EA3.0 says 389hp/359tq at the crank. Jeez, that cam is big. :lol: You might want to use a thin copper headgasket and shave the heads...feed that sucker all the compression you can get. It came out right on 8:1 dynamic with 11:1 compression, so you could run a lot more compression.

My math says that 9.8:1 would have been with a 4.100" gasket, .042" thick, 5cc dish, and .020" below deck? If that's the case, you can run an .020" gasket and get better quench and higher compression.

 

I am still only 9:1 because the piston is .053 in the hole. I wish it was more like 9:5 but Keith Craft did not suggest shaving the head for some reason. AFR says they flat mill them down to 54cc with no issue. Someone on another site brought up the fact that the piston being so far in the hole causes ping even with lower compression...I am going to ask the engine builder today. He never mentioned anything about that.

I didn't think of this cam as being big since it is only .500 lift normally but the 1.72 rocker raises that a good amount. It doesn't idle crazy but it has a nice consistant lope. pulls to 6k with no sign of weakness.

If I even made 350hp at the crank that would be awesome!!!

 

I am still only 9:1 because the piston is .053 in the hole.

Jeez, no wonder it pinged! That's something like .099" quench with a typical gasket! uke:

I'm no veteran engine builder, but I've seen a lot of motors run on pump gas when it seems like they shouldn't and all of them had tight quench and the right cam. An old school cam like yours doesn't make cylinder pressure worth a crap, so you can get away with a LOT of compression.

This is one of those situations where life starts at 10.5:1, to quote Fast & Furious. :lol: 11:1 would put you at 8:1 dynamic, which ought to run on 89 octane all day and 87 if you set up the dist. just right.

 

Blown head gasket into new AFR's? I like your thinking.

Notch your pistons? .538 lift + 2.02 intake valve?

Should be massive flow!

 

Honestly, if I were you I would tear that bottom end down and have the deck milled down so you can get those pistons flushed up with the deck. You will end up having the same problems you just had if you dont fix the cause of the issue which is your quench which is no where near optimal. At a minimum get a super thin, probably custom, head gasket made to tighten your quench.

My program has this motor making mid 360's at the crank and that is when things are optimal. With your quench as far off as it is I dont see this motor making 350hp at the crank; close though.

 

I talked with Wayne at Wayne Calvert Precision engines and he said the only difference it should make is compression. He did not think there would be a big issue with quench. None the less I am still considering having Keith Craft mill the heads from 58 to 55 or 56.

I guess I am not understanding what you mean by quench as opposed to compression ratio...

I am considering tearing the short block apart but I am sure it would run me another 1200 by the time it is said and done...not really wanting to spend all of that. In fact I didn't even think I was going to be doing the heads considering I am trying to close on my first house at the momment.

 

I talked with Wayne at Wayne Calvert Precision engines and he said the only difference it should make is compression. He did not think there would be a big issue with quench. None the less I am still considering having Keith Craft mill the heads from 58 to 55 or 56.

I guess I am not understanding what you mean by quench as opposed to compression ratio...

I am considering tearing the short block apart but I am sure it would run me another 1200 by the time it is said and done...not really wanting to spend all of that. In fact I didn't even think I was going to be doing the heads considering I am trying to close on my first house at the momment.

Sorry to say, but it might be time to stop talking to Wayne. If you do indeed have the pistons .053 down from the deck, something is not right. Yes it will make a difference in compression, but the gain from the tighter quench is golden. .040 normally accepted as good for a steel rod engine. Some go tighter, but have way more experiance in this. Gotstang is pretty much dead on, besides having the tighter quench to really push the mixture around, when it does come to a close collision it transfers some of the heat to the heads to be carried away by cooling system. I am not sure of the shop prices by you, but I don't think decking the block would cost $1200. but this brings up another question ... WHY are they .053 down?

Rusty

 

Quench is calculated by (h/g thickness) +/- (pistons in or out of deck). .040" to .045" is what most people think is best. I've had quench explained to me a few times and I'm not as good with it as I once was.

Google helped me out, this is pretty close to what I was taught:

The general feeling is that the total quench or squish distance should be about .040". The quench distance is the compressed thickness of the head gasket plus the deck clearance. The quench area is the flat part of the piston that would contact a similar part of the head if you had .000 assembled quench height. In a running engine, the .040 quench height decreases to a close collision between the piston and the cylinder head. The shock wave from the near collision drives air at high velocity through the combustion chamber. This movement tends to cool hot spots, averages the chamber temperature, reduces detonation and increases power. The shock wave also provides better fuel/air mixing, and this allows the fuel to ignite better and burn faster. A faster burning fuel charge means less timing is required for optimum power output.

There are a LOT of benefits to having near optimum quench...more power, more compression, and much less prone to pinging. Some of the big time builders seem to think that there is ~30hp left on the table in the average engine, and when it comes to quench, I believe them. OTOH, some of the other stuff that they suggest doing if you think "the devil's in the details" would probably add a good $1500 in just machine work bills...wee bit overkill for most folks if you ask me. :lol:

Pick out the right combo, get the quench right, and that's good enough, IMO; an engine built with those 3 things in mind will kick butt and run better on pump gas than an identical one just "bolted together". Then there are my two pet peeves: the right cam, and enough compression. Most big cams just flat out work better with high compression vs. low compression. You can build an 11:1 87 octane motor if you're careful, the folks "keeping it to 9.5:1 because it's a street motor" are loco.

You have a pretty friggin nice combo, I'd re-do the quench, up the compression, and roll wit it.

Jeez, I let my pet peeves go there...to be clear, no offense intended...after hanging out with an old school rodder who understands things like "cylinder pressure" and "quench", people who think 9.5:1 is for street motors drive me up the friggin wall, and they're all over the net. Not that anyone said anything like that here, it doesn't take much to get me going :lol:

 

Quench is calculated by (h/g thickness) +/- (pistons in or out of deck). .040" to .045" is what most people think is best. I've had quench explained to me a few times and I'm not as good with it as I once was.

Google helped me out, this is pretty close to what I was taught:

There are a LOT of benefits to having near optimum quench...more power, more compression, and much less prone to pinging. Some of the big time builders seem to think that there is ~30hp left on the table in the average engine, and when it comes to quench, I believe them. OTOH, some of the other stuff that they suggest doing if you think "the devil's in the details" would probably add a good $1500 in just machine work bills...wee bit overkill for most folks if you ask me. :lol:

Pick out the right combo, get the quench right, and that's good enough, IMO; an engine built with those 3 things in mind will kick butt and run better on pump gas than an identical one just "bolted together". Then there are my two pet peeves: the right cam, and enough compression. Most big cams just flat out work better with high compression vs. low compression. You can build an 11:1 87 octane motor if you're careful, the folks "keeping it to 9.5:1 because it's a street motor" are loco.

You have a pretty friggin nice combo, I'd re-do the quench, up the compression, and roll wit it.

Jeez, I let my pet peeves go there...to be clear, no offense intended...after hanging out with an old school rodder who understands things like "cylinder pressure" and "quench", people who think 9.5:1 is for street motors drive me up the friggin wall, and they're all over the net. Not that anyone said anything like that here, it doesn't take much to get me going :lol:

I agree completely..I would not want less than 10:1 with an aluminium headed motor..Closer to 11:1 would be even better..

 

Id say around 340-370 depending on the tune.

When you get it dyno'd stick it in the ford horsepower database!

 

WHY are they .053 down?

My guess is its the compression height of the piston...it wasn't matched to the deck height of the motor. Do you remember what pistons you are using? Part #?

Decking a block is usually $100-$200. Optimal quench is what everyone has said; .040"-.045". There is a spot in between that tends to produce pinging; .050"-.060". Then it gets better again but I don't think that .099" is a quench gap you want to be running. You've already obviously had detonation problems and damaged a set of heads because of it. I think that it is going to continue if you dont correct the problem which appears to be the quench.

 

But I don't think you can safely deck .053". it may need pistons.

Rusty

 

But I don't think you can safely deck .053". it may need pistons.

Rusty

That is very possible; its just a mismatch of parts that ended up being the worst of both worlds. A good machine shop will know whether or not he can deck the block that much. Getting a different set of pistons and then decking the block to .000" piston to deck clearance would be the proper way to fix the problem.

 

lol, had my window up for along time before I posted...didnt see frdnt's response about compression height. I agree with him to find another shop to have your work done at.

 

Did Wayne build the shortblock? That does not sound like something he would do. It seems like it would be OK, but not ideal. I would not sweat it. Just keep an eye on the plugs.

 

Yes Wayne built the short block and new I needed an affordable balanced rebuild, nothing fancy. I am no engine builder so I cannot comment on what another engine builder does but he has been there building race engines for 50+ years with a big following.


I also asked Keith Craft Racing and they did not seem to think there was much issue with this situation. I will see if I can talk to Keith himself tommorow. I am considering having them flat mill the heads to 55 or 56 from 58 to at least get 9:4 compression.

Trust me I do not want to put on $1500 heads and have another blown head gasket or issues from this situation but I also don't have another 1k+ dollars for this project. If I can have my short block gone through and decked at least to get it .02 or so maybe that would be affordable but it would include taking everything apart and at that point I might as well do better pistons...I just know how this goes as far as money...never ending.


I will have to keep thinking it over and see what I can come up with. I have about $800 more dollars that I feel comfortable allocating to this thing (yes I know do it right the first time, I don't want to screw this up by any means and I'm not trying to be cheap). I will have Gearheads or C&S (Keith craft in plano) dyno tune this car when it is done to make sure everything is set up right.
I am looking at an old bill from Wayne Calvert Precision Engines and he charged $887 to clean, bore block, polish crank, balance rotating assembly, assemble short block, and check piston to valve clearance. Not too bad...

I am also currently having my headers ceramic coated...pretty excited about that. I will be very happy if I can run solid 8.50's with my skinny street tires and make around 280whp+ but I know it will take careful consideration at this point in the process. Thanks for all of the insight so far. There is alot of bad advice to be had on the internet so I am always sceptical but I feel like what everyone has said so far is from experience!

 

Ok guys I was getting worried about all of this and so I decided to eleviate my questions.


I called John Kaase Racing...probably one of the most respected shops in the nation for Ford. He has won 4 Engine Master competitions or so. I talked to a very knowledgable guy there and he said they build engines with .060 in the hole pistons all of the time for racing. He said my .052 will be fine and not have any issues with quench. He also said what compression you run depends on what part of the country you are in. He said Dallas has little regulation in gas (knew that) and he would not run more than 10:1 here on a street motor. He said they used to build 11:1 aluminum headed street motors but do not recommend that any more. Apperantly going to 10:1 would only get me another 10-15hp on this small of an engine.

I do appreciate all that everyone has said but I must say that what John Kaase Racing said makes me fell better about the whole deal. I am still considering a forged piston at this point and having my shop check piston to valve if they do different pistons as opposed to doing it at home.

 

Don't change a thing. After a dyno tune at Keith Craft/C&S Performance, my 306 went from 285 rwhp to 315 rwhp and a jump in torque. That's about 375 at the crank and it is a wild ride to hang on to now! (Only dif in our motors is 1.6 roller rockers on mine.)

 

Cool Paul. I would be THRILLED with around 300rwhp in this little car. Nice to hear you run a similar combination.

 

OK guys I have probably bored you all to death by now but I am begining to think the quench distance is an issue like many of you stated. I did more research and both Keith black and Speed O motive have articles about this. I also talked to Coast High Performance and AFR and they both said something is not correct if my pistons are flat top and still .04 or .05 in the hole. I could be reading the gauge wrong but I don't think so because when they built the engine I asked him to measure what my compression would be. He said 9:7:3 with my 53cc heads. If the block was zero deck it would have been alot closer to 10:5:1. The piston is def. in the hole and .05 calculates to around 9:7 with 53cc chamber heads and .04 gasket. The pistons do however have small reliefs but this should make a huge change in volume.


I am going to speak with Calvert tommorow about this issue and see what they come up with. If it is indeed a .09 quench distance I have then I will have the block decked about .04-.05 and look into forged pistons with big valve reliefs for the 2.02 valves.

I was hoping to keep the additional work below $1k but this will slowly add up...I will need to change cams probably if the short block comes apart...plus $400+ for good pistons, +++++ Ugh...why can't I just be happy with 9:1 compression stock rebuild???

 

I am going to speak with Calvert tommorow about this issue and see what they come up with. If it is indeed a .09 quench distance I have then I will have the block decked about .04-.05 and look into forged pistons with big valve reliefs for the 2.02 valves.

DO NOT have the deck milled until you have bought your new pistons..A good performance piston will have a taller compression hieght than the ones you have now...In fact you may not need to have it milled at all which will help a little with the cost of going to new pistons..

Also when trying to measure the deck clearance it is very difficult to do it near the edge of the piston..The reason is the piston can rock a little in the bore(depending on clearance) and it will throw your measurements way off...You have to do it at the center of the piston and be sure the piston is at TDC(all the way up).

 

What are you using to measure?
Don't calculate backwards from a CR to find the piston height.
Can you post a picture of the gauge taking the measurement?

Rusty

 

What are you using to check piston to deck clearance? The only way to do it properly is with a bridge and a dial indicator. Its pretty tough to do it any other way.

 

I am using an ancient tool that was my great grandfathers. it is a flat thing...not very long and you turn the middle which runs perpendicular to the bridge and it lowers a small flat probe down. It is not big enough to spand from one side of the cylinder to the other so I measure the edge. I also put a feel gauge where the piston and cylinder wall meet and both seem to be about .04-.05. That being said I know it is not that accurate compared to a piston height dial indiscator.

This picture shows the engine when it was being put together. You can see it is down in the whole a bit...yes I realize this is only a picture and major engine building decisions can't be based on this but I thought it would help. I plan on pulling the short block regardless and having it looked at. I am now between a taller forged piston with deep reliefs for about $500 plus assembly, Decking the block in which case I would still need a piston with bigger reliefs, or buying $850 stroker assembly from CHP with forged pistons already balanced and including shipping and having it installed for $300...this would not include the cost to deck the block and check cylinders.

 

I might also add that I am in the middle of closing on my first house and saving for a ring for my g/f...

I am trying not to put thousands more into this engine since it should be pretty strong with the correct quench distance, AFR CNC 185's, and the current 4.11 gear setup to help it. I will probbaly also need to focus on buying a new wheel/tire combo for the back for grip, and eventually a 3k converter.

 

Blown head gasket/ possible cracked heads so I purchased new Keith Craft CNC ported AFR 185 heads. What type of performance/power should I expect now?

I am hoping for 350hp at engine and mid 8's 1/8 mile with street tires and low 8's with sticky tires? I know tires and a 3000 stall will help this in the future.

For reference with iron GT40's and 9:7 compression and 600 edelbrock I saw 222whp and 250tq

Well I'm new to the carb world but my 3300lb fox body ran a solid 8.7 with no traction and 1.9 60 foots with the following combo with plenty of room to achieve a better time to my poor driving skills and lack of traction.

5.0 explorer engine with stock iron GT40's
stock fuel injection setup
stock explorer gt40 intake
TFS stage one cam

It put down 236 to the rear wheels. AFR 185s are a hell of a lot bigger than GT40s. I wouldn't be shooting for 8's with an 185 headed combo, I'd be shooting for 7's instead.

 

You really need to measure the piston to deck height from the center of the piston, not the edges.

There are two ways you can go. Have a shop get an accurate piston to deck height measurement and see how much they can deck the block without getting into having to angle mill your heads and intake. You need to check out Cometic Custom Gaskets. They make custom gaskets. See how thin of a head gasket you can get away with. If it doesnt work then it doesnt work but it is probably worth a shot. On the other side you could probably find a nice set of hypereutectic pistons that would fit the bill for mid $200's. That may be cheaper in the long haul. You have no need for expensive forged pistons.

 

Here is the link to your pistons you posted on fordmuscle..
Federal Mogul Z273AP40 - Federal Mogul Cast Pistons - Overview - SummitRacing.com
It lists compression hieght at 1.585...My Tom Monroe book lists a 68-72 302 piston @ 1.600 with the piston .016 in the hole..Deck hieght is 8.206
If my math is correct that would put your pistons at .031 in the hole but this assumes your deck hieght is the same as what I listed and has never been touched..Are you sure its a 1968 block?

 

it will throw your measurements way off

Bingo :thumbsup:

 

Thanks for the continued support in this thread.


I am leaning toward a KB hypereutectic flat top 6.5cc piston, zero deck the block or close, and possibly resize rods with 11/32 ARP bolts. Then I should be stronger than the current setup without going crazy and breaking the bank.

I am thinking of having the machine work done and then giving it to a local ford shop to assemble the short block ($300) and put a head on to check PtV and get the correct pushrods. I also purchased a new Flow Kooler water pump to replace the GMB I just bought. The shaft has moved and wore a groove in the backing plate. ALso picked up an ARP hardered oil pump shaft, ARP header studs, and ARP valve cover studs. I already have ARP head and intake manifold bolts. I picked up my headers yesterday from Quality Powder Coating. They did a great job on high temp ceramic coating them!

I am hoping the setup I described above will net close to 10:1 static compression and around .042-.05 total quench distance and be safe to 6200 rpms. I am looking for 350 fwhp or so and I will make sure to have a good dyno tune done to adjust carb and timing ($250 from Gearheads in Arlington). I will eventually get a 2800-3000 converter to replace my 2100 and some sticky tires.


What do you all think for an 80% street and 20% strip car?