Thread: 700 hp 565 cid Bowtie

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I recycled this motor from my Hot Boat. Freshened it with some new parts and installed it in my 1973 Vega with built powerglide, 9" Ford spooled rear end and 8.5 certified cage.
I am running AFR heads, solid roller cam, girdles, dual 600 cfm carbs and MSD. Line lock and transbrake. I only run 10.5 to 1 compression so I can drive it on the street with pump gas. I have about 700 hp, which is more than enough in a 2000 lb car.
My question is: When I first fired it up, the headers turned cherry red in a matter of seconds. The cam was installed straight up. I retarded the cam 4 degrees and getted the hell out of the carbs. It now runs at 180 degrees in the garage for 30 minutes. That is where the cam was set while in the boat.
Does retarding the cam lower the compression? Cranking compression is 100 psi.

Changing the timing cycle of the valves in relation to the pistons can lower / raise cylinder pressure.

True. I know that but I wasn't sure if retarding the cam will lower the static compression.
I know retarding the cam raises upper RPM power and lowers lower RPM torque.
This Bowtie BBC has low end torque to spare.

I'm thinking there's a lot of variables that no-one would know off hand.
You mentioned that it was installed "straight up" but now many hours are on the motor and what kind of stretch is in the chain?
Is that amount of stretch worth 2 degrees? Probably but who's to say?

If you feel like you can give up some more of the torque from the bottom then maybe try an adjustable cam gear or one of the multi keyed crank gears. Wouldn't take long to install and it would give you further options if you liked the results, then you might try advancing the cam and test the results.

I helped a friend install an adjustable cam gear in a SBC, he was thrilled with the results but I was left un-impressed. The butt dyno didn't feel any differences, but I was thinking it would make a huge difference. It didn't.

Originally Posted by arock

I recycled this motor from my Hot Boat. Freshened it with some new parts and installed it in my 1973 Vega with built powerglide, 9" Ford spooled rear end and 8.5 certified cage.
I am running AFR heads, solid roller cam, girdles, dual 600 cfm carbs and MSD. Line lock and transbrake. I only run 10.5 to 1 compression so I can drive it on the street with pump gas. I have about 700 hp, which is more than enough in a 2000 lb car.
My question is: When I first fired it up, the headers turned cherry red in a matter of seconds. The cam was installed straight up. I retarded the cam 4 degrees and getted the hell out of the carbs. It now runs at 180 degrees in the garage for 30 minutes. That is where the cam was set while in the boat.
Does retarding the cam lower the compression? Cranking compression is 100 psi.

Compression in the cylinder does not begin until the intake valve closes, as the piston is coming back up the bore on the compression stroke. So, if the intake valve were closing at, for instance, 50 degrees after bottom dead center @0.050" tappet lift.........and you advanced the cam to close the intake valve at, for instance, 46 degrees after bottom dead center @0.050" tappet lift, then the cranking cylinder pressure should theoretically increase because less of the air fuel mixture that has just been forced into the cylinder by atmospheric pressure is being blown back out the "still open" intake valve by the ascending piston.

A cranking pressure of 100 psi would indicate to me that either the rings and/or valves are due for overhaul/replacement or the cam is much too large for the static compression ratio.......or both, making the motor a dog on the street. Crane Cams recommends a maximum 165 psi cranking pressure for use with pump gas and that's a long way from 100. I might expect 100 psi from a bone-stock flathead Ford, for instance.
http://www.vanpeltsales.com/FH_web/f...48_221-239.htm
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What you say makes a lot of sense when you brake it down step by step. The engine is a fresh complete overhaul. It was in my Hot Boat for a couple of years with a hyd. roller and ran great with an estimated 600 hp. It now has a 296/304 solid roller cam with .714 lift and 10.5:1 comp. ratio. Our pump gas in Cal is only 91. Maybe too much cam for this application. I an running AFR aluminum 335 heads with 112 chamber, Inconel valves, titanium retainers and stud girdles. Everything in the motor is first class. Calleys internally balanced crank, Manley rods, CP pistons and comp cam. New double roller timing set with no slop. I have an Edelbrock dual four intake with 2 600 cfm 1405 carbs that are jetted to hell.
The motor is in a Prostreet Vega Wagon with a build Powerglide, trans brake and 9" spooled Ford rearend. About 2000 lbs. I have about an hour of garage time on the motor now. I just put in the inner valve springs after cam break in.
What didn't make sense is on first install I lined up the dots on the timing set, (straight up) and did a minor check on cam timing. My bad for the short cut. Opened it up again and did a full degreeing process.
Cam card wants 22* BTDC @.050", I have multiple key ways on this timing set. No problem. But this setting shows 4* retard according to the timing set marks. Intake closes at 58* ABDC @.050". Dead on the cam card specs. There is no indication that my cam was ground with an advance in it. Seems like I am missing something. I have built 6 BBC in the last 15 years. All were Hot Boat motors that worked very well. I appreciate the advice.

My long reply did not show up. Took 15 minutes to write it.

Originally Posted by arock

My long reply did not show up. Took 15 minutes to write it.

HATE when that happens! And it's happened to all of us at one time or another. If I have a long detailed post that I want to do, I type it in the "Notepad" program ( any document program like Word etc. will work) and then copy it into here. Then if it gets lost it isn't so bad and easy to reinsert it. It isn't just here, I've had it happen on a few forums and not sure what happens... but it does happen.

Sorry for the frustration... try again?

Originally Posted by arock

My long reply did not show up. Took 15 minutes to write it.

I've had 'em blow out on me after an hours worth of writing. Makes me KILL mad.
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Okay, here goes.
I have all new parts in this rebuild of my Hot Boat motor. Except for the heads that have about 50 hours on them. They are AFR 335 rec ports with 112 chambers. 2.25" intakes and Inconel exhaust. I have Edelbrock dual 4 intake with two Edelbrock 1405 600 cfm's that are jetted very rich.
When I first installed my cam I lined up the dots for straight up. I did a short cut check on the cam timing. (my bad). Now I have degreed the cam properly with the intake set 22* BTDC @ .050", exactly what the cam card says and closing at 58* ABDC. I have a multi key timing set so that is easy but it says I am 4 degrees retarded. There is no indication that my Comp Cam has 4* built in to it. The solid roller Cam specs are 296/304 @ .020" lift. It has .714" gross lift both sides with 108 lobe separation. Maybe a little big for a 10.5:1 comp ratio. We only have 91 octane in Cal.
The boat had a 3* retarded hyd. roller cam. Ran great on 91 octane. I have built 5 BBC in the last 15 years with no problems, all boat motors. This 565 is in my Pro Street Vega with a built Powerglide, trans brake and a 4.88 Ford 9" spooled Diff. I run a 33" Hoosier slick. The car has run in the 9's with a small block.

Looks like the moderator is not approving my post yet. Maybe they will still show up.

Originally Posted by arock

Looks like the moderator is not approving my post yet. Maybe they will still show up.

If you included any links or pictures, your post gets held for moderator approval until you've got a history of no spam, something like 10 posts. Moderator approval may take a while.

From your original post, to me if your headers went cherry red in seconds it says that your timing was severely retarded, pushing unburned fuel into the exhaust which was lighting off just outside of the heads. I'd be more tempted to run the cam straight up, and then ensure that the ignition timing is set to be "all in" at around 3000rpm, and somewhere in the 10-12BTDC at idle. Are you 100% confident in your timing mark on the balancer being dead on TDC? Also, you don't say what your distributor is, other than that you're running an MSD unit. It sounds to me like by retarding your cam 4 degrees you've hosed your performance, and I doubt that you're really getting 700hp but that's just a gut feeling.

Just my $0.02, and welcome to the forum, BTW.

I have included no photos or links in my post. Only my short posts are appearing.
I run an MSD 7AL3 and the standard MSD induction dist. I run 33 degrees, all in. Been running this for 13 years on my 565's when in the 3500 boat. I had two different 565's. One was born as a 502. This one is a GM Bowtie Gen VI, built from scratch.
Until the motor is running correct, who knows what HP I have. When it is tuned properly I know what it can do. Ran 620 with the Smaller Hyd. Roller
in this motor. The HP doesn't matter in this application. It is way more than I need. This is a street legal Novelty Car that will go to the tack as much as I can.
I am over 70 and my racing years are limited. Going to keep it up as long as I can.

Last two post appeared then went away. Very frustrating site.