351 make over
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Joined: Dec 2002
Posts: 17
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From: MN
351 make over
I have a '79 351m w/ 98,000 miles on it. Seems like the oil pressure & compression is good. It has been back firing out the exhaust. Instead of messing with the 2v carb I would like to replace w/ a 4v carb. I also would like to remove all the pollution control stuff. I all ready have a edelbrock 400 performer non-egr intake. Should I get a 600cfm of 650cfm carb? Holley or edelbrock? I think I'm going to pull the heads & replace the valve seals & try to reseat the valves. Can I replace the lifters? Should I replace the timing chain while I'm at it. I have heard alot about the -4 degree timing chain but have also been told by '79 they did not use it.How do I tell? Is there any pros to a new timing chain? Will this give me better gas mileage & performance? Any other ideas of things to do with out messing with the block?
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Get a 600 CFM Edelbrock(1406). Replace the timing chain with a double roller chain set, set it to zero degrees. By setting it to zero degrees, you will improve the low end torque and gas mileage, if it was at -4 degrees. You can also go to roller rockers, Scorpion is one brand.
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
You can buy double roller timing chain sets to fit your motor. It comes with the chain and the timing gears. The links in the chain have roller bearings and they mate to the timing gears. This reduces friction in the timing chain.
If your stock timing set is retarded 4 degrees, your intake valve will close 4 degrees later than it would if the timing was zero degrees. The late closing of the intake valve reduces the Dynamic Compression Ratio, and the power produced on each cycle. However the later closing improves power at high RPM, because the cylinder has more time to fill. So if you run the timing at zero degrees you will get better low end torque and better gas mileage, but you will lose some high RPM power.
If your stock timing set is retarded 4 degrees, your intake valve will close 4 degrees later than it would if the timing was zero degrees. The late closing of the intake valve reduces the Dynamic Compression Ratio, and the power produced on each cycle. However the later closing improves power at high RPM, because the cylinder has more time to fill. So if you run the timing at zero degrees you will get better low end torque and better gas mileage, but you will lose some high RPM power.
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