[88stang419]

I'm new to racing so this question might sound dumb, i have a 419W, dart bolck,12:1 comp, out of the box AFR 205 heads with 58 cc chambers, super victor intake, 1050 custom dominator, a set of MAC 1 3/4 long tube headers with 3 in collectors, the cars best to date 1/8 mile was 6.38 at 105.6 with a 1.41 60 foot, the motor is new with about 13 1/8 mile passes on it. I just recently changed heads to TFS R's fully cnc'd flow 347 at 700, with 2.10 titanium intake and 1.60 titanium exhaust, psi triple springs, and a set of kooks 1 7/8 headers with 3 1/2 in collectors, new heads are 65 cc chambers, just went back to the track and et is off by a tenth and it dropped 1.5 mph best 60 ft with new set up is 1.44, could this be from the compression loss from the higher cc combustion chamber, I thought bigger heads and exhaust would equate to more power. any help would be appreciated.

 

[Jim Monson]

Moved from General tech. Can someone help?

 

[T-flow]

What cam? Have you ported the intake? With that much CI. and those heads, they will want some air.... What size carb? If you have a small roller, than there is your problem. But it's all the induction system that's going to need to get along. T-flow

 

[88stang419]

The intake is a fully ported super victor and cam is same from old set up, and it is a small roller, carb-custom 1050 dominator, and the intake is still port matched to the old AFR heads, im going to take it off and port match them but i thought it would still run better even without them port matched. but i guess i was wrong.
cam dur at .50 252 260
lobe lift .392 .397
valve lift .627 .635

 

[Vader Ta]

I suspect it is a combo of things. You sacraficed compression which will drop horsepower,you went up in header size which will cut down on your low end torque and you upped your cylinder head which will make the motor lazy down low. I would suspect you are in need of a camshaft change with more duration and possibly a rear gear change.JMOP

 

[grocerygetter]

i had same problem happen with my 438w went from dart 225s that flowed 312.9 to a 245 highport that flowed 344 and my car lost a tenth or more,well i found out my chambers werent the same cc so i milled the highports and got the compression the same the car then ran about the same times but 60 was alittle soft,i then dropped the tire size alittle and let the car go thru the traps alittle more rpm and the car went 1 tenth faster than the darts,to make use of your heads you might need the compression back and more cam so you can spin the motor higher

 

[88stang419]

do you guys think it would be better to go back to the old combo or have another cam ground to my new head specs, i plan on spraying this motor so i figured the TFS R's bigger intake and exhaust ports would help me out better when i sprayed,more so than the old AFR's would.

 

[grocerygetter]

do you guys think it would be better to go back to the old combo or have another cam ground to my new head specs, i plan on spraying this motor so i figured the TFS R's bigger intake and exhaust ports would help me out better when i sprayed,more so than the old AFR's would.

that is your decission im not a nos guy hate filling a bottle but if you like motor better, then you might look into cam ,compression bigger stall and more gear,if you want to spray it and dont mind running slower on the motor well them leave it,me i drive mine and had different outlook mine wasnt just race i have no trailer and cant go much more compression being as im on pumpgas and if the heads didnt work not much i could do,i got lucky and hardly any change worked i went from 9.77 to 9.67 with first highports then my new head took me into the 9.50s.
have you tried tunning it at all to see if it wants something different then before

 

[Slow 69 SS]

The intake is a fully ported super victor and cam is same from old set up, and it is a small roller, carb-custom 1050 dominator, and the intake is still port matched to the old AFR heads, im going to take it off and port match them but i thought it would still run better even without them port matched. but i guess i was wrong.
cam dur at .50 252 260
lobe lift .392 .397
valve lift .627 .635

That is not NEARLY enough cam.

 

[88stang419]

what size cam roughly should i be running with this set up???

 

[fastlx]

Your R heads are flowing more cfm but at wath lift they coulb be flowing the same up to ,600 where your cam stops yuo probably need more rpm from this combo & bigger cam !! let see wath the expert say..

 

[Jsup]

I'm new to racing so this question might sound dumb, i have a 419W, dart bolck,12:1 comp, out of the box AFR 205 heads with 58 cc chambers, super victor intake, 1050 custom dominator, a set of MAC 1 3/4 long tube headers with 3 in collectors, the cars best to date 1/8 mile was 6.38 at 105.6 with a 1.41 60 foot, the motor is new with about 13 1/8 mile passes on it. I just recently changed heads to TFS R's fully cnc'd flow 347 at 700, with 2.10 titanium intake and 1.60 titanium exhaust, psi triple springs, and a set of kooks 1 7/8 headers with 3 1/2 in collectors, new heads are 65 cc chambers, just went back to the track and et is off by a tenth and it dropped 1.5 mph best 60 ft with new set up is 1.44, could this be from the compression loss from the higher cc combustion chamber, I thought bigger heads and exhaust would equate to more power. any help would be appreciated.

Don't put a lot of emphisis on exhaust flow. I can show you 1000 HP motors that flow under 250 on the exhaust.

There's a lot to heads, flow numbers don't mean as much as people give them credit for. Hell, Reher Morrison took 30 CFM out of a head and picked up power.

Read anything written by Curtis and don't get hung up in they hype. Because thre's a lot of hype out there.

 

[buschracing]

loss of compression, a cam that is totally mismatched for the induction, and probably a converter and gear that are too conservative. all these things can add up to a performance loss when you go to a bigger induction. there is a misconception that if you put on a set of heads that flow more you will automatically go faster, with the same gear and converter and often less compression than the old heads. i see it all too often.

to make those heads really work you need about .720-.750 net lift (you have plenty of valve spring for it), 3/8 pushrods (TFS sells the guideplates), and more compression if you arent worried about running pump gas, like around 13.5 or so. Flat mill the heads .060" and make sure you check piston to valve clearance with the new cam. I hope you have R head specific pistons. For motor only, put a 6000 stall 8" in it with a 4.30 gear.

 

[T-flow]

Yes, Cam and the intake needs to be ported right. The CS need to be opened up and the plenum needs to be done up..... just to port match the exit to the head is not going to cut it, there is gain's to be made in the plenum.

 

[buschracing]

oh yea, and how about fuel? i hope you didnt use racing gas. since your compression is probably down to 11.0 now, you can run pump gas, 100 oct pump gas, or a 50/50 mix of 93 and Sunoco purple racing fuel. putting a high octane racing fuel in there will slow the car down.

 

[revolutionary]

loss of compression, a cam that is totally mismatched for the induction, and probably a converter and gear that are too conservative. all these things can add up to a performance loss when you go to a bigger induction. there is a misconception that if you put on a set of heads that flow more you will automatically go faster, with the same gear and converter and often less compression than the old heads. i see it all too often.

to make those heads really work you need about .720-.750 net lift (you have plenty of valve spring for it), 3/8 pushrods (TFS sells the guideplates), and more compression if you arent worried about running pump gas, like around 13.5 or so. Flat mill the heads .060" and make sure you check piston to valve clearance with the new cam. I hope you have R head specific pistons. For motor only, put a 6000 stall 8" in it with a 4.30 gear.

Same response here.

For a cam I'd probably look at something in the 270/278 @ .050 range and a tight lsa to help with compression.

 

[RAM Racing Heads]

Well I disagree with alot of ya. Compression comes first, you HAVE to have it. Since you dont have it you sure as hell dont want to put a bigger camshaft in it. If the engiine has no static then you need to use a cam with a tighter lsa maybe 106But if you can get the compression back then it would help to put a larger cam in 276/284. But also if you are trying to run the engine in the same power range you did the other combo, thats gonna be the culprit there. With the larger runners, you are going to have to turn it more rpm. Depennding on the manifold it could probably use a going thru also. cfm is meaningless in this scenerio so dont worry about that. You just need to have the rest of the puzzle to work with the cross section of your heads....First off Compression.

The people who talk about flow and cfm most times are waisting their time worrying about an item that is meaningless. Only thing that matters in the head is the proper Cross sectional area in the smallest part of the port (pushrod area) and the largest part of the port (Over the turn) port shape and profile. I have killed ports by 45 cfm and it ET'd better. Gotta be the right size and the right shape.

Rich