OK Im getting ready to do a 351W stroked to 408. The internals are Eagle 4340 crank and H beam rods, Probe 4340 dish pistons, ARP main studs. It is an OEM 74 seasoned block with 2 piece main seal. I will have a main support girdle on the block to stenghten it up for sure. My question is, how much power can this block handle before cracking? I know different quality of builds will sway the outcome some, but on average what will it hold? Ive heard that 700 is no problem. My builder told me he has seen 600 crank hp with a 300 shot of nitrous on his oem blocks with no problem (not so sure about that quote). Im going to run a Procharger on my 408. So what do yu think I can safely run? I cant afford a Dart or Eagle block right now so Ive gotta go with this route. Thanks in advance
351W experts HELP
- Thread starter quickGT
- Start date
-
Sponsors (?)
88Stangboy
Banned
its not just how much hp you have, it also has to do with the rpms your going to be running and how you drive. If your engine is going into say the 7,000-8,000 rpm range, obviously that engine wont live as long as an engine that only see's 6,500 occasionally. understand? That also has a big part in how long your block will last, but 700 doesn't sound that bad, 800 im not sure about, i dont personally have experience with that..if i were you personally, i would just save up for a dart block...you won't regret it one bit, it's alot of insurance for alot of money your going to spend. It could mean the difference between an engine living along time or one your going to be pulling in three months because it grenaded. Its no fun picking up pieces of your engine because you cut a corner somewhere. But if you have to absoblutely use that block, make sure you put a reputable stud girdle on it, and use NOTHING BUT ARP studs and fasteners all around. But just think about saving up for that dart block, if anything, its more than worth the peace of mind it will give you.
My friend who is an engine builder had a 408W stroker in a 69W block. It put down 650rwhp with a YSi trim. He tore it apart had that block sonic checked and stroked it to a 418W and is going to throw a 250 shot on top. he says these early model 351W blocks that were manufactured in Mexico can handle 1000fwhp.
Now 650rwhp equates to 750fwhp. I personally would be
leary about pushing it past 750 but I do not possess the skills he does. Just my $.02
Now 650rwhp equates to 750fwhp. I personally would be
leary about pushing it past 750 but I do not possess the skills he does. Just my $.02
88Stangboy
Banned
yea, Mexican blocks are prob. the best production block. But hell, the chances of finding one for a decent price, it'd probably come out cheaper just getting an aftermarket block. But 750ish should be just fine, just make sure when you have it balanced, they do a hell of a job. Thoroughness (spelling
) is definatly the key to engine longevity. 
) is definatly the key to engine longevity. 
bluevenom867
I will have images of molesting stuffed animals in
I saw someone run a good 69' block,full filled,steel 4 bolt mains,and ARP studs said they went a whole season on it with over 1000rwhp.
And I do agree,the level you build it as far as machining and cleanleness has a big part in longevity.
And I do agree,the level you build it as far as machining and cleanleness has a big part in longevity.
pb_paulie_b
Founding Member
There are many varying opinions on this but the average is 700 for a 70'-74' and 750-900hp for the 69' model. I had a 74' and 69' bare and side by side. The differences are not obvious but the 69' had better main webbing. AS for handling 750hp? I'll let you know in a few months
1974 block- View attachment 490558
1969 block- View attachment 490560
1974 block- View attachment 490558
1969 block- View attachment 490560
I should have mine done by May at the latest so we will both find out together Paulie, lol. Im hoping I can at least run 750 crank hp and be in the mid to low 10s. I have a pretty good suspension so that will help a lot. Thanks for the replies.
Similar threads
