Club Cobra - 351 Cleveland boss

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351 Cleveland boss

Hi Folks:

I really have a dilemma and here's hoping someone can help. Just got a fresh 351 C Boss 850 Holley about 511 hp. Runs horrid: Only about 4.5 inches of vaccum at idle, have to feather to prevent from backfiring and get the idle up then it seems to get going ok. #2 problem is that I cannot seem to get the temp to stabilize. It just keeps climbing.

Any help or suggestions would be great.

Thanks

gary

Clevelands can tend to run hot. I spent ages trying to get mine to behave itself. One thing that I found was a factor in getting the temp stable was ignition timing. Don't trust the timing marks on your balancer, I've been caught out before. Do a TDC test and mark your balancer with the right TDC. I drilled out and tapped an old spark plug and then put a bolt through it to make a piston stop to check it. I had the curve in my distributor reset and set it up with the specified static advance and most of my cooling problems went away.

I've found my Cleveland is happier with some water flowing through the heater hoses too. If you aren't running a heater you should conenct the 2 heater connections together.

For the motor to make 511HP it'll probably have a fairly big cam. Mine had a reasonable cam and ony pulled 10 inches at idle. With your Holley you might want to check what power valve you have in it. I've found that if the vacume at idle is very low the powervalve will open and dump way to much fuel into the motor. You will need to drop the power valve number to be under the level of vacume at idle to keep it shut. There are probably some people on here who have had more experience with Holleys than me so they may be able to confirm this.

Hope this helps.

Cheers

Mine also ran hot until I added an aluminum oil pan, about 8 quart capacity, twin oil filters mounted behind the radiator, and an oil cooler. With the backfiring timing also sounds like a possibility.

I run at a constant 195f. (the LPG likes it hot).:MECOOL:
Mine's not a Boss though.
I can remember a fellow having a similar problem years ago and it had something to do with the Cleveland water channels not lining up with the Windsor block.
Something like that (can't remember the details)...%/

I always thought the Boss was the windsor block with Cleveland heads on it. I've been looking back through my Ford books and there actually was a Cleveland Boss produced in 1971. It had a 4 bolt bottom the same as the Cobra Jet version but with caps selected for hardness. The Heads were the same as the 4V and CJ but were machined for screw in studs and adjustable rockers and also ran heavier springs. The crank was cast Iron like all Clevelands but was selected for high nodularity. They had shot peened rods and better quality bolts. Forged 11.1:1 comp pistons. Cast aluminium manifold and "ram air" air cleaner.

All in all the motor sounds like a real factory hotrod. The later 72-73 HO motor shared many of the same parts as the Boss but ran a milder cam and only 9.2:1 comp.

Cheers