Need Great HEAD advice (509) MAG
 

Okay... So i have a 01 Baja H2x with 502 mag that has been Freshened up with srp blower pistons and scat rods. 8.50.1 Now a 509 with a ASM502 comp cam. It previously had a m1 on 6.5lbs and i would turn a 26 pitch prop about 5,250 with 4 people in boat and loaded on fuel with stock heads. Which according to my speedo (NON GPS) said about 74mph at 6,000ft elevation. I recently got bored... Sold blower bought a M3 put it on and first trip out blew head gasket with it at 5lbs. I tore motor down. Put in Pro comp 320cc aluminum heads, and a 28 pitch prop. I went out and tuned it. Boat said 70mph with two people in it and half tank fuel on 5lbs. at 4,450ft elevation Turning the new 28 pitch about 4,850rpms roughly. So i'm like hum... More boost... Order smaller pulley tune it... See 8lbs. Then i see 68mph... and about 4,750rpm... So at half throttle plained out not really building boost i see 60mph. From half to full throttle i only get 8 to 9mph lucky to see 10mph. So my thinking is that these pro comp heads suck ass... and possibly seeing valve float... I did compression check on every cylinder and i see 95lbs of pressure accross every one of em. Which is very low... I did research and heard that these heads are coming from china and have been known for quality control issues. SO here are the ones i'm thinking of getting... What do you guys think? And if anything else comes to mind or opinions i'm all ears!

http://www.adperformance.com/index.p...oducts_id=1003

I can get these same heads from my buddy who is afr dealer with hydrolic lifter springs, inconel valves and heads milled down to raise my comp. Which i'm wondering if i should do. Its 8.5 thinking of milling to raise to 9.25 because of elevation here. all for 2,300.00 bucks!

Thoughts????

Thanks!!!!

do a leak down and see why compression is so low and where its going

Yeah... I will! It's about 5 degrees here with a foot of snow on the ground now. So i don't think i'll be playing jack frost anytime soon. But after doing a lot of research i hear it's very common with these heads. My buddy ran him in his dragged out big block s-10 and had same issue... Took heads off and to machine shop had them go through em. But long store i'm sure it's not piston rings or the new mls head gaskets i put on. But i guess you never know... And the engine looked great when pulling off old heads. Like i said engine is fresh with low hrs. So anyone one running these AFR heads? Good? You think 225cc or 235cc for my build?

First you need a GPS speedo. You can even use an I phone with a speed app, I do. Second, 95 psi is low. You should be 110+. When you installed new heads did you size the pushrods corectly? It almsot sounds like you are not getting full valve lift.

AFR heads are great but before you spend $ I would try and figure out what is going on currently.

Wannabe

I'm runnin the AFR 357 cnc heads on my 572s with 8.5 comp ratio 8-71s and mild rollers they make 820hp and 900 ft. lbs all in by 5600 rpm sized correctly they make great power the 325 or 335 cnc would probably be good

make sure you upgrade to inconnel exhaust valves with forced induction, hard coating would add some insurance as well

fixx
 

1 procomp heads suck..cc them and you willsee,all the chambers are going to be off by at leaste 10 cc's..look into a set of afr's 305 heads,,also sounds like your cam is blowing all the boost out the exhaust..they like stock cams,fogducker ran a stock 385 hp cam on his 454 efi and his boat ran 87 mph,,did 67 before that..

Yeah... It's a must to have them valves in marine use. But thanks for advice on heads. I think i'm going the 2101-1 I'm sold!

Yeah... I have that app. Actually on my phone aswell. Used it to tune computer to set speedo when did gear change on my camaro. I compaired it to two other cars and it's like within 1mph. They're pretty accurate. Just never really used it on lake but was always thinking about trying it. I just might have to this summer. Also... I used a pushrod length checker before ordering push rods. That way valve geometry was on. Far as compression check. It was done with rockers off and on. It made no difference!

Really? that big a difference with cam huh. I know i guess the specs on that cam on lift is like 600 intake and 620 exhaust. But the motor in the boat had the same cam with m1 on 6.5lbs with stock head and ran faster. Then Pro comps on m3 with 8lbs. All i changed was blower and heads. But now i am curious what it would done with different cam anyway.