Older 351 Block Limits
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Older 351 Block Limits
I have an early to mid '70's 2 main 351 W block and was wondering how fast you can turn one before throwing the bottom end out. Also I am looking at putting some explorer gt-40P heads on it and was wondering on how many cc's those heads have. I checked some older posts and they seem to be 58cc but I thought I would make sure. I'm building a local circle track car and I know this is a truck forum but you guys have never let me down with the small blocks and also I'm trying to get it to turn about 6,000 rpms and have around 11:1 cr. I've heard the older blocks are stronger but thought I would check with you guys first.
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Thanks guys good to hear the block is good to go and Ill definetly plan on using good hardware and Ill make sure to get enough spring for the cam I choose.
Well you can use up to 351 60 over and you have to have ford factory heads along with stock manifolds thats why i thought the gt40ps would be great because i have to use stock manifolds and they have great flow along with added compression. You can have HEI and no cams above .410 lift at valve which i can live with because this a common .4 lift rule and there are a few cams out there for the windsor with these lifts. The only bad thing is that i will most likely be the only ford in the field (and proud of it 
) which means i probably need to play by the rules for a while because you know how chevy guys can get 
. They do have the fords handicapped by making them run smaller valves than the chevy boys but thats why Im hoping the gt40ps can make up the difference. Also you have to use a magnetic steel crank and rods.
Originally Posted by HemiEater
what are the rules about these mods??
) which means i probably need to play by the rules for a while because you know how chevy guys can get . They do have the fords handicapped by making them run smaller valves than the chevy boys but thats why Im hoping the gt40ps can make up the difference. Also you have to use a magnetic steel crank and rods.
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using stock heads, intake and manifolds with .4 lift cam you might want to shoot for a lower rpm range when you gear it. It might spin to 6000 but how much power will it make there??
not much of a roundy round guy... I'm more tuned for the 1/4 mile..
not much of a roundy round guy... I'm more tuned for the 1/4 mile..
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Originally Posted by Beanscoot
"Also you have to use a magnetic steel crank and rods."
Huh?
Huh?
And the cams i've looked at for the .4 in rule puts the rpms up around 6,000. The rpms do seem high and you would think the motor couldn't breathe but I have to check but I might be able to run an aftermarket aluminum intake either way I know the chevy boys are getting them on average around 5600-6200 rpms.
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Wow.. the 0.410 lift rule sucks.. I hate to say it but your motor will be 75-100hp below what the Chev and Mopar guys will have with the same specs.. the Ford heads don't flow anywhere near what the other guys heads do, so just be aware you are starting with a big handicap. What car are you using and is there a minimum weight limit? If possible use a unibody car and strip it to the bare minimim to make it as light as possible.
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Well I read somewhere in an old post about the flow numbers of the gt40ps and they were quite amazing considering they are stock castings but i cant find the post again and the numbers were compared to other ford heads and aftermarket. I was also considering using a 302 motor because I thought I could feed the motor better because of the shorter stroke which I thought could increase the volumetric efficiency, but I would take a loss in torque. I also might try getting different ratio rockers for valve lift, either way i kinda understand why there are no fords running in this class and i have nothing against a chevy but I really want to run a ford and I have enough parts laying around to build one. You have to run a full frame car and 3200 lbs so I'm going to run an older ltd crown victoria and put a '90s thunderbird body on it for weight and aerodynamics.
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Originally Posted by Bossman89
Well I read somewhere in an old post about the flow numbers of the gt40ps and they were quite amazing considering they are stock castings but i cant find the post again and the numbers were compared to other ford heads and aftermarket.
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Its depressing to know chevys are that easy to build but I made a model engine in desktop dyno and I got a decent power curve that peaks around 5500 rpms and makes approximately 355 hp and 371 ftlbs which isnt that accurate because of the generic exhaust options and Im going to try adding in the 302 with the same stuff. I even plugged in the flow numbers of the gt40p heads from:
http://www.jason.fletcher.net/tech/flowdata/castiron.htm (interesting site with a lot of flow numbers)
Either way Ill try my best and hopefully it wont be to slow but atleast there will be a ford in the pack
because its a sad sight when you dont see any fords racing.
http://www.jason.fletcher.net/tech/flowdata/castiron.htm (interesting site with a lot of flow numbers)
Either way Ill try my best and hopefully it wont be to slow but atleast there will be a ford in the pack
because its a sad sight when you dont see any fords racing.
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Originally Posted by HemiEater
why not build a clevor.... Like mine... stock heads..
Yeah I thought about that because I read your clevor stuff from those links you have a while back but I got a feeling they might notice the adapter plates for the intake but who knows there not used to seeing fords. I also thought about trying a cleveland motor because they are technically a 351 and I have one sitting in an old bronco that has no title.