performance and porting BBC heads 702's
Thread Starter
1st Gear
Joined: Apr 2008
Posts: 1
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performance and porting BBC heads 702's
I just picked up a set of 3872702 heads on Ebay (pictures below), and was wondering if anyone could give me any suggestions -- I am planning on running these on a 402 and will probably end up in the range of 9.5 - 10.0 compression.
1. Would it be worth it to install 2.19/1.88 valves? And go with a 3 angle valve job? Will the difference be noticable?
2. Are these good heads? I know they're not suitable for racing, but will they provide decent upper end power ?
3. Should I take them and have them tanked before I do some port work? Or just do all of my porting first, then take them to get cleaned and machined?
Any other suggestions will be greatly appreciated-- have never ported or rebuilt a set of heads before.
Thanks
1. Would it be worth it to install 2.19/1.88 valves? And go with a 3 angle valve job? Will the difference be noticable?
2. Are these good heads? I know they're not suitable for racing, but will they provide decent upper end power ?
3. Should I take them and have them tanked before I do some port work? Or just do all of my porting first, then take them to get cleaned and machined?
Any other suggestions will be greatly appreciated-- have never ported or rebuilt a set of heads before.
Thanks
Team Owner
Joined: Oct 2004
Posts: 81,242
Likes: 3,061
From: altered state
St. Jude Donor '05
If you can do your own porting it may be worth it.
I usually have heads cleaned before I start porting. They can be done a little dirty but you dont want to breathe that stuff and clog up your bits....Porting cast iron takes LOTS of patience. Where protective eye gear and a good respirator.
Have them magnafluxed for cracks, too. Once porting is done then take them in for valve job, machining etc .
I usually have heads cleaned before I start porting. They can be done a little dirty but you dont want to breathe that stuff and clog up your bits....Porting cast iron takes LOTS of patience. Where protective eye gear and a good respirator.
Have them magnafluxed for cracks, too. Once porting is done then take them in for valve job, machining etc .
Le Mans Master
Joined: Oct 2000
Posts: 7,831
Likes: 5
From: Austin TX
I
1. Would it be worth it to install 2.19/1.88 valves? And go with a 3 angle valve job? Will the difference be noticable?
2. Are these good heads? I know they're not suitable for racing, but will they provide decent upper end power ?
3. Should I take them and have them tanked before I do some port work? Or just do all of my porting first, then take them to get cleaned and machined?
1. Would it be worth it to install 2.19/1.88 valves? And go with a 3 angle valve job? Will the difference be noticable?
2. Are these good heads? I know they're not suitable for racing, but will they provide decent upper end power ?
3. Should I take them and have them tanked before I do some port work? Or just do all of my porting first, then take them to get cleaned and machined?
2) They don't flow quite as well as something like an open chamber 049 or 781 but the bump in compression compared to the open chamber heads makes them pretty nice.
3) I agree with everything cuisinartvette says. They won't need a whole lot of porting - they will probably be fine for a 402 with a simple cleanup.
