOM B said:
The 8.2 is the stock deck height.
the R302 block is ment for racing and not street, this meens that if you not going to race this car all the time then dont spend the extra money because you dont need it, but if you have gobs of money then the R block can be bored and stroked to 360 CI and the Boss only to 347 CI.
The Boss is a very good steet and race block, steet run and weekend race.
It is stronger than the original Boss block which was one of fords strongest at that time. The Boss block looks just like the original for the restorers that dont have there original block. Call Ford racing and ask them these questions before you buy.
Click to expand...

i dont agree. the r302 has been used on the street just fine. as long as your cooling system is good youll be fine.

the boss block is pretty close to the r302 the r302 main caps are better IMO. one thing i dont like about the boss block is that it uses a 2 piece rear main and the r302 uses a one piece rear main seal like the EFI 5.0s did.

the r302 is more expensive to machine when compared to the dart block (sportsman). but the sportsman has been known to need extra metal removal when using dog bones for the lifters and some areas on the timing chain.

i will probably go with the dart sportsman when i start building my engine. big bore is nice but pistons are expensive.


the boss block and r302 are about the same price, the sportsman is $200-300 more but cost of maching will be less.
 
#10
1320stang said:
Look for a Mexican 302 block. Far cheaper than a R302 or A4 block.
Click to expand...


yeah they are good blocks. kinda hard to find and just as strong if not stonger then the ford sportsman block. but they are not on the same level as a dart sportsman or r302.
 
#13
x2 on the mexican block. They are killer blocks. Better than a sportsman block, pretty strong compared to an r302 minus the 4 bolt main. I would run a mexican w/ main girdles if u were worried about it. Had those things well over 7500 RPM :D
 
#16
1320stang said:
Yeah, but he's running a vintage 'vert. I doubt he'll be making 850hp.

A Mexican block is perfect for what he needs, besides, there are Mexican blocks going 8's with a power adder.
Click to expand...


The Mexican block will fit his needs I agree, but to compare them to a Dart block?!?!?! <--- which was my point. I've seen stock 302 blocks run in the (high) 9's, but that doesn't mean they'll last long does it? How readibly available are they (Mexican blocks)?

Duke, there are plenty of companies that build short/long blocks from Dart or R302. Bennet does, Keith Craft does, if you buy the block any local engine builder will do it as well. If you search and find a mexican block, as stated it is perfect for your needs, so pick it up. The Dart & R block, w/out machine work, cost ~1900$. I don't know if you want to spend that coin if you're not going to put at least 700hp down.
 
#17
Who said I compared them to R302s or A4s in anything other than price? There have been bare Mexican blocks sell on Ebay recently for $200 and $330 which is a heck of a lot cheaper than $1900, even with shipping across the country.
 
#19
1320stang said:
There have been bare Mexican blocks sell on Ebay recently for $200 and $330 which is a heck of a lot cheaper than $1900, even with shipping across the country.
Click to expand...

Before I bought my block I checked around for a Mex block, but no go for me. If he can get one for 330$ + shipping :nice: that is a GREAT deal; best bang for the buck IMO.
 
#20
67Dylan said:
Before I bought my block I checked around for a Mex block, but no go for me. If he can get one for 330$ + shipping :nice: that is a GREAT deal; best bang for the buck IMO.
Click to expand...


me too. i found one in KY and had it shipped to me. to bad the seller was a arse hat and banded it to a skid plate with the mains attached. it was dropped on the mains and cracked it where the main journel sits. its ok cause ill just go with a dart block after i plant the money tree and water it :rlaugh:
 
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