OK, I just want to say that I appreciate the help I have been given on changing the cam in my motor but I am a little confused and need a few things cleared up....since my motor is a late model HO motor with the 351W firing order I need a cam that matches that firing order....is the 351W cam the same as the late model 302 cams?? I just saw a listing for a cam in Summit for a 351W and late model 302 HO motors? The reason I ask is because I ordered a cam for my motor and it's the 302 firing order so I need to send it back and get a cam with the 351W firing order......So can I just order a 351W cam?? They have the exact same grind on a 351W cam?? Please help, I'd like to get this figured out today!!!!!
Someone just told me all I needed to do is switch the plug wires around to the early 302 firing order.....Is this all I have to do??
cam for you Actually there is an advantage to the 302HO/351W firing order. It loads the crankshaft more evenly so that it can handle more HP/TQ. You can use a 351W camshaft. You just have to change to the 351W firing order.
If you had a 302 with the 351 firing order....wouldn't you also need the crank to be a 351 crank in order to throw the pistons around in the correct 351 order? Just thought I would ask before someone else did.
I agree with ricky. You are loading that first rod journal with a lot of stress especially when coupled with with the distortion caused by the crank turning the balancer around at high RPM. If it were mine I would go for the 351W firing order. As for the crank, the first and third rod journals ar 180 away from each other. They are always in the same position in their respective bores. For example, when the number 3 piston is at TDC so is the number 5.
I didn't get into crank loading but thats true, the 351 fire order better distributes the load on the main bearings and webs. The crank configuration as far as the throws, are the same in both engines. 351 is just a larger version of the the 302.
A related thought to know about, not that it happens very often, If there is crossfire between the right two cylinder pairs, and a cylinder fires very early on the compression stroke at hi RPM, it can blow the bottom end out of an engine and you would never know what happened.
All the cranks are the same, the firing just occurs at different TDC's. I have heard that the 351W had a different firing order because the 302 order was 1-5-4-2-6-3-7-8 and the 1-5 shot wanted to break the snout of the crank with the 351W's extra torque. I am not sure how true that is, but it makes some sense. The 351W order is 1-3-7-2-6-5-4-8. Another difference it will make is the SOUND. Firing order has a lot to do with how an engine sounds.
When you think about it the cranks have to have the same throws because you can run an early 302 cam in a 351/302HO or a 351/302HO cam in a early 302(just talking firing orders) by just changing the plug wires to match the firing order. All it really does is change the compression stroke to the exhaust stroke and visa versa on the 3-4-5-7 cylinders too load the crank better(also stated earlier). If I remember right it was to get 1-2 changed to the 1-3 to stop some of the harmonics at the front of the crank.
I really dont see where crank loading was an issue. If you think about it, 1,5 are loaded heavily on the early firing order, and 2,6 are loaded close to each other on the later one. Also, this isnt related, but did you know that the late firing order is the same as the chevy's firing order? The cylinders are numbered differently.
cam debate Well after all the debate, yes you can use the 351W firing order in a 302 with a 351W cam in it.
Cool, thanks for all the help everyone....I went ahead and sent the 302 cam back and exchanged it for a 351w cam....I also got a Cloyes Hex-adjust timing chain to make the job easier.... Thanks again....
off the subject cometgt1974, I would like to know what size your rear wheels are and what the backspacing is. I was looking at some wheels that are 15X8 and they offer them with 3 3/4 or 4 1/2 backspacing. I like the way yours looks. Thanks in advance.
