Forthose running compression in 13:1 or higher what cranking compression numbers are you getting. Yes I know intke closing has ton to do with it. Just investigating on a deal going on with a car I am helping at track and checking my thinking on it.

Also have ben to Wallace calculator. Found a discrepancy in it. Says to use seat to seat not .050 cam timing. Way off from actual results, but with .050 number almost dead on readings. So we an call it a K factor there.

Compression, cranking compression and if know intake closing point. Thanks guys.

I have a 15:1 582 and the cranking numbers are all 230 (cold), but I have a 16 volt system so it spins the engine pretty fast. When I first assembled the engine it was 205 across the board.

The Bullet cam is .805 / 287 intake, .798 / 298 exhaust (uses 1.75 T&D's), on a 112 center, it's in a 109*. The timing events @ .050 are 34.5 / 72.5 for the intake and 84 / 34 for the exhaust. This isn't a big cam, but it does work well and it's easy on parts/springs, etc.

No blue bottle, no power adder, gas

Hope this gives you some idea.

Bob

thanks for the info. Straight forward informative reply. Hey, they do exist here.LOL

Not to hijack WO231's thread but I'm wondering what you guys are getting for a cranking rpm....fyi, mine is 850

actually not derailing at all. Cranking spd has big effect on reading you will get.

The reason I am asking is because a car I am working on the gurus tell us we need 300 to 320. I see no way we can get here w/o playing with cam timing. We are at 260 with about 15 to 1 or so Owner think.

Kind of hoping some high compression guys would tell me thay are close to that area and maybe intake closing so I would confirm I am on right track about only way to get there or maybe I am wrong. Hell I am open,well wideopen to info.

i can guarantee you that 300 to 320 wil detonate,there is a reason most compression gauges stop at 300

My 565 pumped 250-260 and I played with valve lash to see if it would change and it did by a little

It cranked fine and started ok and ran very well.

Shelf grind cam....15-1

quote:

Originally posted by rusty:
i can guarantee you that 300 to 320 wil detonate,there is a reason most compression gauges stop at 300

Sorry but considering you only know the question is about cc and not what it is in or what the fuel is. Considering whom it is that told me and being as two very knowledgable men telling me the same thing. I will go with them. This is why I left details out and the question is about getting there more than rather or not advised to do or not. Guessing if I said running 70 degrees total timing reply would be same.Plus with this combo detonation is almost a built-in thing. Hell last 400 or 500 feet it is basically dieseling down track.

quote:

Originally posted by SCDIV1:
My 565 pumped 250-260 and I played with valve lash to see if it would change and it did by a little

It cranked fine and started ok and ran very well.

Shelf grind cam....15-1

About what we are getting now with Cam straight up. I figure 4 to 7 degrees will get us closer to the target. Doubt will get there totally even with that. Straight up intake closes at 71 ABDC and we have way too much piston to valve.

I once read that an engine will run the best with the highest pumping compression you can get by moving the cam around....

Never actually tried it

I also read over 230-240 was to high, cranking and that I did not believe was true...

I don't know how you could get to 300-320....never saw any engine even close to that high....

according to the calculator 290 possible with what we have and jerking cam around some. Bob Auto and Pete Jackson are two who have told us we needed to run. My guess is they have seen it or would not think it needed. We are not far off top guys.Well most weekends. Provided few folks do things differently. Another story.

Actually, new cam I had ground for fed had lot lower cc than I liked. Started advancing the cam and checking. Let's say made some stupid high advances. Got a lot higher cc. Did not set at the highest, wanted to. ended up 5 degrees and gained 40 psi cc. Closing intake early will make a big difference.

Not the same engine and just an example of how much it can affect cranking compression. Only 230 on Fed engine,then only 12:1. For while anyway.LOL If new bigger and higher pistons will get close to 300 I will let you know about detonation.Just set of bearing and some runs and truning with timing to find out.

Maybe just need to check when the barometric pressure is right.LMAO

I had one that was 250 one time and couldn't keep head gaskets in it. Changed the cam and lowered cranking compression. Naturally slowed it down, but the head gasket problems went away.

quote:

Originally posted by moparacer:
I had one that was 250 one time and couldn't keep head gaskets in it. Changed the cam and lowered cranking compression. Naturally slowed it down, but the head gasket problems went away.

Got to ask. If ever had gasket issue before. Anything else done between blown gasket and not having issue.. My knowledge of mopar stuff kind of limited to Hemi stuff.The real stuff and some late model Hemi in truck.

quote:

Originally posted by wideopen231:

quote:

Originally posted by moparacer:
I had one that was 250 one time and couldn't keep head gaskets in it. Changed the cam and lowered cranking compression. Naturally slowed it down, but the head gasket problems went away.

Got to ask. If ever had gasket issue before. Anything else done between blown gasket and not having issue.. My knowledge of mopar stuff kind of limited to Hemi stuff.The real stuff and some late model Hemi in truck.

It was a small block with 10 head bolts. Before the days of MLS gaskets. Felpro 1008's. Trying to make high compression work without being oringed. Cam change and and a drop in cranking compression fixed it.

Guess O-ring thing would be hige difference. Been so long since worked on race engine w/o them just do not think about them. Fuy how you become so accustomed to things. Heck do same thing when someone says they run alcohol automaitc hear injection. Noway just old habits.LOL

After a day of playing with clay, assembling top end half a dozen times. Everyone agreed to try my idea and add 6* advance to the cam. Not at 300 but 285 psi from 255. Well did dop .013 in the gasket too which should be about .5:1 which showed VDL on cc gauge but got to help us get back into 5.20's where we had c ar before pistons, rods and crank all got swapped around. Due to almost impossible to get parts in short order we had to resort to buying used parts and piecing togather another combo after broken crank. Long story short. 3.650 crank replaced with 3.600 and 6.880 rod replaced with 6.900 and pisaton.Hell I do not know yet.not laughing at all.

The reason I asked the original question was to see if anyone here had tried to get as high. Reason never said A/fuel combo(post also on inside top alcohol) was to aviod obvious replie's and just makes get idea if can get there easier.

The two very kn owledgeable men who said I need these numbers by the way are Pete Jackson and Bod Atto both very much up on this stuff.

Thanks for the replies as information. I am working on getting cc along with static compression way up on fed and if it beat bearing out I will have use for these 20 plus sets of rod-bearing top half's that I have. LOL.

quote:

The reason I asked the original question was to see if anyone here had tried to get as high. Reason never said A/fuel combo(post also on inside top alcohol) was to aviod obvious replie's and just makes get idea if can get there easier.

two us replied had tried and had head gasket issues,good luck

yea you had issues with bbc head gasket, Hemi has lot better clamping layout. This and bottom end is only reason Hemi has killed in all out assault on engine strength like top fuel. BBC would run with Hemi if it could just keep a crank in it.

This message has been edited. Last edited by: wideopen231,