THIS CLEVELAND ROCKS! 1970 M-CODE 351C

welcome to another episode of the other guys where we talk about the less well-known but every bit is awesome engine combinations now everyone's heard of the ls the five-leader forward or small block chevy but today we're going to take a look at the most powerful factory small block ever offered by ford of course i'm talking about the 351 cleveland in this video we're going to take a look at the build up dyno test and performance modifications on a 1970 m code 351 cleveland so what's an m code 351 well back in 1970 ford offered a 351 cleveland the m code version offered eleven to one compression four v closed chamber cleveland heads non-adjustable valve train a performance hydraulic flat tappet cam shaft and a four barrel induction system it was a good combination in 1971 they would step things up to an r code boss 351 now that thing included the same compression an adjustable valve train to work with the solid flat tappet camshaft and an aluminum performance intake manifold now look for a video on that because i also built a version of that motor so that video is coming up but right now let's concentrate on our m code 351 cleveland during its lifespan ford offered the 351 cleveland in four different varieties the h code the m code the r code and the q code now to achieve these different varieties they juggle things like static compression the cylinder heads the camshaft and the induction system now the compression ratios obviously started out very high in 1970 as high as 11 to 1 but worked their way down toward the middle of the 70s as a smog air took hold now ford all also offered different cylinder heads the 2b versions got the smaller port 2v heads and the 4v versions got the big hits but within those they also offered open chamber and closed chamber now they also offer these with different valve trains to work with a different cam shift both solid and flat tap so we had adjustable and non-adjustable valve trains now they also offered different cam shafts as i mentioned both solid and hydraulic flat tablet they also offer different induction systems the 2v heads also obviously got a two barrel induction system and the 4v got four barrels but within the four barrels they offered iron and aluminum induction systems but what really set the clevelands apart was where the cylinder hits i mean the cylinder heads flowed a ton so how much well a good set of factory 4v cylinder heads float 275 cfm to put that into perspective a late model 5 liter mustang engine those heads flow 100 cfm less per cylinder even the legendary fuely heads back in 1969 and 1970 flowed only 220 cfm so a cleveland outflowed them by 50 cfm that's a ton of performance potential and why the cleveland is pretty awesome before we get to our test let's talk about power ratings more specifically why the factory power rating of the particular engine might not be the actual power reading now first and foremost during the 1970s they switched over from a gross power rating to a net power rating basically the gross power rating was in optimized conditions no accessories open exhaust so open air intake you know they didn't run the filter on a lot of times and then the net power rating was actually as the motor was running the car it was run at temperature with the full exhaust and accessories and air intake and all that stuff on there and that's carried over up into modern times so there's a difference between the gross power output and the net power output based on the way that they test it now the other reason that the power output that they rated the motor at might not be the actual power rating is because a lot of times manufacturers played marketing games so if they had a power output that they wanted to rate the motor at and the competition had one that was 350 they wanted to rate theirs at 355 because 355 is better than 350 that would help sales now they also went the other direction if they wanted to run a motor in a favorable class let's say in drag racing and they rated the motor at 325 instead of the 350 that it actually made it would be in a more favorable class and it would be it would it would be more competitive and that would help sales help sales too the other thing that they did which is i think is in the case of our 300 horsepower m-class or m-code 351 in cleveland is that they underrated the power output now our 351 actually made quite a bit more than 300 horsepower as we'll see and even though in 1970 that 300 horsepower rating was a gross rating so is in optimized condition and the reason that they would do that is because if they had a high performance version of the motor that they were charging more money for obviously they were charging a premium for that so it had to make more power than the lesser version even though the actual numbers might have been a lot closer which is what i suspect with this m code 351 cleveland so let's take a look at our build up and get to that dyno test the build up of our m code 351 in cleveland from 1970 actually started out as an h code 351 cleveland from 1971 but the only thing we used were the block the crank and the connecting rods we redid all of these made them factory fresh and then replaced the pistons with a set of 11 to 1 forged pistons the thing i liked about these pistons is not only did they produce the desired to 11-1 compression that we needed for our combination they also had slightly bigger valve reliefs that allowed us to run bigger camshafts later on you see later on we would be running a version of the 1971 boss 351 in addition to that we'd also be trying other aftermarket cam shafts so we had our short block done the only thing missing was the cam shaft now elgin supplied a reproduction of our 1970 m code 351 flat tappet camshaft it was a hydraulic flat tappet and we obviously use hydraulic lifters with that as well now topping this combination was a set of 4v closed chamber high performance cylinder heads the one change we did make to this and again this is because later on we would be doing a version of the 1971 boss 351 is we made the valve train adjustable it didn't affect performance at all on this combination because the adjustable valve train just allowed us to use a solid flat tap the camshaft later on but since we were running it with a hydraulic camshaft all we did was adjust it so that we didn't have any preload we you know put a half about a half a turn of preload on the lifter so we had our four v heads they were closed chamber we had 11 to one we had a reproduction camp shaft the only thing missing now was the induction system so we installed a standard iron four-barrel intake manifold now this motor would have originally come with an auto-light four-barrel carburetor but since we didn't have access to one of those we ran it with a 750 holley there might be a little bit of a power game there although there's argument both ways the auto light actually worked very well and the 750 isn't really oversized for this combination we also ran this combination with long tube headers now it would have come with factory cast iron exhaust manifolds and obviously it will make less power with those manifolds than the factory exhaust but we ran this the same way as we ran all of these legendary muscle car motors because i built a ton of stuff i built all of the legendary small block chevys i built the boss 302 a boss 351 a hypo 289 a shelby version the 365 and 375 horse 327 chevys an lt1 a dz-302 you name it i built all those in random because i wanted to find out how much power they actually made and one of my favorites was this m code 351 cleveland because it surprised me the most it was the biggest difference between the rated power output and the actual power power output of any of these combinations that i ran so we had our combination we had it with the holley carburetor and long tube headers so let's find out how it did after installing our 351 cleveland up on the dyno we ran this thing in anger and as i said the only changes we made to it were the holiday carburetor in place of the auto light and then the long tube headers and these were inch and 7 8 headers designed for a mustang chassis their hooker super comp header so they work pretty well so equipped in this manner our otherwise stock m code 351 cleveland produced 365 horsepower and 379 foot pounds of torque so it's doing pretty well and while the big big port cleveland motors are kind of notorious for not making a lot of torque both this one and a boss 351 and the boss 302 that i ran actually did fairly well down low so i'm kind of surprised maybe soggy part throttle response or something but in terms of low speed power these ones actually did pretty well i think ford combined those big port heads with fairly mild cam timing compared to gm i mean if you take a look at their dz 302 and the 365 horse 327 they used pretty well cam timing in those and then the lt1 had a little bit smaller camp timing but on this boss or on this m code 351 cleveland they worked out pretty well so now let's take a look and see what happened after we installed some modifications to make even more power after running the 351 cleveland up on the dyno and basically stock trim with the holley carburetor and hooker headers we decided it was time to make some modifications i mean we knew that the cylinder heads flowed a ton it would support a lot more power so we decided to put a modern camshaft in it and a modern induction system i'll go ahead and put the specs of the comp cam that we installed up there but it was a you know reasonably healthy camshaft but not dramatically bigger than what we had we also installed the edelbrock rpm air gap intake which is always a good choice even though there's a dramatic difference in the port sizing take a look at some of the photos and show you what's going on there but here's what happened after we installed the different camshaft and the different induction system you see we got a dramatic increase in power so the cam and intake manifold using those stock cleveland heads picked up power pushed it all the way up to 450 horsepower and look at that flat torque curve i mean it exceeded 400 foot-pounds for a long ways with a peak of 411 foot-pounds out at 5200 rpm so this is a good combination there was a little bit of a trade-off as you see down here down in the 3000 rpm range that's kind of to be expected given the camshaft that's not an unusual trade-off but if you take a look at the power gains offered everywhere else basically from 3300 rpm all the way out this is a pretty good combination it's still a mild like streetable camshaft that rpm air gap works really well let's get to our conclusion okay guys what did you think now this test run on the m code 351 cleveland is a perfect example of why i like running the other guys so much you find out cool stuff mention an m code 351 cleveland to any chevy owner and they're going to go hey what's that what are you talking about but when you tell them this simple 300 horsepower 351 cleveland made more power than any dz-302 lt1 l76 l79 l84 they're going to go hey what the hell are you talking about but it's true this simple 300 horsepower cleveland made more power than all those muscle car motors in fact there's only two motors that it doesn't make more power than and guess what both of those are cleveland headed i'm richard holder those videos are coming up make sure to like share subscribe ring the bell and i'll keep testing

Channel: Richard Holdener

Views: 74,437

Rating: 4.9504423 out of 5

Keywords: 351C, cleveland, ford, sbf, holley, headers, dyno, 1970, muscle car, motors

Id: dQYBklryzNg

Length: 12min 12sec (732 seconds)

Published: Sat May 16 2020