dandercam1

iTrader: (1)

Any engine guys have any input on running 2.30 intake valves in GM rectangle port heads (088 castings) on a NA 502. My hunch is that by reworking the chambers to un-shroud the valves and possibly adding a bore notch the 4.47 bore would be big enough to take advantage of the 2.30 valve. With a 454 block or without the extra grinder work I would just go with the 2.25 valve but would it be worth the extra effort or just a waste of time?

GPM

Isn't the exhaust flow the bigger problem with the 088 head.

MILD THUNDER

iTrader: (3)

Yes

dandercam1

iTrader: (1)

The exhaust side is something I have a little bit of experience with. I have never messed with the 088 casting before but I have done 2 sets of 990's and had 1 set of 188's professionally ported. The first set of 990's had 2.25 int. 1.88 ext. valves and went on a NA 461 in a pulling truck. The second set which I still have where done for a blown 468 street car project that never got finished (I had more fun boating) this set has 2.25 int. and I tried going with a 1.90 ext. valve knowing that any help on the exhaust side would be a big plus on a blower motor. I prepped the chambers the same way and did a simple port job to the extent of blending the seats in to the bowl smoothing any sharp corners in the bowl area, streamlining the guide boss, smoothing out the short turn, opening the top of the port mouth to the gasket line and polishing everything with 80 grit. Both sets where flow tested and the 1.90 valve showed very little advantage over the 1.88. The only other options on the exhaust side would be a 1.94 ext. valve or pro. port work. After seeing very little change in flow from going to the 1.90 valve I doubt the 1.94 would help much either. As I mentioned I did have a set of 188's pro. ported with significantly better results using 1.88 ext. valves but by the time they where done I could have saved myself a few hundred bucks by going with a new set of AFR's

I have never tried a 2.30 intake valve in a GM casting and was wondering if anyone had, or anyone willing to share there thoughts or opinion would be of interest too. After all interesting discussion is what these boards are all about

Rookie

iTrader: (4)

I should be out to the shop this week and if I remember I will ask JimV. I know he tries to put 2.30"-2.35" in most of his heads. But, I don't remember ever seeing a 2.30" in any 088/188 GM heads.

Budman II

iTrader: (1)

I think this may be the answer to your question. Aftermarket heads with a raised exhaust port offer exhaust flow that the stock ports could never match, plus you have the advantage of a better combustion chamber design.

dandercam1

iTrader: (1)

If all out power was my goal than no doubt the AFR's would be the way to go. That set of 188's taught me a lesson on where "being on a budget" can take you. The reason I went with the 188's is because I had them and I couldn't bring my self to shell out the $2600 or so for the AFR's so I ended up with a $2800 set of 188's more weight and less power. All I can say is live and learn on that one.

I'm looking to build a set of 502's in the 550-580hp range and I think the 088's prepped by me the way I have done in the past will get me there. The AFR's could put 502's in the area of 625hp but that might leave me with a pile of busted bravo 1's also.........well maybe just a bigger pile of busted bravo 1's than with the 088's

dandercam1

iTrader: (1)

I still may be better off going with aftermarket heads..........I do have a hookup on RHS heads $900 a set for Iron $1200 a set for alum. bare castings. Also keep in mind my existing GM rectangle port heads on my 502's have only about 25 hrs. on them since new so selling them would get me about half way to RHS iron castings............. Anybody running RHS heads?

Cobra100+

iTrader: (3)

I love my AFRs. Do it right the first time and you will end up money ahead

Young Performance

I have a set of 088's here that have 2.300 valves in them. I didn't do it nor do I know who did. I pulled them off of an engine and they are just sitting upstairs collecting dust. I haven't flowed them so I have no idea if it helped or hurt. The only thing I can say is that it can be done. However, I don't know that it would be worth it. If you are only looking for 550+, then there is no reason to worry about it. If your castings already have a 2.250, then leave that alone and just clean up the throat and the bowls a little and let it rip. If you have 2.19 valves now, you may want to go to 2.250.
Eddie